Presentation type:
PS – Planetary & Solar System Sciences

EGU24-2888 | Orals | MAL29-PS | David Bates Medal Lecture

Deciphering Mars’ water cycle with missions and models 

Montmessin Franck

My presentation will cover the present and recent configurations of Mars’ water cycle. The Martian water is only visible in two forms: gas and ice. The existence of a water cycle on Mars was deduced from the first seasonal monitoring of water vapor performed by the Viking mission in 1982. It revealed that the same seasonal and spatial pattern repeated itself for nearly two consecutive Martian years. After Viking, other missions have confirmed this initial conclusion: seasonal water vapor variations appear to be controlled by exchanges between various reservoirs, achieving an annual stationary state with some inter-annual differences. These variations are primarily influenced by the seasonal evolution of the climate in the north polar region, as the latter hosts the most massive reservoir of water, consisting of an ice cap of more than 2 million km3. When exposed to sunlight in spring and summer, this cap releases a massive amount of water vapor that then spreads across the Martian globe, only to return to the North Pole the following winter in the form of frost. Decades of theoretical and observational exploration have delivered a nearly comprehensive view of Mars’ water cycle. From the water molecules that leave the cap in summer to the hydrogen atoms that escape Martian gravity and get lost in space; I will show how the Mars missions and the 3D models used to simulate Mars’ climate have laid the foundations for our understanding of the main processes that govern the evolution of water on Mars.

How to cite: Franck, M.: Deciphering Mars’ water cycle with missions and models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2888, https://doi.org/10.5194/egusphere-egu24-2888, 2024.

EGU24-4012 | ECS | Orals | MAL29-PS | PS Division Outstanding Early Career Scientist Award Lecture

Hyperspectral mapping of a kilometer of mantle rock core: insight into active serpentinization systems  

Lucia Mandon, Bethany L. Ehlmann, Rebecca N. Greenberger, Eric T. Ellison, Lisa E. Mayhew, and Alexis S. Templeton and the Oman Drilling Project Science Team

Serpentinization is one of the major processes of silicate alteration in the solar system. Associated reactions are drivers for redox disequilibria and sources of H2, which are favorable to habitability. Minerals formed are responsible for crustal density and magnetization changes, and a significant amount of water can be sequestered. Released gases are expected to affect climate and have been proposed as potentially responsible for warming early Mars [1]. However, depending on protolith and geochemical conditions, a diversity of mineral assemblages exist, and the full spectrum of serpentinization is not well understood. In addition, some products are not well characterized, reducing our ability to assess serpentinization in the solar system.

The Oman Drilling Project [2] is a multi-national collaboration to characterize the Samail ophiolite in Oman, which consists of altered oceanic crust. About 3.2 km of core were recovered and characterized with bulk rock and vein description, thin section photos, rock chemistry and mineralogy, microbial cell abundance, and borehole water properties, performed at regular intervals [2]. In addition, rock cores were analyzed using a hyperspectral imager covering the 0.4–2.6 µm range at a submillimeter spatial resolution (Fig. 1; [2]), allowing fine-scale characterization of the whole cores (as opposed to specific depth intervals), with tracking of most minerals of interest, hydration and Fe redox – of particular interest in understanding the fate of Fe in serpentinized systems and production of H2. This spectroscopy technique is also widely used in planetary exploration to assess composition of surfaces (e.g., [3]); collection of spectra of materials present in the cores will aid in the detection and characterization of serpentinization on Earth, Mars, asteroids and ocean worlds.

Our ongoing study builds on previous hyperspectral analysis of the gabbroic section [4, 5], and focuses on the mantle section, some of which may be actively weathering. We will present our approach to automatically map minerals, hydration and serpentine redox on ~1 km of core from three boreholes, allowing us to investigate how these parameters vary with depth (e.g., what is the extent of carbonation and hydration in the oceanic crust/mantle?) and with variables that influence serpentinization processes (e.g., rock chemistry, faults, biology or fluid chemistry). This approach allows us to better understand serpentinization processes and products and their impacts on planetary crusts.

 

 

Figure 1. Spectral mapping of a portion of the Oman mantle core at a depth of 370 m (left: color composite from data in the visible; right: classification based on SWIR data). 

 

[1] Ramirez et al. (2014), Nat. Geo. 7(1)

[2] Kelemen et al. (2020), Proceedings of the Oman Drilling Project

[3] Carter et al. (2023), Icarus 389

[4] Greenberger et al. (2021), JGR: Solid Earth 126(8)

[5] Crotteau et al. (2021), JGR: Solid Earth 126(11)

How to cite: Mandon, L., Ehlmann, B. L., Greenberger, R. N., Ellison, E. T., Mayhew, L. E., and Templeton, A. S. and the Oman Drilling Project Science Team: Hyperspectral mapping of a kilometer of mantle rock core: insight into active serpentinization systems , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4012, https://doi.org/10.5194/egusphere-egu24-4012, 2024.

PS1 – Terrestrial planets

EGU24-142 | Posters virtual | PS1.1

Astronomy from the Moon: From Exoplanets to Cosmology in Visible Light 

Jean Schneider

I look at what astronomy from the Moon might be like in the visible over the next few decades.
The Moon offers the possibility of installing large telescopes or interferometers with instruments larger than those on orbiting telescopes. I first present examples of ambitious science cases, in particular ideas that cannot be implemented from Earth. I discuss also the issues which I telescope will encounter underlunar conditions. After a general review of observational approaches, from photometry to high contrast and high angular resolution imaging, I propose as a first step a 1-metre-class precursor and explore what science can be done with it.

How to cite: Schneider, J.: Astronomy from the Moon: From Exoplanets to Cosmology in Visible Light, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-142, https://doi.org/10.5194/egusphere-egu24-142, 2024.

EGU24-292 | ECS | Posters on site | PS1.1

Fusion of IIRS and M3 data for the purpouse of finer resolution mineral mapping 

Iskren Ivanov and Lachezar Filchev

Hyperspectral images, despite their rich spectral information, often suffer from low spatial resolution due to physical constraints in imaging sensors. However, when higher spatial resolution data of the same scene are available, we can perform data fusion to generate hyperspectral images with high spatial resolution. This fused data can be viewed as the output of a synthetic sensor that combines the high spatial and spectral resolution data acquired by different sensors. This fusion allows for new applications with increased accuracy, such as high-resolution mapping of minerals and surface materials. Imaging spectroscopy facilitates the identification and discrimination of materials and their constituents. Data fusion enhances both the spatial and spectral characteristics of the initial data. It is based on the synergistic exploitation of data from different sources, aiming to produce superior results. By integrating data from The Moon Mineralogy Mapper (M3) by NASA and the Imaging Infrared Spectrometer (IIRS) by ISRO, we can improve the spatial and spectral resolutions, enhance measurement accuracy, and reduce uncertainties. This will enable a more precise assessment of the mineral composition of the area of interest. The objective is to fuse high spatial resolution data, which has discontinuities in the spectral domain, with low spatial resolution data that has continuous spectra. The ultimate goal is to estimate an image with high spatial and spectral content, providing a more comprehensive and accurate understanding of the area of interest. We replaced the noisy bands in the M3 and IIRS data and used cubic convolution to resample the M3 bands to the IIRS band’s native spatial resolution. However, the M3 bandwidth is different from the IIRS bandwidths. Nevertheless, this gap-filling procedure will allow us to identify endmembers. As a followup study we are going to employ a spectral unmixing technique to obtain endmembers information and high-resolution abundance matrices from the initial images. Data fusion helps overcome the limitations of individual datasets, exploit the strengths of different sensors, and extract more valuable information.

How to cite: Ivanov, I. and Filchev, L.: Fusion of IIRS and M3 data for the purpouse of finer resolution mineral mapping, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-292, https://doi.org/10.5194/egusphere-egu24-292, 2024.

EGU24-1216 | ECS | Orals | PS1.1 | Highlight

Lunar Impact Flashes and their Resultant Craters  

Daniel Sheward, Chrysa Avdellidou, Anthony Cook, and Marco Delbo

Impact craters have been identified on almost every type of celestial body, and are among the most destructive processes. The lunar surface is covered in craters ranging from 2500km in diameter, down to sub-millimetre scale, and >600 lunar impact flash (LIF) events have been observed by ground based telescopes, detecting the generated light. Despite this large volume of data, previously only three freshly formed craters had been both located within LROC imagery, and have the forming LIF documented.
Using PyNAPLE (Sheward et al., 2022) - software which locates fresh craters from the selenographic latitude, longitude, and epoch of a LIF - a search was performed upon the 22 most energetic LIFs within literature. For completeness, this included the three LIF events with already identified craters.

There were sufficient LROC images to locate six new freshly formed craters, in addition to the three already identified. For these nine events, the likely parent meteoroid stream for each event is identified to constrain the velocity, impact geometry, and impactor properties. From this, the pre-impact kinetic energy could be obtained from an estimation for the luminous efficiency, and the luminous energy released by the LIF.

Furthermore, using the crater scaling laws from Melosh (1989), both the predicted crater size from the kinetic energy, and the predicted energy from the observed crater size, could be calculated for each event.

From this, it was found that the predicted crater diameter was consistently larger than the observed crater. While there are several factors that could contribute to this, the single most likely factor is the poorly constrained luminous efficiency. Under this assumption, a more accurate value for the luminous efficiency can be calculated using the observed craters. Using a rearrangement of the crater scaling laws, with the kinetic energy equation, and luminous efficiency, η = Elum/Ekwhere Elum is the energy released by the LIF, and Ekis the kinetic energy. After outlier removal and meteoroid stream identification, this produces an average value of η=0.0171324. While this is slightly larger than the typically used values of between 102and 104, the difference is not drastic.

References

Melosh, H. J. (1989). Impact cratering : a geologic process.
Sheward, D. et al (2022). MNRAS, 514(3):4320–4328

How to cite: Sheward, D., Avdellidou, C., Cook, A., and Delbo, M.: Lunar Impact Flashes and their Resultant Craters , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1216, https://doi.org/10.5194/egusphere-egu24-1216, 2024.

EGU24-1694 | ECS | Posters on site | PS1.1

Newly Discovered Shallow Moonquakes: General Characteristics and Source Parameters 

Keisuke Onodera

Seismic observation is a powerful tool to investigate the Earth’s geological activities and internal structure and has also been applied to the Moon and Mars [e.g., Latham et al., 1969; Banerdt et al., 2020]. For the Moon, a seismic network was constructed on the nearside during the Apollo missions, and nearly eight years of observation provided us with more than 13,000 seismic events [Nakamura et al., 1981]. These events have contributed to understanding the seismicity rate on the Moon and its internal structure [e.g., Garcia et al., 2019; Nunn et al., 2020], both of which are important to know the current geological activity level and trace back to the thermal evolution in the past.

In the Apollo lunar seismic observation, two types of seismometers were installed: Long-Period (LP) and Short-Period (SP) seismometers. While the LP sensor has sensitivity at 0.2 – 1.5 Hz, the SP is sensitive at 1 – 10 Hz [e.g., Nunn et al., 2020]. In previous studies, the LP data were mainly used. In fact, all the cataloged events were detected solely using the LP data [Nakamura et al., 1981]. On the other hand, because of numerous unnatural signals and/or spikey noises, the majority of SP data remained unanalyzed after the initial description of high-frequency quakes by Duennebier and Sutton (1974a, 1974b) [e.g., Frohlich and Nakamura, 2006; Knapmeyer-Endrun and Hammer, 2015]. This fact implies that there are potential seismic events only identifiable in the SP data, and the lunar seismicity might be underestimated.

Lately, Onodera (2023) denoised all the SP data and performed an automatic event detection. As a result, he discovered about 22,000 new seismic events, including thermally driven quakes (thermal moonquakes), impact-induced events, and tectonic-related quakes (shallow moonquakes). While the former two types are useful to understand the surface evolution or degradation processes, the latter type is closely related to the seismic activity level of the Moon. Here, I focus on shallow moonquakes. In the past, since only 28 shallow moonquakes were identified, it was difficult to give a detailed description of their source mechanism, regionality, and correlation with tidal force. In this study, using the newly discovered 46 shallow moonquakes, I’m trying to give new insights into this type of event.

In the presentation, I will describe the general characteristics of newly discovered shallow moonquakes (e.g., waveforms and spectral features) and summarize the estimated source parameters (such as energy release, seismic moment, and body wave magnitude).

 

References

  • Banerdt et al. (2020), Nat. Geosci., 13(3), 183-189.
  • Duennebier and Sutton (1974a), JGR, 79(29), 4365-4374.
  • Duennebier and Sutton (1974b), JGR, 79(29), 4351-4363.
  • Frohlich and Nakamura (2006), Icarus, 185(1), 21-28.
  • Garcia et al. (2019), Space Sci. Rev., 215(8), 50.
  • Knapmeyer-Endrun and Hammer (2015), JGR Planets, 120 (10), 1620-1645.
  • Latham et al. (1969), Science, 165(3890), 241-250.
  • Nakamura et al. (1981), UTIG Technical Report, No. 118.
  • Nunn et al. (2020), Space Sci. Rev., 216(5), 89.
  • Onodera (2023), ESSOAr, DOI: 22541/essoar.169841663.38914436/v1

How to cite: Onodera, K.: Newly Discovered Shallow Moonquakes: General Characteristics and Source Parameters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1694, https://doi.org/10.5194/egusphere-egu24-1694, 2024.

As an important physical property of the Moon, the lunar crustal density provides evidence for the early evolution process of the Moon, such as the asymmetry of its nearside and farside. The apparent density is the average value of the bulk density at a certain depth. The gravity inversion method is an effective tool of determining the apparent density distribution of the lunar crust. Benefiting from the lunar GRAIL mission's high-precision gravity field models, it is theoretically possible to establish a global high-resolution apparent density model through the gravity inversion. However, there are two major problems, namely, the accuracy and efficiency of the inversion. To solve these problems, different from the admittance methods, we develop a high-precision apparent density mapping method in the spherical coordinate. The improved 2D Gauss-Legende formula and adaptive subdivision algorithm are adopted to calculate the high-precision gravity anomalies of the Tesseroid cells. The parallel algorithm based on OpenMP is involved to improve the calculation efficiency of the global data. And the Cordell iterative algorithm is utilized to derive the apparent density model fitting the real gravity anomalies. The synthetic data tests verify the accuracy and efficiency of our method. Subsequently, we use LOLA topographic data to correct the gravity anomalies obtained from GRAIL and derive the global lunar Bouguer gravity anomalies. The lunar crust thickness model given by Wieczorek et al (2013) is chosen as the bottom interface of the density layer. As a result, we obtain a global high-resolution lunar crust apparent density model with a resolution of about 20 km by the presented mapping method. Our model shows that the apparent density of the lunar crust ranges from about 2200 - 2900 kg/m3 with a mean value of about 2600 kg/m3. The Procellarum KREEP Terrane (PKT) and the large impact basins present higher apparent density, while the Feldspathic Highlands Terrane (FHT) varies around the mean apparent density, and there is a significant variation within the South Pole-Aiken Basin Terrane (SPAT). Our apparent density distribution around the PKT and FHT is significantly relevant to the surface grain density model derived from the current FeO and TiO2 abundance map. However, our apparent density distribution around the SPAT differs from the surface grain density, suggesting a more complex density structure in this region.

How to cite: Yang, J. and Guo, L.: The apparent density distribution of the lunar crust revealed by the spherical coordinate-based mapping method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3166, https://doi.org/10.5194/egusphere-egu24-3166, 2024.

Water plays a crucial role in the Moon's evolution and holds significant implications for potential human activities on its surface. Previous studies, based on measurements of a limited number of lunar soil particles, have revealed evidence supporting various sources of lunar water, including its origin from the lunar interior, solar wind implantation, and impacts from comets or asteroids. Nevertheless, the limitation of these studies stems from the restricted number of particle samples, hindering the achievement of adequate statistical significance. As a result, the primary source of water on the Moon remains enigmatic. To address this critical question and advance our understanding of lunar water sources, we initiated new spectral measurements using lunar bulk soil collected by Chang'e-5 under controlled conditions. We observed variations in water content across different particle sizes. Our findings suggest that solar/ Earth wind implantation is likely the primary source of lunar surface water. The controlled experiments conducted on the lunar bulk soil samples provide valuable insights, offering statistical evidence for the origin of water in lunar soil. We also bridged the laboratory, in-situ, and orbital results, offering a cohesive understanding of lunar surface water characteristics as represented by Chang'e-5.

How to cite: Lin, H.: Primary Origin of Lunar Surface Water: Constraints from Observations of Chang'e-5, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3294, https://doi.org/10.5194/egusphere-egu24-3294, 2024.

EGU24-4876 | Orals | PS1.1

Lunar zircon from the Chang’e-5 landing site 

Qin Zhou, Chunlai Li, Jianjun Liu, Weibin Wen, Yu Liu, Saihong Yang, Qiu-Li Li, Guangliang Zhang, Hongbo Zhang, Bin Liu, and Dawei Liu

Zircon is one of the most important U-bearing minerals in the lunar geochronological studies. Since the first lunar zircon grains were analyzed in the early 1980’s, the majority of lunar zircon U(Pb)-Pb ages obtained from the Apollo missions in the last decades were distributed between about 4.4 and 3.9 Ga. Although the crystallization age of Chang’e-5 (CE-5) basalts were obtained from baddeleyite, zirconolite and tranquillityite, we attempted to search for lunar zircon grains from the collected CE-5 lunar sample for comparison with the previous studies. We scanned almost all polished sections of the CE-5 powder sample to identify lunar zircon grains, most of which are isolated grains or mineral clast in agglutinates and impact melt breccias. In our study, only one zircon grain was preserved in the lithic clast of CE-5 basalts after the scanning of hundreds polished sections. This zircon records a precise Pb-Pb isochron age of 2036 ± 19 Ma, which is the youngest crystallization age ever reported for lunar zircon geochronology. Combined with the petrology, mineralogy and geochronology, we have demonstrated that this zircon grain is the extreme fractional product from a non-KREEP mantle source similar to CE-5 basalt. Compared to the zircon from Apollo mission, the sampling site of CE-5 provides a new case that lunar zircon can crystallize from a variety of magmatic compositions in addition to KREEP-related magma. In the future, we plan to perform the studies of zircon grains from CE-5 samples in different lithologies and try to find the origin of these zircons grains.

How to cite: Zhou, Q., Li, C., Liu, J., Wen, W., Liu, Y., Yang, S., Li, Q.-L., Zhang, G., Zhang, H., Liu, B., and Liu, D.: Lunar zircon from the Chang’e-5 landing site, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4876, https://doi.org/10.5194/egusphere-egu24-4876, 2024.

EGU24-4978 | ECS | Posters on site | PS1.1

Three-dimensional MHD simulation of lunar induced magnetic field generated by lunar metallic core 

Siqi Yi, Xiaojun Xu, Lianghai Xie, Xing Wang, Qi Xu, Zilu Zhou, Hengyan Man, Lei Luo, Peishan He, and Pu Yang

Comprehending the internal structure of the Moon is crucial for uncovering its formation and evolution. The existence of the lunar core can be proved by several pieces of evidence, including electromagnetic sounding analyses, mass and moment of inertia analyses, and seismic analyses. However, the precise size and composition of the lunar core are still unknown. In this study, the induced magnetic field generated by the lunar metallic core is illustrated through a three-dimensional MHD simulation. Several cases have been discussed in which the lunar core are set with different electrical conductivities and thicknesses. Compared to the hybrid model, our MHD model can calculate more accurate results with a more refined grid. Our simulation can capture the variations of parameters (plasma densities, temperature, and flow speed) in original and final conditions, while the hybrid model cannot.

How to cite: Yi, S., Xu, X., Xie, L., Wang, X., Xu, Q., Zhou, Z., Man, H., Luo, L., He, P., and Yang, P.: Three-dimensional MHD simulation of lunar induced magnetic field generated by lunar metallic core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4978, https://doi.org/10.5194/egusphere-egu24-4978, 2024.

EGU24-6314 | Orals | PS1.1 | Highlight

LUMIO: a CubseSat to detect meteoroid impacts on the lunar farside 

Fabio Ferrari, Francesco Topputo, Carmine Buonagura, Carmine Giordano, Paolo Panicucci, Felice Piccolo, Antonio Rizza, Angelo Cervone, Detlef Koschny, Eleonora Ammannito, Richard Moissl, and Roger Walker

A large number of meteoroids and micrometeoroids enter the Earth–Moon system continuously, constituting a potential threat to our planet. Lunar meteoroid impacts have caused in the past a substantial change in the lunar surface and its properties. With no atmospheric shield, the Moon is subject to a large number of impacts from meteoroids, typically ranging from a few tens of grams to a few kilograms every day. The high impact rate on the lunar surface has important implications for future human and robotic assets that will inhabit the Moon for significant periods of time. Therefore, a better understanding of the meteoroid population in the cislunar environment is required for future exploration of the Moon. Moreover, refining current meteoroid models is of paramount importance for many applications, including planetary science investigations. For instance, since meteoroids may travel dispersed along the orbit of their parent body, understanding meteoroids and associated phenomena can be valuable for the study of asteroids and comets themselves, and their dynamical paths. Studying meteoroid impacts can help deepening the understanding of the spatial distribution of near-Earth objects in the Solar System. The study of dust particles is also relevant to the topic of space weather. The ability to predict impacts is therefore critical to many applications, both related to engineering aspects of space exploration, and to more scientific investigations regarding evolutional processes in the Solar System. Also, accurate impact flux models would be crucial to support planetary defense actions, as large meteoroids can cause severe damage to our communities.

In this context, the Lunar Meteoroid Impacts Observer (LUMIO) is a CubeSat mission to observe, quantify, and characterise lunar meteoroid impacts, by detecting their impact flashes on the far-side of the Moon. This complements the information available from Earth-based observatories, which are bounded to the lunar near-side, with the goal of synthesising a global recognition of the lunar meteoroid environment. LUMIO envisages a 12U CubeSat form-factor placed in a halo orbit at Earth-Moon L2. The detections are performed using the LUMIO-Cam, an optical instrument capable of detecting light flashes in the visible spectrum (450-950 nm). LUMIO has successfully passed Phases A and B and is currently moving towards Phase C.

We present the latest results on the modelling of the meteoroid environment in the Earth-Moon system, including an estimate of LUMIO’s potential impact on our existing knowledge of meteoroids, supported by high-fidelity simulation data. An overview of the present-day LUMIO CubeSat design is also given, with a focus on the latest developments involving both the ongoing/planned scientific activities and the development of the payload.

How to cite: Ferrari, F., Topputo, F., Buonagura, C., Giordano, C., Panicucci, P., Piccolo, F., Rizza, A., Cervone, A., Koschny, D., Ammannito, E., Moissl, R., and Walker, R.: LUMIO: a CubseSat to detect meteoroid impacts on the lunar farside, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6314, https://doi.org/10.5194/egusphere-egu24-6314, 2024.

EGU24-6905 | Orals | PS1.1

The Variability of Lunar Mare Basalt Properties Inferred from Present-Day Surface Rock Abundance 

Catherine Elder, Rebecca Ghent, James Haber, Paul Hayne, Gareth Morgan, Mark Robinson, Matt Siegler, and Jean-Pierre Williams

The surface rock abundance map derived from the Lunar Reconnaissance Orbiter (LRO) Diviner Lunar Radiometer Experiment (Diviner) revealed variability in the rock abundance across the surface of the lunar maria [1]. Rocks on the lunar surface break down quickly relative to lunar geologic history [2, 3], so surface rock abundance is likely to be strongly tied to subsurface rock content which could include both coherent layers of mare basalts or large boulders mixed in with regolith. Most of the Moon’s surface is now covered in fine grained regolith, and historically various authors have argued that each surface unit started as a flat coherent layer of rock which gradually broke down into a layer of regolith whose thickness is a function of its bombardment history [e.g. 4, 5]. However, recently Head and Wilson (2020) [6] argued that modern understanding of lunar volcanism suggests substantial variability in post eruption surface conditions (e.g. void space, pyroclastic deposits, etc.) which could affect subsequent regolith development possibly leading to surfaces of the same age having regolith layers of different thicknesses and/or suspended rock populations. We compare the Diviner rock abundance [1] in different maria units defined and dated by Hiesinger et al. (2011) [7] to investigate both the change in surface rock abundance with time, and possible regional variability in rock properties [8]. We find that surface rock abundance does decrease with unit age as expected for a thickening layer of regolith. However, there is significant scatter in this relationship. We calculate the best-fit linear relationship between the median rock abundance and age of the units defined by Hiesinger et al. (2011) [7]. Investigation of the residuals of this fit reveals that they are not random. For example, Mare Australe is similar in age to Mare Tranquillitatis, but nearly all units in Mare Tranquillitatis are rockier than those in Mare Australe. Mare Humorum is notable for being one of the rockiest regions in the maria despite its relatively ancient surface (>3 Ga). These observations support the hypothesis of Head and Wilson (2020) [6], and suggest that further investigation into the properties of present-day surface rocks may provide insight into the initial mare basalts before billions of years of communition. Specifically, future in situ missions across diverse mare locations could offer insights into the variability of basaltic eruption styles that may have formed the lunar maria.

 

[1] Bandfield+ (2011), JGR, 116, E00H02.

[2] Basilevsky+ (2013), PSS, 89, 118.

[3] Ghent+ (2014) Geology, 42, 1059.

[4] McKay+ (1991) Lunar Sourcebook, Cambridge Press, 285.

[5] Hörz (1977), PCE, 10, 3.

[6] Head+ (2020) GRL, 47.

[7] Hiesinger+ (2011), GSA Special Papers, 477.

[8] Elder+ (2023) PSJ, 4:244.

How to cite: Elder, C., Ghent, R., Haber, J., Hayne, P., Morgan, G., Robinson, M., Siegler, M., and Williams, J.-P.: The Variability of Lunar Mare Basalt Properties Inferred from Present-Day Surface Rock Abundance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6905, https://doi.org/10.5194/egusphere-egu24-6905, 2024.

EGU24-8297 | ECS | Posters on site | PS1.1

Relating deep moonquake source regions from Apollo missions with their temporal and spatial patterns using machine learning 

Josipa Majstorović, Philippe Lognonné, Taichi Kawamura, and Mark Panning

NASA selected a new in-situ seismic experiment, Farside Seismic Suite (FSS), onboard CP-12 lander with the landing site at the farside of the Moon in Schrödinger Basin. This future mission should provide us with the data to further constrain lunar interior and the Moon seismicity. Due to the single-station nature of the mission, localisation of the newly detected events will be challenging. Therefore, in this study we develop a pipeline for the deep moonquake (DMQ) source region localisation on the legacy of the data acquired during the Apollo missions. We are interested into DMQs since their source regions, called nests, on the near side have been identified, and since their occurrence patterns follow specific spatial and temporal patterns. Spatial patterns are related to tsp=ts-tp travel time measurement. We can show that based on tsp measurements we can form group of nests, called sets, that share similar travel times within error bars and therefore we cannot distinguish between nests that belong to the same set just using the travel time information. Temporal patterns are related to the fact that occurrence of DMQs is closely related to the monthly motion of the Moon around the Earth. Different nests correspond differently to three lunar months: synodic, draconic, anomalistic. By combining the spatial and temporal patterns we try to characterise different nests and exploit this information for their prediction. For this purpose we develop a machine learning model for nets classification. An input data into model we use orbital parameters related to the monthly motion of the Moon around Earth, which we relate to different nests. The ML model is learned to classify between nests that belong to the sam set. We report that models are achieving an accuracy over 70% when those are trained to classify =< 4 nests within the set, and better than 90% when only two DMQ nests are in the same set. This approach opens up a new way to DMQ location estimate, on the near and farside of the Moon, when captured by the future FSS single-station seismometers or other seismic stations on the Moon. 

How to cite: Majstorović, J., Lognonné, P., Kawamura, T., and Panning, M.: Relating deep moonquake source regions from Apollo missions with their temporal and spatial patterns using machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8297, https://doi.org/10.5194/egusphere-egu24-8297, 2024.

EGU24-8305 | ECS | Posters on site | PS1.1

Love numbers for an Andrade planet 

Anastasia Consorzi, Daniele Melini, Juan Luis Gonzáles-Santander, and Giorgio Spada

The Andrade rheological law ε(t)=ε0+βtα has been introduced by Andrade in 1910 for the description of elongation in metal wires. Since then, this model has gained increasing popularity in geophysics and planetary sciences, being extremely effective in the description of numerous materials, including polycrystalline ices, amorphous solids and silicate rocks. Recently, many works in the field of planetology have adopted this model for the description of the response of solar system or extra-solar planets to tidal perturbations, especially for bodies whose properties are still poorly constrained. This is because the Andrade rheology can describe transient deformation using a low number of parameters, a highly valued characteristic for the study of planetary bodies for which few observational constraints are available, such as exoplanets. For the Moon, the Andrade rheology provides an accurate description of the viscoelastic tidal deformation, satisfying the observed frequency dependence of the quality factor.

While for uniform bodies described by a steady-state Maxwell rheology the analytical form of the time-dependent Love numbers (LNs) was established long ago, in the case of the transient Andrade model no closed-form solutions have been determined so far. This is mainly due to the fact that the planetary response is normally studied in the Fourier-transformed frequency domain or by numerical methods in the time domain. Closed-form expressions could be important since they have the potential of providing insight into the dependence of LNs upon the model parameters and the viscoelastic relaxation time-scales of the planet.

In this work, we focus on the Andrade rheological law in 1-D and we obtain a previously unknown explicit expression, in the time domain, for the relaxation modulus in terms of the Mittag-Leffler function Eα,β(z), a higher transcendental function that generalises the exponential function. Second, we consider the general response of a uniform, incompressible planetary model - the “Kelvin sphere” - studying the Laplace-transformed, the frequency domain and the time-domain LNs by analytical methods. By exploiting the results obtained in the 1-D case, we establish closed-form expressions of the time domain LNs and we discuss the frequency-domain response of the Kelvin sphere with Andrade rheology analytically.

Our findings exhibit a complex relation between the planet parameters and the resulting deformation. From the analysis of the frequency-dependent LNs we show that dissipation in Earth-like planets is strongly dependent upon the choice of the planet density, rigidity and viscosity, while the variation of the Andrade creep parameter α has an effect that is limited to short-period tidal forcing. Concurrently, the study of the time dependent LNs shows that α regulates the duration of the transient phase, while the remaining parameters set the value of elastic limit, and the rate at which  the fluid limit is reached. Finally, some examples concerning the tidal deformations of the Moon are presented to point out the relevance that the Andrade rheology assumes in this particular case.

How to cite: Consorzi, A., Melini, D., Gonzáles-Santander, J. L., and Spada, G.: Love numbers for an Andrade planet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8305, https://doi.org/10.5194/egusphere-egu24-8305, 2024.

EGU24-8916 | ECS | Orals | PS1.1

In-situ sample handling and chemical analysis of lunar regolith by laser ablation ionisation mass spectrometry 

Peter Keresztes Schmidt, Nikita J. Boeren, Salome Gruchola, Marek Tulej, Andreas Riedo, and Peter Wurz

With NASA's emphasis on lunar exploration through the Artemis program, novel scientific objectives have been formulated to enhance our understanding of the Solar System's historical context, particularly the evolution of the Earth-Moon system. Simultaneously, the establishment of a permanent human presence on the Moon is proposed as a primary objective within the Artemis program, with the achievement of this goal hinging on in-situ resource utilization (ISRU) of lunar materials. Effective ISRU needs methodologies for chemical analysis and selecting appropriate lunar materials in-situ. To facilitate these tasks, the deployment of sensitive instrumentation capable of determining the element and isotope composition of lunar materials is imperative.

In this contribution, we present the current progress in developing a reflectron-type time-of-flight laser ablation ionisation mass spectrometer (RTOF-LIMS) to allow for direct sensitive chemical microanalysis of lunar regolith grains in-situ on the lunar surface. This LIMS system will operate in the lunar south pole region on a CLPS mission within NASA’s Artemis program.

The contribution will provide a general overview of the instrument and focus primarily on the design and operations of the sample handling system (SHS). Furthermore, we will discuss the results of experiments conducted on lunar regolith simulant. These experiments were performed using a prototype LIMS system to validate the feasibility of the SHS. This prototype system has capabilities representative of the flight instrument currently in development regarding the mass analyser and optical sub-system. The laboratory and flight optical sub-systems are based on a microchip Nd:YAG laser system (~ 1.5 ns pulse width, λ = 532 nm, 100 Hz laser pulse repetition rate, laser irradiance ~ 1 GW/cm2), and custom-made laser optics to achieve a focal spot on the sample surface of ~20 μm. Consequently, the conducted measurements can serve as a qualification baseline for the flight instrument during ground-based tests.

(1) P. Keresztes Schmidt et al., Sample handling concept for in-situ lunar regolith analysis by laser-based mass spectrometry, IEEE Aerospace Conference, 2024, submitted
(2) P. Wurz et al., In Situ Lunar Regolith Analysis by Laser-Based Mass Spectrometry, IEEE Aerospace Conference, 2023, 1-10
(3) P. Keresztes Schmidt, A. Riedo, P. Wurz, Chimia 2022, 76, 257
(4) A. Riedo, A. Bieler, M. Neuland, M. Tulej and P. Wurz, J. Mass Spectrom., 2013, 48, 1-15
(5) P. Wurz, M. Tulej, A. Riedo, V. Grimaudo, R. Lukmanov, and N. Thomas, IEEE Aerospace Conference, 2021, 50100, 1-15.

How to cite: Keresztes Schmidt, P., Boeren, N. J., Gruchola, S., Tulej, M., Riedo, A., and Wurz, P.: In-situ sample handling and chemical analysis of lunar regolith by laser ablation ionisation mass spectrometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8916, https://doi.org/10.5194/egusphere-egu24-8916, 2024.

EGU24-9849 | ECS | Posters on site | PS1.1

The NEPOS Project: Near-Surface Seismic Exploration of Planetary Bodies with Adaptive Networks 

Sabrina Keil, Heiner Igel, Felix Bernauer, Dmitriy Shutin, Ban-Sok Shin, Kai Nierula, Philipp Reiss, Rok Sesko, and Fabian Lindner

Ground motion observations on planetary objects are a prerequisite for a detailed understanding of their interior structure and evolution. The imaging of the near surface structure - in particular on the Moon - has strong practical implications. First, the race is on to detect ice-bearing rocks near the surface from which water could be extracted and used as a resource for crewed missions. Second, due to the substantial bombardment of the lunar surface with meteorites and the lack of an atmosphere, observatories or habitats may have to be built underground. It has been proposed that cavities from ancient lava flows below the lunar surface could be used to place infrastructure. Current mission plans for geophysical exploration focus on static seismic sensors/arrays that would be restricted to the area they can explore.      
With the NEPOS project we want to go beyond these restrictions and develop concepts for mobile seismic arrays that work in an autonomous way using robotic technology. The scientific challenges include the understanding of wavefield effects of icy rocks and caves in a strongly scattering environment, the provision of optimal source-receiver configurations to detect them, as well as an integrated data-processing workflow from observation to subsurface image including the quantification of uncertainties.   
In order to solve these challenges, we first developed a Digital Twin for wave propagation in the strongly heterogeneous lunar crust to generate synthetic seismic data using the spectral element code SALVUS. We compared the synthetic seismograms to data from the Apollo 17 Lunar Seismic Profiling Experiment (LPSE) and find that their main characteristics coincide. We further generated synthetic seismograms for a variety of network configurations and subsurface heterogeneities, which will be used to test appropriate imaging methods for the lunar subsurface structure. Due to the presence of strongly scattering media ambient noise tomography seems to be a promising method, as was already shown in previous studies. We apply seismic interferometry to LPSE data, as well as to our synthetic seismograms, to reconstruct Green’s functions, which give us information on the subsurface properties.

How to cite: Keil, S., Igel, H., Bernauer, F., Shutin, D., Shin, B.-S., Nierula, K., Reiss, P., Sesko, R., and Lindner, F.: The NEPOS Project: Near-Surface Seismic Exploration of Planetary Bodies with Adaptive Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9849, https://doi.org/10.5194/egusphere-egu24-9849, 2024.

EGU24-10730 | Posters on site | PS1.1 | Highlight

Mare Tranquilitatis Hole - a habitable place for a first lunar settlement 

Werner Grandl

Space stations on the lunar surface are exposed to cosmic rays, solar flares, micrometeorites and huge temperature variations. Therefore human outposts on the lunar surface have to be covered by huge layers of regolith. In 2009 the Japanese lunar orbiter SELENE (Selenological and Engineering Explorer) has detected three giant lunar holes: Mare Tranquilitatis Hole (MTH), Marius Hills Hole and Mare Ingenii Hole. The holes differ from normal impact craters and may be the entrances to underground lave tubes. The deepest one is MTH with 107 m and 98 x 84 m in diameter. According to Haruyama et al. the soil of lunar holes could contain water resources (protons from solar-wind hydrogen flux or even water molecules). Lunar holes reduce the effects of cosmic rays because of their limited field of view from the bottom. They provide also milder temperatures than the lunar surface. In the shadowed areas the temperature  ranges from -20°C to +30°C during the lunar day. These benefits make lunar holes become favourite locations to establish initial lunar stations. In a first step we propose to build an initial base on the lunar surface at the edge of MTH. It can be used for storage and as a "site hut" for astronauts to supervise the following work. In a second step the initial base is enlarged by a modular structure down to the bottom of MTH. Robotic and semi-robotic machinery is used to erect the modular structures. Lunar regolith is used for protection against cosmic rays and meteorites (ISRU In Situ Resource Utilization). Finally MTH could be  closed by a transparent dome and filled with air to create a "green" habitat for human settlers.

 

How to cite: Grandl, W.: Mare Tranquilitatis Hole - a habitable place for a first lunar settlement, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10730, https://doi.org/10.5194/egusphere-egu24-10730, 2024.

EGU24-12084 | Posters on site | PS1.1

How do training sets influence crater and boulder detection in machine learning? 

Urs Mall, Yehor Surkov, and Peter Cadogan

The surfaces of planetary bodies reflect their evolution through primary surface shaping via their continuous evolvement over time. Surface formation and degradation processes need to be understood in detail to infer the timescales over which these processes operate.

Planetary surfaces which are heavily cratered offer the opportunity to investigate various aspects of the cratering processes which are initiated when an impactor strikes their surface and ejects rock fragments from the impact point upon the newly-formed crater cavity and its surroundings (e.g. Hörz, F. and Cintala, M., 1997). Among the ejecta material from the impact are boulders covering a wide range of sizes (e.g. Nagori,R. et al., 2024). Dependent on the planet’s environment and the size of the impact fragments, these boulders can form either secondary craters or simply become subject to the various environmental forces which ultimately add through different degradation processes to the formation of planetary regolith. To understand many of the aspects of the above processes, size distributions of both the impact-generated boulders and secondary craters need to be understood (e.g. Cadogan, P., 2024).

As many of the techniques to identify boulders and small craters on albedo images are using shadow-based identification methods one has to be aware that ambiguities can arise through complex topographies and overlapping surface features. These factors can modify the shape of the shadow and make the identification of its borders difficult, thereby preventing a precise determination of both it’s location and it’s radius.

To obtaining high-quality statistics for boulders and craters over large and varied planetary surfaces, machine learning and deep learning methods have been applied to automate the tedious human based detection work (e.g. DeLatte, D. et al, 2019). However, little attention has been paid to investigate the influence of the training sets on the success rates of these efforts (Mall, U. et al., 2023). We are investigating in this study the influence of crater training sets, originating from specifically chosen lunar areas on the resulting confusion matrices produced by specific convolution neural networks and compare these with the results found from traditional imaging methods.

Cadogan, P., (2024), Automated precision counting of small lunar craters - A broader view, Icarus, Volume 408, 2024,115796.

DeLatte, D.M., Crites, S.T., Guttenberg, N., Yairi, T. (2019), Automated crater detection algorithms from a machine learning perspective in the convolutional neural network era, Advances in Space Research, Volume 64, Issue 8, Pages 1615-1628.

Hörz, F. and Cintala, M. (1997), The Barringer Award Address Presented 1996 July 25, Berlin, Germany: Impact experiments related to the evolution of planetary regoliths. Meteoritics & Planetary Science, 32: 179-209. https://doi.org/10.1111/j.1945-5100.1997.tb01259.x.

Mall, U., Kloskowski, D., Laserstein, P., (2023), Artificial intelligence in remote sensing geomorphology—a critical study, Front. Astron. Space Sci., 30 November 2023, Sec. Planetary Science , Volume 10 – 2. https://doi.org/10.3389/fspas.2023.1176325.

Nagori,R., Dagar, A. K., Rajasekhar, R.P., (2024),  Age estimation and boulder population analysis of the West crater at Apollo 11 landing site using Orbiter High Resolution Camera on board Chandrayaan-2 mission, Planetary and Space Science, Volume 240, 2024, 105828.

How to cite: Mall, U., Surkov, Y., and Cadogan, P.: How do training sets influence crater and boulder detection in machine learning?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12084, https://doi.org/10.5194/egusphere-egu24-12084, 2024.

EGU24-13507 | Orals | PS1.1

The DIMPLE Experiment to Date Ina, a Young-Looking Volcanic Structure on the Moon 

F. Scott Anderson, Edward B. Bierhaus, Sarah E. Braden, Amy L. Fagan, Rico G. Fausch, James W. Head III, Katherine H. Joy, Jonathan Levine, Steve Osterman, John Pernet-Fisher, Romain Tartèse, Peter Wurz, and Marcella Yant

            The DIMPLE (Dating an Irregular Mare Patch with a Lunar Explorer) experiment has been selected by NASA for flight to the Moon later this decade. The objective is to date volcanic rocks from Ina, the largest known (3×2 km) irregular mare patch. Ina is remarkable for its scarcity of impact craters; taken at face value, the crater density implies a surface model age of 33 ± 2 Ma [1]. If the Moon was volcanically active this recently, it would require a profound reassessment of our understanding thermal evolution of the lunar interior. An alternative explanation for the anomalously low crater density posits that Ina is a chilled magmatic foam [2], the vesicularity of which favors crumbling rather than cratering during meteoroid impacts. If vesicularity can make a ~3000 Ma old terrane appear to be 100× younger, it begs the question of what other surface age estimates based on crater density, from anywhere in the inner Solar System, can also be wildly inaccurate.  

            The DIMPLE payload includes (i) the CODEX (Chemistry, Organics, and Dating Experiment) instrument, (ii) a sample-handling system including an arm for gripping rocks off the lunar surface, and (iii) a rover-mounted rake for collecting rock samples from farther afield. CODEX works by analyzing hundreds of 35 μm spots over rock samples 1.9-3.8 cm across, using laser-ablation mass spectrometry to measure the abundances of major elements and some trace elements, and using laser-ablation resonance-ionization mass spectrometry to measure the isotopic abundances of Rb and Sr. In this lunar context, the organics capability of CODEX will not be exploited.  The mass spectrometer for CODEX is a re-flight of the mass spectrometer designed for the Luna-Resurs mission, with an optimized ion source to collect resonantly excited ions in addition to ions produced directly by laser ablation. CODEX data will enable dating by the 87Rb-87Sr isochron technique and, by mapping elemental composition, will permit lithologic classification and petrologic interpretation of the analyzed rock samples from Ina.

 

References:        [1] Braden S.E. et al. (2014) Nature Geoscience 7, 787.

                             [2] Qiao L. et al. (2021) Planet. Sci. J. 2 66.

How to cite: Anderson, F. S., Bierhaus, E. B., Braden, S. E., Fagan, A. L., Fausch, R. G., Head III, J. W., Joy, K. H., Levine, J., Osterman, S., Pernet-Fisher, J., Tartèse, R., Wurz, P., and Yant, M.: The DIMPLE Experiment to Date Ina, a Young-Looking Volcanic Structure on the Moon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13507, https://doi.org/10.5194/egusphere-egu24-13507, 2024.

EGU24-14455 | ECS | Posters on site | PS1.1

Origin of pentlandite in Chang’e-5 lunar soils revealed by transmission electron microscopy 

Xu Tang, Lixin Gu, Hengci Tian, Qiuli Li, and Jinhua Li

Sulfides are common minerals in lunar rocks and have great implications for lunar magma origin and subsequent evolution. Pentlandite as an important sulfide, usually coexisted with troilite, which could indicate the geological thermal history of lunar rocks. Previous researchers proposed three potential mechanisms to explain the origin of pentlandite in lunar soil: (i) the reaction between mobilized sulfur and metallic FeNi, ilmenite and an Fe-bearing silicate; (ii) it is formed by the reaction between migrating Ni and troilite; (iii) pentlandite may exsolve from the Ni-rich troilite during the cooling of rocks. Here, we used the scanning electron microscopy (SEM), X-Ray electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM) to decipher the formation mechanisms of pentlandite in Chang’e-5 (CE-5) lunar soils. Our results show that pentlandites occurred as lamella and veinlets in troilites from basalts and breccias, forming a troilite-pentlandite assemblage. Crystallographic data from TEM provide the first robust evidence that pentlandites from both basalts and breccias were exsolved from the host troilite during the magma cooling, rather than formed by the reaction between mobilized sulfur and metallic FeNi, or mobilized Ni with troilite. Furthermore, we found taenite was exsolved from pentlandite in lunar breccia, forming a troilite-pentlandite-taenite assemblage. Given exclusively exsolved taenite and higher Ni content in troilite in breccia than that in basalts, it suggests the origin of pentlandite in breccia may involve a geological process involving the addition of exotic meteorite materials. Finally, we established two atom shuffling models to describe the transformation mechanism from troilite to pentlandite, and pentlandite to taenite. This work provides new insights into the origin and geological evolution of lunar sulfides, and also provides new method for the study of mineral evolution in other extraterrestrial samples.

How to cite: Tang, X., Gu, L., Tian, H., Li, Q., and Li, J.: Origin of pentlandite in Chang’e-5 lunar soils revealed by transmission electron microscopy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14455, https://doi.org/10.5194/egusphere-egu24-14455, 2024.

EGU24-17062 | ECS | Posters on site | PS1.1

Unveiling the characteristics of the lunar surface by massive inversion of the Hapke model 

Dung Tri Nguyen, Stéphane Jacquemoud, Antoine Lucas, Sylvain Douté, Cécile Ferrari, Sophie Coustance, Sébastien Marcq, and Aimé Meygret

Understanding the physical characteristics of terrestrial and planetary surfaces is imperative for unraveling the complexity of landscape formation and evolution, and to develop strategies for future planetary rover missions. Photometry is one of the most widely used methods for studying these characteristics. The light scattered by a surface is quantified by the bidirectional reflectance distribution function (BRDF), providing a uniquely detailed optical measurement for each target observed. Hapke model inversion, an approach widely used over the past decades, reveals complex surface attributes, including roughness, porosity, grain size and shape, micro-texture, mineral composition, and more.

Although the challenges of restrictive data conditions and limited computational capabilities impeded the inversion of the Hapke model for large-scale surface analysis, we’ve addressed these issues with appropriate data and a comprehensive framework. Extracting multiangular surface data requires optical sensors with pointing capabilities and, by extension, images captured from different illumination directions. Earth observation satellites such as the Pleiades constellation managed by the Centre National d’Études Spatiales (CNES), have demonstrated their agility in extracting large-scale BRDF data on the Moon for optical sensor calibration. The processing chain involves geometric correction using digital elevation models supplied by NASA, and inversion of the Hapke model on each pixel, which is facilitated by a fast Bayesian inversion framework (Kugler et al., 2022). Inversion of the Hapke model on the BRDF extracted from each pixel generates maps of the six model parameters for the areas studied on the near side of the lunar surface, primarily the Apollo landing sites.

The BRDFs extracted from Pleiades images over the Apollo 17 landing site are consistent with prior knowledge of the photometric behavior of the Moon's surface. The quality of these BRDFs prompted us to extend our analysis to a 10° x 10° region around the mentioned site. Given the 1.5 km ground sampling distance of Pleiades images, the map size is 200 x 200 pixels (approximately 300 x 300 km). The distribution of the parameter values reflects the topography of the region, with a notable contrast between flat and steeply sloping areas. Optimal fits with an acceptable level of error are obtained on flat terrain, while the algorithm encounters difficulties in steeply sloping areas due to the complexity of the terrain within the large ground sampling distance.  In the current state, the application of the framework is extending to cover the near side of the Moon. The parameters obtained for each terrain unit will be compared with previous works (Souchon et al., 2013; Sato et al., 2014; Gimar et al., 2022; Marshal et al., 2023; Nagori et al., 2023) and correlated with a geological map (Fortezzo et al., 2020).

 

How to cite: Nguyen, D. T., Jacquemoud, S., Lucas, A., Douté, S., Ferrari, C., Coustance, S., Marcq, S., and Meygret, A.: Unveiling the characteristics of the lunar surface by massive inversion of the Hapke model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17062, https://doi.org/10.5194/egusphere-egu24-17062, 2024.

EGU24-17449 | ECS | Orals | PS1.1

Present-day surface heat flux variations on the Moon from global geodynamic and crustal thickness models 

Sabatino Santangelo, Ana-Catalina Plesa, Adrien Broquet, Doris Breuer, and Bart C. Root

High resolution gravity field measurements from GRAIL [1], in-situ heat flux [2] and seismic measurements from Apollo [3,4], surface composition from Clementine and Lunar Prospector [5,6], and the analysis of lunar samples have provided a wealth of information about the thermal evolution of the Moon [7].

Constraints on the present-day thermal state of the lunar interior come from the Apollo surface heat flux measurements: 21±3 mW m-2 at the Apollo 15 and 14±2 mW m-2 at the Apollo 17 landing sites [2]. A peak heat flux of ~180 mW m-2 was recently inferred by [8] from the Chang’E 1 and 2 data at the Compton-Belkovich location, a Thorium anomaly feature on the lunar farside. A lower bound for the lunar heat flux of only ~6 mW m-2 has been suggested, for the so-called Region 5, by measurements of the Diviner Lunar Radiometer Experiment onboard LRO [9]. Additionally, thermal expansion/contraction estimates [10] provide secondary constraints on the thermal state of the interior throughout lunar history.

Here, we model the interior dynamics of the Moon to infer plausible distributions of heat producing elements (HPEs) that, in turn, are directly linked to surface heat flux variations. To this end, we compare the present-day surface heat flux obtained in our models with the above constraints. Similar to [11], we combine global geodynamical models [12] with crustal thickness models derived from gravity and topography data [13]. We include higher HPEs abundances in the Procellarum KREEP Terrane (PKT) and crust compared to the mantle, and a mantle rheology similar to [14]. We test both constant and pressure/temperature dependent thermal conductivity scenarios. In addition to present-day heat flux, we compute the thermal expansion/contraction based on the interior thermal state obtained from our models at different times during lunar evolution and compare these values with available estimates to select best-fit models.

We find that variations in crustal thickness and the distribution of HPEs in the crust, mantle, and PKT region predominantly affect the convection pattern in the lunar interior and the surface heat flux. Models best compatible with the heat fluxes in the Apollo regions and Region 5 show an average Thorium abundance in the PKT region of ~2.4 ppm, smaller than the observed surface values [6], suggesting a strong Thorium enrichment close to the surface. These models have a crustal thermal conductivity of ~1.2 W/(mK), ~3 times lower than that of the mantle. None of our models matches the heat flux estimated at the Compton-Belkovich location, indicating either specific local processes [8] or large measurement uncertainties.

References:

[1] Zuber et al., 2013; [2] Langseth et al., 1976; [3] Garcia et al., 2019; [4] Nunn et al., 2020; [5] McEwen et al., 1997; [6] Lawrence at al., 2003; [7] Jaumann et al., 2012; [8] Siegler et al., 2023; [9] Paige & Siegler, 2016; [10] Andrews-Hanna et al. 2013; [11] Plesa et al., 2016; [12] Hüttig et al., 2013; [13] Broquet & Andrews-Hanna, 2023; [14] Laneuville et al., 2013.

How to cite: Santangelo, S., Plesa, A.-C., Broquet, A., Breuer, D., and Root, B. C.: Present-day surface heat flux variations on the Moon from global geodynamic and crustal thickness models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17449, https://doi.org/10.5194/egusphere-egu24-17449, 2024.

EGU24-20166 | Posters on site | PS1.1

Constraints on the spatial distribution of lunar crustal magnetic sources from orbital magnetic field data 

Joana S. Oliveira, Foteini Vervelidou, Mark A. Wieczorek, and Marina Diaz Michelena

We know from spacecraft measurements that the crust of the Moon is heterogeneously magnetized. With the exception of a few magnetic anomalies related to craters and swirls, the origin of most of the lunar magnetic anomalies is not understood. Here we evaluate the performance of an inversion methodology, initially conceived to infer the direction of the underlying magnetization from magnetic field measurements, commonly referred to as Parker's method, to elucidate the origin of the magnetic sources by constraining the location and geometry of the underlying magnetization. We assess the performance of the method by conducting a variety of tests, using synthetic magnetized bodies of different geometries. These have been chosen such that they mimic  the main geological structures potentially magnetized within the lunar crust. Our test results show that the Parker method successfully localizes and delineates the two-dimensional surface projection of subsurface three-dimensional magnetized bodies, when certain conditions are fulfilled. In particular, the magnetization should be close to unidirectional, and the magnetic field data should have a higher spatial resolution than the smallest dimension of the magnetized body as well as a high signal-to-noise ratio. As an additional evaluation test, we applied this inversion methodology to two lunar magnetic anomalies that are associated with visible geological features, the Mendel-Rydberg impact basin and the Reiner Gamma swirl. For Mendel-Rydberg,  our analysis shows that the strongest magnetic sources are located within the basin's inner ring in agreement with previous studies showing that during an impact, the crust inside the newly formed crater undergoes demagnetization and potentially remagnetization (if an ambient magnetic field is present). For Reiner Gamma, we found the strongest magnetic sources form a narrow dike-like body that emanates from the center of the Marius Hills volcanic complex. The reason that only one such dike emanating from Marius Hills is magnetized could be linked to an atypical iron-metal composition or to the lunar ambient magnetic field being only intermittently present. Future applications of this method can focus on constraining the origin of the many lunar magnetic anomalies that are not associated with visible geological features.

How to cite: Oliveira, J. S., Vervelidou, F., Wieczorek, M. A., and Diaz Michelena, M.: Constraints on the spatial distribution of lunar crustal magnetic sources from orbital magnetic field data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20166, https://doi.org/10.5194/egusphere-egu24-20166, 2024.

EGU24-20971 | Orals | PS1.1

Lunar Penetrating Radar Reveals Three Phases of Volcanism at Von Kármán Crater 

Iraklis Giannakis, Craig Warren, and Antonis Giannopoulos

The Chinese Lunar mission Chang'E-4 soft-landed on the far side of the Moon on January 2019 marking a significant milestone in space exploration. The mission's landing site is on the eastern floor of Von Kármán (VK) crater (45.4446°S, 177.5991°E), within the South Pole–Aitken (SPA) basin, one of the oldest and largest impact craters in the solar system.

Yutu-2 is the rover of the Chang;E-4 mission. Similar to its twin rover Yutu-1, amongst its scientific payloads Yutu-2 carries a set of ground-penetrating radar (GPR) systems. GPR is a well-established geophysical method and has been instrumental in the new era of planetary exploration. Chang’E-3 was the first mission incorporating in-situ planetary GPR, a trend continued by subsequent Lunar and Martian missions, including Chang'E-4, Perseverance, Chang'E-5 and Tianwen-1; with plans for future missions such as Chang'E-7 and ExoMars [1].

Existing Lunar GPR studies often assume that the dielectric properties of Lunar materials can be modelled via a constant electric permittivity and a conductive term. However, treating the electric permittivity as non-dispersive overlook the frequency-dependent complex electric permittivity of ilmenite. Ilmenite is a titanium mineral, particularly abundant in Lunar mare basalts and soils. Recent investigations [1] using a complex Cole-Cole function have shown that ilmenite-mixtures act as low-pass filters, causing a decrease in the pulse's central frequency as the wave propagates through an ilmenite formation. This frequency shift, proportional to the ilmenite content, serves as a basis for inferring the presence of basalts and approximating their ilmenite content.

In this study, we explore the frequency shift of signals received both from Channel-2B and Channel-1. Our analysis reveals a sequence of basaltic layers extending to approximately 300 m depth, displaying varying thickness and ilmenite content. Based on the estimated ilmenite content, the GPR data indicates three distinct phases of Lunar volcanism: an early phase with high-Ti basalts, followed by a low-Ti volcanic activity, and a final phase with high-Ti basalts. These findings align with generic models of Lunar lava emplacement [1]. According to these models, Lunar volcanic history includes an early "blue" titanium-rich volcanic event (~ 3.8-3.5 Ga), followed by low-Ti "red" basalts (~ 3.5-3 Ga), and a subsequent phase of "blue" high-Ti basalts (~3 Ga) [2].

References

[1]   Giannakis, I., Martin-Torres, J., Su, Y., Feng, J., Zhou, F., Zorzano, M-P., Warren, C., Giannopoulos, A., (2024). Evidence of Shallow Basaltic Lava Layers in Von Kármán Crater from Yutu-2 Lunar Penetrating Radar, Icarus, 2024.

 

[2] Cattermole, P. J., (1996). Planetary Volcanism: A Study of Volcanic Activity in the Solar System, Wiley, Chichester, 2ndEdition, 1996.

 

How to cite: Giannakis, I., Warren, C., and Giannopoulos, A.: Lunar Penetrating Radar Reveals Three Phases of Volcanism at Von Kármán Crater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20971, https://doi.org/10.5194/egusphere-egu24-20971, 2024.

EGU24-21481 | Orals | PS1.1

New paleointensity measurements of Apollo samples and implications for the lunar dynamo 

Foteini Vervelidou, Benjamin P. Weiss, Claire I. O. Nichols, Mary Murray, Jay Shah, France Lagroix, Helena McDonald, and Claire Carvallo

Spacecraft magnetic field measurements and paleomagnetic studies on Apollo lunar samples indicate that the Moon once sustained a core dynamo. However, strength and  duration of the dynamo field are key unknowns that may constrain the mechanism that powered it. Shedding light on these questions can improve our understanding about the generation of dynamos on small planetary bodies. Here, I will present new paleointensity measurements of the lunar magnetic field, based on alternating field and controlled atmosphere thermal demagnetization. In particular, we measured mare basalts and regolith breccias from the Apollo 16 and Apollo 17 missions, with ages ranging from 1.7 to 3.75 Gy old. I will discuss the results in the context of two issues surrounding lunar paleomagnetism. Firstly, I will show, through the example of an Apollo 17 mare basalt specimen carrying magnetizations acquired at two different epochs, that the magnetic record of these rocks is of lunar origin, as opposed to spacecraft or terrestrial contamination. Secondly, I will show results from the Apollo 16 regolith breccias suggesting that the lunar dynamo was fluctuating in intensity at least since 3.4 Ga. A fluctuating dynamo has been proposed as a possible resolution to the energy conundrum of the early phase of the lunar dynamo. Over a period of several hundred million years, extending up to 3.5 Gy ago, various paleomagnetic studies have inferred paleointensities that require an energy budget in excess of what numerical simulations, assuming a dynamo powered by thermochemical convection, estimate to have been available, given the Moon’s small metallic core. While our results do not directly address the energy budget conundrum during that time period, the fact that magnetic field fluctuations have occurred at least since 3.4 Gy ago, hints at the possibility that they could have occurred also at earlier times. If these fluctuations were large enough, they could allow for a reconciliation between paleomagnetic studies and numerical simulations, without the need to evoke alternative dynamo mechanisms.

How to cite: Vervelidou, F., Weiss, B. P., Nichols, C. I. O., Murray, M., Shah, J., Lagroix, F., McDonald, H., and Carvallo, C.: New paleointensity measurements of Apollo samples and implications for the lunar dynamo, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21481, https://doi.org/10.5194/egusphere-egu24-21481, 2024.

EGU24-21578 | Posters on site | PS1.1

Lunarleaper – Unlocking a Subsurface World 

Anna Mittelholz, Simon C. Stähler, Hendrik Kolvenbach, Valentin Bickel, Joseph Church, Svein-Erik Hamran, Ozgur Karatekin, Birgit Ritter, Jordan Aaron, Barthélémy Anhorn, Sofia Coloma, Larissa de Palézieux dit Falconnet, Matthias Grott, Cristophe Ogier, Johan Robertsson, and Krzysrof Walas

We present LunarLeaper, a robotic explorer concept in response to the ESA 2023 Small Missions call. Pits, volcanic collapse features with near-vertical walls, have been identified across the lunar and Martian surface. These pits are high priority exploration destinations because some, referred to as skylights, might provide access to subsurface lava tube systems. Lava tubes are of particular interest for future human exploration as they offer protection from harmful radiation, micrometeorites and provide temperate and more stable thermal environments compared to the lunar surface. We propose to use a small legged robot (ETH SpaceHopper, <10 kg), to access and investigate the pit edge, using its ability to access complex and steep terrain more safely than a wheeled rover. LunarLeaper will land in Marius Hills within a few 100 m of the pit and traverse across the lateral extent of the hypothesized subsurface lava tube. On its traverse it will take measurements with a ground penetrating radar and a gravimeter, measurements that will allow us to survey the subsurface structure and detect and map lava tube geometry if present. The robot will approach the pit edges and acquire high resolution images of the pit walls containing uniquely exposed layers of the geophysically mapped lava flows and regolith layers. These images will allow not only scientific advances of lunar volcanism and regolith formation, but also enable assessment of the stability of the pit structure and its use as a possible lunar base. The mission is expected to last 1 lunar day. The robot could be delivered to the surface by a small lander, as they are currently developed and planned by various national and commercial agencies and hop off the landing platform without the need for a robotic arm. It is highly flexible in accommodation and can thus make full use of the new international lunar ecosystem.

How to cite: Mittelholz, A., Stähler, S. C., Kolvenbach, H., Bickel, V., Church, J., Hamran, S.-E., Karatekin, O., Ritter, B., Aaron, J., Anhorn, B., Coloma, S., de Palézieux dit Falconnet, L., Grott, M., Ogier, C., Robertsson, J., and Walas, K.: Lunarleaper – Unlocking a Subsurface World, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21578, https://doi.org/10.5194/egusphere-egu24-21578, 2024.

EGU24-21717 | Posters on site | PS1.1

The Lunar Vertex PRISM Payload: Ready for the Moon 

Sarah Vines, George Ho, and David Blewett and the The Lunar Vertex Science Team

Lunar Vertex, selected as NASA’s first Payloads and Research Investigations on the Surface of the Moon (PRISM) delivery, will explore a portion of Reiner Gamma (7.585° N, 58.725° W) with instruments mounted on a lander and small rover. Reiner Gamma (RG) is home to a magnetic anomaly, a region of magnetized crustal rocks. The RG magnetic anomaly is co-located with the type example of a class of irregular high-reflectance markings known as lunar swirls. The Lunar Vertex payload was designed to address three science goals: (1) test hypotheses for the origin of the RG magnetic anomaly, (2) test hypotheses for the origin of the RG swirl, and (3) determine the structure of the RG mini-magnetosphere. The payload suite consists of three instruments on the lander, and two instruments on a small commercial rover.

The Lunar Vertex payload will be carried to the lunar surface on a commercial lander as part of NASA's Commercial Lunar Payload Services (CLPS) program. The lander and payload are designed for operation during one lunar daylight period (i.e., no night operations or survival). NASA selected Intuitive Machines as the CLPS provider for the Reiner Gamma delivery. At the time of this writing, the launch will be no earlier than June of 2024.

Lander Instruments: The three Lunar Vertex lander instruments were delivered to Intuitive Machines in June 2023. The Magnetic Anomaly Plasma Spectrometer (MAPS), built by the Southwest Research Institute, is capable of measuring the ion and electron velocity distribution over a 292.5° x 90° FOV from 8 eV/e to 17.5 keV/e. The Vector Magnetometer–Lander (VML) suite, built by APL, is comprised of a tetrahedral array of four commercial fluxgate magnetometers mounted on the bottom of a 0.5-meter mast, with a science-grade dual-ring core fluxgate magnetometer at the top of the mast. Together, MAPS and VML will characterize the magnetic field and surface plasma environment within RG. The Vertex Camera Array (VCA) suite, built by Redwire, is a set of three clusters of three RGB cameras. VCA images will be used to characterize the landing site geology and to understand the physical properties of the lunar regolith around the lander.

Rover and Rover Instruments: The rover vehicle is from vendor Lunar Outpost. The rover instruments were integrated with the vehicle at APL, and environmental testing was carried out on the integrated system. The Vector Magnetometer–Rover (VMR), built by APL, is also comprised of a tetrahedral array of commercial fluxgate sensors, mounted on a 0.2-meter mast. With VML, VMR will characterize local spatial structuring of the magnetic field at RG. The Rover Multispectral Microscope (RMM), mounted inside the rover body, is a close-up imager that can provide information on soil texture, as well as active LED illumination at a set of UV to NIR wavelengths chosen for their utility in determining the composition and maturity state of the regolith. The rover will be delivered to Intuitive Machines in early January 2024.

How to cite: Vines, S., Ho, G., and Blewett, D. and the The Lunar Vertex Science Team: The Lunar Vertex PRISM Payload: Ready for the Moon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21717, https://doi.org/10.5194/egusphere-egu24-21717, 2024.

EGU24-228 | ECS | Orals | PS1.2

A Correlation Study on Volcanic Features and their Geological Context on Mercury. 

Melissa Mirino, Matteo Massironi, and Riccardo Pozzobon

The Planet Mercury has been studied by the earlier MESSENGER mission which results show that Mercury’s history is expressed by: (i) volcanism, (ii) global contraction with consequent formation of tectonic-compressive features, and (iii) impact cratering with consequent formation of basins or minor craters [e.g., 1, 2]. However, it is still unclear how the interplay between tectonic induced by impact basins and compressional activity has influenced volcanism. Thus, we investigated the presence and the absence of a correlation between the various volcanic features and their geological context (e.g., inside craters and/or basins, relationship with tectonic structures) to understand which processes could have influenced the volcanic activity of the planet. The study was developed using the ESRI ArcGIS (Geographic Information System) software package. The data and base maps used in the main part of the project come from the MESSANGER mission. To carry out the correlation study on a global scale, a new GIS database was created in which all the volcanic structures identified so far on Mercury, their morphological characteristics and their associations with various other tectonic or volcanic have been specified. Specifically, we included 346 samples comprehensive of (i) volcanic vents and their morphological classification [3, 4], (ii) presumed volcanic cones [5], and (iii) irregular pitted terrains [6, 7]. Once this global database was created, the study was divided into two parts. The first qualitative part was based on the study of the global distribution of the volcanic features considered concerning the basin structures [8] and global compressional tectonic features [9]. This part allowed us to identify patterns and areas of interest for more detailed observations and analyses. A second quantitative part evaluated the presence of a correlation between the different parameters and geological features considered. Our study has highlighted how the majority of these volcanic centers are distributed on the margins of large basins whether they were formed inside or outside craters. The studied volcanic features are also often related to compressive tectonic structures at distances ranging from 10 to 200 km. Explosive volcanic activity on a global scale seems to have been triggered mainly in areas where minor impacts were formed near critically stressed tectonic basin structures (caused by the large impact) reactivated by the global compression. Dike propagation along those areas has likely caused the explosive eruptions in weaker areas often triggered by smaller impacts.

References: [1] Denevi, et al., (2018), Cambridge Planetary Science, 144-175. [2] Rothery et al., (2020), Space Science Reviews, 216, 66 (2020). [3] Pegg et al., (2021), Icarus, Volume 365, 114510. [4] Jozwiak et al., (2018), Icarus Volume 302, 191-212. [5] Wright et al., (2018), JGR Planets, 123, 952–971. [6] Ru Xu et al. (2022), Remote Sens., 14(17), 4164. [7] Goudge et al., (2014), J. Geophys. Res.Planets,119, 635–658. [8] Orgel et al., (2020), Journal of Geophysical Research: Planets,125, e2019JE006212. [9] Byrne et al., (2014), Nature Geoscience volume 7, 301–307 (2014).

How to cite: Mirino, M., Massironi, M., and Pozzobon, R.: A Correlation Study on Volcanic Features and their Geological Context on Mercury., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-228, https://doi.org/10.5194/egusphere-egu24-228, 2024.

EGU24-798 | ECS | Posters on site | PS1.2

Comparison of Exospheric Mg Distributions Observed by BepiColombo/PHEBUS During the 2nd and 3rd Mercury Swing-bys 

Yudai Suzuki, Eric Quémerais, Rozenn Robidel, Jean-Yves Chaufray, Go Murakami, François Leblanc, Kazuo Yoshioka, and Ichiro Yoshikawa

Mercury’s exospheric atoms are mainly ejected from the surface through several processes such as thermal input, UV irradiation, solar wind particle sputtering, and micro-meteoroid impact. Observations by the MESSENGER spacecraft have shown that Mercury magnesium (Mg) exosphere is related to its surface abundance. Additionally, Mg is an interesting species as its surface abundance reflects the non-uniformity of magma compositions. However, spatial distribution (especially in the latitude direction) and seasonal variability of Mg exosphere is not well understood due to its dark brightness and the geometry of observations.

BepiColombo, the Mercury orbiting mission led by ESA and JAXA, is on its way to the planet. The 2nd and 3rd Mercury swing-bys were conducted on 22/06/2022 and 19/06/2023 (UTC), respectively, and many instruments observed the Mercury environments then. In this study, we analyzed Mg exosphere data from PHEBUS, the UV spectrometer onboard BepiColombo, to deduce temperature and production rate of Mg exosphere during each swing-by.

As a result, similar signals were obtained through both swing-bys. Season, local time, and longitude of Mercury during both observations were similar, but boresights of PHEBUS were different (2nd: northward, 3rd: southward). These results show that Mg production rates have little year-to-year variability, which is consistent with the fact that Mg is mainly ejected by micro-meteoroid impact. Besides, these results mean that dust impact flux has little north-south asymmetry.

In this presentation, we introduce the results obtained by observations of the spectrometer onboard BepiColombo, PHEBUS, during the 2nd and 3rd swing-bys. 

How to cite: Suzuki, Y., Quémerais, E., Robidel, R., Chaufray, J.-Y., Murakami, G., Leblanc, F., Yoshioka, K., and Yoshikawa, I.: Comparison of Exospheric Mg Distributions Observed by BepiColombo/PHEBUS During the 2nd and 3rd Mercury Swing-bys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-798, https://doi.org/10.5194/egusphere-egu24-798, 2024.

EGU24-2214 | ECS | Posters on site | PS1.2

Modeling Mercury's magnetosheath by the potential-mapping method  

Henry Holzkamp, Daniel Schmid, Daniel Heyner, Kristin Pump, and Yasuhito Narita

Modeling the plasma and magnetic field state in Mercury's magnetosheath is one of the most urgent tasks in Mercury science in view of the upcoming BepiColombo mission. By considering the steady-state and constructing the Laplace equation for the scalar magnetic potential in the magnetosheath (eliminating the interplanetary magnetic field in the magnetosphere and vice versa), the plasma and magnetic field state is obtained as a function of the solar wind condition and the spatial coordinates of the magnetosphere. We make extensive use of the exact solution of the Laplace equation for the parabolically shaped magnetosheath, and map the solution onto the realistic shape of magnetosheath by assuming the magnetosheath thickness is scalable between the parabolic shape and the realistic shape along the magnetopause-normal direction. The quality of the constructed model can successfully be tested against the global hybrid simulation of Mercury's magnetosheath, promising that the model serves as a useful tool for BepiColombo's detailed magnetosheath studies at Mercury.

How to cite: Holzkamp, H., Schmid, D., Heyner, D., Pump, K., and Narita, Y.: Modeling Mercury's magnetosheath by the potential-mapping method , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2214, https://doi.org/10.5194/egusphere-egu24-2214, 2024.

EGU24-3429 | Orals | PS1.2

On the Hermean near-planet boundaries response under different orbital interplanetary conditions 

Emanuele Cazzola, Dominique Fontaine, and Ronan Modolo

This work aimed to study the dynamical response of the near-Mercury environment to different interplanetary conditions experienced along its orbit by means of 3D multi-species hybrid simulations.

Mercury features an eccentric and rapid orbit around the Sun, with its extreme aphelion (0.47 AU) and perihelion (0.31 AU) positions being embedded in significantly different interplanetary conditions.
Given the different environments and its weak magnetic field strength, the position, size and behavior of the bow-shock, magnetosheath and magnetopause can vary significantly as highly coupled with the interplanetary medium.

In this work, we consider an interplanetary magnetic field aligned along the Parker spiral direction at the Mercury's distance from the Sun, i.e., quasi-radial, and the case of an interaction with slow and fast solar winds. We show the response of the bow-shock due to such quasi-radial interplanetary field and the compression of the bow-shock / magnetosheath /  magnetopause system as the planet passes from the aphelion to perihelion orbital points, as well as the solar wind velocity increases.
 
In particular, certain portions of the planet no longer present a significant protection from the interplanetary environment, so that the surface is exposed to the precipitation of interplanetary ions. An analysis of their fluxes revealed that the high latitude polar cusps are still the main regions for the interplanetary particles to reach out the surface. However, when the interplanetary conditions are sharp enough to cause a strong bow-shock and magnetosheath compression, the interplanetary particles are able to directly penetrate these boundaries and can precipitate at much lower latitudes.

These results are particularly timely for the BepiColombo mission, and are compared with its first fly-bys observations.

How to cite: Cazzola, E., Fontaine, D., and Modolo, R.: On the Hermean near-planet boundaries response under different orbital interplanetary conditions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3429, https://doi.org/10.5194/egusphere-egu24-3429, 2024.

EGU24-3528 | ECS | Posters on site | PS1.2

Plasma environment of Mercury’s magnetosphere as seen by BepiColombo during its third flyby 

Lina Hadid and the MSA, MIA and MEA / MPPE teams

On June 19th 2023, BepiColombo performed its third (MFB3) gravity assist maneuvers at Mercury. During this flyby, the spacecraft approaching the planet from dusk-nightside toward dawn-dayside and traveling down to close distances ~ 235 km altitudes above the planet’s surface. Even though BepiColombo is in a so-called “stacked configuration” during cruise (meaning that most of the instruments cannot be fully operated yet), a number of instruments can still make interesting observations. Particularly, despite their limited field-of-view, the particle sensors allow us to get a hint on the plasma composition and dynamics along a unique path across the magnetosphere and very close to the planet. In this presentation, we will show an overview of the plasma environment from the Mercury Ion Analyzer (MIA) and the Mercury Electron Analyzer (MEA); moreover we will present the first ion composition observations of the Mass Spectrum Analyzer (MSA). MIA, MSA and MEA are part of the Mercury Plasma Particle Experiment (MPPE, PI: Y. Saito) consortium that is a comprehensive instrumental suite for plasma, high-energy particle and energetic neutral atom measurements onboard Mio (Saito et al. 2021). During this flyby, MSA and MIA revealed the presence of energetic (> 10 keV) and cold (< 100 eV) heavy ions inside the magnetosphere around closest approach. Moreover, we will show major features of the Mercury magnetosphere highlighting different regions: 1) plasma sheet, 2) nightside bounday-layer and 3) magnetosheath [Hadid et al., Nature Communications, under review].

How to cite: Hadid, L. and the MSA, MIA and MEA / MPPE teams: Plasma environment of Mercury’s magnetosphere as seen by BepiColombo during its third flyby, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3528, https://doi.org/10.5194/egusphere-egu24-3528, 2024.

EGU24-4391 | ECS | Orals | PS1.2

Mercury's crustal heterogeneity revealed by gravity data modelling  

Salvatore Buoninfante, Maurizio Milano, Barbara Negri, Christina Plainaki, Giuseppe Sindoni, and Maurizio Fedi

The study of the internal structure of Mercury is fundamental for understanding the formation and evolution of the planet and of the entire Solar System. The main purpose of this work was the analysis of the MESS160A gravity field model [1] to show the presence of crustal heterogeneities in density. According to the flexural isostatic response curve, we noted that the lithospheric flexure occurs in the spherical harmonic degree range 5-80, consistently with a flexural compensation model, while for degrees lower than 5 the flexural rigidity tends to 0 and a local compensation model can be assumed. Removing spherical harmonic components up to degree 4, as they are associated with the polar mass deficit and to the morphological contrasts, we assumed a flexural compensation model [2] to first estimate a mean elastic thickness of 30 ± 10 km. We, then, modeled the lithospheric flexure regardless of the gravity field and calculated the isostatic gravity anomalies by subtracting the gravity effect caused by the isostatic compensation to Bouguer anomalies. In this way, we proved that considerable lateral density variations occur within the Mercury's crust [3]. We also estimated the curst-mante interface depth, varying from 19 to 42 km. Isostatic anomalies are mainly related to density variations in the crust: gravity highs mostly correspond to large-impact basins, suggesting intra-crustal magmatic intrusions as the main origin of these anomalies. Isostatic gravity lows prevail, instead, above intercrater plains and may represent the signature of a heavily fractured crust.

 

Acknowledgements: We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0.

 

References:

[1] Konopliv, A. S. et al. (2020). Icarus, 335.

[2] Turcotte, D. L. et al. (1981). J. Geophys. Res., 86.

[3] Buoninfante, S. et al. (2023). Sci. Rep., 13.

How to cite: Buoninfante, S., Milano, M., Negri, B., Plainaki, C., Sindoni, G., and Fedi, M.: Mercury's crustal heterogeneity revealed by gravity data modelling , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4391, https://doi.org/10.5194/egusphere-egu24-4391, 2024.

EGU24-4401 | ECS | Posters on site | PS1.2

Geology and tectonic structures of the Michelangelo (H12) quadrangle 

Salvatore Buoninfante, Valentina Galluzzi, Luigi Ferranti, Maurizio Milano, and Pasquale Palumbo

Geological cartography and structural analysis are essential for understanding Mercury’s geological history and tectonic processes. This work focuses on the geological and structural analysis of the Michelangelo quadrangle (H12), located at latitudes 22.5°S-65°S and longitudes 180°E-270°E. We present the first geological map of H12 at 1:3,000,000 scale, based on the photointerpretation of the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Mercury Dual Imaging System (MDIS) imagery. The present study is a contribution to the 1:3M geological map series, planned to identify targets to be observed at high resolution during the ESA-JAXA BepiColombo mission [1]. 

We mapped tectonic structures and geological contacts using the MDIS derived basemaps, characterized by an average resolution of 166 m/pixel. Linear features are subdivided into large craters (crater rim diameter > 20 km), small craters (5 km < crater rim diameter < 20 km), subdued or buried craters, certain or uncertain thrusts, certain or uncertain faults, wrinkle ridges and irregular pits. Geological contacts, mapped as certain or approximate, delimit the geological units grouped into three classes of crater materials (c1-c3) based on degradation degree, and plains (smooth, intermediate and intercrater plains).

Michelangelo appears as a densely cratered quadrangle dominated by degraded crater materials (c2) and intermediate plains. We identified two main regional thrust system trending NW-SE and NE-SW. We found that many lobate scarps developed at the edges of ancient, large impact basins. Clear examples of such tectonic structures in the Michelangelo quadrangle are provided by the Beethoven basin (20.8°S–236.1°E) or by the Vincente-Yakovlev basin (52.6°S–197.9°E). We propose a thick-skinned tectonic model according to which the lobate scarps were formed after positive reactivation of previous impact-related normal faults, due to the contractional tectonic regime deriving from the global contraction. Evidence of thick-skinned tectonics on Mercury are provided by the presence of fault systems exceeding the basin rim, and by the estimated rooting depth of thrusts bordering large basins (e.g., Discovery Rupes, Soya Rupes).

Following [2], we found that the NW-SE system largely borders the southwestern edge of the HMR. We also show that the volcanic vents on Mercury are often associated with impact craters and/or lobate scarps (e.g., [3,4]), which can be considered as possible preferential areas for magma uprising.

 

Acknowledgements: We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0.

 

References:

[1] Galluzzi, V. et al. (2021). LPI Contrib., 2610.

[2] Galluzzi, V. et al. (2019). J. Geophys. Res., 124(10), 2543-2562.

[3] Thomas, R. J. et al., (2014). J. Geophys. Res., 119, 2239-2254.

[4] Jozwiak, L. M. et al., (2018). Icarus, 302, 191-212.

 

How to cite: Buoninfante, S., Galluzzi, V., Ferranti, L., Milano, M., and Palumbo, P.: Geology and tectonic structures of the Michelangelo (H12) quadrangle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4401, https://doi.org/10.5194/egusphere-egu24-4401, 2024.

Mercury possesses a dynamic magnetosphere driven primarily by magnetic reconnection occurring regularly at the magnetopause and in the magnetotail. Using the Magnetohydrodynamics with Adaptively Embedded Particle-in-Cell (MHD-AEPIC) model, we have performed a series of global simulations with different upstream conditions to study in detail the kinetic signatures, asymmetries, and flux transfer events (FTEs) associated with Mercury’s dayside magnetopause reconnection. By treating both ions and electrons kinetically, the embedded PIC model reveals crescent-shaped phase-space distributions near reconnection sites, counter-streaming ion populations in the cusp region, and strong temperature anisotropies within FTEs. A novel algorithm has been developed to automatically identify reconnection sites in our 3D simulations. The spatial distribution of reconnection sites as modeled by the PIC code exhibits notable dawn-dusk asymmetries, likely due to such kinetic effects as X-line spreading and Hall effects. Across all simulations, simulated FTEs occur quasi-periodically every few seconds with their key properties showing clear dependencies on the upstream solar wind Alfvénic Mach number and the IMF orientation, consistent with MESSENGER observations and previous Hall-MHD simulations. FTEs formed in our MHD-AEPIC model are found to contribute a significant amount (~ 3% - 36%) of the total open flux generated at the dayside magnetopause. Taken together, the results from our MHD-AEPIC simulations provide new insights into the kinetic processes associated with Mercury’s magnetopause reconnection that should prove useful for interpreting in situ observations from MESSENGER and BepiColombo.

How to cite: Jia, X., Li, C., Chen, Y., and Toth, G.: Kinetic signatures, asymmetries, and FTEs associated with Mercury’s dayside magnetopause reconnection as revealed by 3D MHD-AEPIC simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4716, https://doi.org/10.5194/egusphere-egu24-4716, 2024.

EGU24-6003 | Posters on site | PS1.2

Geological map of Tolstoj quadrangle (H08) of Mercury 

Lorenza Giacomini, Laura Guzzetta, Valentina Galluzzi, Luigi Ferranti, and Pasquale Palumbo

Tolstoj quadrangle is located in the equatorial area of Mercury, between 22.5°N and 22.5°S of latitude and 144° and 216°E of latitude. In this work we present the geological map (1:3M scale) performed on the quadrangle. The main basemap used for the mapping is the MDIS (Mercury Dual Imaging System) 166 m/pixel BDR (map-projected Basemap reduced Data Record) monochrome mosaic compiled using NAC (Narrow Angle Camera) and WAC (Wide Angle Camera) 750 nm-images. Moreover, to distinguish spectral characteristics and topography of the surface, MDIS global color mosaics [Denevi et al., 2016)] and the MDIS global DEM [Becker et al., 2009), have been taken into account. Then, the quadrangle has been mapped using ArcGIS at an average scale of 1:400k for a final out-put of 1:3M. The mapping highlights as Caloris basin related features dominate the geology of H08. Indeed, the southern half of the basin is located in the upper left corner of quadrangle. Inside and outside the basin extended smooth plains were emplaced and they represent the most extended volcanic deposits in the quadrangle. Also structural framework is mainly linked with the basin with radial and concentric grabens located in its floor and wrinkle ridges widespread both on the interior and exterior Caloris smooth plains. Further, lobate scarps have been detected in the quadrangle: they are located outside the Caloris basin but they are absent within its floor. These thrusts show a preferential orientation in the smooth plains located outside the basin whereas they are more randomly oriented in the intercrater plains. Besides smooth plains, products of effusive volcanism, features related to explosive volcanism have also been frequently detected. Interestingly, several volcanic vents have been identified in the inner Caloris smooth plains, aligned with the rim of Caloris basin, suggesting a correlation between these two features. However, vents are not clustered only inside Caloris basin, but other crater floors are affected by this type of features. The vents are surrounded by extended pyroclastic deposits appearing in bright yellow in MDIS enhanced global color mosaics. Finally, hollow fields have also been mapped, although they are not very frequent. Some of them are associated to the pyroclastic deposits located along Caloris rim, the others are detected within floors or peaks of a few craters in the intercrater plains.

The geological map will be integrated into the global 1:3M geological map of Mercury (Galluzzi et al., 2021), which is being prepared in support to ESA/JAXA (European Space Agency, Japan Aerospace Agency) BepiColombo mission.

 

Acknowledgements:  We gratefully acknowledge funding from the Italian Space Agency (ASI) under ASI-INAF agreement 2017-47-H.0 and from the GMAP, Europlanet RI 20-24 grant n.: 871149-GMAP

References:

Becker K. J., et al. AGU, Fall Meeting, ab-stract#P21A-1189, 2009

Denevi et al.:LPS XLVII. Abstract#1264, 2016

Galluzzi V. et al.:. Planetary Geologic Mappers 2021, LPI #2610, 2021

How to cite: Giacomini, L., Guzzetta, L., Galluzzi, V., Ferranti, L., and Palumbo, P.: Geological map of Tolstoj quadrangle (H08) of Mercury, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6003, https://doi.org/10.5194/egusphere-egu24-6003, 2024.

EGU24-6397 | Posters on site | PS1.2

Geological mapping of Kuiper Crater: a break within Mercury crust 

Cristian Carli, Lorenza Giacomini, Matteo Massironi, Francesca Zambon, Anna Galiano, Fabrizio Capaccioni, and Pasquale Palumbo

The results from planetary investigation in the last years strongly point out that the integration of compositional information with the morphology, stratigraphy and tectonics permits to produce a more comprehensive geological approach, obtaining geological maps instead of purely morpho-stratigraphic maps. In this view, firstly PLANMAP project, and then GMAP (within EUROPLANET-RI 20-24), have given indications on different approaches to follow for such integration.
Investigating the surface of Mercury is an important task of the Bepicolombo mission. To be prepared for this task we are investigating the data obtained by past MESSENGER mission in order to understand which geological features and/or region of Mercury should hide key information.
In this work we investigate the Kuiper crater (62 kilometer in diameter) which overlies the northern rim of the larger crater Murasaki. The Kuiper crater is one of the highest albedo features on the surface of Mercury with an important ray system, indicative of  its young age. From this point of view Kuiper can be considered an important feature on hermean surface history, such as to give the name at the last period of Mercury timeline (the Kuiperian age). However, on the other side,its relatively young age does not permit it to investigate the local geology by using the global basemaps, since the albedo is saturating within the crater, making difficult to understand the variegation on it and on the proximal and distal ejecta. Whereas considering the color variegation from the different filters of the WAC camera onboard MESSENGER, at relatively high spatial resolution (385 m/px), we clearly highlighted how several peculiar geological features arise. These regions have been later investigated by ad-hoc mosaics considering the highest resolution images available (~ 120 m/pixel) from the NAC camera onboard MESSENGER.
The extension of the ejecta could be improved and differentiated from reflectance properties of the crater floor, showing an asymmetry towards S-SE. Moreover, the crater wall seems to reveal the possible impact direction. Evidence of pyroclastic-like material, from spectral reflectance properties, are present on the N-E wall, whereas from north to west the terraced wall seems to show the presence of re-melted material. Interestingly, two different hollows-like terrain are present on both the inner peaks and on the southern wall, indicating that hollows could be emplaced on different bedrock terrains. In addition, the spectral indication shows a clear distinction from Kuiper material with respect to the Murasaki terrains.
We want to acknowledge the GMAP, Europlanet RI 20-24 grant n.: 871149-GMAP and the Bepicolombo (SIMBIO-SYS) project, ASI-INAF agreement n.: 2017-47-H.0

How to cite: Carli, C., Giacomini, L., Massironi, M., Zambon, F., Galiano, A., Capaccioni, F., and Palumbo, P.: Geological mapping of Kuiper Crater: a break within Mercury crust, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6397, https://doi.org/10.5194/egusphere-egu24-6397, 2024.

EGU24-6547 | ECS | Orals | PS1.2

PHEBUS observations of exospheric calcium and potential detection of exospheric manganese during BepiColombo first three flybys of Mercury. 

Rozenn Robidel, Eric Quemerais, Jean-Yves Chaufray, Francois Leblanc, and Dimitra Koutroumpa

BepiColombo, the ESA/JAXA joint mission, has already performed three out of the six flybys of Mercury scheduled during its journey to the innermost planet of our solar system. The first two flybys were conducted at a similar True Anomaly Angle (TAA~265°), while the third one occurred closer to the perihelion (TAA=311°).

During these three flybys, several instruments observed the planet and its environment, including PHEBUS (Probing of Hermean Exosphere By Ultraviolet Spectroscopy), the UV spectrograph on board BepiColombo/MPO. The two visible channels of PHEBUS, centered at 404nm and 422nm, observed Mercury’s exosphere during each of the three flybys. The third flyby provided the first observations of the southern hemisphere of Mercury. Indeed, PHEBUS was pointing towards the south ecliptic direction during the third flyby while the instrument was pointing towards the north ecliptic direction during the first two flybys.

We report the detection of the calcium (Ca) emission line at 422.8nm during each of the three flybys. Our results reveal that Mercury Ca exosphere is very extended on the morning side (up to ~10,000 km of altitude) and is enhanced near the dawn region. We then discuss year-to-year variability and potential source processes.

We also report the detection of additional species with the visible channel centered at 404nm during the three flybys, potentially manganese (Mn) or potassium (K). The detection is confined to the predawn region. Mn was detected by MESSENGER at similar local times (2-5 A.M.) but at different TAA (0-70°). However, the K doublet near 404nm has never been detected by MESSENGER.

Finally, we briefly discuss the geometric configuration of the next flybys of Mercury that will take place in September 2024, December 2024 and January 2025.

How to cite: Robidel, R., Quemerais, E., Chaufray, J.-Y., Leblanc, F., and Koutroumpa, D.: PHEBUS observations of exospheric calcium and potential detection of exospheric manganese during BepiColombo first three flybys of Mercury., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6547, https://doi.org/10.5194/egusphere-egu24-6547, 2024.

EGU24-6904 | ECS | Posters on site | PS1.2

Mercury’s Field-aligned Currents: Hybrid Simulation Results 

Zhen Shi, Zhaojin Rong, Shahab Fatemi, Chuanfei Dong, Jiawei Gao, and Yong Wei

Observations from the MESSENGER (MErcury Surface, Space Environment, GEochemistry, and Ranging) mission have demonstrated the presence of the region 1-like field-aligned currents (FACs) in Mercury’s northern hemisphere. Due to the limitations of the single-point measurement, the upstream solar wind condition is blind to MESSENGER when it’s inside the magnetosphere. Thus, the statistical analyses of FACs are hard to be carried out and the results could be obscured. Here, we used a hybrid model to investigate Mercury’s FACs. The two-layer model was concerned. We studied how Mercury’s conductivity profile controls the establishment and closure of the FACs, and how the IMF orientation regulated the intensity and the spatial distributions of the FACs. Previous statistical results of MESSENGER’s observations can be well explained by the simulations. And future observations from BepiColombo will help us gain a better understanding of Mercury’s FACs. 

How to cite: Shi, Z., Rong, Z., Fatemi, S., Dong, C., Gao, J., and Wei, Y.: Mercury’s Field-aligned Currents: Hybrid Simulation Results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6904, https://doi.org/10.5194/egusphere-egu24-6904, 2024.

EGU24-7623 | ECS | Posters on site | PS1.2

Insights into Mercury’s tidal stresses: Linking present and past potentials 

Liliane Burkhard and Nicolas Thomas

A planet’s orbital eccentricity can experience major changes over time as a result of planetary secular perturbations. Mercury's proximity to the Sun, its unique 3:2 spin-orbit resonance, and its high orbital eccentricity makes it an intriguing subject for investigating tidal forces and their resulting stresses. Throughout its history, Mercury may have experienced a state of further heightened eccentricity, potentially leading to tidal forces significant enough to modify the planet's surface. In the study presented here, we explore the tidal potential currently influencing Mercury and examine possible historical values of eccentricity to estimate past stress values. Employing a four-layer crustal model, we calculate Love numbers that reflect Mercury's internal physical properties and compute global tidal potential, surface stresses, and radial tidal displacement with respect to location and position in orbit. A suggested past orbital eccentricity of e = 0.41 could produce estimated maximum principal surface stresses of ~ +/-70 kPa which are comparable to current diurnal tidal principal stress values for Europa and Enceladus (~ +/-85 kPa). At present, Mercury experiences tidal stress values of up to ~ +/-15 kPa with a tidal bulge that can radially displace the surface by a mean of ~ 2.3 m. As tidal stresses could have been significantly higher in the past, we can hypothesize that Mercury might have experienced surface alterations induced by its orbital dynamics. On the other hand, the present-day surface of the planet has not retained evidence of any tidal stress modifications, suggesting that these characteristics, if present, would have been likely covered by the volcanic activity that persisted up to 3 billion years ago. Sophisticated instruments like the BepiColombo Laser Altimeter (BELA), to be inserted into orbit around Mercury in early 2026 onboard the European Space Agency’s BepiColombo mission, promise to provide unprecedented data and will be instrumental in precisely measuring Mercury's global topography, contributing to a more accurate understanding of the planet's surface variations. This, in turn, will aid in refining our calculations and representations of Mercury's internal structure and its evolution.

How to cite: Burkhard, L. and Thomas, N.: Insights into Mercury’s tidal stresses: Linking present and past potentials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7623, https://doi.org/10.5194/egusphere-egu24-7623, 2024.

EGU24-7659 | ECS | Posters on site | PS1.2

Hybrid plasma simulation around Mercury: ion counting statistics 

Daniel Teubenbacher, Willi Exner, Yasuhito Narita, Ali Varsani, and Gunter Laky

Understanding Mercury's magnetosphere is a primary goal of the BepiColombo mission. In addition to spacecraft observations, numerical modeling efforts have shown to add invaluable insight to the Hermean magnetic field topology, current systems and plasma distributions. However, existing comparisons between observed and modeled data are predominantly qualitative, lacking quantitative agreement due to diverse mathematical approaches. Notably, quantitative inconsistencies of observed and modeled ion densities and energies are particularly affected. Hence, this study addresses systematic and stochastic deviations, focusing on establishing confidence intervals for "ion counting" within the hybrid AIKEF (Adaptive Ion Kinetic Electron Fluid) model. The kinetic treatment of the ions enables to directly compare model results with observations of the Planetary Ion Camera (PICAM), which is a part of the SERENA suite onboard the BepiColombo mission. Multiple ion counting methods are introduced and evaluated, including a simple sphere method, an omnidirectional method, and a field-of-view method. Our findings demonstrate that applying the field-of-view method to the modeled data, within the derived confidence interval, yields ion velocity distributions consistent with PICAM observations of Mercury’s magnetosheath. The AIKEF model and the developed analysis tools serve as a powerful and convenient method of reproducing the ion and electro-magnetic field profile around Mercury for the BepiColombo mission, both in flyby and in-orbit measurements.

How to cite: Teubenbacher, D., Exner, W., Narita, Y., Varsani, A., and Laky, G.: Hybrid plasma simulation around Mercury: ion counting statistics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7659, https://doi.org/10.5194/egusphere-egu24-7659, 2024.

EGU24-8409 | Orals | PS1.2

First observations of whistler waves in Mercury’s magnetosphere by BepiColombo/Mio spacecraft 

Fouad Sahraoui, Mitsunori Ozaki, Satoshi Yagitani, Yasumasa Kasaba, Yoshiya Kasahara, Shoya Matsuda, Yoshiharu Omura, Mitsuru Hikishima, Laurent Mirioni, Gérard Chanteur, Satoshi Kurita, Satoru Nakazawa, and Go Murakami

Whistler-mode chorus waves are natural electromagnetic emissions known to play a key role in electron acceleration and loss mechanisms via wave–particle interactions in planetary magnetospheres. Chorus waves have not yet been detected in Mercury’s magnetosphere due to the limited capabilities of the instruments onboard the spacecraft that already visited the planet. Here, we present the first detection of chorus waves in the localized dawn sector during the first and second Mercury flybys by the BepiColombo/Mio spacecraft. Mio’s search coil magnetometers measured chorus waves with tens of picotesla intensities in the dawn sector, while no clear wave activity was observed in the night sector. The simulation results suggest that this dawn-dusk asymmetry could be explained by the impact of background magnetic field inhomogeneities on the nonlinear wave generation process. Potential direct comparisons with electron data will be discussed. This observational evidence is crucial for understanding the dynamics of energetic electron in the localized dawn sector of Mercury’s magnetosphere.

How to cite: Sahraoui, F., Ozaki, M., Yagitani, S., Kasaba, Y., Kasahara, Y., Matsuda, S., Omura, Y., Hikishima, M., Mirioni, L., Chanteur, G., Kurita, S., Nakazawa, S., and Murakami, G.: First observations of whistler waves in Mercury’s magnetosphere by BepiColombo/Mio spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8409, https://doi.org/10.5194/egusphere-egu24-8409, 2024.

EGU24-9496 | ECS | Posters on site | PS1.2

Ab-Initio Model for Mercury’s Helium Exosphere 

Jonas Hener, Audrey Vorburger, Peter Wurz, Fabian Weichbold, and Helmut Lammer

In this study, we suggest a model for the origin and abundance of exospheric Helium at Mercury. It was derived ab initio, assuming He-saturated regolith at the surface and a “steady-state” Helium exosphere. A 1D Monte Carlo computer simulation [1] was used to calculate the exospheric He density profiles according to the model.

The Helium abundance in the Hermean exosphere was first constrained from UV Spectrometer measurements aboard Mariner 10 [2] and has been discussed extensively since, also in the light of probable analogies to the Lunar He environment. It is believed that there are two major sources for exospheric Helium: release of Solar Wind implanted He from the regolith of the Hermean surface and outgassing of radiogenic He from the interior [3]. However, there is no agreement on the quantitative contribution of the two possible origins. Through a larger volume and diversity of data, new insights concerning the origins and other aspects of the Hermean Helium system could be derived. Novel approaches are allowing the derivation of Helium density profiles from MESSENGER data [4], and soon the SERENA plasma/neutral particles package [5] on BepiColombo’s Mercury Planetary Orbiter (MPO) is expected to add the first ever in-situ density measurements to the picture.

The presented model shows that the Helium exosphere is dominated by exospheric recycling. This term describes the process in which particles that have been released into the exosphere at energies below Eesc return to the surface and bounce back into the exosphere immediately at the energy corresponding to the local surface temperature. The Helium accumulates in the exosphere, where its abundance is eventually limited by the exospheric loss processes of Jeans escape and ionization. This model can build the foundation for an evaluation of future data and can allow a quantification of the two exospheric Helium sources.

[1] Wurz, P. and Lammer, H. (2003). Icarus 164.1 (2003): 1-13.
[2] Broadfoot, A. L., et al. (1976). Geophys. Res. Lett., 3: 577-580.
[3] Hartle, R. E., et al. (1975),  J. Geophys. Res.,  80(25)
[4] Weichbold, F., et al. (2024), in preparation.
[5] Orsini, S., et al. (2021), Space Sci Rev 217, 11

How to cite: Hener, J., Vorburger, A., Wurz, P., Weichbold, F., and Lammer, H.: Ab-Initio Model for Mercury’s Helium Exosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9496, https://doi.org/10.5194/egusphere-egu24-9496, 2024.

EGU24-9733 | ECS | Posters on site | PS1.2

Influence of the IMF direction on Mercury's magnetosphere 

Kristin Pump, Daniel Heyner, Ferdinand Plaschke, and Willi Exner

Mercury, the smallest and innermost planet of our solar system, is exposed to a strong solar wind. The internal field is dipole-dominated, relatively weak, axisymmetric and significantly offset towards north. Through the interaction with the strong solar wind, this field leads to a comparatively small and dynamic magnetosphere.

To first order the magnetopause completely separates the magnetosphere from the magnetosheath and thus no magnetic field may penetrate this boundary. In reality, the magnetosheath magnetic field may diffuse across the very thin boundary within a finite time.  We first investigate how the magnetosheath magnetic field changes under different IMF conditions and directions. Second, we can investigate the penetration of the magnetic field from the magnetosheath through the magnetopause inside the magnetosphere and obtain the structure of the IMF influence on the Hermean magnetosphere. 

How to cite: Pump, K., Heyner, D., Plaschke, F., and Exner, W.: Influence of the IMF direction on Mercury's magnetosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9733, https://doi.org/10.5194/egusphere-egu24-9733, 2024.

EGU24-10358 | ECS | Orals | PS1.2

Mercury's Helium Exosphere determined by Ion Cyclotron Waves 

Fabian Weichbold, Helmut Lammer, Daniel Schmid, Martin Volwerk, Jonas Hener, Audrey Vorburger, and Peter Wurz

Mariner 10 detected the existence of an exosphere around Mercury in 1974-1975 by remote spectrometric observations during flybys. More than four decades later the MErcury Surface, Space ENvironment, Geochemistry and Ranging (MESSENGER) spacecraft confirmed the existence of the exosphere. So far, the neutral helium (He) number density around Mercury’s exosphere was based on assumptions related to the spectroscopic observations, which are applied to exospheric models to derive an altitude-dependent density profile of the neutral helium around the planet. Here, we present the first on-site measured density profile of He, using in-situ magnetic field measurements from MESSENGER. These data were analyzed for the identification of Ion-Cyclotron Waves (ICWs) that originated from exospheric pick-up He+ ions. The results reveal an extended He-exosphere with a lower surface number density as expected by previous studies. To provide further context, the results are compared with measurements obtained by Mariner 10 and BepiColombo (first flyby), which shows that the measurements of the PHEBUS UV-instrument onboard of the MPO align very well with the determined density from this study.

How to cite: Weichbold, F., Lammer, H., Schmid, D., Volwerk, M., Hener, J., Vorburger, A., and Wurz, P.: Mercury's Helium Exosphere determined by Ion Cyclotron Waves, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10358, https://doi.org/10.5194/egusphere-egu24-10358, 2024.

EGU24-10851 * | Posters on site | PS1.2 | Highlight

BepiColombo Mission Update 

Johannes Benkhoff and Go Murakami

Following its launch, BepiColombo has already performed three flybys at Mercury. The next three flybys at Mercury are time wise very close together and are planned with about four months starting in September 2024. About 10 months after these flybys the orbit insertion preparation will start. When in orbit, BepiColombo with its state of the art and very comprehensive payload will perform measurements to increase our knowledge on the fundamental questions about Mercury’s evolution, composition, interior, magnetosphere, and exosphere.
Although the two BepiColombo spacecraft are in a stacked configuration during the cruise and only some of the instruments can perform scientific observations, the mission produces already some very valuable results. As an example, Mercury’s southern inner magnetosphere, a so far unexplored region, has been observed by the BepiColombo ion and fields instruments during the pass.  Data taken during the Mercury's flybys revealed a magnetosphere populated by diverse populations and confirmed a really dynamic regime. 
BepiColombo is a joint mission between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) for comprehensive exploration of planet Mercury. BepiColombo, has been launched on 20 October 2018 from the European spaceport Kourou in French Guyana and it is currently on a seven-year-long cruise to Mercury. BepiColombo consists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). In late 2025/early 2026 these orbiters will be put in orbit around the innermost planet of our Solar System. 
During the talk a status of the mission and results from science operations during cruise will be presented.

How to cite: Benkhoff, J. and Murakami, G.: BepiColombo Mission Update, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10851, https://doi.org/10.5194/egusphere-egu24-10851, 2024.

EGU24-11148 | Orals | PS1.2

Global occurrences of very smooth plains patches on Mercury: geologic settings and implications for effusive volcanism 

Annie Lennox, David Rothery, Chris Malliband, Matt Balme, Jack wright, and Susan Conway

Introduction:  Large scale effusive volcanism, responsible for most of Mercury's 'smooth plains', is accepted to have ended by ca. 3.5 Ga [1]. We present local occurrences of smooth surfaces, often with the evidence for being topographically ponded. These examples are seldom larger than a few 10s of km across and are characterised by extremely smooth surfaces with a paucity of impact craters. Some of these deposits may provide evidence for a protracted phase of waning effusive volcanism post-3.5 Ga. We present a map of the global occurrences of very smooth plains patches and investigate their implications for the effusive volcanic evolution of Mercury.

Previously reported occurrences: :  During the Mariner 10 era, the partial geological map of H15 was unique in including small very smooth plains (pvs) deposits commonly associated with craters or tectonic features [2]. Similar patches have recently been identified in H10 [3] and an association with tectonic features was discovered (e.g. Calypso, Soya and Enterprise Rupes). Additionally, some patches of very smooth plains have been mapped in the survey of smooth plains deposits < 105 km of Wang et al. [4]. Previous works propose a range of origins which we will explore, namely:

·        Impact-related origin: Either as impact melt or fluidized impact ejecta

·        Small-volume effusive volcanic origin: where the age of such deposits are somewhat contested

Newly Identified occurrences: The global survey so far has identified approximately 500 potential patches, with varying confidence dependent on the degree of textural difference between the patch and surrounding terrain. These occur in a variety of settings, including low-lying areas of both smooth and intercrater plains, associated with craters or tectonic features, or catenae-hosted. Ongoing work involves mapping each patch, exploring emplacement scenarios and analysis of the association between patches and structural weaknesses.

Data and method: We map using NAC (single frame) and WAC (global mosaic) images obtained by MESSENDER’s MDIS. Mapping is carried out on a 116 m/p monochrome primary basemap; high-incidence east and west, and low-incidence angle secondary basemaps; a 665 m/p enhanced color mosaic; and a 665 m/p stereo-derived digital elevation model. Mapping is carried out using ArcGIS Pro. Each image is mapped in the projection most suited to that quadrangle.

 

References: [1] Byrne P. K., et al., (2016). Geophys. Res. Letters. [2] Strom et al., (1990). USGS Astorgeol. Sci. Center [3] Malliband C., et al. (2020). PhD Thesis. [4] Wang et al., (2021). Geophys. Res. Letters.

 

 

How to cite: Lennox, A., Rothery, D., Malliband, C., Balme, M., wright, J., and Conway, S.: Global occurrences of very smooth plains patches on Mercury: geologic settings and implications for effusive volcanism, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11148, https://doi.org/10.5194/egusphere-egu24-11148, 2024.

EGU24-13502 | ECS | Posters on site | PS1.2

Mutual impedance and quasi-thermal noise to measure electron properties at Mercury: merging simulations of the magnetosphere and of the instrumental apparatus 

Pietro Dazzi, Federico Lavorenti, Pierre Henri, and Karine Issautier

Mercury is the only telluric planet of the solar system, apart from Earth, possessing an intrinsic magnetic field. This magnetic field influences the dynamics of the solar wind plasma impinging on the planet, forming a magnetosphere. Mercury’s magnetosphere has been investigated by multiple space missions in the past, notably the NASA Mariner10 and MESSENGER missions, and is today the target of the joint ESA/JAXA BepiColombo mission, currently en route, with orbit insertion scheduled for December 2025. BepiColombo instruments will observe for the first time the electron kinetic physics at Mercury. In order to interpret and plan BepiColombo’s in-situ observations, an interplay is needed between numerical simulations of Mercury’s magnetosphere and instrumental modelling.

In this work, we present a study of the expected instrumental response of the PWI/AM2P and PWI/SORBET experiments onboard BepiColombo, based on a two-step, fully-kinetic numerical approach.

First, we run fully-kinetic, three-dimensional, global simulations of the interaction between Mercury’s magnetic field and the solar wind using the implicit particle-in-cell code iPIC3D. Non-maxwellian electron distribution functions are observed in the simulations.

Second, we use the electron distribution function derived from the previous step as input for a numerical model of the electric antennas used by both the AM2P and SORBET experiments onboard the JAXA Mio craft (part of BepiColombo). The influence of the spacecraft and antennas geometries is included self-consistently in this second step.

Our 3D full-PIC simulations show that magnetic reconnection in the tail accelerates and heats electrons up to energies of few keVs when the interplanetary magnetic field (IMF) is southward. Such high-energy electrons are ejected from the neutral line in the tail planetward in a substorm-like process, leading to strong particle precipitation in the nightside of Mercury, especially at local time 0-6 h. Double Maxwellian electron distribution functions are inferred from the simulations in the nightside of Mercury (with temperature and density ratio of order 10 and 0.1-1, respectively). We investigate the possibility of detecting these two Maxwellian populations using the AM2P and SORBET experiments, operating at Mercury after orbit insertion. We also explore regions where the AM2P experiment can be calibrated in-flight.

How to cite: Dazzi, P., Lavorenti, F., Henri, P., and Issautier, K.: Mutual impedance and quasi-thermal noise to measure electron properties at Mercury: merging simulations of the magnetosphere and of the instrumental apparatus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13502, https://doi.org/10.5194/egusphere-egu24-13502, 2024.

EGU24-15341 | ECS | Posters on site | PS1.2

Variations of Heat Flux and Elastic Thickness of Mercury derived from Thermal Evolution Modeling 

Aymeric Fleury, Ana-Catalina Plesa, Nicola Tosi, Michaela Walterová, and Doris Breuer

The very low obliquity of Mercury causes important surface temperature variations between its polar and equatorial regions [1]. At the same time, its 3:2 spin orbit resonance leads to longitudinal temperature variations [2]. The combination of these two effects creates a peculiar surface temperature distribution with equatorial hot and warm poles, and cold poles at the geographic poles of the planet. Models that considered the insolation pattern were found compatible with the low-degree shape and geoid from MESSENGER [3]. The models of [3] showed that the insolation pattern imposes a long wavelength thermal perturbation throughout the mantle, whose temperature distribution is strongly correlated with the surface temperature variations. In addition to surface temperature variations, lateral variations of crustal thickness can also affect the temperature distribution of the lithosphere and mantle as it was suggested for Mars [4]. With the topography and gravity data from MESSENGER, a series of models of Mercury’s crustal thickness have been derived assuming constant or variable crustal density, based on the composition of the surface [5].

In this study we include crustal thickness and surface temperature variations of Mercury in the geodynamical code GAIA [6], similar to [4]. We tested several crustal thickness models from [5]. All the simulations are carried in a full 3D spherical geometry, use the extended Boussinesq Approximation, and consider core cooling and radioactive decay. We also use a pressure- and temperature-dependent viscosity in the mantle. The crust is  enriched in heat producing elements (HPEs) compared to the depleted mantle according to a fixed enrichment factor. We model the entire thermal evolution of Mercury to determine the variations of surface and core-mantle boundary heat fluxes in addition to the temporal evolution and distribution of the elastic lithosphere thickness.

Our models indicate that the surface temperature variations of Mercury induce a long-wavelength pattern on both the elastic lithosphere thickness and the heat fluxes, while the crustal thickness variations lead to smaller scale variations of the two quantities. Our models show that different geochemical terranes such as the North Volcanic Plains (NVP) or the High Mg-Region [7] could have experienced drastically different thermal histories throughout the evolution of Mercury.

Future data from the BepiColombo mission [8] will provide a better resolution for the gravity and topography of Mercury, as well as measurements of its surface composition. These data could be used to provide additional estimates of the elastic lithosphere thickness and to constrain the time of formation of the associated geological features. This will help to improve our geodynamical models and in turn constrain Mercury’s thermal evolution.

References:

[1] Margot et al., 2012. [2] Siegler et al., 2013. [3] Tosi et al., 2015. [4] Plesa et al., 2018. [5] Beuthe et al., 2020. [6] Hüttig et al., 2013. [7] Weider et al., 2015. [8] Benkhoff et al., 2021.

How to cite: Fleury, A., Plesa, A.-C., Tosi, N., Walterová, M., and Breuer, D.: Variations of Heat Flux and Elastic Thickness of Mercury derived from Thermal Evolution Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15341, https://doi.org/10.5194/egusphere-egu24-15341, 2024.

EGU24-15387 | Posters on site | PS1.2

Updated status of BepiColombo and initial reports on Mercury flyby observations 

Go Murakami and Johannes Benkhoff

The ESA-JAXA joint mission BepiColombo is now on the track to Mercury. After the successful launch of the two spacecraft for BepiColombo, Mio (Mercury Magnetospheric Orbiter: MMO) and Mercury Planetary Orbiter (MPO), commissioning operations of the spacecraft and their science payloads were completed. BepiColombo will arrive at Mercury in the end of 2025, and it has 7-years cruise with the heliocentric distance range of 0.3-1.2 AU. The long cruise phase also includes 9 planetary flybys: once at the Earth, twice at Venus, and 6 times at Mercury. Even before arrival, we already obtained fruitful science data from Mercury during three Mercury flybys completed on 1 October 2021, 23 June 2022, and 19 June 2023. We performed science observations with almost all the instruments onboard Mio and successfully obtained comprehensive data of Mercury’s magnetosphere such as magnetic fields, plasma particles, and waves. Here we present the updated status of BepiColombo/Mio, initial results of the science observations during the Mercury flybys, and the upcoming observation plans.

How to cite: Murakami, G. and Benkhoff, J.: Updated status of BepiColombo and initial reports on Mercury flyby observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15387, https://doi.org/10.5194/egusphere-egu24-15387, 2024.

EGU24-16068 | ECS | Posters on site | PS1.2

First detection of Lithium in Mercury's exosphere 

Daniel Schmid, Helmut Lammer, Martin Volwerk, Fabian Weichbold, Manuel Scherf, Ali Varsani, Owen Wyn Roberts, Cyril Simon-Wedlund, and Ferdinand Plaschke

Mercury has an extended exosphere that consists of various species. Based on theoretical considerations, the existence of Lithium (Li) in the exosphere around Mercury is predicted to be less than 5x107 cm-2. Because these density values are well below the detection limits of remote observation instruments on board past missions, Li has never been directly observed. Here we show the first on-site determined altitude-density profile of atomic Li7, derived from in-situ magnetic field observations by the MESSENGER spacecraft. The results suggest that the source of Li at Mercury is most likely meteoritic ablation. The findings will help to interpret the remote observations of Mercury's exosphere that will be realized in the near future by the BepiColombo mission.

How to cite: Schmid, D., Lammer, H., Volwerk, M., Weichbold, F., Scherf, M., Varsani, A., Roberts, O. W., Simon-Wedlund, C., and Plaschke, F.: First detection of Lithium in Mercury's exosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16068, https://doi.org/10.5194/egusphere-egu24-16068, 2024.

EGU24-17612 | ECS | Posters on site | PS1.2

Seasonal variation of Ca and Ca-bearing molecules in Mercury's exosphere as a product of micro-meteoroids and comet stream particles impact 

Martina Moroni, Anna MIlillo, Alessandro Mura, Christina Plainaki, Valeria Mangano, Alessandro Aronica, Alexey Berezhnoy, Elisabetta De Angelis, Dario Del Moro, Pier Paolo Di Bartolomeo, Adrian Kazakov, Stefano Massetti, Stefano Orsini, Rosanna Rispoli, Roberto Sordini, and Mirko Stumpo

The NASA/MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) mission provided measurements of Mercury’s Ca exosphere, allowing the study of its configuration and its seasonal variations. The observed Ca column densities exhibit a scale height consistent with a temperature > 50,000 K, and with a source located mainly on the dawn-side of the planet. It was suggested that the originating process is due to MMIV (Micro-Meteoroids Impact Vaporization), but previous estimations were not able to justify the observed intensity and energy. The most likely origin of this exospheric element is very probably a combination of different processes involving the release of atomic and molecular surface particles. We use an exospheric Monte Carlo model (Mura et al., 2007) to simulate the 3-D spatial distribution of the Ca-bearing molecule and atomic Ca in the exosphere of Mercury generated by the MMIV process. We investigate the possible pathways to produce the observed Ca exosphere and we discuss about the generating mechanism. Following previous studies, we consider that the atomic Ca in Mercury’s exosphere may be produced in a sequence of different processes: the exospheric energetic Ca component derives from the shock-induced non-equilibrium dissociative ionization and neutralization of Ca+ during the vapor cloud expansion, while a low energy Ca component is generated later by the photo-dissociation of the CaO molecules released by micro-meteoroid impact vaporization. Since the exact temperature, the photolysis lifetimes of the produced molecules and the excess energy during photolysis processes are still not well constrained by observations, we investigate different model assumptions. The theoretical calculations better agree with observations at shorter photolysis lifetimes and higher excess energy of Ca atoms obtained during photolysis of Ca-bearing species. In that case we show the presence of two Ca components: energetic Ca component more intense at high altitudes, and a low energy component in the post-dawn region at low altitudes. The total Ca content obtained through a best fit to the observations shows excess emission near TAA ∼ 25° and TAA ∼150°, which was attributed to the vaporization of surface material induced by the impact of a meteor stream. We investigate the possible contribution due to the comet 2P/Encke for explaining the excess Ca emission at specific orbit positions; the simulation results show some discrepancy when compared to the observations.

How to cite: Moroni, M., MIlillo, A., Mura, A., Plainaki, C., Mangano, V., Aronica, A., Berezhnoy, A., De Angelis, E., Del Moro, D., Di Bartolomeo, P. P., Kazakov, A., Massetti, S., Orsini, S., Rispoli, R., Sordini, R., and Stumpo, M.: Seasonal variation of Ca and Ca-bearing molecules in Mercury's exosphere as a product of micro-meteoroids and comet stream particles impact, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17612, https://doi.org/10.5194/egusphere-egu24-17612, 2024.

EGU24-17752 | Orals | PS1.2

Spectral Modelling the Induction Effect of a Strong CME Hitting Planet Mercury 

Daniel Heyner, Luis Langermann, Kristin Pump, and Sophia Zomerdijk-Russell

Planet Mercury, with its weak internal magnetic field, is continuously exposed to an intense solar wind. This interaction becomes particularly dynamic during coronal mass ejections, resulting in a strong compression of the magnetosphere. Such events drive electrical currents within the planet, which, depending on the planetary conductivity structure, lead to secondary magnetic fields detectable outside. Analysis of these induced fields provides insights into Mercury’s interior structure.
Here, we utilized data from the Helios-1 probe, recorded during a CME at 0.31 AU, to evaluate changes in solar wind conditions and their impact on Mercury's magnetosphere. We applied a semi-empirical model to estimate the external field variations and employed endmembers of radial symmetric conductivity models to calculate the range of induced magnetic fields. Our analysis highlights the influence of these variations on Mercury's upper mantle layers, taking into account both dipolar and quadrupolar components of the magnetic field. Eventually, we predict the potential induced magnetic fields at the future location of the BepiColombo spacecraft, currently en route to Mercury.

How to cite: Heyner, D., Langermann, L., Pump, K., and Zomerdijk-Russell, S.: Spectral Modelling the Induction Effect of a Strong CME Hitting Planet Mercury, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17752, https://doi.org/10.5194/egusphere-egu24-17752, 2024.

EGU24-18499 | ECS | Posters on site | PS1.2

Expected performance of the MORE geodesy experiment during the orbital phase of BepiColombo 

Ariele Zurria, Ivan di Stefano, Paolo Cappuccio, Umberto De Filippis, and Luciano Iess

The BepiColombo spacecraft, designed by ESA/JAXA, is currently in its cruise phase towards Mercury. The Mercury Orbiter Radio-science Experiment (MORE), one of the scientific investigations of the mission, will exploit a multi-frequency microwave tracking system with an advanced Ka-band transponder to fulfill scientific goals in Mercury’s geodesy and fundamental physics. Thanks to the precise measurements enabled by the state-of-the-art radio tracking system, MORE is expected to provide new insights on the planet and its interior, expanding and improving the results of the MESSENGER mission. In this work, we assess the performance of the geodesy investigation conducted by MORE, focusing on the orbital phase, starting in early 2026. In particular, this study evaluates how BepiColombo's refined gravity data can reduce the uncertainty in the estimate of the Love Number k2, rotational state and crustal thickness of Mercury.  We report the results of the numerical simulation based on the up-to-date mission scenario, which consists of a two-year orbital phase. We simulate synthetic radio observables and estimate the model parameters through a precise analysis of the spacecraft orbital motion. We include different sources of mismodelling to reproduce a perturbed dynamical state of the probe, such as errors in the thermo-optical coefficients of the spacecraft, wheel off-loading maneuvers with unbalanced ΔVs and random fluctuations of solar irradiance, which cannot be modelled or measured by the onboard accelerometer. We use the covariance matrix coming from this analysis to perform a Monte Carlo simulation to obtain a set of gravity fields statistically compatible with a reference field (HgM009, derived from a recent reanalysis of the MESSENGER dataset). By combining these gravity fields with available topographic data, we produce a distribution of Mercury’s crustal thickness maps, from which we infer the corresponding estimation uncertainty. We compare the expected accuracies of the BepiColombo gravity experiment with the current state of knowledge. We show that MORE shall fulfill its scientific goals by improving the estimate of the planet’s gravity field, tidal response and rotational state. Our findings demonstrate how the estimate of Mercury’s crustal thickness benefits from BepiColombo’s high precision gravity measurements. The uncertainties derived from our simulation show that MORE will provide a reliable and high resolution basis for associating gravity anomalies with geological surface features on Mercury, such as impact craters, rift zones, and lobate scarps.

How to cite: Zurria, A., di Stefano, I., Cappuccio, P., De Filippis, U., and Iess, L.: Expected performance of the MORE geodesy experiment during the orbital phase of BepiColombo, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18499, https://doi.org/10.5194/egusphere-egu24-18499, 2024.

EGU24-18888 | ECS | Posters on site | PS1.2

Multi-technique investigation of Mercury's southern magnetosphere based on BepiColombo first swingbys 

Léa Griton, Willi Exner, Daniel Heyner, Ahmed Houeibib, Karine Issautier, Yasumasa Kasaba, Hirotsugu Kojima, Michel Moncuquet, and Filippo Pantellini

The recent swingbys of Mercury by BepiColombo were the first ones ever to pass through the southern magnetosphere, revealing unseen signatures in observational data.

Our electron instrument SORBET/PWI can be used to identify signatures of boundary crossings, such as shock, magnetopause, but also trapped plasma population on closed magnetic field lines in the night side. To bring the observations along the swingbys into a global magnetospheric context, we employ the global 3D magnetohydrodynamic and hybrid models ARMVAC_PLANET (Lesia, l’Observatoire de Paris) and AIKEF (TU Braunschweig/ESA). A new step consists of injecting test particles (especially electrons) in the MHD simulations.

Exploring Mercury's magnetosphere is important both for modeling Mercury's intrinsic magnetic field and for recovering the properties of the upstream IMF once the probe is inside the magnetosphere. These latest results are a major asset for future coordinated observations planned for BepiColombo two spacecraft.

How to cite: Griton, L., Exner, W., Heyner, D., Houeibib, A., Issautier, K., Kasaba, Y., Kojima, H., Moncuquet, M., and Pantellini, F.: Multi-technique investigation of Mercury's southern magnetosphere based on BepiColombo first swingbys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18888, https://doi.org/10.5194/egusphere-egu24-18888, 2024.

EGU24-19987 | Posters on site | PS1.2

Bursty reconnection during BepiColombo's third Mercury flyby 

Ali Varsani, Daniel Schmid, Helmut Lammer, Rumi Nakamura, Kristin Pump, Daniel Heyner, Gunter Laky, Harald Jeszenszky, Gabriel Giono, Martin Volwerk, Anna Milillo, Stefano Orsini, David Fischer, Werner Magnes, Wolfgang Baumjohann, and Ayako Matsuoka

Mercury is known to possess a Magnetosphere that is highly responsive to the upstream Solar Wind conditions. Previous studies using MESSENGER data have contributed to understanding the dynamics of Mercury's respond to the upstream. However, the interactions between the Magnetospheric plasma and the Solar Wind is yet to be fully understood; and it is indeed one of the main focuses of the ESA/JAXA's current mission, BepiColombo. We report the observations of BepiColombo's flyby-3 at Mercury on 19th June 2023, using ion data from SERENA-PICAM and magnetic field data from MAG/MGF instruments. The preliminary analyses have given an insight into the rapidly changing plasma, at the inbound Magnetopause crossing. There is evidence that bursty reconnection could be the main contributor to such dynamic boundary.

How to cite: Varsani, A., Schmid, D., Lammer, H., Nakamura, R., Pump, K., Heyner, D., Laky, G., Jeszenszky, H., Giono, G., Volwerk, M., Milillo, A., Orsini, S., Fischer, D., Magnes, W., Baumjohann, W., and Matsuoka, A.: Bursty reconnection during BepiColombo's third Mercury flyby, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19987, https://doi.org/10.5194/egusphere-egu24-19987, 2024.

EGU24-20477 | Posters on site | PS1.2

The non-axial dipolar magnetic field of Mercury 

Zhaojin Rong

Here,  we use a state-of-art method to diagnose the Mercury’s dipolar field which is assumed to originate from a magnetic dipole. This method can effectively separate and solve the dipole parameters, and gives the error of how much the dataset of sampled magnetic field deviated from the dipole field . By employing this method and the MESSENGER field data, the derived optimum dipole parameters demonstrated that the dipole center is at [x=5.0;y=-16.0;z=480.5]km, the dipole moment is about M=2.5*10^19 nA.m^2 (or 172 nT*RM^-3), the dipole tilt angle is 3.7 degree. Our yielded dipole moment is weaker than that estimated in previous studies. We compared and discussed with previous studies.

How to cite: Rong, Z.: The non-axial dipolar magnetic field of Mercury, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20477, https://doi.org/10.5194/egusphere-egu24-20477, 2024.

EGU24-20823 | ECS | Posters on site | PS1.2

Strofio Operations: A New Molecular Beam Facility 

Jared Schroeder, Stefano Livi, Edward Patrick, and John Turner

We will present the design and establishment of a cutting-edge molecular beam facility at Southwest Research Institute (SwRI). The primary focus of this facility is to support the operations of Strofio, the neutral mass spectrometer and payload of the BepiColombo mission. Testing of this instrument requires a molecular beam with an average speed of 3 km/s. Beyond serving the immediate needs of Strofio, our vision extends to collaborative efforts with other organizations in the development of future instrumentation. We look forward to fostering partnerships that will collectively advance the capabilities of in-situ particle instruments and contribute to the broader scientific community.

How to cite: Schroeder, J., Livi, S., Patrick, E., and Turner, J.: Strofio Operations: A New Molecular Beam Facility, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20823, https://doi.org/10.5194/egusphere-egu24-20823, 2024.

EGU24-21257 | Orals | PS1.2

Measuring the tidal deformation of Mercury through co-registration of MLA profiles 

Haifeng Xiao, Alexander Stark, Pedro J. Gutierrez, and Luisa M. Lara

We focus on the radial deformation of planet Mercury during its orbital period due to tidal forces exerted by the Sun. Bertone et al. (2021) obtained the first measurement of the tidal Love number h2 of Mercury via least squares minimization of height discrepancies at the cross-overs of the profiles obtained by the Mercury Laser Altimeter (MLA) onboard NASA’s MESSENGER spacecraft. However, height discrepancies at cross-overs, intersection points of profiles, can suffer from significant interpolation errors when the separation of consecutive footprints is large and the underlying terrain is rough. Here, we re-analyze the MLA profiles using new techniques of co-registration analysis that also include a post-correction procedure based on pseudo cross-overs. We have successfully applied these techniques to obtain the spatio-temporal thickness variations of the seasonal deposits on Martian poles (Xiao et al., 2022a, 2022b). Provided that a reference DTM is available, any particular pair of profile segments forms a pseudo cross-over. The height misfit at a pseudo cross-over is assigned as the difference in height corrections in the co-registrations of the profile pair, that form the pseudo cross-over, to the underlying reference DTM. Pseudo cross-overs can have great advantages over real cross-overs: (1) Lateral shifts of the profiles can be naturally compensated and interpolation errors avoided through the co-registration process in forming the height misfits at the pseudo cross-overs; (2) Since the profile segments do not necessarily have to intersect, the available number of "cross-overs" is normally multiplied in number; (3) Furthermore, the profile segment pair forming a pseudo cross-over can be widely separated across the research region, offering "global" constraints on the adjustment. For the uncertainty and sensitivity quantification, we create synthetic MLA observations by adding realistic errors and tidal deformation assuming an a priori tidal h2 and invert for the tidal h2 using the proposed techniques. Our measurement of tidal h2, combined with refined determination of the tidal potential Love number k2 from radio science experiments, will be used to discuss updated bounds of interior structure parameters of Mercury, especially the inner core size, which will improve our understanding of its thermal evolution and magnetic dynamo.

Bertone et al. (2021). JGR: Planets, 126(4), e2020JE006683.
Xiao et al. (2022a). PSS, 214, 105446.
Xiao et al. (2022b). JGR: Planets, 127(10), e2021JE007158.

How to cite: Xiao, H., Stark, A., Gutierrez, P. J., and Lara, L. M.: Measuring the tidal deformation of Mercury through co-registration of MLA profiles, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21257, https://doi.org/10.5194/egusphere-egu24-21257, 2024.

EGU24-3129 | ECS | Orals | PS1.3

 Viscosity of Venus' mantle as inferred from its rotational state 

Yann Musseau, Caroline Dumoulin, Gabriel Tobie, Cédric Gillmann, Alexandre Revol, and Emeline Bolmont

Venus' rotation is the slowest of all planetary objects in the solar system and the only one in the retrograde direction. It is commonly admitted that such a rotation state is the result of the balance between the torques created by the gravitational and atmospheric thermal tides1. The internal viscous friction associated with gravitational tides drive the planet into synchronization (deceleration) while the bulge due to atmospheric thermal tides tend to accelerate the planet out of this synchronization1,6. Other torque components (related to the two first one) also affect the rotation2. This work first provide an estimate of the viscosity of Venus' mantle explaining the current balance with thermal atmospheric forcing. Second, this study quantify the impact of the internal structure and its past evolution on the gravitational tides and thus on the rotation history of Venus. Using atmospheric pressure simulations from the Venus climate database4,5,7, we first estimated the atmospheric thermal torque and showed that topography and interior response to atmospheric loading, usually ignored in previous studies, have a strong influence on the amplitude of thermal atmospheric torque. Computing the viscoelastic response of the interior to gravitational tides and atmospheric loading3, we showed that the current viscosity of Venus' mantle must range between 2.3x1020 Pa.s and 2.4x1021 Pa.s to explain the current rotation rate as an equilibrium between torques. We then evaluated the possible past evolution of the viscosity profile of the mantle considering different simple thermal evolution scenarios.  We showed that in absence of additional dissipation processes, viscous friction in the mantle cannot slowdown the rotation to its current state for an initial period shorter than 2-3 days, even for an initially very hot mantle. Beyond Venus, these results has implications for Earth-size exoplanets indicating that their current rotation state could provide key insights on their atmosphere-interior coupling.

1Correia, A. C. M. and J. Laskar (2001), Nature.
2Correia, A. C. M. (2003), Journal of Geophysical Research.
3Dumoulin, C., G. Tobie, O. Verhoeven, P. Rosenblatt and N. Rambaux (2017), Journal of Geophysical Research.
4Lebonnois, S., F. Hourdin, V. Eymet, A. Crespin, R. Fournier and F. Forget (2010),  Journal of Geophysical Research.
5Lebonnois, S., N. Sugimoto and G. Gilli (2016), Icarus.
6Leconte, J., H. Wu, K. Menou and N. Murray (2015), Science.
7Martinez, A., S. Lebonnois, E. Millour, T. Pierron, E. Moisan, G. Gilli and F. Lefèvre (2023), Icarus.

How to cite: Musseau, Y., Dumoulin, C., Tobie, G., Gillmann, C., Revol, A., and Bolmont, E.:  Viscosity of Venus' mantle as inferred from its rotational state, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3129, https://doi.org/10.5194/egusphere-egu24-3129, 2024.

EGU24-4022 | Posters on site | PS1.3

Ground-based thermal mapping of Venus:  HDO and SO2 monitoring and upper limits of NH3, PH3 and HCN at the cloud top 

Therese Encrenaz, Thomas Greathouse, Rohini Giles, Thomas Widemann, Bruno Bezard, Franck Lefevre, Maxence Lefevre, Wencheng Shao, Hideo Sagawa, Emmanuel Marcq, and Anicia Arredondo

As part of a long-term monitoring program, full disk thermal maps of HDO (near 7 microns) and SO2 (near 7 and 19 microns) have been obtained at the cloud top of Venus in 2023, using the TEXES(Texas Echelon Cross-Echelle Spectrograph)  imaging spectrometer at the Infrared Telescope Facility (IRTF) at Mauna Kea Observatory. Assuming a constant D/H isotopic ratio, the water abundance has been more or less constant since 2018, at about half its value in 2012-2016. In contrast, the SO2 abundance, which was very high in 2018-2019 and very low between July 2021 and March 2023, has increased by a factor of about 5 between February and July 2023 (close to its maximum level of 2018-2019), and has remained at its high level in September 2023. The origin of these long-term variations is still unclear. In addition, stringent upper limits of NH3 (at 927-931 cm-1), PH3 (at 1161-1164 cm-1) and HCN at 744-748 cm-1) at the cloud top have been obtained in July 2023. These results will be presented and discussed.

How to cite: Encrenaz, T., Greathouse, T., Giles, R., Widemann, T., Bezard, B., Lefevre, F., Lefevre, M., Shao, W., Sagawa, H., Marcq, E., and Arredondo, A.: Ground-based thermal mapping of Venus:  HDO and SO2 monitoring and upper limits of NH3, PH3 and HCN at the cloud top, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4022, https://doi.org/10.5194/egusphere-egu24-4022, 2024.

Coronae are crown-like, tectono-volcanic features found on Venus that typically range in diameter from 100-700 km. Diapirs of warm upwelling material impinging on the lithosphere are often invoked to explain coronae formation. With more than 500 coronae identified on the surface of Venus, if these diapirs are individually linked to a mantle plume, Venus must have a very different mantle structure than Earth. I consider three cases designed to assess the potential relationship between large-scale, long-wavelength lower mantle structure and smaller-scale upper mantle structure that could potentially form diapirs consistent with those that are envisioned to interact with the lithosphere and form coronae. I use the geoid and topography to identify the large-scale pattern of convection because the geoid contains and integral of the temperature anomalies over the depth of the mantle. Plume tails—narrow vertical conduits—integrate to give a positive geoid anomaly while small-scale, time-dependent drips or upwellings are minimized in the depth integration. The first case—the reference case—has a small, stepwise decreases in viscosity between the lower mantle (1022 Pa s), transition zone (1021 Pa s), and upper mantle (5x1020 Pa s) with no phase transformations. This led to 20 ~1000-km diameter mantle plumes that remained stationary for more than 1.5 Gyr. This calculation is consistent with a number of geophysical observations it does not support the formation of coronae by plume-lithosphere interaction. To decouple the lower and upper mantle, I further decrease both the upper mantle and transition zone viscosities to 1020 Pa s while leaving all other parameters unchanged. In this calculation the same 20 ~1000-km diameter mantle plumes formed and remained stationary for more than 1.5 Gyr. The geoid and topography are anti-correlated, inconsistent with the observed values on Venus and, the spatial scale, number, and topographic evolution of the plumes are not consistent with coronae. This calculation does not support the formation of coronae by plume-lithosphere interaction. In an attempt to further decouple the upper and lower mantle I add an endothermic phase transformation at the ringwoodite-bridgmanite boundary in addition to the decreased upper mantle and transition zone viscosities while leaving all other parameters unchanged. Unique to this calculation, a very large number of ~100-km diameter small topographic upwellings form some associated with the large-scale geoid high but never associated with the large-scale geoid low. The inclusion of a phase transformation decoupling the upper and lower mantle has the potential to create diapir-like structures in the upper mantle consistent with coronae formation.

How to cite: King, S.: Linking global-scale mantle flow with diapir-like coronae formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5857, https://doi.org/10.5194/egusphere-egu24-5857, 2024.

EGU24-5946 | ECS | Posters on site | PS1.3

Thermal evolution and magmatic history of Venus 

Carianna Herrera, Ana-Catalina Plesa, Julia Maia, Stephan Klemme, and Lauren Jennings

The recent analysis of radar data from NASA’s Magellan mission suggests that volcanic activity is ongoing on Venus [1], providing unprecedented evidence that Venus’s evolution and present day state has been dominated by volcanic processes. Venus’s geodynamics and tectonics seem to be well characterized by the so-called “plutonic squishy lid” regime, where part of the melt that is formed in the interior rises to the surface but a significant part remains trapped in the crust and lithosphere forming intrusions [2]. These intrusions strongly influence the mantle’s thermal evolution, heat flow, and the present-day thermal state of the subsurface.

This study focuses on the effects of intrusive magmatism on the lithosphere thickness and thermal gradient. The latter is used to evaluate our models by comparing our results to estimates based on studies of the elastic lithosphere thickness [3,4,5]. We use the geodynamic code Gaia in a 2D spherical annulus geometry [6]. Our models vary the intrusive to extrusive ratio from a fully intrusive case to a fully extrusive one and the intrusive melt depth from 10 km to 90 km.

Our models show that depending on the percentage of extrusive melt and the depth of magmatic intrusions, the maximum thermal gradient varies from a few K/km up to almost 40 K/km at present day, with higher values obtained for higher percentages of intrusive melt and shallower the magmatic intrusions. Moreover, our results show that the thermal gradients have remained similar during the last 750 Myr. Models in which the extrusive magmatism is higher than 60% and the depth of magmatic intrusions lies deeper than 50 km cannot explain high local thermal gradients as suggested by studies of elastic lithosphere thickness [3,4,5].

In a recent study [7], the presence of a low viscosity layer (LVL) in the shallow Venusian mantle has been suggested to be related to the presence of partial melt. The LVL starts beneath the lithosphere at depths shallower than 200 km. This places constraints on the depth of melting that we can use to select successful models. Models that are compatible with partial melting starting at depth of 200 km or less beneath the surface require less than 40% extrusive magmatism and an intrusive melt depth strictly higher than 10 km.

We use our models to estimate ranges for melting conditions in the interior at present day. The range of melt temperatures lies between 2000 and 2250 K and the depth of melting between ~200 and 360 km. These estimations serve as a starting point for and will be compared with high-pressure-high-temperature laboratory experiments that will be performed at the University of Münster to select the most likely mantle compositions of Venus that can explain the Venera and Vega data.

References:

[1] Herrick & Hensley, Science, 2023. [2] Rolf et al., SSR, 2023. [3] Smrekar et al., Nature Geoscience, 2023. [4] Borelli et al., JGR, 2021. [5] Maia et al., JGR, 2022. [6] Hüttig et al., PEPI, 2013. [7] Maia et al., GRL, 2023.

How to cite: Herrera, C., Plesa, A.-C., Maia, J., Klemme, S., and Jennings, L.: Thermal evolution and magmatic history of Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5946, https://doi.org/10.5194/egusphere-egu24-5946, 2024.

EGU24-7533 | ECS | Orals | PS1.3

Breaking New Ground in Venusian Atmospheric Sulfur Chemistry 

Benjamin Frandsen and Robert Skog

The Venusian atmosphere has rich and diverse chemistry and much of it remains to be explored. Here I present our recent work in identifying new reactions and quantifying their rate constants, along with UV-Vis spectral simulation using quantum chemistry calculations. The research focuses on elemental sulfur allotropes and sulfur oxides. Our UV-Vis spectral simulations are used to narrow the search of the unknown UV absorber by excluding molecules/isomers/conformers without the appropriate absorption and similarly include those with absorption profiles that fit the unknown absorber. Furthermore, we present a mechanism for how substituted sulfuric acid molecules can be formed in the Venusian atmosphere which can impact aerosol formation.

How to cite: Frandsen, B. and Skog, R.: Breaking New Ground in Venusian Atmospheric Sulfur Chemistry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7533, https://doi.org/10.5194/egusphere-egu24-7533, 2024.

EGU24-8135 | ECS | Posters on site | PS1.3

Investigating the volcanic activity on Venus with Magellan data 

Davide Sulcanese, Giuseppe Mitri, and Marco Mastrogiuseppe

Previous studies have inferred volcanic activity on Venus from indirect evidence, including variations in atmospheric composition and thermal emissivity data [1, 2, 3]. More recently, a study hypothesized ongoing volcanic activity on Venus, evidenced by a volcanic vent that collapsed between two different Magellan observing cycles [4]. Expanding upon this premise, we are investigating the surface geology of Venus using the extensive radar and altimetric data acquired by the Magellan spacecraft.

In particular, by properly processing the SAR images, we are conducting a detailed geomorphological analysis of Venus' surface, in order to identify and characterize various surface morphologies. Additionally, the altimetric data provided valuable insights into the topographical variations across Venus, further contributing to the geomorphological assessment.

Our research not only enhances the understanding of the geology of Venus but also underscores the significance of radar imaging in the study of planetary surfaces, where no other imaging techniques are available. The findings highlight the crucial role of continued exploration of Venus, which could be greatly advanced by upcoming missions such as VERITAS and EnVision [5, 6]. Equipped with superior radar technology, these missions are expected to provide images of Venus's surface at an unprecedented resolution and signal-to-noise ratio, far surpassing that of the Magellan SAR, thus enabling a more detailed characterization of Venus's surface morphology.

 

References

1. Truong, N. & Lunine, J. Volcanically extruded phosphides as an abiotic source of Venusian phosphine. Proceedings of the National Academy of Sciences 118, e2021689118 (2021).

2. Esposito, L. W. Sulfur dioxide: Episodic injection shows evidence for active Venus volcanism. Science 223, 1072-1074 (1984).

3. Smrekar, S. E. et al. Recent hotspot volcanism on Venus from VIRTIS emissivity data. Science 328, 605-608 (2010).

4. Herrick, R. R. & Hensley, S. Surface changes observed on a Venusian volcano during the Magellan mission. Science, eabm7735 (2023).

5. Hensley, S. et al. VISAR: Bringing Radar Interferometry to Venus. In Proceedings of International EnVision Venus science workshop, Berlin, Germany (2023).

6. Ghail, R. C. et al. VenSAR on EnVision: Taking earth observation radar to Venus. International journal of applied earth observation and geoinformation 64, 365-376 (2018).

Acknowledgments

G.M., D.S., and M.M. acknowledge support from the Italian Space Agency (2022-15-HH.0).

How to cite: Sulcanese, D., Mitri, G., and Mastrogiuseppe, M.: Investigating the volcanic activity on Venus with Magellan data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8135, https://doi.org/10.5194/egusphere-egu24-8135, 2024.

EGU24-8798 | ECS | Posters on site | PS1.3

Simulating UV-VIS Spectra for Polysulfur Species in the Venusian Atmosphere 

Robert Skog, Benjamin Frandsen, and Theo Kurtén

The Venusian atmosphere has everything to be an exciting natural sulfur laboratory. In addition to relatively high concentrations of sulfur dioxide, suitable conditions in the atmosphere make both thermo- and photochemical reactions possible, allowing for complex chemical reactions and the formation of new sulfur containing compounds. These compounds could explain or contribute to the enigmatic 320-400 nm absorption feature in the atmosphere. One of the proposed absorbers is polysulfur compounds. While some experimentally obtained UV-VIS spectra have been published, studying the different polysulfur species individually is extremely difficult due to the reactive nature of sulfur. In this work UV-VIS spectra for polysulfur species S2 to S8 were simulated using the nuclear ensemble approach to determine if they fit the absorption profile of the unknown absorber.

Geometries were optimized at the ωB97X-D/aug-cc-pV(T+d)Z level of theory, with the S2, S3, and S4 structures also being optimized at the CCSD(T)/aug-cc-pV(T+d)Z level of theory. For the lowest energy isomers UV-VIS spectra were simulated using a nuclear ensemble of 2000 geometries, with vertical excitations calculated at the EOM-CCSD/def2-TZVPD or the ωB97X-D/def2-TZVPD levels of theory.

The simulated UV-VIS spectra for the smaller species were in quite good agreement with experimental results. Two different molecules were identified with substantial absorption cross sections in the range of the unknown absorber: The open chain isomer of S3, and the trigonal isomer of S4 However, the mixing ratios of these species in the Venusian atmosphere are also needed to make a more conclusive statement. Other polysulfur compounds have insignificant absorption cross sections in the 320-400 nm range and can therefore be excluded.

The calculated absorption cross sections can be used to calculate photolysis rates, which can be straight away added to atmospheric models of Venus. In addition, this work will help future space missions to Venus, for example by focusing their search for the unknown absorber.

How to cite: Skog, R., Frandsen, B., and Kurtén, T.: Simulating UV-VIS Spectra for Polysulfur Species in the Venusian Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8798, https://doi.org/10.5194/egusphere-egu24-8798, 2024.

EGU24-9470 | ECS | Orals | PS1.3

Influence of Possible Bulk Compositions on the Long-Term Evolution and Outgassing of Venus 

Diogo Louro Lourenço, Paul Tackley, Tobias Rolf, Maria Grünenfelder, Oliver Shah, and Ravit Helled

Venus’ mass and radius are similar to those of Earth. However, Venus’ interior structure and chemical composition are poorly constrained. Seemingly small deviations from the Earth might have important impacts in the long-term evolution and dynamics of Venus when compared to our planet and could help to explain the different present-day surface and atmospheric conditions and geophysical activity between these two planets. Shah et al. (ApJ 2022) presented a range of possible bulk compositions and internal structures for Venus. Their models, designed to fit Venus’ moment of inertia and total mass, predict core radii ranging from 2930-4350 km and include substantial variations in mantle and core composition. In this study, we pick ten different Venus models from Shah et al. (ApJ 2022) that range from a small to a big, and from a S-free to a S-rich core. We run mantle convection evolution models for the different scenarios using the code StagYY (Tackley, PEPI 2008; Armann and Tackley, JGR 2012) and explore how different interior structures and chemical compositions affect the long-term evolution and dynamics of Venus. In our models, the bulk composition of the mantle affects the basalt fraction and the solidus and liquidus temperature profiles. We investigate how the composition and size of the core affects magmatism hence outgassing of water and other volatiles to the atmosphere, the basalt distribution, heat flow, temperature of the mantle and lithosphere, and observables such as the moment of inertia and Love numbers. Since the tectonic regime active on Venus is still unknown, we test different evolution scenarios for a planet covered by a stagnant lid, an episodic lid, and a plutonic-squishy lid. The models produce a range of predictions that can be compared to observations by planned missions to Venus, including EnVision measurements by the VenSpec spectrometers, comprising outgassing of water and other volatiles and surface composition. These can be used to constrain Venus’ interior composition and structure, and reveal key information on the differences between Earth and Venus.

How to cite: Louro Lourenço, D., Tackley, P., Rolf, T., Grünenfelder, M., Shah, O., and Helled, R.: Influence of Possible Bulk Compositions on the Long-Term Evolution and Outgassing of Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9470, https://doi.org/10.5194/egusphere-egu24-9470, 2024.

EGU24-10478 | ECS | Orals | PS1.3

Cloud radiative feedback on the Venus climate simulated by a General-Circulation Model 

Wencheng Shao, Joao Mendonca, and Longkang Dai

Venus has regained great interest from planetary scientists in recent years because of the multiple upcoming Venus missions (e.g., EnVision, DAVINCI+ and VERITAS). Studying Venus is crucial for understanding the evolution of terrestrial planets as well as projecting the Earth’s future. One important component of the Venus climate system, the sulfuric acid clouds, has exhibited spatial and temporal variabilities. These variabilities are closely connected with the interactions between dynamics, photochemistry, radiative transfer and cloud physics. Current modeling studies of the Venus atmosphere have shed light on the underlying physics of the cloud variabilities. However, none of them has resolved the cloud radiative feedback. As an essential step to fully understanding the complex interactions, we develop a state-of-the-art General-Circulation Model (GCM), with cloud condensation/evaporation and radiative feedback processes included. In this talk, I will quantify the radiative forcing caused by the acidic clouds and provide indications of how the radiative forcing can influence the Venus climate evolution.

How to cite: Shao, W., Mendonca, J., and Dai, L.: Cloud radiative feedback on the Venus climate simulated by a General-Circulation Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10478, https://doi.org/10.5194/egusphere-egu24-10478, 2024.

EGU24-10655 | ECS | Posters on site | PS1.3

Unraveling Venus's Atmospheric Composition: Insights into CO, H2O, and OCS Abundances through Observations and Modeling 

Ting-Juan Liao, Eliot Young, Mark Bullock, dave crisp, and Yuk Yung

The investigation into Venus's atmosphere has highlighted deficiencies in photochemical models when it comes to explaining the distribution of trace gas species, particularly crucial elements like CO and OCS, which play a vital role in Venus's sulfur cycle and cloud formation.

To gain a comprehensive understanding of the abundance and variability of these trace gases ahead of the DaVinci probe's descent, we initiated an observational study using NASA's IRTF telescope equipped with the high-resolution ISHELL spectrometer. Conducted from June 11 to June 30, 2023, our study involved capturing K, H, and J-band spectra of Venus's night side. We employed the SMART software to calculate synthetic spectra, considering various gas abundances and emission angles.

With our high-resolution spectral data (R=λ/Δλ~25,000), we successfully mapped the abundances of CO, H2O, and OCS in the equatorial region, revealing both daily and latitudinal variations. Our focus was on examining the delicate balance between chemistry and transport, evident in the observed anti-correlation between OCS and CO abundance with cloud opacity.

Through near-infrared observations, this study aims to unravel the intricate interplay between atmospheric dynamics and chemical reactions in Venus's cloud formation. By providing insights into observed cloud patterns and elucidating the relationship between atmospheric chemistry, dynamics, and cloud creation on Venus, we contribute crucial parameters to refine existing photochemical models.

How to cite: Liao, T.-J., Young, E., Bullock, M., crisp, D., and Yung, Y.: Unraveling Venus's Atmospheric Composition: Insights into CO, H2O, and OCS Abundances through Observations and Modeling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10655, https://doi.org/10.5194/egusphere-egu24-10655, 2024.

EGU24-12316 | ECS | Posters on site | PS1.3

The link between internal and rotational dynamics of Venus: The amplitude of mantle convection-driven wobble 

Vojtěch Patočka, Julia Maia, and Ana-Catalina Plesa

The spin period of Venus is anomalously large. With one Venusian day being 243 Earth days, the rotational bulge of
Venus has the amplitude of only tens of centimetres, making the Earth’s hotter twin the least rotationally stable planet in
the Solar System. Being a slow-rotator creates a unique link between internal and rotational dynamics. This is because,
on a slow-rotator, convection driven redistribution of mass may produce perturbations of the body’s inertia tensor that
are comparable in amplitude with the inertia of the rotational bulge. Venus thus may respond to mantle convection by
wobbling (Spada et al., 1996), and wobbling is detectable when both the rotational and the figure axes are measured
accurately. The present-day estimate of the angle between the two axes is 0.5°, but it is based on gravity models with a
limited resolution (Konopliv et al., 1999). Future missions to Venus, namely VERITAS and EnVision, are likely to provide
a more robust measurement.

The geodynamic regime of Venus’ mantle remains enigmatic. Observational data does not support the existence of
continuous plate tectonics on its surface, but some recent evidence of ongoing tectonic and volcanic activity (e.g. Herrick
and Hensley, 2023) and crater statistics analyses (e.g. O'Rourke et al., 2014) indicate that the planet is unlikely to be in a
stagnant lid regime (see also Rolf et al., 2022). Here we perform 3D spherical mantle convection simulations of the different
possible tectonic scenarios and compute the resulting reorientation of Venus. The reorientation is accompanied by a wobble
whose average amplitude we evaluate and compare to the present day estimate of 0.5° (Konopliv et al., 1999). Since the
different convective regimes predict vastly different rotational dynamics, the comparison provides a useful constraint on
the interior dynamics of Venus. This work was supported by the Czech Science Foundation through project No. 22-20388S.

References
Herrick, R., Hensley, S., 2023. Surface changes observed on a venusian volcano during the magellan mission. Science
doi:10.1126/science.abm7735.

Konopliv, A., Banerdt, W., Sjogren, W., 1999. Venus gravity: 180th degree and order model. Icarus 139, 3–18.
doi:10.1006/icar.1999.6086.

O'Rourke, J.G., Wolf, A.S., Ehlmann, B.L., 2014. Venus: Interpreting the spatial distribution of volcanically modified
craters. Geophys. Res. Lett. 41, 8252–8260. doi:10.1002/2014gl062121.

Rolf, T., Weller, M., Gulcher, A., Byrne, P., O’Rourke, J.G., Herrick, R., Bjonnes, E., Davaille, A., Ghail, R., Gillmann,
C., Plesa, A.C., Smrekar, S., 2022. Dynamics and evolution of venus’ mantle through time. Space Science Reviews 218,
70. doi:10.1007/s11214-022-00937-9.

Spada, G., Sabadini, R., Boschi, E., 1996. Long-term rotation and mantle dynamics of the Earth, Mars, and Venus.
J. Geophys. Res. Planets 101, 2253–2266. doi:10.1029/95JE03222.

How to cite: Patočka, V., Maia, J., and Plesa, A.-C.: The link between internal and rotational dynamics of Venus: The amplitude of mantle convection-driven wobble, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12316, https://doi.org/10.5194/egusphere-egu24-12316, 2024.

EGU24-12790 | ECS | Posters on site | PS1.3

Seismicity on Venus: optimal detection methods and target regions 

Iris van Zelst, Barbara De Toffoli, Raphaël F. Garcia, Richard Ghail, Anna J. P. Gülcher, Anna Horleston, Taichi Kawamura, Sara Klaasen, Maxence Lefevre, Philippe Lognonné, Julia Maia, Sven Peter Näsholm, Mark Panning, Ana-Catalina Plesa, Leah Sabbeth, Krystyna Smolinski, Celine Solberg, and Simon Stähler

With the selection of multiple missions to Venus by NASA and ESA that are planned to launch in the coming decade, we will greatly improve our understanding of Venus. However, none of these missions have determining the seismicity of the planet as one of their primary objectives. Nevertheless, constraints on the seismicity remain crucial to understand the tectonic activity and geodynamic regime of the planet and its interior structure. 

Funded by the International Space Science Institute (ISSI) in Bern, Switzerland, we have gathered an interdisciplinary team of experts in seismology, geology, and geodynamics to assess the potential seismicity of Venus, specific regions that could be seismically active at present, and the methods to detect them.

Here, we present the findings from our second ISSI team meeting (January 29 - February 2, 2024), aiming to review knowledge on Venus's seismicity and interior and identify the best approaches for future missions. We present the feasibility, advantages, and disadvantages of different seismic observation techniques on the surface (e.g., broadband seismometers, distributed acoustic sensing methods), from a balloon (acoustic sensors), and from orbit (airglow imagers). We make a recommendation for the instrumentation of a future seismology-focused mission to Venus. 

We also suggest target regions with a high likelihood of significant surface deformation and/or seismicity. These targets are useful for the upcoming VERITAS (Venus Emissivity, Radio Science, InSAR, Topography and Spectroscopy) and EnVision missions and would specifically benefit from the repeat pass interferometry of VERITAS, which detects surface deformation and can therefore in principle constrain the maximum displacement of surface faulting at locations that are visited twice during the mission. 

How to cite: van Zelst, I., De Toffoli, B., Garcia, R. F., Ghail, R., Gülcher, A. J. P., Horleston, A., Kawamura, T., Klaasen, S., Lefevre, M., Lognonné, P., Maia, J., Näsholm, S. P., Panning, M., Plesa, A.-C., Sabbeth, L., Smolinski, K., Solberg, C., and Stähler, S.: Seismicity on Venus: optimal detection methods and target regions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12790, https://doi.org/10.5194/egusphere-egu24-12790, 2024.

EGU24-13314 | ECS | Posters on site | PS1.3

Estimation of Venus' atmospheric density through EnVision precise orbit determination 

Anna Maria Gargiulo, Antonio Genova, Flavio Petricca, Edoardo Del Vecchio, Simone Andolfo, Tommaso Torrini, Pascal Rosenblatt, Sébastien Lebonnois, Jean-Charles Marty, and Caroline Dumoulin

EnVision radio science investigation will deepen our understanding of Venus’ gravity, interior structure and atmospheric properties. To address these scientific questions, a two-way link communication (configuration X/X/Ka-band) is established with the ESA ESTRACK ground stations enabling precise orbit determination (POD) during the science phase. An accurate modeling of the spacecraft’s dynamics, including the atmospheric drag acceleration, is key for retrieving EnVision’s trajectory and constraining Venus’ gravity field, tides and orientation parameters.

Dedicated radio occultation campaigns are designed to characterize electron density profiles in the ionosphere and atmospheric density, pressure and temperature in the mesosphere and upper troposphere of Venus. Furthermore, an accurate POD of the spacecraft also provides complementary information on the atmospheric density at the altitudes crossed by the probe, extending the science return of the EnVision mission.

The atmospheric drag perturbation strongly affects spacecraft trajectories that are characterized by a pericenter altitude above Venus’ surface of less than 220 km. By accounting for different Venus’ atmospheric models, e.g., the Venus Climate Database (VCD) and the Venus Global Reference Atmospheric Model (Venus-GRAM), we investigate the impact of potential errors and uncertainties in the predicted atmospheric properties on the orbit evolution of the spacecraft. We note significant inconsistencies between Venus’ atmospheric models at the spacecraft altitudes including atmospheric density differences of more than 200%. These discrepancies may be representative of the current knowledge of Venus’ upper atmosphere and thermosphere. Thus, we carried out a perturbative analysis of the dynamical forces by introducing a mismodeling in the atmospheric density profiles. We assumed the VCD for the simulation of the radio tracking measurements and we included as a priori model in the estimation process the Venus-GRAM. By developing a batch sequential filter that adjusts a set of atmospheric density scale factors, we compensated for the mismodeling and improved the quality of the dynamical model and of the orbit determination. The proposed approach enables an estimation of the atmospheric density at the spacecraft altitudes with an accuracy of 25% and accuracies in the orbit reconstruction of 1-2 m, 30-40 m and 20-30 m in the radial, transverse and normal directions.

How to cite: Gargiulo, A. M., Genova, A., Petricca, F., Del Vecchio, E., Andolfo, S., Torrini, T., Rosenblatt, P., Lebonnois, S., Marty, J.-C., and Dumoulin, C.: Estimation of Venus' atmospheric density through EnVision precise orbit determination, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13314, https://doi.org/10.5194/egusphere-egu24-13314, 2024.

EGU24-13391 | ECS | Posters virtual | PS1.3

New Evidence for a Global Atmospheric Electric Circuit on Venus 

Blair McGinness, Giles Harrison, Karen Aplin, Martin Airey, and Keri Nicoll

The electrical environment of Venus has been investigated through extensive considerations of whether lightning has been detected in the atmosphere [1]. Although an important process, the presence or absence of lightning does not completely describe Venus’ electrical environment. Little consideration has been made of other related aspects, such as the possible presence of a global atmospheric electric circuit, as is present on Earth. In this context, lightning would be regarded as the source in a possible global circuit, which distributes charge across a planet. New arguments for and against a global electric circuit in Venus’ atmosphere are presented here which arise from re-analysis of data from the Venera 13 & 14 landers.

On Earth, the global atmospheric electric circuit connects regions of disturbed weather to distant regions of fair weather, by current flow between the conducting ionosphere and surface. Disturbed weather regions produce the potential difference between these conducting layers, which drives the current flow. The presence of a similar global circuit on other planets has been proposed, but their existence remains an open question, which motivates further work [2].

The Venera 13 & 14 landers descended through Venus’ atmosphere carrying a wealth of instrumentation. Each lander carried a point discharge sensor, which recorded electrical discharges between the spacecraft and the atmosphere [3]. The discharges recorded were difficult to explain using existing models of Venus’ environment, so it was previously proposed that low atmosphere haze layers could have caused them [4]. Further evidence for these haze layers has been provided by spectroscopic data from the Venera landers, which showed significant atmospheric extinction in the same region [5]. We have attempted to investigate whether it would be plausible for haze layers to cause both the electrical and extinction effects, and whether this favours a global electric circuit in Venus’ atmosphere.

To investigate this, a model describing electrical interactions in Venus’ atmosphere has been produced. The effects of different haze layers on Venus’ electrical environment were able to be studied, via different inputs to the model. The haze layer properties have been constrained by the spectroscopic observations. Results from the electrical modeling were compared with the electrical discharges recorded by the landers, allowing us to determine the conditions which best recreate these observations. Our investigations show that similar results to the observed Venera data can be produced by the electrical model when the effects of a global atmospheric electric circuit are included, but not when they are neglected. These findings are not definitive, but they do provide supporting evidence for the presence of a global electric circuit in Venus’ atmosphere.

References:
[1] R.D. Lorenz (2018). Progress in Earth and Planetary Science, 5. [2] K.L. Aplin (2006). Surveys in Geophysics 27. 63-108. [3] L. Ksanfomality et al. (1982). Soviet Astronomy Letters, 8. 230–232. [4] R.D. Lorenz (2018). Icarus, 307. 146-149. [5] B. Grieger (2003). Proceedings of the International Workshop Planetary Probe Atmospheric Entry and Descent Trajectory Analysis and Science. 63–70.

How to cite: McGinness, B., Harrison, G., Aplin, K., Airey, M., and Nicoll, K.: New Evidence for a Global Atmospheric Electric Circuit on Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13391, https://doi.org/10.5194/egusphere-egu24-13391, 2024.

EGU24-14161 | ECS | Orals | PS1.3

Exploring origin of life chemistry and exoplanet biosignatures with GCMs 

Stephanie Olson, Jonathan Jernigan, Emilie Lafleche, and Haleigh Brown

Studies of exoplanet habitability involving GCMs typically consider the potential for long-lived surface liquid water—or, in other words, climates that Earth-life may find survivable. However, the presence of life and remotely detectable biosignatures on an exoplanet additionally requires an independent origin of life and that life subsequently thrives rather than simply survives. The origin and proliferation of life are both strongly influenced by climate, and both can therefore be informed by GCM studies in parallel with traditional habitability metrics. 

Wet-dry cycles are thought to be an essential ingredient for the origin of life. Cyclic wetting and drying may arise from either diurnal or seasonal cycles, and thus the likelihood of an origin of life may differ between worlds with very different rotation rates, obliquities, or eccentricities. At the same time, seasonal mixing in aqueous environments can trigger highly productive blooms and amplify biosignatures relative to scenarios lacking temporal variability.  

We used ExoPlaSim (an atmospheric GCM) and cGENIE-PlaSim (a 3D model for ocean dynamics and marine biogeochemistry coupled to a 3D atmospheric GCM) to explore diurnal and seasonal cycles on other worlds—with an eye towards origin of life chemistry and biosignatures. This presentation will ultimately identify the planetary scenarios most conducive to exoplanet life detection. 

How to cite: Olson, S., Jernigan, J., Lafleche, E., and Brown, H.: Exploring origin of life chemistry and exoplanet biosignatures with GCMs, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14161, https://doi.org/10.5194/egusphere-egu24-14161, 2024.

EGU24-14443 | Posters on site | PS1.3

Henie Quadrangle (V-58, Southern Venus); Large Igneous Province Features 

Katherine Boggs, Jordan Shackman, Jerry Demorcy, Christine Pendleton, Jess Hall, Mahdi Chowdhury, Holly Bley, Ember Varga, Julia Shustova, Bridgette Dear, Parke Fontaine, Lovleen Dhami, Shane Herrington, Richard Ernst, Hafida El Balil, Erin Bethell, and Simon Hamner

The NASA Magellan Mission (1990 to 1994) produced a valuable resource that planetary geologists continue to use three decades later to unravel the geological characteristics of Venusian Large Igneous Provinces. The ability to be the first to map the surface of Venus is a powerful engagement tool to inspire the next generation of planetary geologists, as illustrated by the size of the Mount Royal University (MRU) Venus geological mapping team (now 25, nearly ¼ of the MRU Geology Major program). MRU is a public undergraduate university. Students are recruited out of 1st and 2nd year courses. In year one (Y1) of the research program students learn how to use the ArcGIS software while being introduced to the geological features of Venus as they map their quadrant, in Y2 or Y3 the students present a poster at an internal research day. The goal by Y4 is for these students to publish a peer-reviewed journal article. Currently one student who ran into pandemic roadblocks through high school could be published while she upgrades her marks, before she is in the MRU Geology Major Program. Such opportunities could prove to be incentives to guide other students past similar roadblocks (we will start working with local junior and high school students in the near future). Collectively we are working towards completing the geological map of the Henie Quadrangle (V-58, south Venus). Detailed mapping (at 1:500,000) revealed that lava canali extend across the entire quadrangle, with evidence for at least three generations of canali. Three canali originate from corona features (e.g. the circumferential dykes around Fotla Corona) suggesting that some canali may be linked to corona formation. The orientation of compressional wrinkle ridges (WR) in northern Henie suggest that these WRs were formed due to strain associated with the formation of the Artemis tectonomagmatic feature which is directly north of Henie. Artemis is possibly the largest such feature in the Solar System. The extent of the Artemis influence is being constrained across the Henie Quadrangle. The source of strain that formed a differently oriented WR swarm to the south of Henie is unknown. There is no evidence for the strain localization into master faults that we see on Earth. More work is needed to develop a model for the formation of the paired Latmikaik-Xacau Coronae and the associated Tellervo Chasma, Sunna-Laverna Dorsae and the Sonmunde-Mdeb-Arubani Flucti. A fissure eruption out of the Sunna Dorsa is proposed as the origin for the surrounding Arubani Fluctus.      

How to cite: Boggs, K., Shackman, J., Demorcy, J., Pendleton, C., Hall, J., Chowdhury, M., Bley, H., Varga, E., Shustova, J., Dear, B., Fontaine, P., Dhami, L., Herrington, S., Ernst, R., El Balil, H., Bethell, E., and Hamner, S.: Henie Quadrangle (V-58, Southern Venus); Large Igneous Province Features, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14443, https://doi.org/10.5194/egusphere-egu24-14443, 2024.

EGU24-14638 | ECS | Orals | PS1.3

Constraining the interior structure and thermal state of Venus 

Michaela Walterová, Ana-Catalina Plesa, Philipp Baumeister, Tina Rückriemen-Bez, Frank W. Wagner, and Doris Breuer

Often termed the twin sister of the Earth, Venus represents an alternative outcome of the evolutionary path taken by large terrestrial planets. Given its extreme surface conditions, lack of surface water, and the absence of plate tectonics, the present-day thermal state of its mantle is likely very different from the Earth. Venus also remains the most enigmatic of terrestrial worlds in terms of interior structure. Both its tidal Love number k2 and the moment of inertia factor, the main sources of information on the core size and interior structure, are known with a large uncertainty of about 10% [1, 2], and the magnitude of tidal dissipation, sensitive to the planet’s thermal state, has only been determined indirectly [e.g., 3]. Yet, the set of observables acquired by the Magellan and Pioneer Venus Orbiter missions can still be used to put constraints on the interior structure.

In this study, we perform a Bayesian inversion of several observational and theoretical constraints (such as the tidal Love number, maximum elastic thickness, or absence of intrinsic magnetic field) to gain insight into the present-day interior structure and thermal state of Venus. This is done by combining the calculation of a global tidal deformation with a 1d parameterised model of mantle convection in the stagnant-lid regime [4,5]. The convection model is based on the thermal boundary layer theory and incorporates partial melting, crustal growth, and inner core crystallization. The elastic structure of the mantle for three selected mineralogical models is obtained from the software Perple_X, based on the minimisation of Gibbs free energy [6]. Finally, to find the tidal parameters, we calculate the deformation of a layered compressible viscoelastic sphere [7]. The mantle is described by the Andrade rheological model, which has proven essential for distinguishing between a fully solid and a fully or partially liquid Venusian core [8]. We vary a large set of rheological, structural, and thermodynamic parameters and predict a range of mantle temperatures consistent with previous stagnant-lid models, average mantle viscosities between 1020-1022 Pa.s, and a tidal quality factor of Q=50+74-24, corresponding to a phase lag of 1.12+1.06-0.67 degrees. Additionally, we discuss how the future measurements of the tidal deformation and the moment of inertia of Venus from EnVision [9] and VERITAS (Venus Emissivity, Radio Science, InSAR, Topography, and Spectroscopy) [10] can improve our understanding of the planet's interior.

[1] Konopliv & Yoder (1995), doi:10.1029/96GL01589.

[2] Margot et al. (2021), doi:10.1038/s41550-021-01339-7.

[3] Correia & Laskar (2003), doi:10.1016/S0019-1035(03)00043-5.

[4] Morschhauser et al. (2011), doi:10.1016/j.icarus.2010.12.028.

[5] Baumeister et al. (2023), doi:10.1051/0004-6361/202245791.

[6] Connolly (2009), doi:10.1029/2009GC002540.

[7] Takeuchi & Saito (1972), doi:10.1016/B978-0-12-460811-5.50010-6.

[8] Dumoulin et al. (2017), doi:10.1002/2016JE005249.

[9] Rosenblatt et al. (2021), doi:10.3390/rs13091624.

[10] Cascioli et al. (2023), doi:10.3847/PSJ/acc73c.

How to cite: Walterová, M., Plesa, A.-C., Baumeister, P., Rückriemen-Bez, T., Wagner, F. W., and Breuer, D.: Constraining the interior structure and thermal state of Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14638, https://doi.org/10.5194/egusphere-egu24-14638, 2024.

EGU24-14689 | Orals | PS1.3

Venus atmosphere dynamics: digging into the Venus Express observations 

Dmitrij Titov, Igor Khatuntsev, and Marina Patsaeva

Dynamics of the Venus atmosphere is still an unsolved fundamental problem in the planetary physics. ESA’s Venus Express collected long imaging time series in several wavelengths from UV to near-IR. It was later complemented by JAXA’s Akatsuki observations, thus providing the longest almost uninterrupted monitoring of the Venus atmosphere dynamics for about 26 Venus years. Tracking of cloud features allowed determination of wind speed at different levels within the cloud deck thus enabling significant progress in characterization of the mean atmospheric circulation. The analysis revealed wind variability including changes with altitude, latitude, local solar time as well as influence of the surface topography and long term 12.5 years periodicity.

The images also provided morphological evidences of dynamical processes at the cloud level. UV dark low latitudes were found to be dominated by convective mixing that brings UV absorbers from depth, while bright uniform clouds at middle-to-high latitudes are typical for the regions with suppresses vertical mixing. The latter feature correlates with drastic increase of the total cloud opacity poleward from ~60° latitude that likely indicates presence of a dynamical mixing barrier here. Similarity of the global UV cloud morphology at the cloud top (~70 km) and that in the deep cloud (50-55 km) observed in the near-IR on the night side suggested similar morphology shaping processes throughout the cloud deck. Venus Express observed gravity waves poleward of 65°N concentrated at the edges of Ishtar Terra likely indicating their generation by wind interaction with the surface. 

Venus Express performed about 800 radio occultations providing precise measurements of the atmospheric temperature structure and static stability parameter in the altitude range 40-90 km. The Richardson number latitude-altitude field derived from the wind and temperature measurements suggests presence of convection in the cloud deck and stable mesosphere above it with the convective layer extending to greater depth at high latitudes. The talk will present recent results on the atmospheric circulation, supplemented by a summary of the Venus Express observations related to the atmospheric dynamics and an outlook for further analysis of these data.  

How to cite: Titov, D., Khatuntsev, I., and Patsaeva, M.: Venus atmosphere dynamics: digging into the Venus Express observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14689, https://doi.org/10.5194/egusphere-egu24-14689, 2024.

The dynamic regime prevailing in the mantle of present-day Venus is still unknown. The surface of Venus seems uniformly quite young; it has  been proposed that it was due to a catastrophic resurfacing 150-700 Ma, and that the planet was in a stagnant lid regime since. Indeed, Magellan observations have failed to reveal a continuous set of accretion ridges and subduction zones, signatures of plate tectonics. But subduction features (trench, elastic bulge) are present in a number of localized spots, for exemple around two of the largest coronae, Artemis and Quetzelpetlal. There, subduction would be mainly by roll-back and could have been induced by the impingement of a mantle plume under the lithosphere, as predicted by our recent fluid dynamics laboratory experiments. Further analysis of our experiments suggest that subduction would be facilitated by the presence of a few % of a liquid phase in the asthenosphere. Melt would be most likely for the Venusian case, as anyway hinted by the amount of volcanic features on the surface of the planet. The experimental scaling laws further suggest that roll-back and subduction could be quite fast (10 cm/yr) because of the old age of the subducting lithosphere and the transformation to eclogite of the basaltic crust. This is turn would generate the rapid opening of a back-arc basin. Laboratory experiments show that for Venus temperature conditions, the produced crust and lithosphere could be quite disorganized with a contorted spreading center, large transforms and microplates. Moreover, the buoyancy of the newly created plate would cause it to remain quite elevated compared to the surrounding plains. Hence, inspection of the topography of Venus suggests several new plates created by subduction: beside the interior of Artemis coronae, Enyo Fossae and Asthik Planum could be plausible candidates. 

How to cite: Davaille, A.: Signatures of a regime of episodic localized subduction: from laboratory experiments to Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16255, https://doi.org/10.5194/egusphere-egu24-16255, 2024.

EGU24-16442 | ECS | Posters on site | PS1.3

Sensitivity studies for the VeSUV/VenSpec-U instrument onboard ESA’s EnVision mission 

Lucile Conan, Emmanuel Marcq, Benjamin Lustrement, Nicolas Rouanet, Ann Carine Vandaele, and Jörn Helbert

The next ESA mission to Venus, EnVision, aims to study the planet as a whole, including its various constituting parts as well as their interactions and coupling processes. Several instruments will therefore compose the payload: a synthetic aperture radar (VenSAR, NASA), a subsurface radar sounder and a suite of three spectrometers (VenSpec) will be embedded, and a radioscience experiment will be implemented. Among them, the UV channel of the spectrometer suite, VenSpec-U, will observe the atmosphere above the clouds and will focus on the characterisation of the sulphured gases SO2 and SO, the monitoring of the unknown UV absorber and dynamical processes. These four topics have been identified as the main science objectives of the instrument and have driven the elaboration of a preliminary design based on the requirements (e.g. spectral range, spectral and spatial resolution) that were formulated with respect to these goals.

The compliance of the current design with respect to these requirements, regarding in particular the precision of the retrieved science data, can then be assessed. Sensitivity studies are therefore performed using the Radiative Transfer Model (RTM), updated from the one used for SPICAV-UV/Venus Express retrievals (Marcq et al., 2020), that allows to link atmospheric features and UV reflectance spectra. Two types of perturbations are considered : errors of random nature arising from the presence of noise on the signal, or systematic errors caused by various effects that induce biases on the measurements. The first ones can be characterised through the influence of the Signal-to-Noise Ratio (SNR) on the uncertainties associated to each retrieved parameter through the fitting algorithm. Limits in terms of SNR can then be defined in order to ensure the compliance with the specifications. The second ones are referring to the impact of biases on the retrievals’ accuracy, and evaluate more specifically the effects of the similarities between the spectral characteristics of these biases and those of the atmospheric components aiming to be detected. The implemented method is based on the Effective Spectral Radiometric Accuracy (ESRA) requirement, previously defined within the framework of the ESA Sentinel missions. It allows to study biases independently as well as potential compensations, so that allowable envelopes of residual errors can then be estimated for each of the considered biases.

How to cite: Conan, L., Marcq, E., Lustrement, B., Rouanet, N., Vandaele, A. C., and Helbert, J.: Sensitivity studies for the VeSUV/VenSpec-U instrument onboard ESA’s EnVision mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16442, https://doi.org/10.5194/egusphere-egu24-16442, 2024.

EGU24-16505 | ECS | Posters on site | PS1.3

Influence of the UV absorber distribution on the temperature and circulation ofthe Venusian cloud region 

Peng Han and Sébastien Lebonnois

Until now, the Venus PCM (Planetary Climate Model) was using precomputed tables for the distribution of the solar heating rates in the atmosphere of Venus. A new scheme is now implemented to compute online the radiative transfer of the solar flux, which allows more flexibility to study sensitivity to opacity sources. We have investigated the sensitivity of the temperature and circulation of the Venusian cloud region to the distribution of the UV absorber. Different vertical distributions of the UV absorber, as well as variations of this along latitudes, have been tested, and comparison is discussed of the vertical profile of computed solar heating rates, temperature distribution in the cold collar region, as well as the resulting mean zonal wind field.

How to cite: Han, P. and Lebonnois, S.: Influence of the UV absorber distribution on the temperature and circulation ofthe Venusian cloud region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16505, https://doi.org/10.5194/egusphere-egu24-16505, 2024.

EGU24-16898 | ECS | Posters on site | PS1.3

Laboratory studies and modelling of ferric chloride as the cause of the anomalous UV absorption in the Venusian atmosphere 

Joanna Egan, Wuhu Feng, Alexander James, James Manners, Daniel R. Marsh, and John M. C. Plane

The cause of the inhomogeneous near-ultraviolet absorption observed in the upper clouds of Venus remains a key question in Venusian research. One possible candidate in the literature is ferric chloride. The absorption spectrum of ferric chloride currently in use by models uses ethyl acetate as a solvent and does not reproduce the absorption features observed on Venus. The study of the optical properties and chemistry of ferric chloride in the sulphuric acid cloud droplets is required to draw valid conclusions regarding its suitability as a candidate for the near-UV absorption.

In this study, we measure the absorption spectrum of ferric chloride in sulphuric acid from 200 – 600 nm at a range of temperatures and measure the rate of conversion of the ferric chloride ions into ferric sulphate ions. We then use the resulting ferric chloride absorption coefficients in a 1D radiative transfer model and estimate the required concentration of ferric chloride in the clouds to be 0.6 – 0.9 wt% in the mode 1 (~0.3 µm radius) cloud droplets to match observations. We also predict the atmospheric concentrations of ferric chloride formed from the reaction of iron ablating from cosmic dust entering Venus’ atmosphere around 120 km with hydrogen chloride emitted by volcanic activity, and estimate the accumulation timescale of ferric chloride to produce the required concentrations in the clouds.

How to cite: Egan, J., Feng, W., James, A., Manners, J., Marsh, D. R., and Plane, J. M. C.: Laboratory studies and modelling of ferric chloride as the cause of the anomalous UV absorption in the Venusian atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16898, https://doi.org/10.5194/egusphere-egu24-16898, 2024.

EGU24-17524 | Posters on site | PS1.3

Planetary-scale wave study in Venus cloud layer, simulated by the Venus PCM 

Dexin Lai, Sebastien Lebonnois, and Tao Li

High-resolution runs of the Venus PCM (1.25° in longitude and latitude) successfully simulated Venus atmospheric superrotation. The results show a clear spectrum and structure of atmospheric waves, primarily with periods of 5.65 days and 8.5 days. The simulation successfully reproduces long-term quasi-periodic oscillation of the zonal wind and primary planetary-scale wave seen in observations. These oscillations are obtained with a period of about 163-222 days close to the observations. The Rossby waves show robustness in wave characteristics and angular momentum transport due to Rossby-Kelvin instability by comparing the 5.65-day wave with the 5.8-day wave simulated by another Venus GCM, AFES-Venus. Similarities are also evident between the 8.5-day wave in our simulation and the 7-day wave obtained in AFES-Venus. Furthermore, the long-term variations in angular momentum transport indicate that the 5.65-day wave is the dominant factor of the oscillation on the superrotation, and the 8.5-day wave is the secondary. When the 5.65-day wave grows, its angular momentum transport is enhanced and accelerates (decelerates) the lower-cloud equatorial jet (cloud-top mid-latitude jets). Meanwhile, the 8.5-day wave weakens, reducing its deceleration effect on the lower-cloud equator region. Consequently, this flattens the background wind and weakens instability, leading to the decay of the 5.65-day wave. And vice versa when the 5.65-day wave is weak.

How to cite: Lai, D., Lebonnois, S., and Li, T.: Planetary-scale wave study in Venus cloud layer, simulated by the Venus PCM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17524, https://doi.org/10.5194/egusphere-egu24-17524, 2024.

EGU24-18247 | Orals | PS1.3

Science objective and status of the EnVision Mission to Venus 

Anne Grete Straume-Lindner, Mitch Schulte, Anne Pacros, Thomas Voirin, Lorenzo Bruzzone, Paul Byrne, Lynn Carter, Caroline Dumoulin, Gabriella Gilli, Joern Helbert, Scott Hensley, Kandis Lea Jessup, Walter Kiefer, Emmanuel Marcq, Philippa Mason, Alberto Moreira, Ann Carine Vandaele, and Thomas Widemann

EnVision is ESA’s next mission to Venus, in partnership with NASA, where NASA provides the Synthetic Aperture Radar payload and mission support. The ESA mission adoption is scheduled for January 2024, and the launch for 2031. The start of the science operations at Venus is early 2035 following the mission cruise, and aerobraking phase around Venus to achieve a low Venus polar orbit. The scientific objective of EnVision is to provide a holistic view of the planet from its inner core to its upper atmosphere, studying the planets history, activity and climate. EnVision aims to establish the nature and current state of Venus’ geological evolution and its relationship with the atmosphere. EnVision’s overall science objectives are to: (i) characterize the sequence of events that formed the regional and global surface features of Venus, as well as the geodynamic framework that has controlled the release of internal heat over Venus history; (ii) determine how geologically active the planet is today; (iii) establish the interactions between the planet and its atmosphere at present and through time. Furthermore, EnVision will look for evidence of past liquid water on its surface.

The nominal science phase of the mission will last six Venus cycles (~four Earth years), and ~210 Tbits of science data will be downlinked using a Ka-/X-band communication system. The science objectives will be addressed by five instruments and one experiment, provided by ESA memberstates and NASA. The VenSAR S-band radar will perform targeted surface imaging as well as polarimetric and stereo imaging, radiometry, and altimetry. The high-frequency Subsurface Radar Sounder (SRS) will sound the upper crust in search of material boundaries. Three spectrometers, VenSpec-U, VenSpec-H and VenSpec-M, operating in the UV and Near- and Short Wave-IR, respectively, will map trace gases, search for volcanic gas plumes above and below the clouds, and map surface emissivity and composition. A Radio Science Experiment (RSE) investigation will exploit the spacecraft Telemetry Tracking and Command (TT&C in Ka-/X bands) system to determine the planet’s gravity field and to sound the structure and composition of the middle atmosphere and the cloud layer in radio occultation. All instruments have substantial heritage and robust margins relative to the requirements, with designs suitable for operation in the Venus environment, and were chosen to meet the broad range of measurement requirements needed to support the EnVision scientific objectives. The EnVision science teams will adopt an open data policy, with public release of the scientific data after verification and validation. Public calibrated data availability is <6 months after data downlink.

The mission phase B1 was concluded in December 2023 following the successful Mission Adoption Review and positive science review and recommendations by the ESA Solar System and Exploration Working Group (SSEWG) and Space Science Advisory Committee (SSAC). The mission adoption is scheduled for 25 January 2024. The scientific objectives and status of the EnVision mission preparations will be presented, including an overview of the scientific topics being studied and the next steps in the mission preparation.

How to cite: Straume-Lindner, A. G., Schulte, M., Pacros, A., Voirin, T., Bruzzone, L., Byrne, P., Carter, L., Dumoulin, C., Gilli, G., Helbert, J., Hensley, S., Jessup, K. L., Kiefer, W., Marcq, E., Mason, P., Moreira, A., Vandaele, A. C., and Widemann, T.: Science objective and status of the EnVision Mission to Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18247, https://doi.org/10.5194/egusphere-egu24-18247, 2024.

EGU24-18366 | Posters on site | PS1.3

Zonal winds in Venus mesosphere from VIRTIS/VEx temperature retrievals 

Arianna Piccialli, Davide Grassi, Alessandra Migliorini, Romolo Politi, Giuseppe Piccioni, and Pierre Drossart

Venus is a natural laboratory to study the atmospheric circulation on a slowly rotating planet. The dynamics of its upper atmosphere (60-120 km) is a combination of retrograde zonal wind found in the lower mesosphere and solar-to-antisolar winds that characterize the thermosphere, and it is subject to a strong turbulence and a dramatic variability both on day-to-day as well as longer timescales. Moreover, several wavelike motions with different length scales have been detected at these altitudes within and above the clouds and they are supposed to play an important role in the maintenance of the atmospheric circulation. The basic processes maintaining the super-rotation (an atmospheric circulation located at the clouds level and being 80 times faster than the rotation of the planet itself) and other dynamical features of Venus circulation are still poorly understood [1].

Different techniques have been used to obtain direct observations of wind at various altitudes: tracking of clouds in ultraviolet (UV) and near infrared (NIR) images give information on wind speed at cloud top (~70 km altitude) [2] and within the clouds (~61 km, ~66 km) [3], while ground-based measurements of doppler-shift in CO2 band at 10 μm [4] and in several CO (sub-)millimeter lines [5,6] sound thermospheric and upper mesospheric winds, showing a strong variability.

In the mesosphere, at altitudes where direct observations of wind are not possible, zonal wind fields can be derived from the vertical temperature structure using the thermal wind equation. Previous studies [7,8,9] showed that on slowly rotating planets, like Venus and Titan, the strong zonal winds at cloud top can be successfully described by an approximation of the Navier–Stokes equation, the cyclostrophic balance in which equatorward component of centrifugal force is balanced by meridional pressure gradient.

We will present zonal thermal winds derived by applying the cyclostrophic approximation from the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) temperature retrievals. VIRTIS was one of the experiments on board the European mission Venus Express [10]. For this study, we will analyze the complete VIRTIS dataset acquired between December 2006 and January 2010 [11,12].

References

[1] Sanchez-Lavega, A. et al. (2017) Space Science Reviews, Volume 212, Issue 3-4, pp. 1541-1616.

[2] Goncalves R. et al. Atmosphere, 12:2., 2021. doi: 10.3390/atmos12010002.

[3] Hueso, R. et al. (2012) Icarus, Volume 217, Issue 2, p. 585-598.

[4] Sornig, M. et al. (2013) Icarus 225, 828–839.

[5] Rengel, M. et al. (2008) PSS, 56, 10, 1368-1384.

[6] Piccialli, A. et al. A&A, 606, A53 (2017) DOI: 10.1051/0004-6361/201730923

[7] Newman, M. et al. (1984) J. Atmos. Sci., 41, 1901-1913.

[8] Piccialli A. et al. (2008) JGR, 113,2, E00B11.

[9] Piccialli A. et al. (2012) Icarus, 217, 669–681

[10] Drossart, P. et al. (2007) PSS, 55:1653–1672

[11] Grassi D. et al. (2008) JGR., 113, 2, E00B09.

[12] Migliorini, A. et al. (2012) Icarus 217, 640–647.

How to cite: Piccialli, A., Grassi, D., Migliorini, A., Politi, R., Piccioni, G., and Drossart, P.: Zonal winds in Venus mesosphere from VIRTIS/VEx temperature retrievals, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18366, https://doi.org/10.5194/egusphere-egu24-18366, 2024.

EGU24-19372 | ECS | Posters on site | PS1.3

Water and the tectonic regime of Venus 

Marla Metternich, Paul J. Tackley, Nickolas Moccetti Bardi, and Diogo L. Lourenço

Observations of Venus imply ongoing tectonic and volcanic activity, suggesting the planet is dynamically active[1,2]. Tectonically altered regions, such as ridges or tesserae, indicate surface mobility. However, unlike Earth, no evidence of active plate tectonics has been identified. The tectonics and volcanism of terrestrial planets are closely tied to active mantle convection modes. Rheology, a crucial element in tectonics, is influenced by the presence of water[3]. Despite this, the impact of water has largely been overlooked in Venus studies, as its interior is typically assumed to be dry. This assumption is being challenged by indications of significant hydrodynamic escape into space, requiring volcanic replenishment. Consequently, water is likely still present in Venus' interior, even if the concentrations are unknown. Importantly, the potential effects of water on Venus' dynamics and evolution remain poorly understood. The interplay between water, mantle dynamics, and volcanic activity would likely contribute to a more comprehensive understanding of Venus' evolution.  This underlines the need to consider complex dynamic thermo-magmatic models that account for water, including composition-dependent finite water solubilities.

 

In this study, we use the numerical code StagYY to perform state-of-the-art 2D models in a spherical annulus geometry to assess the effects of water on the tectono-magmatic evolution of Venus[4,5]. Particular attention will be given to the way water influences mantle convection and tectonics. Indeed, results show that the presence of water can dramatically change the geodynamic regime through the rheology, melting and outgassing. With the introduction of composition-dependent water solubility maps, dehydration processes will redistribute water throughout the mantle[6]. Since water content is directly related to the viscosity structure, the convective regime is expected to change as well. The main question we want to address is how dehydration processes and water distribution influence the convective and tectonic regimes of Venus. Studying the impact of water on Venus's interior may not only unveil insights into its tectonic evolution but also sets the stage for crucial future research, advancing our broader understanding of planetary processes and habitability.

 

[1] Smrekar, S. E., Stofan, E. R., Mueller, N., Treiman, A., Elkins-Tanton, L., Helbert, J., ... & Drossart, P. (2010). Recent hotspot volcanism on Venus from VIRTIS emissivity data. Science, 328(5978), 605-608.

[2]Gülcher, A. J., Gerya, T. V., Montési, L. G., & Munch, J. (2020). Corona structures driven by plume–lithosphere interactions and evidence for ongoing plume activity on Venus. Nature Geoscience13(8), 547-554.

[3]Karato, S. I. (2015). Water in the evolution of the Earth and other terrestrial planets. Treatise on Geophysics, 9, 105-144.

[4] Tackley, P. J. (2008). Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid. Physics of the Earth and Planetary Interiors, 171(1-4), 7-18.

[5]Tian, J., Tackley, P. J., & Lourenço, D. L. (2023). The tectonics and volcanism of Venus: New modes facilitated by realistic crustal rheology and intrusive magmatism. Icarus, 399, 115539.

[6]Nakagawa, T. (2017). On the numerical modeling of the deep mantle water cycle in global-scale mantle dynamics: The effects of the water solubility limit of lower mantle minerals. Journal of Earth Science, 28(4), Article 4. https://doi.org/10.1007/s12583-017-0755-3

How to cite: Metternich, M., Tackley, P. J., Moccetti Bardi, N., and Lourenço, D. L.: Water and the tectonic regime of Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19372, https://doi.org/10.5194/egusphere-egu24-19372, 2024.

EGU24-22187 | Orals | PS1.3

Steam atmospheres and the implications for Venus and Venus-like planets  

Franck Selsis, Jérémy Leconte, Martin Turbet, Guillaume Chaverot, and Emeline Bolmont

A planet with a significant water content can give rise to a steam atmosphere (dominated by water vapor) when the incoming stellar flux exceeds the so-called runaway limit or after large impacts or accretion. All steam-atmosphere current models predict that the greenhouse effect of an ocean worth of water vapor is sufficient to generate a surface magma ocean. This has far reaching consequences for the early evolution of warm rocky planets and the coupling of their interior with the atmosphere. In this paradigm, the solidification of the mantle of Venus is believed to have happened only after the escape of its steam atmosphere to space, leaving the mantle desiccated.

However, these conclusions rely on the assumption that atmospheres are fully convective below their photosphere. This hypothesis was introduced in the 80s and is used in a large part of the literature on the subject. Its validity had however not been assessed thoroughly. We will present the results of a climate model that has been specifically designed to model the radiative-convective equilibrium of steam atmospheres without any a priori hypothesis on their convective nature. These results show that steam atmospheres are generally not fully convective, which yields much cooler surfaces than previous models. A runaway greenhouse does not systematically melt the surface. This changes completely our view of the early evolution of Venus', with even more drastic changes for planets around stars redder than the Sun.

The equilibrium thermal structure of a steam atmosphere, which affects observable signatures and mass-radius relationships of warm Earth-like to water-rich planets, becomes strongly dependent on the stellar spectrum and internal heat flow. Our current constraints on the water content of the internal Trappist-1 planets should for example be revisited. For ultracool dwarfs, these results even question the nature of the inner edge of the sometimes called habitable zone.

How to cite: Selsis, F., Leconte, J., Turbet, M., Chaverot, G., and Bolmont, E.: Steam atmospheres and the implications for Venus and Venus-like planets , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22187, https://doi.org/10.5194/egusphere-egu24-22187, 2024.

EGU24-4948 | Orals | PS1.5

A New Global Color Image Dataset and Reference Frame for Mars by Tianwen-1 

Wei Yan, Jianjun Liu, Xin Ren, Wangli Chen, Xingguo Zeng, Weibin Wen, Chunlai Li, Yan Geng, and Jiawei Li

Global-scale Mars remote-sensing image datasets with accurate and consistent spatial positions contain a wealth of information on its surface morphology, topography, and geological structure. These data are fundamental for scientific research and exploration missions of Mars. Prior to China's first Mars exploration mission (Tianwen-1), none of the available global color-image maps of Mars with a spatial resolution of hundreds of meters were true-color products. On the other hand, there is currently a lack of global optical image datasets on a scale of several tens of meters with high-precision positioning and consistency that can be served as a reference frame for Mars.

Global remote sensing of Mars is one of the primary scientific goals of Tianwen-1. As of July 25, 2022, The Moderate Resolution Imaging Camera (MoRIC) onboard the orbiter has obtained 14,757 images, which have allowed acquiring global stereo images of the entire Martian surface. Additionally, the Mars Mineralogical Spectrometer (MMS) has returned 325 strips of visible and near-infrared spectral measurement data. These measurement data have laid the foundation for the development of a high-resolution global color-image map of Mars with high positioning accuracy and internal consistency. After processing of radiometric calibration (atmospheric correction, photometric correction and color correction), geometric correction (global adjustments and orthorectification) and global image cartography (global color uniformity, mosaicking and subdivision), the development of the Tianwen-1 Mars Global Color Orthomosaic and datasets based on these data was completed, with a spatial resolution of 76m and a planar position accuracy of 68m (a root mean square (RMS) residual of 0.9 pixels for tie points). This is currently the highest resolution global true color image map of Mars in the world, which can be served as a new Mars geodetic control network and reference frame. It can provide crucial foundational data for Mars scientific research and engineering implementation.

How to cite: Yan, W., Liu, J., Ren, X., Chen, W., Zeng, X., Wen, W., Li, C., Geng, Y., and Li, J.: A New Global Color Image Dataset and Reference Frame for Mars by Tianwen-1, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4948, https://doi.org/10.5194/egusphere-egu24-4948, 2024.

EGU24-6424 | Orals | PS1.5

Lateral variations of density and composition in the Martian south polar layered deposits 

Antonio Genova, Flavio Petricca, Simone Andolfo, Anna Maria Gargiulo, Davide Sulcanese, Giuseppe Mitri, and Gianluca Chiarolanza

A joint analysis of subsurface sounding, topography and gravity data is presented in this study to provide constraints on the lateral density variations of the south polar layered deposits (SPLD). The enhanced resolution of the gravity field enables a thorough characterization of the signal associated with the polar deposits that highly correlates to the surface global topography. A novel iterative method is used to determine the radial gravity disturbances that depend on the density contrast and topography of the surface deposits across the polar cap. By using a constrained least-squares approach on localized three-dimensional mass concentrations (mascons), we locally inverted the bulk density from the gravity disturbances, leading to a new map of its lateral variations.

We thus leverage our retrieved map of the lateral density variations to provide bounds on the volumes of the main constituents of the SPLD. By assuming that the polar cap is composed of water ice, carbon dioxide ice and dust, a preliminary analysis of the compositional distribution is carried out. Our results show with unprecedented resolution extensive regions with bulk density consistent with pure water ice. The resulting map of the SPLD composition is fully consistent with complementary data, including the mass fraction of water-equivalent hydrogen measured through epithermal neutron and fast neutron counting rates acquired by the Mars Odyssey Neutron Spectrometer (MONS).

How to cite: Genova, A., Petricca, F., Andolfo, S., Gargiulo, A. M., Sulcanese, D., Mitri, G., and Chiarolanza, G.: Lateral variations of density and composition in the Martian south polar layered deposits, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6424, https://doi.org/10.5194/egusphere-egu24-6424, 2024.

EGU24-7059 | ECS | Posters on site | PS1.5

Effects of regolith properties on the Martian subsurface water distribution using a global climate model 

Mirai Kobayashi, Arihiro Kamada, Takeshi Kuroda, Hiroyuki Kurokawa, Shohei Aoki, Hiromu Nakagawa, and Naoki Terada

In today’s extremely dry Mars, water vapor “adsorption” on regolith grains is thought to play crucial roles in subsurface water retention and water vapor exchange with the atmosphere (Fanale & Cannon, 1971; Zent et al., 1993, 1995, 2001; Böttger et al., 2005; Savijärvi et al., 2016, 2020). Global models that explicitly account for water diffusion in the shallow subsurface and calculate subsurface water distribution have assumed globally uniform regolith properties to simplify assumptions (Böttger et al., 2005; Schorghofer & Aharonson, 2005; Steele et al., 2017). However, Pommerol et al. (2009) examined the adsorption efficiency of six samples similar to the Martian regolith and found that the samples with smaller grain sizes store more adsorbed water due to their larger specific surface areas. Therefore, we have newly implemented a regolith scheme in a Mars Global Climate Model (MGCM), considering regolith properties like grain size, porosity, and the specific surface area. The grain size distribution was obtained from the empirical equation as a function of thermal conductivity (Presley & Christensen, 1997). The distributions of porosity and the specific surface area are also determined, referring to the laboratory experiments of Sizemore & Mellon (2008). Our results clarify that regolith grains with large specific surface areas in the northern low and mid-latitudes and the southern high latitudes, which have high adsorption coefficients, affect water storage. Subsurface water in the northern low and mid-latitudes exists up to 0.5–1wt% as adsorbed water. Regolith with high adsorption properties makes the depth of subsurface ice shallower in the southern high latitudes. Pore ice accumulates in regions poleward of 50°N and 50°S and the west of Elysium Mons and Olympus Mons, which is consistent with previous simulations. Also, with a homogeneous specific surface area, seasonal increases in pore ice were calculated at a depth of about 60 cm in mid-latitudes with low thermal inertia and high atmospheric water vapor content, but with the specific surface area map, the seasonal increases were not demonstrated. This study suggests that adsorption properties influence subsurface water dynamics, emphasizing the importance of considering inhomogeneous regolith properties in models of subsurface water distributions and the atmospheric water cycle including the regolith.

How to cite: Kobayashi, M., Kamada, A., Kuroda, T., Kurokawa, H., Aoki, S., Nakagawa, H., and Terada, N.: Effects of regolith properties on the Martian subsurface water distribution using a global climate model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7059, https://doi.org/10.5194/egusphere-egu24-7059, 2024.

EGU24-7065 | ECS | Orals | PS1.5 | Highlight

Long-term evolution of the subsurface water environment on Mars over the past million years 

Arihiro Kamada, Takeshi Kuroda, Yasuto Watanabe, Mirai Kobayashi, Takanori Kodama, Ralf Greve, Hiromu Nakagawa, Yasumasa Kasaba, and Naoki Terada

Mars is an extremely cold and dry planet today, but it is thought to have been a water-rich planet in the past. Most of the water reservoir could represent hydrated crust and/or ground ice interbedded within sediments. Unlike Earth, Mars does not have a large satellite, so its obliquity varies greatly, and atmospheric circulation, water circulation, and subsurface water distribution are expected to change significantly over time. Currently, water ice is unstable at the pressure-temperature conditions found at the surface or subsurface of low/mid-latitude Mars, but recent observations by SHARAD revealed that large amounts of water remain beneath Utopia Planitia, which is thought to have formed during periods of high obliquity.

Here, we have newly developed a fully coupled global water circulation model for the atmosphere, hydrosphere, and cryosphere down to a depth of 1 km in the subsurface, and we used an iterative time integration scheme. We performed a series of simulations with changing Martian obliquity and eccentricity over the last few million years, and north polar layer deposit as an initial water reservoir. Our model implemented a water exchange scheme between the atmosphere and the regolith/crust for different porosities and grain sizes. We found that in the recent Milankovitch cycle, during the smaller obliquity periods, subsurface ice was mainly distributed around higher latitudes, but during the larger obliquity periods, the distribution of subsurface ice extended to lower latitudes of around 40° N. It is possible that water ice with a volume content of more than 10% may remain at high latitudes above 60° N. The abundance of water at such high latitudes could be an important indicator in the search for possible life on Mars, or a valuable water resource in future manned Mars missions.

How to cite: Kamada, A., Kuroda, T., Watanabe, Y., Kobayashi, M., Kodama, T., Greve, R., Nakagawa, H., Kasaba, Y., and Terada, N.: Long-term evolution of the subsurface water environment on Mars over the past million years, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7065, https://doi.org/10.5194/egusphere-egu24-7065, 2024.

EGU24-7073 | Orals | PS1.5

Progress and achievement of Tianwen-1 mission 

Yan Geng, Jianjun Liu, Lihua Zhang, and Xiao Zhang

Tianwen-1 mission is the first in the world to achieve Mars orbiting, landing and roving exploration through a single launch, and has developed technologies for planetary exploration launch and flight, planetary capture control, Mars entry and descent landing, Mars surface roving for Zhurong, scientific payload design and operation, long-distance deep space TT&C communication, etc. The mission has obtained a large number of scientific exploration data, formed a series of basic information such as true color image maps covering Mars surface, and a series of new discoveries such as new evidence of water and wind and sand activities in the Martian Utopia Plain. It enriches mankind's scientific understanding of Mars.

The report will introduce the progress and achievements of the Tianwen-1 mission in terms of technological development and scientific discovery.

How to cite: Geng, Y., Liu, J., Zhang, L., and Zhang, X.: Progress and achievement of Tianwen-1 mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7073, https://doi.org/10.5194/egusphere-egu24-7073, 2024.

EGU24-9136 | ECS | Posters on site | PS1.5

Simulation of a satellite gravimetry mission at Mars 

Marvin Bredlau, Stefanie Bremer, Manuel Schilling, and Noa Katharina Wassermann

Improving the data on the gravitational field of Mars can yield enhanced knowledge about Martian planetary dynamics and subsurface water reservoirs. In this study, we augment the VENQS software tool to perform simulations for a future dedicated satellite gravimetry mission at Mars following the archetype of GRACE-FO and as a result to study the challenges of such a mission.

The VENQS software tool consists of two parts: the VENQS App and the VENQS library. The VENQS App provides users with an easy access to a variety of simulation models, that can be combined to an individual VENQS library setup. These simulation models include amongst others orbit propagation of single satellites with embedded test masses, simulations of satellite constellations, and detailed disturbance analysis for satellites due to the space environment. Interaction with versioning systems allows the VENQS App to effectively track the software of the simulation models. In addition, a dedicated release management system enables the provision of different versions of the VENQS library.

Initially designed for satellites orbiting Earth, we are working on an augmentation of the VENQS library for interplanetary spacecraft or to be more precise for satellites orbiting arbitrary celestial bodies. In this context we want to propose the adaptation of VENQS for precise orbit propagation at Mars, which can assist the assessment of different mission influences on gravity field recovery (via dedicated software tools such as GRAVFIRE). We present the general simulation procedure including the modelling of perturbating forces along with gravitational acceleration for the orbit integration. Furthermore, we explain the differences to simulations of terrestrial spacecraft and outline occurring challenges with Martian atmosphere, time and reference frames, solid Mars tides as well as more complex satellite geometries inducing micro-vibrations and the non-availability of GNSS, that may deteriorate gravity field solutions.

How to cite: Bredlau, M., Bremer, S., Schilling, M., and Wassermann, N. K.: Simulation of a satellite gravimetry mission at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9136, https://doi.org/10.5194/egusphere-egu24-9136, 2024.

EGU24-10083 | ECS | Posters on site | PS1.5

Unraveling the climate evolution on Mars and Earth with AI-driven surface mapping and explainable AI 

Lida Fanara, Shu Su, Oleksii Martynchuk, Ernst Hauber, Anastasia Schlegel, Jakob Ludwig, David Melching, Ronny Hänsch, and Klaus Gwinner

Our research leverages state-of-the-art deep learning techniques to automate surface mapping and continuous monitoring on planetary bodies. We are also developing tools to analyze the model uncertainty and decision-making in AI models with evaluation in our surface mapping projects and beyond.

We focus on one of the solar system's most dynamic Earth-analog environment on terrestrial planets - Mars' northern polar region, a repository of the planet's climatic history within its extensive ice-layered dome. We detect small blocks [1] and their sources yielding a reliable method for monitoring mass wasting activity with valuable present-day erosion rate results [2].

In parallel, we investigate and map polygonal patterns on both Earth and Mars to assess the global distribution of polygons and their potential as indicator for climate conditions and changes. On Earth, polygons are indicators of the volume of ground ice and provide insights into permafrost vulnerability to climate change. On Mars, similar young landforms could be linked to geologically recent freeze-thaw cycles. This would be conflicting with the current environment and would have implications for the recent hydrologic past of the planet. The distribution of polygonal ground on Mars can provide valuable information on the role of liquid water in the recent past by shedding light on the formation mechanism.

We use AI models for automated surface mapping because they achieve highly complex decision-making. However, they are usually treated as Black-Box systems. To tackle this problem, we are developing software tools for analyzing model uncertainty and decision-making within an application-independent framework. Typical questions are why did the model produce exactly this response and how certain is it about the correctness of its results?

References: [1] Martynchuk O. et al., 2024. EGU 2024. [2] Su S. et al., AGU 2023.

How to cite: Fanara, L., Su, S., Martynchuk, O., Hauber, E., Schlegel, A., Ludwig, J., Melching, D., Hänsch, R., and Gwinner, K.: Unraveling the climate evolution on Mars and Earth with AI-driven surface mapping and explainable AI, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10083, https://doi.org/10.5194/egusphere-egu24-10083, 2024.

EGU24-10784 | ECS | Orals | PS1.5

Recent ice ages on Mars by destabilization of the Northern Polar Cap at 35° obliquity 

Joseph Naar, François Forget, Ehouarn Millour, Eran Vos, Charlotte Segonne, Lucas Lange, Jean-Baptiste Clément, and Franck Montmessin

Surface water ice is unstable on present-day Mars outside of the polar regions. However, prominent geological features show that during its recent past the surface of Mars was covered, on multiple occasions, by a « latitude-dependent mantle » (LDM) of water ice, from the polar regions to the tropics [1].

Different studies conducted with Global Climate Models, in particular the Mars PCM (previously Mars LMD-GCM) led to the formulation of a climate scenario for the emplacement of ice ages : during high obliquity phases (>45°, as opposed to present-day ~25°), strong destabilization of the Northern Cap allowed for the aerial deposition of ice on the flank of tropical volcanoes, forming glaciers. When returning at lower obliquity, these glaciers were in turn destabilized but ice accumulated in the mid and high latitudes, and thus formed the observed surface ice deposits (LDM) [2]. However, the 45° obliquity excursions occurred before the last 5 million years, while the last ice age occurrence is dated of 400 000 years at most.

Previous numerical experiments did not account for the radiative effect of water-ice clouds. Previous studies show that, even though somewhat negligible in the present-day Martian climate, this effect is overriding at higher obliquity with the intensification of the water cycle [3]. We have conducted new experiments at 35° obliquity with the Mars PCM using an improved physical package for the radiatively active clouds (RACs) and surface ice. Here, we present the resulting climate regime in our simulations. At 35° obliquity, the atmosphere is almost two orders of magnitude wetter than present-day, due to the greenhouse effect of RACs over the polar regions. In the high to mid latitudes, the seasonal winter ice accumulation is increased dramatically, while the summer sublimation is dampened by the latent heat cooling. Surface water ice thus accumulates at rates corresponding to tens of meters at each high obliquity excursion, reconciling the climatic scenario with the inferred age of emplacements of the LDM.

References:

[1] Head et al. (2003), Recent ice ages on Mars, Nature, 426, 797.

[2] Madeleine et al. (2009), Amazonian northern mid-latitude glaciation on Mars: A proposed climate scenario, Icarus, 203, 390

[3] Madeleine et al. (2014), Recent Ice Ages on Mars: The role of radiatively active clouds and cloud microphysics, Geophysical Research Letters, 41, 4873

Acknowledgements:

This project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No 835275).

How to cite: Naar, J., Forget, F., Millour, E., Vos, E., Segonne, C., Lange, L., Clément, J.-B., and Montmessin, F.: Recent ice ages on Mars by destabilization of the Northern Polar Cap at 35° obliquity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10784, https://doi.org/10.5194/egusphere-egu24-10784, 2024.

EGU24-12473 | Posters on site | PS1.5

Thermal state of the Martian interior at present day as constrained by elastic lithosphere thickness estimates and recent volcanic activity 

Ana-Catalina Plesa, Adrien Broquet, Joana R. C. Voigt, Mark A. Wieczorek, Ernst Hauber, and Doris Breuer

Previous studies have constrained the lithosphere at the north and south poles of Mars to be thick and cold, with elastic thicknesses of 330 to 450km [1], and >150km [2], respectively. The elastic thickness characterizes the stiffness of the lithosphere in response to loading and is directly linked to the thermal state of the lithosphere and the surface heat flow. Thus, elastic thickness estimates at the north and south poles provide crucial constraints on the present-day surface heat flow on Mars. Additional information on the present-day planetary thermal state comes from evidence of ongoing melting in the mantle, as indicated by the presence of both young lava flows in Tharsis and Elysium provinces and an active mantle plume beneath Elysium Planitia [3,4,5]. 

In this study we explore the thermal evolution of Mars using global 3D geodynamic models. These models improve upon our previous work [6] by including updated interior structure information from the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission [7,8] and by considering constraints on the present-day thermal state of the planet as noted above. Thermal evolution models using the most recent crustal thickness estimates [8,9], require that the crust contains more than half of the total amount of heat producing elements (HPEs) to explain localized recent volcanic activity on Mars [8]. 

We find that the crustal thickness variations control the surface heat flow and the elastic thickness pattern, as well as the location of melting zones in the present-day Martian mantle. The strongest constraint for the thermal history and present-day state of the interior is given by the elastic thickness at the north pole. While at the south pole, all models show values >150km, compatible with the latest estimate [2], only a few models present an elastic thickness >300km at the north pole, with values still lower than the recent estimate of [1].  A larger elastic thickness at the north pole could indicate: 1) a northern crust less enriched in HPEs, 2) a colder lithosphere due to a weaker blanketing effect caused by a thinner or higher-conductivity crust on the northern hemisphere, 3) ongoing viscoelastic relaxation, suggesting that the observed surface deflection beneath the north polar cap is not the final one [1], or a combination thereof. 

In contrast to the cold lithosphere inferred for the Martian polar regions, recent volcanic activity suggests a warmer interior beneath Tharsis and Elysium provinces [3,4]. This reveals an important spatial variability in the thermal state and thickness of the Martian lithosphere. Our work shows that only a narrow range of models can match elastic thickness estimates at the polar caps and explain Mars’ recent volcanic activity, thereby providing important insights into the structure and thermal evolution of the interior.

References:

[1] Broquet et al., 2020. [2] Broquet et al., 2021. [3] Voigt et al., 2023. [4] Hauber et al., 2011. [5] Broquet & Andrews-Hanna, 2023. [6] Plesa et al., 2018. [7] Stähler et al., 2021. [8] Knapmeyer-Endrun et al., 2021. [9] Wieczorek et al., 2023.

How to cite: Plesa, A.-C., Broquet, A., Voigt, J. R. C., Wieczorek, M. A., Hauber, E., and Breuer, D.: Thermal state of the Martian interior at present day as constrained by elastic lithosphere thickness estimates and recent volcanic activity, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12473, https://doi.org/10.5194/egusphere-egu24-12473, 2024.

EGU24-12497 | Posters on site | PS1.5

Lander Induced Thermo-Elastic Noise at InSight Location on Mars 

Sreejaya Kizhaekke Pakkathillam, Philippe Lognonne, Sébastien De Raucourt, and Taichi Kawamura

Understanding the intricate thermal dynamics on Mars is crucial for accurate scientific measurements, particularly for seismological studies. The InSight Mission to study the interior structure and composition of Mars has recorded the Mars seismograms and in-situ data for the initial assessment of Mars' geothermal heat flow. Given that these measurements are obtained in close proximity to the lander at the surface, a primary concern is the presence of thermo-elastic noise, originating from fluctuations in solar radiation, within the collected data. Experiments such as those conducted by SEIS on Mars have specifically identified this phenomenon, detecting noise during the eclipse of Phobos (Stähler et al, 2020). While managing periodic temperature variations of instruments is feasible, challenges arise with other factors, such as those associated with moving shadows on the ground and solar radiation fluctuations. This implies that the presence of the lander will introduce thermal perturbations, causing alterations in both local surface and subsurface temperature measurements. These challenges necessitate numerical quantification due to difficulties in filtering them from the data. Hence, this study investigates first how the shadowing effect from the lander's structure and solar radiation variations impacts subsurface soil temperatures and consideration of this effect on the tilt recorded on the seismometers. We develop a 3D numerical model within Comsol Multiphysics 6.1 finite element package. The key element in adapting this model for use on Mars is accurately replicating the illumination conditions on the surface. Based on sub solar latitude and longitude derived using the JPL Horizons Ephemeris output, an illumination model is set at the instrument site for a desired duration. Unlike the Moon, where no atmospheric contribution affects temperature variations, Mars possesses a thin atmosphere that contributes to convective heat transfer. First, an analytical model is employed to find the transient solution of temperature at any given depth and time instances. The solution to the energy balance analysis determines the boundary conditions at the ground surface, which are then applied in the heat conduction equations governing subsurface temperature distribution.  The numerical temperature distribution output at an unperturbed location, far away from the lander is then compared with the analytical solution.  Once the 3D model is calibrated, the resulting temperature profiles can be utilized to assess the tilt of the seismometer feet and the sensitivity to additional solar radiation fluctuations. The findings suggest that the presence of a lander can exert substantial effects on the surrounding temperature environment under Martian conditions. This can introduce noise into the data collected by the seismometer, emphasizing the importance of accounting for and mitigating such influences in both the design and data analysis.

How to cite: Kizhaekke Pakkathillam, S., Lognonne, P., De Raucourt, S., and Kawamura, T.: Lander Induced Thermo-Elastic Noise at InSight Location on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12497, https://doi.org/10.5194/egusphere-egu24-12497, 2024.

EGU24-12635 | Posters on site | PS1.5

A quantum gradiometry mission concept for the improvement of Mars gravity field models 

Mirko Reguzzoni, Lorenzo Rossi, and Federica Migliaccio

The excellent performances of quantum accelerometers, due to their very good behaviour in the low frequency measurement bandwidth and to their intrinsic stability, which does not call for periodic calibration of the sensors, foster their application to extra-terrestrial investigations. In particular, the study of Mars and of its planetary composition, evolution, density and surface properties is going to be of great importance in the next decades for many reasons, both for the enhancement of the scientific knowledge and for applications in future missions.

So far, the gravity models of Mars have been derived from tracking data of different missions. Preliminary simulations performed at POLIMI considering a one-arm gradiometer pointing in the radial direction, flying on a polar orbit and acquiring data for a time span of two months show that a significant improvement in the knowledge of the gravity field of Mars could be achieved by launching a dedicated mission collecting gravity gradiometry observations by means of a quantum sensor. Even taking into account a degradation of the solution due to more realistic conditions, allowing for a possible mission lifetime of a few years (which is feasible under Mars conditions) would mean that the already available CAI technology could lead to very high benefits in terms of the scientific knowledge of the Martian gravity field.

How to cite: Reguzzoni, M., Rossi, L., and Migliaccio, F.: A quantum gradiometry mission concept for the improvement of Mars gravity field models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12635, https://doi.org/10.5194/egusphere-egu24-12635, 2024.

EGU24-13493 | Orals | PS1.5

Study of Martian Polar Caps with GISS ROCKE-3D GCM 

Igor Aleinov, Donald Glaser, Scott Guzewich, Jan Perlwitz, Kostas Tsigaridis, Michael Way, and Eric Wolf

Martian polar caps consist of both H2O and CO2 ice. While H2O ice is mainly passive on modern Mars, it may have not been the case in recent Martian history, when its obliquity was higher, or when it was changing rapidly. The distribution of ice species in the snowpack affects its physical and thermodynamic properties. In the upper layers, it determines its albedo and thermal emissivity. Thus understanding the mutual effect between these ices and their interaction with the atmosphere is crucial for understanding the evolution of Martian polar regions. In this study, we employ a newly-developed Exotic Ices snow model coupled to the NASA Goddard Institute for Space Studies (GISS) ROCKE-3D planetary General Circulation Model (GCM) [1]  to study the behavior of Martian polar caps. ROCKE-3D is a planetary GCM developed at NASA GISS as an extension of its Earth climate model, modelE [2]. It has been extensively used to simulate climate of various planets, including Mars (e.g. [3,4]).

The Exotic Ices snow model was specially developed for planetary applications which involve more than one condensable in the atmosphere, in which case snow can contain multiple species of ice (CO2 and H2O in the Mars case). For each species of ice, the model uses their proper physical properties and phase diagram, but otherwise it treats all species of ice on an equal footing.  The combined effects on albedo, thermal inertia and mutual insulation are treated accordingly. The snowpack interacts with the atmospheric dust cycle, and can accumulate a prognostic amount of dust, though the effect of dust on snow properties is not currently treated explicitly, and is prescribed. 

In this study, we first validate our model against the modern Martial climate, for which we use mission results from Mars Climate Sounder (atmospheric temperature and dust optical depth), SPICAM on Mars Express (atmospheric water), and Viking 2 (surface pressure). We investigate the effect of snow radiative properties on CO2 and water cycles and the ability of our model to accurately reproduce those with minimal model tuning. We then perform simulations for several obliquities from a recent Martian past, and investigate the behavior of the Martian polar caps in such conditions.

References: [1] Way, M. J. et al. (2017) ApJS, 231, 12. [2] Kelley, M. et al. (2020) J. Adv. Model. Earth Syst., 12, no. 8, e2019MS002025. [3] Schmidt, F. et al. (2022) Proc. Natl. Acad. Sci., 119, no. 4, e2112930118. [4] Guzewich, S.D. et al. (2021) J. Geophys. Res. Planets, 126, no. 7, e2021JE006825.

How to cite: Aleinov, I., Glaser, D., Guzewich, S., Perlwitz, J., Tsigaridis, K., Way, M., and Wolf, E.: Study of Martian Polar Caps with GISS ROCKE-3D GCM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13493, https://doi.org/10.5194/egusphere-egu24-13493, 2024.

EGU24-14925 | ECS | Posters virtual | PS1.5

Thickness of the seasonal deposits by examining the shadow variations of the fallen ice blocks at Martian North Pole 

Haifeng Xiao, Yuchi Xiao, Shu Su, Frédéric Schmidt, Luisa M. Lara, and Pedro J. Gutierrez

Due to its axial tilt of ~25°, Mars has seasons. During its fall and winter, when temperature drops, there exist two depositional mechanisms of atmospheric CO2, that is, precipitation as snowfall and direct surface condensation in the form of frost (Hayne et al., 2012). Up to one third of the atmospheric CO2 exchanges with the polar surface through the seasonal deposition/sublimation process. Therefore, accurate measurements of the evolution of the seasonal polar caps can place crucial constraints on the Martian climate and volatile cycles. 

Recently, by reprocessing and co-registering the MOLA profiles, Xiao et al. (2022a, 2022b) derived both spatial and temporal thickness variations of the seasonal polar caps at grid elements of 0.5° in latitude and 10° in longitude. However, the MOLA-derived results can suffer from biases related to various processes, for example, pulse saturation due to high albedo of the seasonal deposits, non-Gaussian return pulses due to rough terrain and dynamic seasonal features, incomplete correction for the global temporal bias, and penetration of the laser pulses into the translucent slab ice. Furthermore, MOLA altimetric observations are limited to Mars Year 24 and 25 which prevents the detection of possible interannual variations in the CO2 seasonal transport. 

In this contribution, we will show how the shadow variations of fallen ice blocks at the bottom of steep scarps of the North Polar Layered Deposits (NPLDs) allow us to infer the thickness evolution of the seasonal deposits (Xiao et al., 2024). For this, we utilize the High Resolution Imaging Science Experiment (HiRISE/MRO) images with a spatial resolution of up to 0.25 m/pixel (McEwen et al., 2007). We successfully conduct an experiment at a steep scarp centered at (85.0°N, 151.5°E). We assume that no, or negligible, snowfall remains on top of the selected ice blocks, the frost ice layer is homogeneous around the ice blocks and their surroundings, and no significant moating is present. These assumptions enable us to separately determine the thickness of the snowfall and frost. We find that maximum thickness of the seasonal deposits at the study scarp in MY31 is 1.63±0.22 m to which snowfall contributes 0.97±0.13 m. Interestingly, our thickness values in the northern spring are up to 0.8 m lower than the existing MOLA results (Smith et al., 2001; Aharonson et al., 2004; Xiao et al., 2022a, 2022b). We attribute these differences mainly to the remaining biases in the MOLA heights. Furthermore, we demonstrate how the long time span of the HiRISE images (2008—2021; Mars Year 29—36) allows us to measure the interannual variations of the deposited CO2. Specifically, we observe that snowfall in the very early spring of Mars Year 36 is 0.36±0.13 m thicker than that in Mars Year 31. 

 

Hayne et al. (2012). JGR: Planets, 117(E8).

Xiao et al. (2022a). JGR: Planets, 127(7), e2022JE007196.

Xiao et al. (2022b). JGR: Planets, 127(10), e2021JE007158.

Xiao et al. (2024). JGR: Planets (In Revision).

McEwen et al. (2007). JGR: Planets, 112(E5).

Smith et al. (2001). Science, 294(5549), 2141-2146.

Aharonson et al. (2004). JGR: Planets, 109(E5).

How to cite: Xiao, H., Xiao, Y., Su, S., Schmidt, F., Lara, L. M., and Gutierrez, P. J.: Thickness of the seasonal deposits by examining the shadow variations of the fallen ice blocks at Martian North Pole, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14925, https://doi.org/10.5194/egusphere-egu24-14925, 2024.

Mars harbors two geologically young (<100 Ma) and large (~1000 km across) polar ice caps, which represent the only million-year-old surface features that induce measurable surface deformations. In the absence of in situ heat flow measurements, analyses of these deformations is one of the few methods that give access to the present-day planetary thermal state. The latter is indicative of the concentration of radiogenic elements in the interior, which is an important metric to determine the planet’s bulk composition, structure, and geologic evolution (Plesa et al., 2022). In previous work, we have imaged the deformed basements beneath the two polar caps and have determined the present-day thermal state of Mars (Broquet et al., 2020; 2021). The results of these studies are currently widely used as firm constraints on Martian thermal evolution models (e.g., Plesa et al., 2022). However, these models struggle to explain both the thick lithospheres inferred at the poles and the planet’s young volcanism and ongoing plume activity (e.g., Broquet & Andrews-Hanna, 2023). Importantly, Broquet et al. have assumed the polar deformations to be at equilibrium, which is only valid if the time elapsed since the polar caps’ formation is greater than the time required for viscous adjustments. This assumption is central to these models and depends upon the poorly known age of the polar caps and the internal viscosity structure of Mars. In this work, we couple a novel viscoelastic modelling approach of the polar deformations to thermal evolution models that account for InSight seismic measurements and observational constraints on recent volcanic activity. Our preliminary investigations reveal that viscosity structures, outlined in the thermal models presented in Plesa et al. (2022), lead to polar deformations reaching equilibrium in a few Myr and up to hundreds of Myr. These findings demonstrate that viscoelastic relaxation can surpass the polar caps’ ages, emphasizing the necessity for a comprehensive exploration of polar viscoelastic relaxation. This approach will yield critical insights into the internal viscosity structure of Mars together with the polar caps' age and formation history, ultimately leading to a better understanding of the planet’s geologic and climatic evolution.

 

Broquet A., et al., (2021). The composition of the south polar cap of Mars derived from orbital data. JGR:Planets 126, e2020JE006730. 10.1029/2020JE006730.

Broquet A. et al., (2020). Flexure of the lithosphere beneath the north polar cap of Mars: Implications for ice composition and heat flow. GRL 47, e2019GL086746. 10.1029/2019GL086746.

Broquet A., & Andrews-Hanna J. C., (2023). Geophysical evidence for an active mantle plume underneath Elysium Planitia on Mars. Nat. Astro. 7, 160–169. 10.1038/s41550-022-01836-3.

Plesa A.-C., et al., (2022). Interior Dynamics and Thermal Evolution of Mars – a Geodynamic Perspective. Adv. Geophys. 63, 179–230. 10.1016/bs.agph.2022.07.005.

How to cite: Broquet, A., Wieczorek, M. A., and Breuer, D.: Viscoelastic relaxation of the lithosphere beneath the Martian polar caps: Implications for the polar caps’ formation history and planetary thermal evolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15270, https://doi.org/10.5194/egusphere-egu24-15270, 2024.

EGU24-19019 | Orals | PS1.5

Evolution Strategy-Based Approach for Joint Analysis of Laser Altimeter Tracks and Photogrammetric Stereo DTMs: MOLA and HRSC 

Konrad Willner, Klaus Gwinner, Alexander Stark, Stephan Elgner, and Hauke Hussmann

Introduction: Data by the MGS MOLA [1] instrument provide a dense global network of laser shots with unprecedented height precision for Mars. The extraction of planetary radii from laser pulses requires precise knowledge of spacecraft trajectory and the instrument’s orientation in space. Limited knowledge of these extrinsic parameters causes deviating height information at cross-over points of the laser tracks and occasionally substantially offset outlier profiles. Applying adjustment techniques, the final mission data products [2] minimized the cross-over residuals while still showing considerable variability in height differences when compared to HRSC Mars quadrangle DTMs [3].

We accurately co-register MOLA profiles to existing HRSC DTMs allowing to increase the accuracy of the co-registration of the single laser tracks while providing similar internal a-posteriori cross-over accuracies as in [2]. The method applies Evolution Strategy (ES) [4] to directly solve for extrinsic observation parameters. Combined HRSC / MOLA DTMs will provide a most comprehensive, best resolved global data product currently available for Mars.

Method: Starting with a seed vector the ES repeatedly creates sets of random parameter vectors that are evaluated by the quality function. The latter is defined by the RMS of the height difference between DTM and corrected laser shots. The lowest RMS vector of each generation will be the seed for the next generation random vectors.

The optimization of the parameter vector for each laser data segment is performed on an equatorial HRSC half-quadrangle and parameters are applied to all data of a laser data segment reaching from North to South pole.

Results: ES-based adjustment of MOLA tracks was applied using two existing equatorial HRSC DTM half-quadrangles (MC-13E and MC-21E) and the laser track segments intersecting these quadrangles. The quality of the adjustment was evaluated by visual inspection of gridded DTM data products generated from the adjusted tracks and by analyzing the consistency of the results in terms of height residuals at cross-overs. Inspection of DTM products is sensitive to outlier track detection, that commonly occur in the uncorrected MOLA data but also appear in the ES adjusted DTMs. The average absolute residual height differences at cross-overs amount to 4.44 m for the nominal profile solutions, 4.58 m in the crossover-adjusted version [2], and to only 2.78 m with ES-adjusted profiles. The same values are also derived eliminating globally the 3s-blunder height differences. The corresponding values are then 3.48 m (nominal case), 2.93 m [2], and 2.09 m (ES-adjusted). The method establishes a high-quality co-registration between MOLA and HRSC DTMs considered very promising for future joint HRSC/MOLA DTMs. We discuss the potential to re-assess temporal variation in the MOLA data record not uniquely resolved in the past, such as estimates of the seasonal deposition  and sublimation in the polar areas.

References:
[1] Smith, D. E. et al. JGR 106, 23689-23722 (2001). Doi:10.1029/2000JE001364
[2] Smith, D. E. et al. NASA PDS (2003). MGS-M-MOLA-5-MEGDR-L3-V1.0.
[3] Gwinner, K. et al. PSS 126, 93-138 (2016). Doi: 10.1016/j.pss.2016.02.014
[4] Rechenberg, I. Evolutionsstrategie 94. Vol. 1 (Frommann-Holzboog, 1994).

How to cite: Willner, K., Gwinner, K., Stark, A., Elgner, S., and Hussmann, H.: Evolution Strategy-Based Approach for Joint Analysis of Laser Altimeter Tracks and Photogrammetric Stereo DTMs: MOLA and HRSC, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19019, https://doi.org/10.5194/egusphere-egu24-19019, 2024.

EGU24-19493 | ECS | Posters on site | PS1.5

Erosion rate of the north polar steep scarps on Mars 

Shu Su, Lida Fanara, Haifeng Xiao, Ernst Hauber, and Jürgen Oberst

Mass wasting activity, in the form of ice block falls, has been observed as the main erosion process at steep scarps of the North Polar Layered Deposits (NPLD) [1,2]. Our study focuses on leveraging a state-of-the-art deep learning technique to map the sources of such events throughout the entire NPLD region. By quantifying water ice loss, we derive the current erosion and retreat rate for each active NPLD scarp. We notice that these scarps have varying degrees of erosion, from less than 0.01 up to 0.88 m3 per Mars Year per meter along the scarp. The current most active scarp shows a retreat rate of ~6 mm per Mars Year. We want to compare our results to the detected ice block falls at the underlying Basal Unit (BU) region [3], to understand the difference between the two units’ geological processes, and help to constitute important constraints to the present-day mass flux of the north polar region.

 

References

[1] Herkenhof et al., 2007. Science, 317(5845), pp.1711-1715.

[2] Dundas et al., 2021. J. Geophys. Res. Planets, 126(8), p.e2021JE006876.

[3] Martynchuk, et al., 2023. AGU23, 11-15 Dec.

How to cite: Su, S., Fanara, L., Xiao, H., Hauber, E., and Oberst, J.: Erosion rate of the north polar steep scarps on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19493, https://doi.org/10.5194/egusphere-egu24-19493, 2024.

EGU24-19665 | Posters on site | PS1.5

Spectral Albedo of Dusty Martian CO2  Snow and Ice 

Sehajpal Singh, Deepak Singh, and Chloe A. Whicker

There is ample evidence to conclude that the ice deposits on solar system bodies—aside from Earth—have complex chemical constitutions. Carbon dioxide ice is prevalent at the poles of Mars and owing to its substantial reflectivity and seasonal variability, it significantly influences the planet's energy budget. Recent evidence of the existence of CO2 ice glaciers on Mars explains the volumetric distribution and accumulation of CO2 ice into the curvilinear basins at the south pole of Mars. While spectral measurements of martian ice have been made, no model of the dusty martian firn or CO2 glacier ice exists at present. Due to their significant effects on snow and ice's albedo reduction, dust and snow metamorphism must be taken into consideration. Here, we adapt the terrestrial Snow, Ice, and Aerosol Radiation (SNICAR) model and apply it to martian glaciers by incorporating CO2 ice capabilities in the model and validating with the observed remote sensing data. Compared with CO2 snow, we find that CO2 glacier ice albedo is much lower in visible and near-infrared (NIR) spectra. CO2 ice albedo is more sensitive to layer thickness than CO2 snow. We observe a noticeable transition between snow albedos and firn/glacier ice albedos. In particular, the absorption features at 1.435 µm and 2.0 µm caused by asymmetric stretching overtones and combinations of fundamental vibrational modes become damped. At these two wavelengths, the albedo is very small; the glacier ice has a higher albedo than coarse-grained snow because of specular reflection. We observe that small amounts (<1%) of Martian dust can lower the albedo of CO2 ice by at least 50%. Once validated, our model can be used to characterize orbital measurements of martian CO2 ice and refine climate-model predictions of ice stability. In the future, we plan to study the spectral albedo of other exotic ices in the solar system (N2 and methane ice in case of Pluto, CO ice on Umbriel).

How to cite: Singh, S., Singh, D., and Whicker, C. A.: Spectral Albedo of Dusty Martian CO2  Snow and Ice, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19665, https://doi.org/10.5194/egusphere-egu24-19665, 2024.

EGU24-20145 | ECS | Orals | PS1.5

Next Generation Intersatellite Laser Ranging Interferometry for Mars Gravity Research 

Alexander Koch, Gerald Bergmann, Moritz Fock, Kévin Grossel, and Julia van den Toren

The Laser Ranging Interferometer (LRI) technology demonstrator on-board the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission has proved an unmatched sub-nanometer per square root of Hertz ranging performance above 100 mHz surpassing the noise floor of the until then state-of-the-art K/Ka-band ranging instrument by orders of magnitude. The LRI’s reliability and its outstanding performance have led to the decision of implementing LRI-like systems as primary instruments for the measurement of the intersatellite range in all currently planned NASA, DLR and ESA Earth gravity missions.

Interferometric laser ranging has proven to be an indispensable technique for the long-term monitoring of Earth’s gravitational field and its spatial and temporal variations, enabling in-depth analyses of many Essential Climate Variables (ECVs). We propose to bring this proven technology to an application in a constellation of satellites dedicated to Mars gravity research as outlined in the paper titled “MaQuIs—Concept for a Mars Quantum Gravity Mission”.

In this talk we will give an overview of the architecture of the LRI as it is currently flying on GRACE-FO as well as the measurement principle and its consequences for the overall mission design. Additionally, we are going to highlight a few of the following development activities, which could be applied for a mission around Mars: enhancement of the long-term stability of the laser frequency, improved redundancy schemes as well as a novel sensor type for the acquisition and maintenance of the constellation. Progress with respect to these aspects will yield a next generation of intersatellite laser interferometers with improved performance and enhanced reliability.

How to cite: Koch, A., Bergmann, G., Fock, M., Grossel, K., and van den Toren, J.: Next Generation Intersatellite Laser Ranging Interferometry for Mars Gravity Research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20145, https://doi.org/10.5194/egusphere-egu24-20145, 2024.

EGU24-22233 | ECS | Posters on site | PS1.5

Computer vision model for monitoring block falls in the Martian north polar region 

Oleksii Martynchuk, Lida Fanara, Klaus Gwinner, and Jürgen Oberst

The north polar region of Mars is one of the most active places of the planet with avalanches and ice block falls being observed every year on High Resolution Imaging Science Experiment (HiRISE) data. Both phenomena originate at the steep icy scarps, which exist on the interface between two adjacent geological units, the older and darker Planum Boreum Cavi unit, also called Basal Unit (BU) and the younger and brighter Planum Boreum 1 unit, which is a part of the so called North Polar Layered Deposits (NPLD). These exposed layers of ice and dust contain important information about the climate cycles of the planet. We are primarily interested in monitoring the current scarp erosion rate (quantified through analyzing ice debris) at the same time differentiating between the activity originating in the NPLD [1] from that originating in the BU

The large scale of the region of interest, combined with a growing amount of available satellite data makes automation key for this project. To achieve the latter we propose a computational pipeline consisting of three consecutive steps, namely: scarp segmentation, single image super-resolution and ice-block detection. For the final analysis Mean Average Precision (mAP.95) was used as a benchmark metric. The performance value of 93.6% was obtained on a test dataset, leading us to conclude that the network is able to perform even on small ice fragments (which comprise the majority of the debris). On a system running 4 RTX3090 GPUs the finished pipeline processes a single HiRISE product in just under 20 minutes, returning the scarp outline and precise ice boulder coordinates. Using this pipeline, we next plan to robustly monitor the mass wasting activity in the whole north polar region and throughout the entire Mars Reconnaissance Orbiter (MRO) mission.

[1] Su, S. et al., 2024. EGU 2024.

How to cite: Martynchuk, O., Fanara, L., Gwinner, K., and Oberst, J.: Computer vision model for monitoring block falls in the Martian north polar region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22233, https://doi.org/10.5194/egusphere-egu24-22233, 2024.

EGU24-3 | ECS | Orals | PS1.8

A Novel Backtracing Model to Study the Emission of Energetic Neutral Atoms at Titan 

Tyler Tippens, Elias Roussos, Sven Simon, and Lucas Liuzzo

To study the emission of energetic neutral atoms (ENAs) at Titan, we have developed a novel model that takes into account a spacecraft detector’s limited field of view and traces energetic magnetospheric particles backward in time. ENAs are generated by charge exchange between Titan’s atmospheric neutrals and energetic magnetospheric ions. By tracing these ions through the draped electromagnetic fields in Titan’s environment, we generate synthetic ENA images and compare them to Cassini observations from the TA flyby. Our model can reproduce the intensity and morphology of the observed images only when field line draping is included. Using a realistic detector geometry is necessary to determine the influence of this draping on the ENA images: the field perturbations eliminate a localized feature in the emission pattern, which is a different effect than found by previous models utilizing an infinitely extended detector. We demonstrate that ENA observations from TA contain signatures of the time-varying Saturnian magnetospheric environment at Titan: the modeled ENA emission morphology and the effect of field line draping are different for the background field vectors measured during the inbound and outbound legs of TA. The visibility and qualitative effect of the draping on observed ENA images vary strongly between different detector locations and pointings. Depending on the viewing geometry, field line draping may add features to the synthetic ENA images, remove features from them, or have no qualitative effect at all. Our study emphasizes the challenges and the potential for remote sensing of Titan’s interaction region using ENA imaging.

How to cite: Tippens, T., Roussos, E., Simon, S., and Liuzzo, L.: A Novel Backtracing Model to Study the Emission of Energetic Neutral Atoms at Titan, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3, https://doi.org/10.5194/egusphere-egu24-3, 2024.

EGU24-691 | ECS | Orals | PS1.8

A study of very high resolution visible spectra of Titan: Line characterisation in visible CH4 bands and the search for C3 

Rafael Rianço-Silva, Pedro Machado, Zita Martins, Emmanuel Lellouch, Jean-Christophe Loison, Michel Dobrijevic, João Dias, and José Ribeiro

The atmosphere of Titan is a unique natural laboratory for the study of atmospheric evolution and photochemistry akin to that of the primitive Earth (1), with a wide array of complex molecules discovered through infrared and sub-mm spectroscopy (2) (3). Here, we present the results of the exploration of original, ground-based, very high-resolution visible spectra of Titan, obtained with VLT-UVES (4). We have developed a new, Doppler-based line detection method which allowed to retrieve an empirical, high resolution (R = 100.000) line list of methane between 525 nm and 618 nm, for which no similar line lists are yet available (5), identifying and characterising more than 90 new high energy CH4 absorption lines at low temperature (T = 150 K).

Furthermore, we searched for the predicted, but previously undetected carbon trimer molecule, C3, (6) (7), on the atmosphere of Titan, at its 405.1 nm band, by comparing VLT-UVES Titan spectra with a line-by-line (8) model spectrum of Titan’s atmosphere with C3. Our results are consistent with the presence of C3 at the upper atmosphere of Titan, with a column density of 1013 cm-2. This study of Titan's atmosphere with very high-resolution visible spectroscopy presents a unique opportunity to observe a planetary target with a CH4-rich atmosphere, from which CH4 optical proprieties can be studied (9). It also showcases the use of a close planetary target to test new methods for chemical retrieval of minor atmospheric compounds, in preparation for upcoming studies of cold terrestrial exoplanet atmospheres (10).

References: (1) Hörst S., 2017; J. Geophys. Res. Planets, doi:10.1002/2016JE005240; (2) Nixon C., et al, 2020; The Astronomical Journal, doi:10.3847/1538-603881/abb679; (3) Lombardo N., et al, 2019, The Astrophysical Journal Letters, 2019, doi:10.3847/2041- 658213/ab3860; (4) Rianço-Silva R., et al, 2023, submitted to Planetary and Space Sciences (under peer-review). (5) Hargreaves R., et al, 2020; The Astrophysical Journal Supplement Series, doi:10.3847/1538-4365/ab7a1a; (6) Hérbad E., et al, 2013; Astronomy & Astrophysics, doi:10.1051/0004-6361/201220686; (7) Dobrijevic M., et al, 2016; Icarus, doi.org/10.1016/- j.icarus.2015.12.045; (8) Schmidt M., et al, 2014; MNRAS, doi.org/10.1093/mnras/stu641; (9) Thompson M., et al, 2022; PNAS, doi.org/10.1073/pnas.2117933119; (10) Tinetti G., et al, 2018; Experimental Astronomy, doi:10.1007/s10686-018-9598-x;

How to cite: Rianço-Silva, R., Machado, P., Martins, Z., Lellouch, E., Loison, J.-C., Dobrijevic, M., Dias, J., and Ribeiro, J.: A study of very high resolution visible spectra of Titan: Line characterisation in visible CH4 bands and the search for C3, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-691, https://doi.org/10.5194/egusphere-egu24-691, 2024.

EGU24-793 | ECS | Orals | PS1.8

Exploring the Venusian clouds: Atmospheric Gravity Waves with Akatsuki UVI instrument 

Daniela Espadinha, Pedro Machado, Javier Peralta, José Silva, and Francisco Brasil

Atmospheric gravity waves are oscilatory disturbances that occur on a specific layer of the atmosphere and whose restoration force is buoyancy [2]. Because of this, these waves can only exist in a continuously stably stratified atmosphere. These waves play an essential role in the global circulation of a planets atmosphere. They are responsible for very important dynamic phenomena such as, for example, the vertical transfer of energy, momentum and chemical species (atmospheric gravity waves transport energy and momentum from the troposphere and deposit it in the thermosphere and mesosphere) since they can form on one region of the atmosphere and travel through it, sometimes over great distances [1]. As such, the study of the properties of atmospheric gravity waves is an essential tool to answer some of the fundamental questions regarding the Venusian atmosphere dynamics, in particular, the fascinating mechanism of superrotation of the atmosphere.

With this work we present observations of wave-like structures on the dayside of Venuss atmosphere using the ultraviolet wavelength of 365nm from Akatsuki’s UVI instrument. The main goal is to evaluate the population of atmospheric waves in Akatsuki’s public database by measuring their physical properties(crest number, horizontal wavelength, packet length, width and orientation ), dynamical properties and distribution in order to establish possible links with previous studies of waves. This work follows a previous study performed by Peralta et al. (2008)[1] and by Silva et al. (2021) [3].


[1] Peralta et al., Characterization of mesoscale gravity waves in the upper and lower clouds of venus from vex-virtis images. Journal of Geophysical Research: Planets, 113(E5), 2008.
[2] Piccialli et al., High latitude gravity waves at the venus cloud tops as observed by the venus monitoring camera on board venus express. Icarus, 227:94 111, 01 2014.
[3] Silva et al., Characterising atmospheric gravity waves on the nightside lower clouds of Venus: a systematic analysis, AA 649 A34, 2021.

How to cite: Espadinha, D., Machado, P., Peralta, J., Silva, J., and Brasil, F.: Exploring the Venusian clouds: Atmospheric Gravity Waves with Akatsuki UVI instrument, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-793, https://doi.org/10.5194/egusphere-egu24-793, 2024.

EGU24-1333 | ECS | Posters on site | PS1.8

Atmospheric Tides Near the Equator on Mars 

Joonas Leino, Ari-Matti Harri, Don Banfield, Manuel de la Torre Juárez, Mark Paton, Jose-Antonio Rodriguez-Manfredi, Mark Lemmon, and Hannu Savijärvi

Diurnal solar radiation forces global oscillations in pressure, temperature, and wind fields. They are called atmospheric or thermal tides and are additionally modified by topography, surface properties, and atmospheric absorber consentration. They propagate around the planet in periods that are integer fractions of a solar day and are only relevant in the upper atmosphere on Earth, but they represent a very large part of the atmospheric circulation on Mars. First two harmonic components (diurnal and semi-diurnal), with periods of 24 and 12 hr at the locations of InSight and Mars Science Laboratory (MSL) are represented here with the comparison to Mars Climate Database (MCD) predictions.

Both of these landers are located in the tropics, InSight on Elysium Planitia (4.5°N, 135.6°E) and MSL within the Gale Crater (4.6°S, 137.4°E). In this study, we utilized observations of the time period from Martian year (MY) 34 solar longitude (Ls) 296° to MY 36 Ls 53°. Diurnal amplitude was larger than semi-diurnal amplitude on both platforms and similar sensitivity to atmospheric dust content was found. However, the amplitude of the semi-diurnal component was smoother than the diurnal amplitude due to its sensitivity to global atmospheric dust content. One clear difference between the platforms was the average amplitude of the diurnal tide, which was 17 Pa for InSight and 33 Pa for MSL. Lateral hydrostatic adjustment flow, generated by the topography causes this difference since it increases the diurnal range of pressure within the Gale. Diurnal tide phase at the InSight was lower than that at the MSL, with averages of 03:39 and 04:25 LTST. In addition, MSL detected roughly contant diurnal tide phase, but InSight observed much more variation. Semi-diurnal phase pattern was very similar on both platforms.

Diurnal tide amplitude predicted by the MCD mimicked the observations quite well at both locations, except during MY 35 Ls 0°–180°. During that time, MCD amplitudes were lower than observed. This is very likely explained by the atmospheric dust conditions, due to the sensitivity of the diurnal tide to the local atmospheric dust loading. MCD dust optical depth was in good agreement with MSL observed optical depth during MY 35 Ls 180°–360°, but was lower than observed during MY 35 Ls 0°–180°. MCD semi-diurnal amplitudes mimicked the observations well throughout MY 35 due to its sensitivity to global atmospheric dust loading.

How to cite: Leino, J., Harri, A.-M., Banfield, D., de la Torre Juárez, M., Paton, M., Rodriguez-Manfredi, J.-A., Lemmon, M., and Savijärvi, H.: Atmospheric Tides Near the Equator on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1333, https://doi.org/10.5194/egusphere-egu24-1333, 2024.

EGU24-2981 | ECS | Orals | PS1.8

Diurnal Temperature Variations and Thermal Tides in the Martian Atmosphere before and during Regional Dust Storms Observed by EMIRS 

Siteng Fan, François Forget, Michael Smith, Sandrine Guerlet, Khalid Badri, Samuel Atwood, Roland Young, Christopher Edwards, Philip Christensen, Justin Deighan, Hessa Almatroushi, Antoine Bierjon, Jiandong Liu, and Ehouarn Millour

The Martian atmosphere experiences large diurnal variations due to its small thickness and low heat capacity. Driven by diurnal solar insolation and influenced by topography and radiative drivers (clouds and dust), diurnal temperature changes propagate from lower atmosphere into higher altitudes as forms of atmospheric tides. However, our understanding of diurnal variations in the Martian atmosphere is poor due to the lack of observations, especially those covering the entire planet and all local times, until recent. In its novelly designed high-altitude orbit, instruments onboard the Hope probe of the Emirates Mars Mission (EMM) could obtain a full geographic and local time coverage of Mars every 10 Martian days (Almatroushi et al., 2021). The Emirates Mars InfraRed Spectrometer (EMIRS, Edwards et al., 2021) observes surface temperature, temperature profile, dust content, water clouds, and water vapor in the lower atmosphere. Diurnal variations of such properties are derived on a planetary scale for the first time without significant gaps in local time or interference from seasonal changes. Such a rapid full planetary-scale coverage is ideal for investigating the fast-changing dust storms on Mars. In this talk, we present results of diurnal temperature variations and thermal tides before, during, and after several regional dust storms in Martian Year (MY) 36 and 37, and their coupling with dust and clouds. The results are also compared with numerical simulations by the Mars Planetary Climate Model (PCM), providing valuable information on physical processes controlling the diurnal climate of Mars.

Almatroushi, H., AlMazmi, H., AlMheiri, N., AlShamsi, M., AlTunaiji, E., Badri, K., et al. (2021). Emirates Mars Mission Characterization of Mars Atmosphere Dynamics and Processes. Space Science Reviews, 217(8), 89. https://doi.org/10.1007/s11214-021-00851-6

Edwards, C. S., Christensen, P. R., Mehall, G. L., Anwar, S., Tunaiji, E. A., Badri, K., et al. (2021). The Emirates Mars Mission (EMM) Emirates Mars InfraRed Spectrometer (EMIRS) Instrument. Space Science Reviews, 217(7), 77. https://doi.org/10.1007/s11214-021-00848-1

How to cite: Fan, S., Forget, F., Smith, M., Guerlet, S., Badri, K., Atwood, S., Young, R., Edwards, C., Christensen, P., Deighan, J., Almatroushi, H., Bierjon, A., Liu, J., and Millour, E.: Diurnal Temperature Variations and Thermal Tides in the Martian Atmosphere before and during Regional Dust Storms Observed by EMIRS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2981, https://doi.org/10.5194/egusphere-egu24-2981, 2024.

EGU24-3253 | Posters on site | PS1.8

Remote Sensing of Column CO2, Atmospheric Pressure, and Vertical Distribution of Dust and Clouds on Mars using Differential Absorption Lidar at 1.96 µm on an Orbiter 

Zhaoyan Liu, Joel Campell, Bing Lin, Jirong Yu, Jihong Geng, and Shibin Jiang

By utilizing progress in millijoule-level pulsed fiber lasers operating in the 1.96 µm spectral range, we propose a novel concept introducing a differential absorption barometric lidar designed for remote sensing of Martian atmospheric properties on an orbiter. Our emphasis is on the online wavelength situated in the trough region of two absorption lines, chosen for its insensitivity to laser frequency variations, thereby mitigating the need for stringent laser frequency stability. Our investigation centers around a compact lidar configuration, featuring reduced telescope dimensions and lower laser pulse energies. These adjustments are aimed at minimizing costs for potential forthcoming Mars missions.

The primary measurement objectives include determining column CO2 absorption optical depth, columnar CO2 abundance, surface atmospheric pressure, as well as vertical distributions of dust and cloud layers. By combining surface pressure data with atmospheric temperature insights obtained from sounders and utilizing the barometric formula, the prospect of deducing atmospheric pressure profiles becomes feasible. Simulation studies validate the viability of our approach. Notably, the precision of Martian surface pressure measurements is projected to better than 1 Pa when the aerial dust optical depth is anticipated to be under 0.7, a typical airborne dust scenario on Mars, considering a horizontal averaging span of 10 km.

How to cite: Liu, Z., Campell, J., Lin, B., Yu, J., Geng, J., and Jiang, S.: Remote Sensing of Column CO2, Atmospheric Pressure, and Vertical Distribution of Dust and Clouds on Mars using Differential Absorption Lidar at 1.96 µm on an Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3253, https://doi.org/10.5194/egusphere-egu24-3253, 2024.

EGU24-5297 | Orals | PS1.8

Consequences of Impact Erosion and Volatile Loss Processes on the Evolution of Venus. 

Cédric Gillmann and Gregor Golabek

We model the long-term evolution of Venus through volatile exchanges and compare observed and simulated present-day states. This work focuses on quantifying the effect of different parameterizations for loss processes on the overall evolution.

Due to both the striking similarities and the obvious differences between Earth and Venus, understanding Venus might hold keys to how planets become -and cease to be- habitable. It has been suggested that the divergence between Earth and Venus could occur during the first few hundred million years due to interaction between the interior of the planet, its atmosphere and escape mechanisms. 

We develop coupled numerical simulations of the atmosphere and interior to test what evolutionary paths can reproduce the observed present-day state of Venus. They include modeling of mantle dynamics, core evolution, volcanism/outgassing, surface alteration, atmospheric escape (hydrodynamic and non-thermal), volatile deposition and loss through impacts. Impact histories representing different possible scenarios for late accretion are generated using n-bodies simulations.

Our previous efforts used hydrocode results to model impact erosion. A new parameterization has since been proposed by Kegerreis et al. (2020), with increased losses for high-energy collisions. We test if these results induce divergences between different impact histories (e.g., giant impact vs. small impactors) and combine these different parameterizations depending on impactor size.

Post-hydrodynamic escape, non-thermal loss mechanisms can remove low amounts of water and oxygen, from the surface/atmosphere (4 mbar to a few bar), making it quite difficult to accommodate large bodies of water, especially during Venus’ recent past. Trapping oxygen on the surface through oxidation of newly emplaced volcanic material through solid-gas reactions appears inefficient (totalling loses similar to non-thermal escape). Runaway greenhouse resulting in a molten surface could lead to the loss of multiple bars of oxygen but still leaves behind a significant atmospheric inventory. These results imply a maximum limit to water delivery by impacts.

Atmospheric delivery and erosion by impacts seem to be the largest source/sink of volatile species during evolution. The choice of parameterization for erosion can induce a large difference in total inventory (up to several 1-10 bar of H2O and CO2). However maximum delivery by impactors over Late Accretion are still limited by loss processes. Previously obtained upper limits for water content of the Late Accretion (95-98% dry enstatite chondrite, 2-5% of carbon chondrite) are revised upward to 5-10% Carbon chondrites for efficient atmospheric erosion models.

How to cite: Gillmann, C. and Golabek, G.: Consequences of Impact Erosion and Volatile Loss Processes on the Evolution of Venus., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5297, https://doi.org/10.5194/egusphere-egu24-5297, 2024.

EGU24-6486 | Orals | PS1.8

The Structure and Evolution of Titan’s Daytime Planetary Boundary Layer 

Scot Rafkin, Guillermo Chin Canche, and Alejandro Soto

The structure and evolution of Titan’s daytime planetary boundary layer (PBL) are investigated through large eddy simulation (LES) modeling.  The PBL is the interface between the surface and the free atmosphere through which energy, mass, and momentum are exchanged via turbulent eddies.  The sounding from the Huygens probe provided the only direct, vertically resolved measurement of the structure of the PBL at a single moment in time. How the observed structures develop and evolve remain uncertain, and the turbulent exchange processes are challenging to constrain from the single profile. LES techniques provide a mechanism for understanding the observed structure and dynamics of the PBL, better constraining turbulent atmosphere-surface exchange, and improving the parameterization of the PBL in larger-scale models.  Results from LES studies forced by diurnally-varying radiation are presented for Titan.  The development of three distinct PBL layers are noted: 1) a near-surface layer dominated by frictional dissipation; 2) a mixed-layer of near neutral stability; and 3) a relatively deep entrainment layer capping the top of the PBL.  The three layers are similar in character to what is often observed in the Earth’s convective PBL. The interpretation of the modeled structures and PBL evolution in the current LES study differs significantly from previous mechanisms inferred from GCM studies and shows important differences from prior work that lacked diurnally-varying radiative forcing.

How to cite: Rafkin, S., Chin Canche, G., and Soto, A.: The Structure and Evolution of Titan’s Daytime Planetary Boundary Layer, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6486, https://doi.org/10.5194/egusphere-egu24-6486, 2024.

EGU24-7015 | ECS | Posters on site | PS1.8

A Linearized Coupled Model of Acoustic-gravity Waves and the Lower Ionosphere at Mars 

Xing Wang, Xiaojun Xu, Jun Cui, Siqi Yi, Hao Gu, Zilu Zhou, Hengyan Man, Lei Luo, Peishan He, and Pu Yang

Highly variable ionospheric structures on Mars have been recently observed via spacecraft measurements. Acoustic-gravity waves (AGWs) could be an underlying mechanism. Studying the response of the Martian ionosphere to AGWs could provide us with an important understanding of the neutral wave-ionospheric coupling process. To explore the plasma-neutral coupling driven by AGWs in the lower ionosphere of Mars, a linearized wave model has been developed. This model can describe the propagation and dissipation of AGWs in a realistic atmosphere and first incorporates plasma behaviors associated with photochemistry and electromagnetic fields. We adopted a full-wave model as the first part of our coupled model to delineate wave propagation in a realistic atmosphere. The second part of our model consists of the governing equations describing the plasma behaviors. Therefore, our model not only replicates the result of the full-wave model but also investigates the wave-driven variations in the plasma velocity and density, electromagnetic field, and thermal structures. Our model results reveal that ions are mainly dragged by neutrals and oscillate along the wave phase line below ~200 km altitude. Electrons are primarily subject to gyro-motion along magnetic field lines. The wave-driven distinct motions among charged particles can generate the perturbed electric current and electric field, further contributing to localized magnetic field fluctuations. Major charged constituents, including electrons, O+, O2+, and CO2+, have higher density amplitudes when interacting with larger-periodic waves. The presence of photochemistry leads to a decrease in the plasma density amplitude, and there exists a moderate correlation between plasma density variations and those in the neutrals. Our numerical results indicate that the wave-driven variations range from several percent to ~ 80% in the plasma density and from ~ 0.2% to 17% in the magnetic field, which are consistent with the spacecraft observations. Further calculations reveal that the wave-induced plasma-neutral coupling can heat the neutrals yet cool the plasmas. Electrons are cooler than ions in the coupling process. The wave-driven heating by neutral-ion collisions exceeds that by neutral-electron collisions but tends to be lower than the wave dissipative heating and photochemical heating. Our model has potential applications in studying the AGWs-driven variable ionospheric structures and can be used for other planets.

How to cite: Wang, X., Xu, X., Cui, J., Yi, S., Gu, H., Zhou, Z., Man, H., Luo, L., He, P., and Yang, P.: A Linearized Coupled Model of Acoustic-gravity Waves and the Lower Ionosphere at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7015, https://doi.org/10.5194/egusphere-egu24-7015, 2024.

EGU24-8133 | Orals | PS1.8

Ephemeral Ice Clouds in the Upper Atmosphere of Venus 

John Plane, Benjamin Murray, Thomas Mangan, and Anni Määttänen

Venus is well known for extreme heat at its surface and being shrouded in clouds composed of sulphuric acid. However, there are regions of Venus’ atmosphere around 120 km that are cold enough to harbour ice clouds, under conditions similar to the upper mesospheres of Earth and Mars where ice clouds form. In this presentation we will show, using published satellite products and numerical modelling, that the upper mesosphere of Venus can be cold enough for both H2O and CO2 to condense and form particles. Amorphous solid water particles (ASW) are likely to nucleate both heterogeneously on meteoric smoke (formed from the condensation of the metallic vapours which ablate from cosmic dust particles entering  Venus’ atmosphere) and also homogeneously, resulting in clouds of nano-scaled particles at around 120 km that will occur globally. The temperatures may become cold enough (below ~90 K) that CO2 particles nucleate on ASW particles. Taking account of the uncertainty associated with retrievals of temperature in the upper mesosphere (using the SOIR instrument on Venus Express), CO2 ice cloud formation could occur more than 30% of the time poleward of 60o. Since the main component of Venus’ tenuous atmosphere is CO2, any CO2 crystals that form will grow and sediment on a timescale of a few minutes. Mie calculations show that these Venusian mesospheric clouds (VMCs) should be observable by contemporary satellite instruments, although their short lifetime means that the probability of detection is small. We suggest that VMCs are important for the redistribution of meteoric smoke and may serve as a cold-trap, removing some water vapour from the very upper mesosphere of Venus through the growth and sedimentation of cloud particles, and possibly reducing the loss of water to space.

How to cite: Plane, J., Murray, B., Mangan, T., and Määttänen, A.: Ephemeral Ice Clouds in the Upper Atmosphere of Venus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8133, https://doi.org/10.5194/egusphere-egu24-8133, 2024.

EGU24-9716 | Posters on site | PS1.8

Probing the Mars upper atmosphere through simultaneous NOMAD/UVIS observations of the NO ultraviolet and O2 visible nightglow 

Lauriane Soret, Jean-Claude Gérard, Francisco González-Galindo, Ian Thomas, Bojan Ristic, Ann-Carine Vandaele, and Benoit Hubert

While extensive studies have been conducted on Mars' dayside airglow emissions using instruments of various missions (Mariner, Mars Express, MAVEN, TGO and EMM), only the ultraviolet and infrared emissions have been investigated on the nightside (MEx and MAVEN). The middle ultraviolet spectrum is dominated by the v’=0 δ and γ bands of nitric oxide excited by radiative association of nitrogen and oxygen atoms. Although this emission is present at all latitudes and local times, extensive mapping has shown that it is enhanced in winter at high latitudes in both hemispheres (Schneider et al., 2020). This seasonal brightening at high latitudes is the signature of the global transport of O and N atoms ascending from the sunlit summer polar regions that are carried downward by vertical winds and diffusion to the 40-60 km region of the dark winter hemisphere. The O2 nightglow at 1.27 μm has already been monitored as well (Bertaux et al., 2012). However, nightglow emissions in the visible domain have begun only very recently with the NOMAD-UVIS instrument, which can, for the first time, simultaneously monitor the UV and visible domains in the Martian atmosphere. Gérard et al. (2023) have discovered the presence of the (0,5) to (0,11) bands of the O2 Herzberg II system between 400 and 650 nm in the nightglow. We present here a comprehensive statistical analysis of this nightglow based on a dedicated NOMAD-UVIS campaign of 30 orbits acquired between May and October 2023 in the southern hemisphere during the winter season. Combining both the inertial and limb tracking modes allows for intensity retrieval, latitudinal variability analysis, and the generation of limb profiles.

The O2 emission is expected to solely originate from the three-body recombination of O atoms O + O + M → O2* + M.  The oxygen density can therefore directly be retrieved from the Herzberg II observations. Furthermore, simultaneous NO nightglow observations with NOMAD-UVIS combined with the retrieved oxygen density, allows to calculate the nitrogen density and its downward flux. As atomic oxygen serves as a precursor to both NO and O2 nightglows, arising from O atom recombination with either oxygen or nitrogen, this dual investigation presents a remarkable opportunity to unravel their shared characteristics (stemming from oxygen density) and their distinguishing features (emanating from nitrogen), including variations in brightness and altitudes. It will provide valuable constraints for improving 3-D models that simulate global circulation and dynamic processes. In particular, it will help solving the current discrepancy between the predicted and modeled altitude distribution of the NO nightglow, a proxy of insufficiently vigorous downward transport of N atoms.

 

References:

Bertaux et al. (2012), First detection of O2 1.27 µm nightglow emission at Mars with OMEGA/MEX and comparison with general circulation model predictions, JGR, 117, E00J04, doi:10.1029/2011JE003890.

Gérard et al. (2023). Observation of the Mars O2 visible nightglow by the NOMAD spectrometer onboard the Trace Gas Orbiter. Nature Astronomy, https://doi.org/10.1038/s41550-023-02104-8

Schneider et al. (2020) Imaging of Martian circulation patterns and atmospheric tides through MAVEN/IUVS nightglow observations. JGR Space Physics 125(8), e2019JA027318.

How to cite: Soret, L., Gérard, J.-C., González-Galindo, F., Thomas, I., Ristic, B., Vandaele, A.-C., and Hubert, B.: Probing the Mars upper atmosphere through simultaneous NOMAD/UVIS observations of the NO ultraviolet and O2 visible nightglow, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9716, https://doi.org/10.5194/egusphere-egu24-9716, 2024.

EGU24-10193 | Posters on site | PS1.8

New insight into the surface composition of Zhurong landing area 

Qing Zhang, John Carter, Mathieu Vincendon, François Poulet, Maxime Pineau, Lin Guo, Yuxuan Luo, Dawei Liu, Jean-Pierre Bibring, Jianjun Liu, and Chunlai Li

The Zhurong rover conducted in-situ spectral investigations of southern Utopia Planitia, where orbital observations revealed the presence of spectrally featureless dust. However, in-situ reflectance spectra collected by the Short Wave Infrared (SWIR) spectrometer exhibit hydrated features for all observations along the traverse. These features have been interpreted as being associated with groundwater (Liu Y. et al., 2022) or ocean (Liu C. et al., 2022; Xiao et al., 2023) or atmospheric water (Zhao et al., 2023). Here, we combine the Multispectral Camera (MSCam) and SWIR data to characterize the spectra of landing site and provide some new insights into the surface composition diversity.

Multispectral images suggest that most of surfaces are consistent with the presence of dust whereas a few of rock surfaces exhibiting dark tones are compositionally distinct. The co-observational SWIR data can be used to further constrain the surface compositions. With Principal Component Analysis (PCA) and unmixing analysis of the SWIR data, we found that these dusty surfaces are ubiquitously characterized with faint 1900 and 2200 nm absorptions and the dark rock surfaces exhibit strong blue slopes in the NIR.

The hydrated dust features seem to contrast with previous knowledge, that the dust does not exhibit obvious NIR hydration features from orbital observations. Such discrepancies were also observed at Jezero crater, where the fine soils or dusty rocks exhibit a 1900 nm H2O absorption but without 2200 nm band (Mandon et al., 2023). Spectral variation may reflect distinct surface dust compositions between the Perseverance and Zhurong landing site, indicating different dust reservoirs or dust alteration processes. The surface dust of different sites may be mixtures of globally well-mixed fine materials and local/regional distinct hydrated phases. Another possibilities is that the dust underwent different post-deposition aqueous alteration.

The dark rock surfaces may represent less dust-coated surfaces. The strong blue slope features have been previously attributed to coatings on a dark substrate. Furthermore, the morphological properties show that these surfaces exhibit relatively fragile surface context, consistent with surface coatings or rinds.

How to cite: Zhang, Q., Carter, J., Vincendon, M., Poulet, F., Pineau, M., Guo, L., Luo, Y., Liu, D., Bibring, J.-P., Liu, J., and Li, C.: New insight into the surface composition of Zhurong landing area, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10193, https://doi.org/10.5194/egusphere-egu24-10193, 2024.

EGU24-10357 | Posters on site | PS1.8

Mars Singular Clouds: Dots, Rings and Narrow-Elongated 

Agustin Sanchez-Lavega, Jorge Hernandez-Bernal, Ethan Larsen, Teresa del Rio-Gaztelurrutia, Beatriz Sánchez-Cano, and Anni Määttäanen

We report two extreme cases of clouds in Mars, on the one hand what we call “isolated dot clouds” and on the other hand new cases of extremely “elongated long and narrow clouds” reminiscent in their shape of the one that develops in Arsia Mons. We use the images obtained by the VMC-camera on board the Mars Express mission that from its advantageous polar elliptical orbit allows to image Mars at different local times (in particular at twilight hours).

We present the properties of the “dot clouds” that develop abundantly in the Terra Cimmeria region, particularly around the Kepler crater (longitude 140.9 East and 46.8 South) in Mars solar longitudes Ls from 30 to 100 deg. These are compact rounded clouds with sizes of about 50 km in diameter and altitudes in the range 50-80 km as measured from their shadows. Sometimes they appear isolated at dawn, others in twilight clusters, but we also present a singular case in which they exhibited a ringed shape. We discuss possible mechanisms underlying their formation, such as convection and the possible intervention of the crustal magnetic field concentrated in this region.  On the other hand, we report new cases of extremely narrow and elongated clouds observed at mid and high latitudes in both hemispheres. We study in particular the properties of these clouds in the volcanic region of Alba Patera, in Thaumasia Highlands and in Lyot crater, where they can reached lengths from 1,000 km to 2,000 km and widths of 50 km.  

How to cite: Sanchez-Lavega, A., Hernandez-Bernal, J., Larsen, E., del Rio-Gaztelurrutia, T., Sánchez-Cano, B., and Määttäanen, A.: Mars Singular Clouds: Dots, Rings and Narrow-Elongated, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10357, https://doi.org/10.5194/egusphere-egu24-10357, 2024.

EGU24-12597 | Posters on site | PS1.8

Monitoring Condensation Flow on Mars with Landed X-ray Spectrometers: A Summary of 11,000 Sols Across Three Landing Sites 

Scott VanBommel, Ralf Gellert, Jeff Berger, John Christian, Abigail Knight, Michael McCraig, Cat O'Connell-Cooper, Lucy Thompson, Albert Yen, and Nick Boyd

Alpha Particle X-ray Spectrometers (APXS) were an integral component of the science payload that flew on the twin Mars Exploration Rovers (MER) Spirit and Opportunity. An updated version of the MER APXS instrument, further optimized for in situ geochemical analyses on Mars, is currently operational within Gale crater onboard the Mars Science Laboratory (MSL) rover Curiosity. APXS on MER and MSL were designed and calibrated for high-precision in situ analyses of geologic materials on Mars. The use of curium-244 sources provides high sensitivity to lower-Z elements. This low-Z sensitivity is important for characterizing the abundance of rock forming elements such as Na, but also enables analyses of Ar, which makes up ~2% of the Martian atmosphere, and thus ~40% all non-condensable gas species.

Atmospheric dynamics on Mars are driven in large part by condensation flow. The temperature and pressure at the winter pole leads to the deposition of carbon dioxide (which makes up ~95% of the atmosphere) onto the polar cap. The following spring, carbon dioxide sublimates from the cap, a cycle which creates a pressure gradient across the planet. Non-condensable gases, such as Ar, are not deposited on the polar cap and become enriched relative to carbon dioxide. Most environmental monitoring hardware flown to Mars can measure the absolute pressure of the atmosphere, but not specifically the abundance of non-condensable species. In the case of the Sample Analysis at Mars (SAM) instrument on MSL, atmospheric constituents can be deduced with great accuracy, but not with a high frequency.

We summarize efforts on MER and MSL to characterize variability in non-condensable gas density on Mars using instruments designed to measure the composition of rocks and regolith. Analyses by Spirit enabled calibration of the MER APXS for atmospheric analyses. The Opportunity mission, spanning ~5000 sols, acquired around 2250 hours of atmospheric data with its APXS. This data set revealed an annual short-lived Ar enrichment occurring around Ls 150, previously unreported in the literature and not present in climate models at that time. This phenomenon has since been regularly targeted on MSL with APXS (and SAM), with ~800 hours of atmospheric analyses conducted by APXS thus far. We report recent findings from Mars Year 37, where dedicated high-frequency APXS atmospheric campaigns were conducted, coinciding with solar conjunction and extended holiday plans, significantly improved constraints on the timing of this short-lived enrichment at Gale crater, and compare the observed results to those from Opportunity.

How to cite: VanBommel, S., Gellert, R., Berger, J., Christian, J., Knight, A., McCraig, M., O'Connell-Cooper, C., Thompson, L., Yen, A., and Boyd, N.: Monitoring Condensation Flow on Mars with Landed X-ray Spectrometers: A Summary of 11,000 Sols Across Three Landing Sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12597, https://doi.org/10.5194/egusphere-egu24-12597, 2024.

EGU24-12803 | ECS | Orals | PS1.8

Photochemistry of the Recent Martian Atmosphere at Different Obliquities 

Yangcheng Luo, Franck Lefèvre, and François Forget

Due to gravitational perturbations from nearby planets, Mars has undergone large obliquity variations through its history. Modeling suggested that in the past 10 million years, the obliquity of Mars has varied by up to 20°, from 15° to 35°. During time periods of high obliquity, the polar regions of Mars received more solar insolation and became warmer, leading to more rapid sublimation of water ice and higher atmospheric water content. During periods of low obliquity, on the contrary, water vapor condensed in polar regions and the atmosphere became dry. This variation has a significant impact on the photochemistry of the Martian atmosphere, as HOx radicals, which are photolytic products of water vapor, are key catalysts to the photochemistry of the Martian atmosphere. It is then of interest to explore the photochemistry of Mars at different obliquities and its effects on the climate and surface of Mars, as part of the objectives of the “Mars Through Time” European Research Council project. In preparation for future Mars sample return missions, it is important to evaluate the preservability of potential organic matter buried in the shallow subsurface with different oxidizing capacities of the atmosphere at different obliquities.

In view of the three-dimensional nature of the sublimation, transport, and condensation of water, we employ a fully coupled photochemical-radiative-dynamical model—the Mars Planetary Climate Model, developed at LMD in collaboration with other institutions—to simulate the photochemistry of the recent Martian atmosphere at obliquities between 15° and 35°. We find that at high obliquities, water content of the Martian atmosphere could exceed the present-day value by more than one order of magnitude, and the OH concentration could be higher by up to two orders of magnitude. These drastic changes result in a significantly lower CO concentration. Opposite effects are observed from low-obliquity simulations. The nonlinearity in the photochemical system, however, has led to more complex behaviors of the HO2 and H2O2 concentrations. We will explain the mechanisms behind these effects and discuss their implications in the paleoclimate of Mars and the preservation of potential biogenic organic matter in the shallow subsurface. We will also address the long-standing “CO-deficit” problem in Mars photochemical modeling, and show how the state-of-the-art 3D photochemical modeling helps to mitigate the problem.

How to cite: Luo, Y., Lefèvre, F., and Forget, F.: Photochemistry of the Recent Martian Atmosphere at Different Obliquities, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12803, https://doi.org/10.5194/egusphere-egu24-12803, 2024.

EGU24-15988 | ECS | Orals | PS1.8

The Martian Recurring Slope Lineae: Granular Flows Linked with Wind and Dust  

Yann Leseigneur, Mathieu Vincendon, and Qing Zhang

Recurring Slope Lineae (hereinafter RSL) are seasonal dark flows observed on steep slopes (≳ 25°) of Mars that are overall dark (slope albedo < 0.2) (McEwen et al., 2011). These movements of up to a few hundred meters long appear and grow downwards (more or less incrementally), fade (partially or totally) more or less progressively, and recur almost every year. After considering it as liquid water or brine flows, the RSLs are now widely considered as granular flows of dark sand or dust, both involving dust at different levels. Mechanisms that may drive these movements are however not precisely understood. One of the main common features between RSL and dust is seasonality: major RSL formations are for example observed during the dust storm season, and RSL formation is enhanced after global dust storms. Here, we aim to better understand the role of dust and winds in these movements.

 

We have first concentrated our study on Hale crater (323.48°E, 35.68°S), a well-studied RSL site located within an area of higher dust storm detections in the OMEGA/Mars Express dataset. Images taken by the HiRISE camera onboard Mars Reconnaissance Orbiter (during Martian Years 31, 32 and 33) have been used to characterise the RSL annual activities. We defined 3 intensity levels to classify formations and disappearances. Then, we compared these RSL activities to atmospheric dust optical depth measurements and Mars Climate Database (MCD) predictions of dust deposition and winds. Finally, we computed the effective reflectance values of several consecutive HiRISE images, taking into account the local slope of the surface, to quantify darkening and brightening.

 

We observed that RSL formation and disappearance are correlated with the atmospheric dust optical depth variations. We also noticed that the prediction of dust deposition rate reaches two maxima during the dust storm season that occur simultaneously with intermediate and high RSL disappearance levels. Reflectance variations showed that RSL can disappear both by brightening and darkening, with relative variations from a few per cent to 40%, suggesting that RSL can also disappear by widespread dust removal all over the RSL slope. We also identified some correlations between RSL activities and wind predictions: the maximum of surface wind stress is reached during the first period (of the year) of high RSL formation level, and the convective winds reach high values during the dust storm season (Ls ~ 180-360°), corresponding to intermediate and high RSL formation levels. Overall, these results suggest that dust deposition/removal and winds are involved in the RSL disappearance and formation mechanisms at Hale crater.

How to cite: Leseigneur, Y., Vincendon, M., and Zhang, Q.: The Martian Recurring Slope Lineae: Granular Flows Linked with Wind and Dust , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15988, https://doi.org/10.5194/egusphere-egu24-15988, 2024.

EGU24-16259 | ECS | Orals | PS1.8

Clouds and Seasonality on Terrestrial Planets with Varying Rotation Rates  

Daniel Williams, Xuan Ji, Paul Corlies, and Juan Lora

Clouds have been observed on Venus, Mars and Titan, and a growing number of exoplanets, yet the connection between planetary rotation rate and cloud distribution has not previously been extensively investigated. Using an idealised climate model incorporating seasonal forcing, we investigate the impact of rotation rate on the abundance of clouds on an Earth-like aquaplanet, and the resulting impacts upon albedo and seasonality. We show that the cloud distribution varies significantly with season, depending strongly on the rotation rate, and is well explained by the large-scale circulation and atmospheric state. Planetary albedo displays non-monotonic behaviour with rotation rate, peaking around one half of Earth’s rotation rate. Clouds reduce the surface temperature and total precipitation relative to simulations without clouds at all rotation rates, and reduce the dependence of precipitation on rotation rate. Clouds also affect the amplitude and timing of seasonality, in particular by modifying the width of the Hadley cell at intermediate rotation rates. The timing of seasonal transitions varies with rotation rate; the addition of clouds further modifies this phase lag, most notably at Earth-like rotation rates. Our results may inform future characterisation of terrestrial exoplanets, in particular informing estimates of planetary rotation for non-synchronous rotators.

How to cite: Williams, D., Ji, X., Corlies, P., and Lora, J.: Clouds and Seasonality on Terrestrial Planets with Varying Rotation Rates , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16259, https://doi.org/10.5194/egusphere-egu24-16259, 2024.

EGU24-16561 | Posters on site | PS1.8

The Titan PCM : a fully coupled climate model to study thermal structures, haze, clouds and their seasonal variations 

Sebastien Lebonnois, Bruno de Batz de Trenquelleon, Lucie Rosset, Jan Vatant d'Ollone, and Pascal Rannou

We have developed a new version of the IPSL Titan GCM, now called the Titan Planetary Climate Model (Titan PCM), including a new microphysical model for haze and clouds. Observations of Titan have long revealed the presence of seasonal cycles on Titan (haze, clouds, organic compounds), the ins and outs of which are still poorly understood. In particular, the lack of information on the different flows that govern these cycles prevents us from understanding all the phenomena taking place in Titan’s atmosphere. The need to develop a complete climate model, including microphysics, therefore becomes essential.

The latest improvements in the Titan PCM radiative transfer, now based on a flexible correlated-k method and up-to-date gases spectroscopic data, lead to a better modelling of the temperature profiles in the middle atmosphere. The photochemical solver extends computation of the composition above the top of the PCM (roughly 500 km) up to 1300 km. Radiative transfer is coupled with a new microphysics model in moments. This model includes phenomena such as the nucleation and condensation of clouds, and precipitation that shape the satellite’s landscape.

We are now able to model the processes involved in the formation of tropospheric (CH4) and polar (C2H2, C2H6 and HCN) clouds on Titan. Cloud formation induces new seasonal cycles, particularly at the tropopause where clouds empty the lower layers of the atmosphere of aerosols, featuring two boundary, the main haze layer and a layer of condensed organic compounds. Higher up, in the lower stratosphere, the haze follows a new cycle constrained solely by the circulation, leading to a better modelling of the temperature profiles in the low stratosphere and the troposphere.

From the results of coupled simulations, we can discuss multiple questions raised by observations. Special interest is bear on the overall control of the thermal structure, and impact of the coupling on equinoctial circulation reversal. We also discuss the radiative destabilization of the lower polar winter stratosphere, observed by Cassini radio-occultations.

How to cite: Lebonnois, S., de Batz de Trenquelleon, B., Rosset, L., Vatant d'Ollone, J., and Rannou, P.: The Titan PCM : a fully coupled climate model to study thermal structures, haze, clouds and their seasonal variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16561, https://doi.org/10.5194/egusphere-egu24-16561, 2024.

EGU24-17142 | Posters on site | PS1.8

A 3 Martian Year climatology of aerosols with ExoMars TGO-NOMAD: seasonal cycles and new insights 

Giuliano Liuzzi, Geronimo Villanueva, Shohei Aoki, Loic Trompet, Frank Daerden, Lori Neary, Sebastien Viscardy, Sara Faggi, Shane W. Stone, Ian Thomas, Manish Patel, and Ann Carine Vandaele

The Nadir and Occultation for MArs Discovery (NOMAD) spectrometer has been collecting Mars observations since 2018, providing a massive amount of information regarding its atmospheric composition, its vertical structure and bridging the gap between the previous knowledge of the lower atmosphere and the data from other missions (e.g., MAVEN) regarding atmospheric escape. The capability of the Solar Occultation (SO) channel to map the vertical structure of the atmosphere with a very high (>1000) signal-to-noise ratio, at a very high spectral resolution (>17000) and a high vertical sampling (0.5 to 2 km) is valuable in many contexts, ranging from the search for trace species in the lower atmosphere (10 to 40 km) to mapping the isotopic composition of the main atmospheric constituents (H2O, CO2, CO) or exploring the vertical structure of dust, water ice and CO2 ice clouds.

Aerosols are some of the main drivers of the Martian climate, and the study of their spatial distribution and microphysical properties can advance our knowledge of their impact on the climate of the planet and on their formation and dynamics. This work will show the extension of previous investigations focused on dust, water ice and CO2 ice using NOMAD data, by presenting the mapping of these atmospheric components on a global scale over 3 Martian Years (MY34 Ls 160 to MY37 Ls 170). The acquisition by NOMAD of several diffraction orders during a single occultation allows in fact to obtain spectrally broad information that can be used to map dust and water ice vertical distributions and particle sizes. The information content of NOMAD data about particle sizes of water ice has been demonstrated to be particularly high and to give important information about the nucleation processes of water ice. NOMAD data can also be used to look for CO2 ice by combining broad spectral information with localized CO2 ice features at 3600 and 3710 cm-1, which are well identifiable in the NOMAD spectra.

Besides presenting the climatology of aerosols, we will illustrate specific features occurring during the Martian Year and their repeatability; more specifically, we will look into the differences between MY 34, characterized by a Global Dust Storm, and following years, to highlight the impact of dust-induced heating over cloud formation. We will also give some insights into CO2 ice cloud formation, which was confirmed to be surprisingly heterogeneous compared to results obtained before TGO operations.

How to cite: Liuzzi, G., Villanueva, G., Aoki, S., Trompet, L., Daerden, F., Neary, L., Viscardy, S., Faggi, S., Stone, S. W., Thomas, I., Patel, M., and Vandaele, A. C.: A 3 Martian Year climatology of aerosols with ExoMars TGO-NOMAD: seasonal cycles and new insights, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17142, https://doi.org/10.5194/egusphere-egu24-17142, 2024.

EGU24-17539 | ECS | Posters on site | PS1.8

Martian aerosol Climatology on Mars as Observed by NOMAD UVIS on ExoMars TGO 

zachary flimon, Justin Erwin, Severine Robert, Lori Neary, Arianna Piccialli, Loic Trompet, Yannick Willame, Frank Daerden, Sophie Bauduin, Michael Wolff, Ian Thomas, Bojan Ristic, Giancarlo Bellucci, Manish Patel, Cedric Depiesse, Ann-Carine Vandaele, Jon Mason, José juan Lopez-Moreno, and Filip Vanhellemont

The NOMAD (“Nadir and Occultation for MArs Discovery”) spectrometer suite onboard the ExoMars Trace Gas Orbiter (TGO) is composed of three spectrometers. In this work, we will use the UVIS channel in occultation mode. An aerosol climatology had been produced covering the second half of MY 34 up to the end of MY 36. 
Aerosols are an important part of the Martian atmosphere and have a strong relationship with the atmospheric temperature. They are composed of dust, H2O ice, and CO2 ice. Dust is the main aerosol and has a significant contribution to the radiative transfer budget, as it absorbs solar radiation, leading to local heating of the atmosphere. Dust is confined to lower altitudes during the aphelion season and can reach higher altitudes during the perihelion, especially during dust storms that frequently arise on Mars during this period. The ice clouds are more present during the aphelion when the temperature is colder and follow a seasonal pattern. Several types of clouds can be found throughout the year, contrary to the dust they reflect the sunlight and cool locally the atmosphere. 
Using only the spectral range of UVIS dust, H2O ice, and CO2 ice cannot be differentiated because the three aerosols have similar spectral features in the UV-visible. Dust represents most of the aerosols present in the atmosphere, therefore only dust refractive indices are used in this work. Detection of CO2 and water ice will be investigated in future work using the infrared channel of NOMAD. Nevertheless, we presented a way of indirectly recognizing the composition of the aerosols using indirect parameters such as the temperature or comparison with other datasets.It is possible to distinguish the particle size between 0.1 to 0.8 µm with confidence. When the particles are larger it is not possible to retrieve the precise size. 
In conclusion we present a climatology of Martian aerosols, including vertical extinction profiles as well as vertical profiles of particle size distributions. The seasonal cycle of the dust is observed and recurring structures over different Martian years such as dust storms or ice clouds are detected. We also present a comparison with water vapor profiles and aerosol profiles during regional dust storms, we showed that the water vapor during the storm could condense to water ice due to the presence of dust condensation nuclei at high altitudes. The thermal and dynamical structure of the atmosphere, and chemical species are all sensitive to the aerosol’s abundance and size.

How to cite: flimon, Z., Erwin, J., Robert, S., Neary, L., Piccialli, A., Trompet, L., Willame, Y., Daerden, F., Bauduin, S., Wolff, M., Thomas, I., Ristic, B., Bellucci, G., Patel, M., Depiesse, C., Vandaele, A.-C., Mason, J., Lopez-Moreno, J. J., and Vanhellemont, F.: Martian aerosol Climatology on Mars as Observed by NOMAD UVIS on ExoMars TGO, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17539, https://doi.org/10.5194/egusphere-egu24-17539, 2024.

EGU24-18377 | ECS | Posters on site | PS1.8

A comprehensive study on the sputtering of the lunar surface 

Johannes Brötzner, Herbert Biber, Noah Jäggi, Andreas Nenning, Lea Fuchs, Paul Stefan Szabo, André Galli, Peter Wurz, and Friedrich Aumayr

The Moon is subjected to a variety of influences in the space environment. One of these is the solar wind, a plasma stream consisting of mostly H+ and He2+ ions, that impinges on the lunar surface. As a consequence, material is released through the process of ion sputtering, mostly on an atomic level. These ejecta subsequently take part in the formation of the lunar exosphere [1]. Constraining their physical properties, most notably the parameters sputtering yield, ejecta angular distribution and their energy distribution, is thus crucial to properly model the exosphere creation [2]. Such investigations have been of interest for decades and have recently been carried out with samples representative for the lunar mineralogy [3–6].

In this contribution, we present our current investigations on the aforementioned parameters using samples prepared from material collected during the Apollo 16 mission. Using a quartz crystal microbalance (QCM), we are able to measure mass changes due to sputtering caused by H and He ions and therefore also the sputtering yield. Additionally, we place another QCM in the experimentation chamber in a rotatable manner that collects the ejecta. Doing so enables us to probe the angular distribution of the ejecta. For these experiments, we use two types of samples: flat vitreous films as well as pellets pressed from lunar regolith and prepared according to [7]. Along with numerical simulations considering the sample morphology, this allows us to untangle intrinsic material properties from modifications thereof due to surface roughness. Lastly, we will present plans for future measurements to experimentally resolve the ejecta energy distribution. These energy distributions of particles sputtered from compound materials (rather than monatomic ones) are an actively researched area, especially from a numerical standpoint [8–11] – experimental data are scarce, however. This study combining the three physical quantities describing the sputtering process will therefore close a knowledge gap and be applicable not only to the Moon, but also to the sputtering of other planetary bodies.

[1] B. Hapke, J. Geophys. Res. Planets 106 (2001) 10039–10073
[2] P. Wurz, et al., Icarus 191 (2007) 486–496
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[4] H. Biber, et al., Nucl. Instrum. Methods. Phys. Res. B 480 (2020) 10–15
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[7] N. Jäggi, et al., Icarus 365 (2021) 114492
[8] L.S. Morrissey, et al., J. Appl. Phys. 130 (2021) 013302
[9] H. Hofsäss, A. Stegmaier, Nucl. Instrum. Methods. Phys. Res. B 517 (2022) 49–62
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How to cite: Brötzner, J., Biber, H., Jäggi, N., Nenning, A., Fuchs, L., Szabo, P. S., Galli, A., Wurz, P., and Aumayr, F.: A comprehensive study on the sputtering of the lunar surface, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18377, https://doi.org/10.5194/egusphere-egu24-18377, 2024.

EGU24-18637 | ECS | Posters virtual | PS1.8

Interannual Variability of Dust Storms between Mars Years 24 and 36 and analysis of dust vertical distribution of the MY 34 late-storm. 

Carolina Martín-Rubio, Alvaro Vicente-Retortillo, Gema Martínez-Esteve, Felipe Gómez, and Jose Antonio Rodríguez-Manfredi

Dust storms on Mars cause variations in atmospheric temperatures and dynamics due to direct solar heating and its dynamic response. These effects are most intense during the dust storm season (Ls 180º - 360º), when most global and regional storms occur and when the suspended dust reaches higher altitudes in the atmosphere. The thermal impact of these events affects the regional and global circulation of Mars. Thanks to measurements taken by the Thermal Emission Spectrometer (TES) onboard the Mars Global Surveyor (MGS) and the Mars Climate Sounder (MCS) onboard the Mars Recoinnasance Orbiter (MRO) it is possible to study the spatial and temporal variability of these storms over the last 12 Martian years (Martín-Rubio et al., 2024). Although each storm must be considered independently, it is possible to observe how the storms recur seasonally following specific patterns that allow them to be grouped according to their time of occurrence and evolution, with the recurrence patterns named as type A, B and C (Kass et al., 2016). Late northern winter large regional storms (C-type storms) show the highest variability; it appears that the occurrence of Global Dust Storms does not have a simple direct effect in the intensity of the subsequent C-type storm. We analyze recent intense type C storms (MY 34, 35 and 36, with particular focus on MY 34, when a Global Dust Storm occurred), studying the vertical, latitudinal and longitudinal dust distribution that occurred between solar longitudes Ls = 318° - 335°. This study is important to better understand the interannual variability of regional dust storms on Mars, as well as dust transport during late northern winter regional storms.

References:

Martín Rubio, C., Vicente-Retortillo, A., Gómez, F. and Rodríguez-Manfredi, J.A., 2024. Interannual variability of Regional Dust Storms between Mars Years 24 and 36, Icarus (under review).

Kass, D. M., Kleinböhl, A., McCleese, D. J., Schofield, J. T., Smith M.D. 2016. Interannual similarity in the Martian atmosphere during the dust storm season

How to cite: Martín-Rubio, C., Vicente-Retortillo, A., Martínez-Esteve, G., Gómez, F., and Rodríguez-Manfredi, J. A.: Interannual Variability of Dust Storms between Mars Years 24 and 36 and analysis of dust vertical distribution of the MY 34 late-storm., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18637, https://doi.org/10.5194/egusphere-egu24-18637, 2024.

EGU24-19315 | ECS | Posters on site | PS1.8

MSL TLS-SAM measurements consistent with localized methane containment and transport by 3-D atmospheric circulation in Gale crater 

Jorge Pla-Garcia, Scot C.R. Rafkin, María Ruíz-Pérez, and Sushil Atreya

The Curiosity rover has traversed more than 30 km from the landing site at the very bottom of Gale crater and has climbed more than ∼750 m into the Mt. Sharp foothills over more than five Martian years. Modeling and observations strongly suggest that the rover has ascended to elevations above a cold pool of air at the bottom of the crater [Ruíz-Pérez et al. 2024 in preparation]. During nighttime, downslope winds originating from both Mt. Sharp and crater rims would prevent the nighttime accumulation of methane released along the slopes above the cold pool and facilitate the convergence and accumulation of methane in the bottom of the crater. As a result, any methane released along the slopes at night is quickly transported downslope. After sunrise, the crater circulation transitions to an upslope regime. The reversal of the circulation should transport the methane accumulated in the bottom of the crater upslope as shown in MRAMS model tracer fields, that also indicate a substantial horizontal mixing that rapidly dilutes the methane-enriched air mass. Any methane released along the slopes is transported horizontally and vented out of the crater. MRAMS model predicts a methane front of peak values to pass higher elevations at increasingly later times after sunrise, moreover later in the morning (~10:00 LMST), but usually with highly and increasingly diluted with time methane values. At mid-morning, upslope circulation along surface rims is fully developed and there is a clear horizontal divergence at bottom of crater where methane is highly diluted due to 3-D atmospheric mixing and increasingly advected upslope out of crater. At dusk, downslope winds starts to develop through sloped surfaces of Mt. Sharp, as well as the cold pool of air at the bottom of the crater, which begins to trap methane released from the ground to start the cycle again. Consistent with [Pla-García et al. 2019] and [Moores et al. 2019] the 3-D crater circulation supplemented by the growth and collapse of the PBL is necessary to explain the TLS-SAM methane observations.

How to cite: Pla-Garcia, J., C.R. Rafkin, S., Ruíz-Pérez, M., and Atreya, S.: MSL TLS-SAM measurements consistent with localized methane containment and transport by 3-D atmospheric circulation in Gale crater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19315, https://doi.org/10.5194/egusphere-egu24-19315, 2024.

EGU24-19629 | Posters on site | PS1.8

Modelling Stellar Energetic Particles effects on the atmospheres of terrestrial (exo)planets: INCREASE 

Lee Grenfell, Nicolas Iro, Miriam Sinnhuber, Konstantin herbst, Andreas Bartenschlager, Klaus Scherer, and Benjamin Taysum

We present numerical studies of star/planet interactions, specifically the effects of Stellar Energetic Particles (SEPs) on the atmospheres of terrestrial (exo)planets. This work was performed as part of the INCREASE project (INfluence of strong stellar particle Events and galactic Cosmic Rays on Exoplanetary AtmoSpherEs) funded by the German Research Council (DFG).

 

We have developed and applied a new Model Suite which couples magnetospheric and atmospheric propagation and interaction models PLANETOCOSMICS (Desorgher et al. 2006) and AtRIS (Banjac et al. 2019) with the atmospheric chemistry and climate models 1D-TERRA (e.g., Wunderlich et al. 2020) and ExoTIC (Sinnhuber et al., 2012).

 

We are able to assess the influence of the stellar activity on the planetary atmospheric structure, its chemical composition, and infer spectroscopic observables as well as the effects on biosignatures.

How to cite: Grenfell, L., Iro, N., Sinnhuber, M., herbst, K., Bartenschlager, A., Scherer, K., and Taysum, B.: Modelling Stellar Energetic Particles effects on the atmospheres of terrestrial (exo)planets: INCREASE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19629, https://doi.org/10.5194/egusphere-egu24-19629, 2024.

EGU24-2138 | ECS | PICO | GD3.2

Modelling magma-induced surface uplift and dynamic fracturing around laccoliths on the Moon, Mars, and Earth 

Sam Poppe, Alexandra Morand, Claire E. Harnett, Anne Cornillon, Marek Awdankiewicz, Michael Heap, and Daniel Mège

Dome-shaped uplifted and fractured terrain observed at the surface of the Moon and Mars includes floor-fractured impact craters. Such deformation features are inferred to form by the emplacement and inflation of sill- and laccolith-shaped magma bodies in the shallowest 1-2 km of a planetary body’s rocky crust. Only the final surface deformation features can be observed from space, modelling helps to understand the emplacement dynamics and the deformation of the overlying rock. A mismatch exists, however, between the complex mechanical response of host rocks to magma-induced stresses observed on Earth in exposed volcanic plumbing systems and the linearly elastic deformation assumed by most of the often-used numerical models.

We have implemented simulations of the inflation of a laccolith intrusion in a particle-based host medium in the two-dimensional (2D) Discrete Element Method (DEM). Our approach allows us to investigate magma-induced, highly discontinuous, deformation and dynamic fracturing and visualizes the localization of subsurface strain. We systematically varied a range of numerical model parameters that govern host rock strength (bond cohesion, bond tensile strength, bond elastic modulus), and specific gravity known for the Moon, Mars and Earth. For equal rock stiffness and amounts of intruded magma, our model results show that we can expect more vertical surface displacement on the Moon due to the lower gravity there compared to Mars, and Earth. Rock toughness and rock stiffness control the amount of fracturing more than gravity does.

We also tested how host rock strengths in our 2D DEM model could be upscaled from intact strengths of rock samples collected at Earth analogue sites, or by implementing a digital crack network that simulates the highly fractured conditions of the intensively impacted Lunar and Martian crusts. Our results show that laccolith inflation in pre-cracked host rocks results in higher surface displacements and a higher amount of magma-induced cracking in broader fractured zones. We expect that our model results will induce a better understanding of the emplacement and architecture of shallow magmatic intrusions below magma-induced uplifted terrain and floor-fractured craters on the Moon and Mars.

How to cite: Poppe, S., Morand, A., Harnett, C. E., Cornillon, A., Awdankiewicz, M., Heap, M., and Mège, D.: Modelling magma-induced surface uplift and dynamic fracturing around laccoliths on the Moon, Mars, and Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2138, https://doi.org/10.5194/egusphere-egu24-2138, 2024.

The rock and rock-ice mixtures of the core-enveloping spherical shells comprising terrestrial body interiors have thermally determined viscosities well described by an Arrhenius dependence. Accordingly, the implied viscosity contrasts determined from the activation energies (E) characterizing such bodies can reach values exceeding 1040, for a temperature range that spans the conditions found from the lower mantle to the surface. In this study, we first explore the impact of implementing a cut-off to limit viscosity magnitude in cold regions. Using a spherical annulus geometry, we investigate the influence of core radius, surface temperature, and convective vigour on stagnant lid formation resulting from the extreme thermally induced viscosity contrasts. We demonstrate that the cut-off viscosity must be increased with decreasing curvature factor, ƒ (=rin/rout, where rin and rout are the inner and outer radii of the annulus, respectively), in order to obtain physically valid solutions. We find that for statistically-steady systems, the mean temperature decreases with core size, and that a viscosity contrast of at least 107 is required for stagnant lid formation as ƒ decreases below 0.5. Inverting the results from over 80 calculations featuring stagnant lids (from a total of approximately 180 calculations), we apply an energy balance model for heat flow across the thermal boundary layers and find that the non-dimensionalized temperature in the Approximately Isothermal Layer (AIL) in the convecting layer under a stagnant lid is well predicted by T'AIL=½{ -(2T'out+γ) + √[γ2 + 4γ(1+T'out)] } where γ is a function of E and ƒ, and T'out is the non-dimensionalized surface temperature. Moreover, the normalized (i.e., non-dimensional) thickness of the stagnant lid, L', can be obtained from a measurement of the non-dimensional surface heat flux once T'AIL is determined. Stagnant-lid thicknesses increase from 10 to 30 percent of the shell thickness as ƒ is decreased, and thick lids can overlie vigorously convecting underlying layers in small core bodies, potentially delaying secular cooling and suggesting that small objects with small cores may have developed thick elastic outer shells early in the solar system's history while maintaining vigorously convecting interiors. However, we also find that for the small number of 3-D calculations that we examined, parametrizations based on 2-D calculations overestimate the temperature of the convecting layer and the thickness of the conductive lid when ƒ is small (less than 0.4).

How to cite: Javaheri, P., Lowman, J., and Tackley, P.: Spherical geometry convection in a fluid with an Arrhenius thermal viscosity dependence: the impact of core size and surface temperature on the scaling of stagnant-lid thickness and internal temperature, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3226, https://doi.org/10.5194/egusphere-egu24-3226, 2024.

Nearly three decades of investigation has made steady progress towards self-consistently generating multiple features of plate tectonics from global mantle convection models.  Accordingly, the modelling of dynamic plates with migrating boundaries and evolving areas has become commonplace in both 2-D and 3-D geometries. Investigating the properties required for obtaining durable deep mantle formations similar to the Large Low Shear-wave Velocity Provinces (LLSVPs) has received similar attention. In this study, we model LLSVPs by assuming their composition is persistent  (i.e, we assume steady-state chemistry). To this end, we incorporate a Compositionally Anomalous Intrinsically Dense (CAID) mantle component comprising 2–3.5 per cent of the total mantle volume. We explore the impact of both an intrinsic contrast in density and viscosity for the CAID component, in an effort to stimulate the formation of a pair of LLSVP-like structures and a surface that exhibits the principle features of terrestrial plate tectonics; including recognizable and narrowly focused divergent, convergent and (in 3-D) transform plate boundaries that separate 8–16 distinct plate interiors. Although we find that a pair of CAID material provinces can be readily obtained in 2-D calculations while maintaining a surface exhibiting plate-like behaviour, specifying the same system parameters in 3-D calculations does not yield a pair of enduring provinces for any values of the parameters investigated.  In addition, CAID component inclusion in the calculations can affect global geotherms, so that in comparison to the surface behaviour obtained for the initial condition isochemical model, the cases incorporating the dense component do not yield surfaces that simulate plate tectonics. In general, CAID material components that are 3.75–5 percent denser than the surrounding mantle (at surface temperatures), and up to a factor of 100 times greater in intrinsic viscosity, form layers populated by voids, or nodes connected by ridges that reach across the core–mantle boundary (CMB), rather than distinct piles resembling the morphology of the LLSVPs. However, due to their temperature, we find the CAID material forms masses on the CMB that are relatively less dense (0.625–1.5 per cent) and viscous than the adjacent mantle material, in comparison to the percentage differences obtained at common temperatures. By adjusting our yield stress model to account for the influence of the CAID material on the geotherm, we find a highly satisfactory plate-like surface can be re-attained. Nevertheless, the formation of a pair of LLSVP-shaped masses remains elusive in 3-D calculations with plate-like surface behaviour and we suggest that caution is required if inferring the physical properties of the LLSVPs from 2-D models.

How to cite: Lowman, J., Langemeyer, S., and Tackley, P.: Model geometry determined contrast in the feedback between compositionally originating LLSVPs and dynamically generated plates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4709, https://doi.org/10.5194/egusphere-egu24-4709, 2024.

EGU24-6343 | ECS | PICO | GD3.2

Large impacts and their contribution to the water budget of the Early Moon. 

Tristan Engels, Julien Monteux, Maud Boyet, and Ali Bouhifd

The Earth/Moon system likely results from a giant impact between a Mars-size object and the proto-Earth 70 to 110 Myrs after the formation of the first solids of the Solar System. This high-energy context leads to extreme conditions under which volatile elements would not normally be preserved in the protolunar disk. However, recent measurements of lunar samples highlight the presence of a significant amount of water in the Moon's interior (1.2 to 74 ppm). The aim of the present work is to quantify the water contribution of the late accretion on the early Moon. Here, we use a 2D axisymmetric model with the hydrocode iSALE-Dellen to study the fate of a large impactor on a target body similar to the early Moon with a crust, a magma ocean, and a mantle. For this purpose, we compute different models to monitor the depth to which the impacted material is buried at the end of the impact event and the degree of devolatilisation of the impactor. Three parameters are explored: the crustal thickness (ranging from 10 to 80 km), the impactor radius (ranging from 25 to 200 km) and the impactor velocity (ranging from 1 to 4 times the target escape velocity). Our models show that impactors with a radius greater than 50 km impacting a partially molten lunar body with a crust thinner than 40 km could significantly contribute to the water content of the lunar mantle even for impact velocities of less than 5 km s-1. For larger impact velocities (≥ 10 km s-1) the impactor material is significantly molten and its water content is devolatilised within the lunar atmosphere. Depending on the water content of the impactor material and the ability of the lunar magma ocean to maintain chemical heterogeneities, the late lunar accretion following the Moon-forming giant impact could explain the differences in water content between the lunar samples.

How to cite: Engels, T., Monteux, J., Boyet, M., and Bouhifd, A.: Large impacts and their contribution to the water budget of the Early Moon., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6343, https://doi.org/10.5194/egusphere-egu24-6343, 2024.

EGU24-6814 | ECS | PICO | GD3.2

Magnitude estimation of Paleo-moonquakes from boulder tracks in Finsen crater 

Sha Tao, Yaolin Shi, and Bojing Zhu

High-resolution images taken by the Lunar Reconnaissance Orbiter show the existence of many boulder tracks within the Finsen crater. Current research suggests that shallow moonquakes and meteorite impacts are likely to be the cause of boulder falls. Based on a simplified model, we simulate the rolling process of the boulder along the slope when the lunar surface shakes and provide the critical PGA (peak ground acceleration) required for the boulder to start rolling under different conditions. The results show that boulders may roll down slopes within one or more cycles under strong ground shaking. The critical PGA of seismic waves required for a boulder to conduct slope rolling is related to the size of the boulder, the slope at the initial location, the dominant period of the seismic wave, and the ratio of horizontal and vertical peak ground accelerations. Except for rolling against the slope, in some cases, boulders may jump and roll downhill. Using the high-resolution images taken by the LRO to determine how the boulders rolled downhill, we can then estimate the lower limit of the magnitude of moonquakes in the region under different conditions. Finally, we provide a preliminary estimation of the lower limit of the paleo-moonquakes magnitude in the Finsen Crater.

How to cite: Tao, S., Shi, Y., and Zhu, B.: Magnitude estimation of Paleo-moonquakes from boulder tracks in Finsen crater, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6814, https://doi.org/10.5194/egusphere-egu24-6814, 2024.

The Large Low-Velocity Provinces (LLVPs) beneath West Africa and the Southern Pacific are characterized by low seismic wave velocities and are associated with plate-unrelated magmatism such as hotspots, large igneous provinces, and kimberlite. Despite their significance, the structure, origin, and feeding processes of LLVPs remain elusive.

Previous studies have suggested that the LLVPs have remained stationary for over 300 million years, but their morphology appears to have changed. While geodynamic simulations favor denser LLVPs, a recent free-oscillation analysis has suggested lighter ones. The High-Velocity Region (HVR), which surrounds the LLVPs, is located beneath present and past subduction zones. Plumes of varying morphology are imaged between hotspots and LLVP margins, with intensive plumes revealing ultra-low velocity zones (ULVZs) at their roots. Ocean island basalts (OIBs) from hotspots are geochemically enriched and originate from multiple reservoirs. Interestingly, OIB chemistry does not correlate with seismic plume imaging and differs between the two LLVPs. OIB near the African LLVP is influenced by fluid-related subducted materials.

In the light of these results, I propose the following new model for the LLVPs. The LLVPs are at higher temperatures than the HVR and the surrounding mantle. They are composed of Fe-enriched mono-mineral bridgmanite rock, called bridgmanitite. The large grain size of bridgmanitite results in high viscosity despite the high temperatures, thereby stabilizing the LLVPs. The LLVPs are block-structured and the relative movement of the blocks changes the LLVP morphology. Bridgmanitite was formed by the solidification of a primordial magma ocean. Its deposition at the core-mantle boundary forms LLVP precursors in the early mantle. These LLVP precursor blocks can be moved by the thrust and sweep of subducted slabs to form the present-day LLVPs. Erosion and plume formation have reduced the volume of the LLVPs and resulted in different LLVP heights. The HVR consists of harzburgite brought from the surface by subduction. It contains only a limited amount of basaltic rock because the basaltic rock was detached from slabs in the mid-mantle due to suppressed grain growth. As a result, the HVR material is high-density due to the low temperature but is intrinsically low-density due to its chemistry. The HVR material has been heated using the LLVP heat to form plumes. Plumes are geochemically depleted when they have formed in the deep mantle. However, they are enriched in incompatible elements and volatiles in the shallow mantle. This enrichment results from melt migration due to the temperature gradient around the plume. Thus, although LLVP heat drives plume formation, the plate-unrelated magmas such as OIB are not directly derived from the LLVPs.

How to cite: Katsura, T.: Large Low-Velocity Provinces (LLVPs): a new model for their structure, origin, and evolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8054, https://doi.org/10.5194/egusphere-egu24-8054, 2024.

EGU24-8194 | ECS | PICO | GD3.2

High pressure phase of Magnesiowustite: Implications to the mineralogy of super-Earths 

Anjitha Karangara and Pratik Kumar Das

Recent years have seen the discovery of a huge number of exoplanets, including several planets with very high densities suggesting that they also have rocky interiors which may be 9 – 10 times more massive than Earth. Mineralogy of these so called ‘super-Earth’ planets have been an interesting topic, as it gives implications on the planetary processes (Plate tectonics, geodynamo, etc.) and their habitability. Many studies concluded that such planets may contain ultra-high-pressure analogues of Earth’s lower mantle minerals. (Mg,Fe)O, a binary solid solution of MgO-FeO system is the second most abundant mineral of Earth’s lower mantle. If these super-Earth’s interior can have high pressure analogue of perovskite which is another most abundant phase of lower mantle of Earth as shown by some recent studies then there is a possibility of finding high pressure phase of (Mg,Fe)O also in the lower mantle of those super-Earths. MgO is stable in a NaCl structure (B1) in lower mantle condition of earth. It transforms to CsCl2 (B2) at high pressure (p) and Temperature (T) conditions. However, FeO is stable in B1 structure which transforms to a rhombohedral phase first and then to NiAs-type structure (B8) with increasing p. Finally, above 240 GPa and 4000 K, FeO transforms directly from B1 to B2. Along with structural phase transitions, FeO also undergoes a spin transition from high spin (HS) to low spin (LS) state with increasing pressure. In this study, we performed first principles DFT calculations on the structural phase transitions of MgxFe1-xO (x % = 0, 25, 50, 75 & 100) from B1 to B2 coupled with spin transition. Their mechanical and thermal properties under pressures ranging from 0 – 500 GPa relevant to super-earth planets have also been estimated. Our investigations have confirmed the presence of B1 phase of (Mg,Fe)O in lower mantle of earth with a spin transition from HS -LS which is thought to be responsible for the seismic anomalies of lower mantle of Earth. Spin transition of magnesiowustite and its effect on mechanical and thermal properties have been the topic for several experimental studies for many years. Most of them tried to explain the shear anisotropy of lower mantle with the help of (Mg,Fe)O with various Fe concentrations. Present study attempts to explore the stable phases of MgxFe1-xO relevant to super-Earth conditions. Both mechanical and dynamical behaviour have been investigated in the entire pressure range. Results show a new tetragonal phase of Mg0.25Fe0.75O above 125 GPa, which is found to be both mechanically and dynamically stable. These findings will also attempt to predict the mineralogy and seismicity of those giant planets.

How to cite: Karangara, A. and Das, P. K.: High pressure phase of Magnesiowustite: Implications to the mineralogy of super-Earths, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8194, https://doi.org/10.5194/egusphere-egu24-8194, 2024.

EGU24-9734 | ECS | PICO | GD3.2

Thermochemical models of early Earth evolution constrained by geochemical data 

Charitra Jain, Stephan Sobolev, Alexander Sobolev, and Adrien Vezinet

Isotopic systems and trace elements are ideal proxies to constrain the production and recycling of crust (both mafic and felsic) over time. Within the Rubidium-Strontium (Rb-Sr) system, Rb-87 decays to Sr-87 and due to the preferential partitioning of Rb into the crust (relative to Sr) during partial melting, 87Sr/86Sr ratio of the crust is higher than that of the mantle over time. Trace elements such as Niobium (Nb) and Uranium (U) do not fractionate when mantle melts to form mafic magma (oceanic crust) but they do fractionate when oceanic crust is recycled and undergoes fluid-present melting, i.e., during the production of felsic magmas (continental crust) [Hofmann et al., 1986], thereby resulting in a lower Nb/U of the felsic crust compared to the mantle. In this work, we couple the evolution of the above-mentioned geochemical proxies with the melting processes in global convection models using the code StagYY [Tackley, 2008]. Results from these geodynamic models are then compared with geochemical data obtained from olivine-hosted melt inclusions extracted from komatiites of 3.27 Ga Weltevreden formation (Barberton Greenstone Belt, South Africa).

These models self-consistently generate oceanic and continental crust while considering both plutonic and volcanic magmatism [Jain et al., 2019] and incorporate a composite rheology for the upper mantle. Pressure-, temperature-, and composition-dependent water solubility maps calculated with Perple_X [Connolly, 2009] control the ingassing and outgassing of water between the mantle and surface [Jain et al., 2022]. These models show intense production and recycling of continental crust during the Hadean and the early Archean, which is in agreement with new geochemical data [Vezinet et al., in review] and previous geochemical box models [Rosas & Korenaga, 2018; Guo & Korenaga, 2020]. The thermal evolution is also consistent with cooling history of the Earth inferred from petrological observations [Herzberg et al., 2010].

As the estimates of total amount of water (at the surface and in the deep interior) vary from 5-15 ocean masses (OMs) based on magma ocean solidification models to 1.2-3.3 OMs based on petrological models [Nakagawa et al., 2018], different initial values of water are also tested, which show a strong influence on the amount of felsic melts produced. Ongoing work includes incorporating the effect of water on the density and viscosity of mantle minerals and adapting the lithospheric strength with surface topography.

How to cite: Jain, C., Sobolev, S., Sobolev, A., and Vezinet, A.: Thermochemical models of early Earth evolution constrained by geochemical data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9734, https://doi.org/10.5194/egusphere-egu24-9734, 2024.

EGU24-9939 | PICO | GD3.2

Compressible convection in large rocky planets 

Yanick Ricard, Thierry Alboussière, and Stéphane Labrosse

The radial density of planets increases with depth due to compressibility, leading to impacts on their convective dynamics. To account for these effects, including the presence of a quasi-adiabatic temperature profile and entropy sources due to dissipation, the compressibility is expressed through a dissipation number proportional to the planet's radius and gravity. In Earth's mantle, compressibility effects are moderate, but in large rocky or liquid exoplanets (super-earths), the dissipation number can become very large. We explore the properties of compressible convection when the dissipation number is significant. We start by selecting a simple Murnaghan equation of state that embodies the fundamental properties of condensed matter at planetary conditions. Next, we analyze the characteristics of adiabatic profiles and demonstrate that the ratio between the bottom and top adiabatic temperatures is relatively small and probably less than 2. We examine the marginal stability of compressible mantles and reveal that they can undergo convection with either positive or negative superadiabatic Rayleigh numbers. Lastly, we delve into simulations of convection in 2D Cartesian geometry performed using the exact equations of mechanics, neglecting inertia (infinite Prandtl number case), and examine their consequences for super-earth dynamics.

How to cite: Ricard, Y., Alboussière, T., and Labrosse, S.: Compressible convection in large rocky planets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9939, https://doi.org/10.5194/egusphere-egu24-9939, 2024.

Plate tectonics is a fundamental framework for understanding the geodynamic processes shaping our planet, including seismicity, volcanism, mountain building, and even the long-term climate system and habitability of our planet. However, how plate tectonics evolved over 4.5 billion years remains a major unanswered question. In this study, we employ dynamically self-consistent three-dimensional thermochemical geodynamic models to simulate plate tectonics evolution with physically realistic parameters. Our results demonstrate that plate tectonics undergoes three main stages due to differing dominant mantle cooling modes. Initially, magmatism dominates surface heat transport, with extrusive volcanism leading to a mobile heat-pipe mode, characterised by a high level of volcanism, large surface heat flux, and highly mobile plates in the first 1.5 billion years. This differs from the "heat-pipe" mode occurring on Jupiter's satellite Io by additionally having plate-like behaviour as well as crustal delamination and lithospheric dripping. As the mantle cools, it transitions to a stable mode where mantle convection patterns and their surface expressions become stable for around 1-2 billion years, followed by a smooth evolution to present-day plate tectonics. Our model matches key observations of the surface heat flux, strain rate, plate velocity, and plate distribution patterns, indicating that the early mobile heat pipe mode plays a crucial role in efficiently extracting heat from the mantle. Magmatic intrusion is also expected to have important effects, which we will examine. This study may provide insights into the Earth's dynamic processes and mantle-atmosphere feedback related to plate tectonics and the dynamic evolution of other terrestrial planets, which ultimately affect the long-term climate system and habitability of our planet.

How to cite: Yan, J. and Tackley, P.: How did plate tectonics evolve? Insights from 3-D spherical thermochemical convection simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11554, https://doi.org/10.5194/egusphere-egu24-11554, 2024.

EGU24-12766 | PICO | GD3.2

Why does Earth have plate tectonics and what was before? 

Stephan Sobolev, Charitra Jain, and Michael Pons

The Earth is the only planet in our Solar System with active plate tectonics. Answering questions such as why plate tectonics started on Earth and which tectonic regime came before are fundamentally important for understanding the evolution of the early Earth. Currently, the most popular answers are (i) before plate tectonics on Earth, there was stagnant lid or plutonic-squishy-lid tectonic regime with no or minor contribution of subduction; (ii) plate tectonics took over when the initially high mantle temperature on Earth dropped by 100-200K due to secular cooling. In this work, we challenge both these statements based on published and new data and models.

Plenty of observations suggest that plate tectonics started on Earth during mid-Archean. At the same time, the numerical models and petrological data on the thermal evolution of the Earth show that mid-Archean was likely the time of the highest temperature of the Earth’s mantle and that significant secular cooling took place later in the Proterozoic. Moreover, previously published and our new thermochemical models also suggest that among all proposed tectonic regimes, only mobile-lid regime (i.e. plate tectonics) can lead to significant cooling of the Earth. Therefore, we conclude that plate tectonics in mid- or early Archean was unlikely to be initiated due to the significant secular cooling of the Earth’s mantle. The existence of no-subduction regimes, such as stagnant-lid or plutonic-squishy-lid, prior to plate tectonics are challenged by the new geochemical data which suggest extensive subduction and continental crust production already in the Hadean and early Archean.

Here we present global geodynamic models of Earth’s evolution computed using StagYY and ASPECT codes in 2D spherical annulus and 3D geometries respectively. StagYY models suggest that during the Hadean and the early Archean, the tectonic regime was oscillating between plume-induced subduction and plutonic-squishy-lid. The mantle temperature remains high during this time, but significant amount of continental crust is produced in these models, which is in agreement with the new geochemical data (melt inclusions from Weltevreden komatiites). After the emergence of continents in the mid- to late Archean, we decrease the effective friction of the oceanic lithosphere in the models to mimic the lubricating effect of continental sediments in subduction channels. This leads to a transition of the tectonic regime from oscillatory to continuous mobile-lid and to an efficient secular cooling of Earth, which is consistent with petrological observations. Being 2D, all plume-induced subduction zones in StagYY models are global. With the preliminary 3D ASPECT models, we show how a number of plume-induced regional subduction zones in early Earth evolve into a global network of plate boundaries and result in plate tectonics.

How to cite: Sobolev, S., Jain, C., and Pons, M.: Why does Earth have plate tectonics and what was before?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12766, https://doi.org/10.5194/egusphere-egu24-12766, 2024.

Constraining the heat flow across the core-mantle boundary (CMB) is crucial for understanding the thermal history of Earth’s mantle and the core. The primary mechanism governing heat transfer at the CMB is conduction, with lattice vibration (lattice thermal conductivity) commonly considered to be the dominant mechanism of thermal conduction in the lower mantle. However, there are large uncertainties in current estimates of lattice thermal conductivity of mantle material under CMB condition, due to the influence from mineral composition and the post-perovskite phase transition (e.g., Hsieh et al., 2018 PNAS; Ohta et al., 2017 EPSL). On the other hand, the role of radiative contribution (radiative thermal conductivity) remains less well understood. Several recent studies have attempted to measure the radiative thermal conductivity of bridgmanite and pyrolitic materials under lower mantle conditions, but the resulting experimental data have yielded divergent estimations for the radiative thermal conductivity of average mantle material at CMB conditions, ranging from 0.35 W/(m K) to 4.2 W/(m K) (Lobanov et al., 2020 EPSL; Murakami et al., 2022 EPSL). Adopting the highest estimate could result in an approximate 50% increase in the estimated bulk thermal conductivity compared to conventionally assumed values.  

To address the implications of these thermal conductivity uncertainties on mantle convection, we have incorporated variable thermal conductivities into a global thermochemical geodynamic model, StagYY. The simulations use a 2D spherical annulus geometry and extend over a 4.5 Gyr timespan. The geodynamic model includes parameterized core cooling, heat-producing elements partitioning, and crust formation, but it does not include an initial primordial reservoir at CMB. Preliminary findings from our study reveal that the relationship between thermal conductivity and CMB heat flux is not always straightforward. For models with stagnant-lid tectonics, higher thermal conductivity leads to higher CMB heat flux in the initial 1 Gyr and lower CMB heat flux at 4.5 Gyr. However, in models with mobile-lid tectonics, the CMB heat flux also increases with higher thermal conductivity in the first 1 Gyr, but CMB heat flux varies more and becomes unrelated to thermal conductivity at 4.5 Gyr. In summary, deep mantle thermal conductivity has little effect on the present-day CMB heat flux due to plate tectonics on Earth. Varying thermal conductivity mainly influences the amount of core cooling, particularly in early planetary evolution. 

How to cite: Tian, J. and Tackley, P.: The influence of deep mantle thermal conductivity on the long-term thermal evolution of Earth's mantle and core, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12993, https://doi.org/10.5194/egusphere-egu24-12993, 2024.

Outgassing from the interior is a key process influencing the evolution of the atmospheres of rocky planets. For planets with a stagnant lid tectonic mode, previous models have indicated that increasing planet size very strongly reduces the amount of outgassing, even to zero above a certain planet mass (Dorn et al., A&A 2018). This is because melt is buoyant only above a certain depth, which becomes shallower with increasing planet size (hence "g"); for large enough planets this depth may even lie within the lithosphere, preventing eruption and outgassing.

            However, uncertainties in rheology strongly influence the temperature structure of planets, hence (i) the depth at which melt is generated and (ii) the thickness of the lithosphere. One major uncertainty is the rheology of post-perovskite, which constitutes a large fraction of the mantle in large super-Earths. Ammann et al. (Nature 2010) find that diffusion is anisotropic; it is not clear whether the "upper bound" or "lower bound" is relevant to large-scale deformation, but both result in high viscosity at very high pressures, strongly influencing the radial temperature profile (Tackley et al., Icarus 2013). In contrast, Karato (2011, Icarus) argues that a different mechanism - interstitial diffusion - acts to make viscosity almost independent of pressure and relatively low in the post-perovskite regime.

            Another uncertainty is the reference viscosity (the viscosity at a reference temperature, pressure and stress), as this depends on bulk composition, water content, grain size and other properties. Lower reference viscosity results in thinner lithosphere and crust (e.g., Armann & Tackley, JGR 2012).

            Thus, numerical simulations are performed of the long-term (10 Gyr) thermo-chemical evolution of stagnant-lid planets (coupled mantle and core) with masses between 1 to 10 Earth masses, varying the reference viscosity and the rheology of post-perovskite. The simulations are based on the setup of Tackley et al. (2013 Icarus) with the addition of partial melting and basaltic crustal production, and outgassing of a passive tracer that partitions into the melt and outgasses 100% upon eruption.

            Results indicate that:

  • the previously-found trend of lower percentage outgassing with larger planet size is reproduced, but
  • outgassing does not fall to zero even in a 10 Earth mass planet. Outgassing of between 15% and 70% is found for 10 Earth mass planets (up to ~100% for Earth mass planets).
  • Post-perovskite rheology (interstitial, lower-bound or upper-bound) makes only a minor difference to long-term outgassing, but does influence the timing of outgassing.
  • Reference viscosity makes a large difference to outgassing, with lower viscosities leading to substantially larger outgassing percentages.
  • Internal heating plays a major role: stagnant-lid planets initially heat up due to low heat transfer efficiency, thinning the lithosphere and producing widespread melting.

How to cite: Tackley, P.: Outgassing on Stagnant-Lid Planets: Influence of Rheology, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13059, https://doi.org/10.5194/egusphere-egu24-13059, 2024.

EGU24-13510 | ECS | PICO | GD3.2

Investigating the stability and composition of LLSVP-like material in mantle convection models 

Nicolas Récalde, J. Huw Davies, James Panton, Donald Porcelli, and Morten Andersen

The Large Low Shear Velocity Provinces (LLSVPs) are basal mantle structures, located beneath the Pacific and Africa, which are defined by their negative anomaly in δVs. Since the first detection of LLSVPs, the reason for their seismic signature has been questioned, whether it is purely thermal, chemical or thermo-chemical in nature. The origin and age of LLSVPs have also been interrogated in the context of mantle dynamics as plumes seem to be associated with these structures and correlate with intraplate volcanism locations. The LLSVPs are often invoked as a potential reservoir to store primitive mantle in order to explain primitive He ratios observed in oceanic island basalts. Such a scenario would suggest that at least some part of the LLSVPs are long-lived, quasi-stable structures. Previous 3D geodynamic experiments suggest that LLSVP longevity is achieved through replenishment of the constituent material [1], potentially disqualifying them as a reservoir of primordial material. However, 2D experiments have shown that remnants of a primordial layer may become trapped within accumulations of recycled, dense oceanic crust for extended periods of time [2]. It remains to be seen if a similar process may occur in 3D simulations.

Using the 3D spherical mantle convection code TERRA [3] and seismic conversion tables [1], we investigate the ability of geodynamic models to generate such seismic structures and the preservation of primordial material within them. We explore various mantle viscosities, densities of material (buoyancy of primitive and enriched material) and concentrations of heat-producing elements. We track the core-mantle boundary coverage and volume of the detected structures to evaluate their stability as a function of time and geodynamical context. Results focus on the composition of these structures, the amount of primitive and early enriched material stored within them and how they evolve with time.

[1]  James Panton, J. Huw Davies, and Robert Myhill. “The Stability of Dense Oceanic Crust Near the Core-Mantle Boundary”. In: Journal of Geophysical Research: Solid Earth 128.2 (2023).

[2]  T. D Jones, N Sime, and P. E van Keken. “Burying Earth’s Primitive Mantle in the Slab Graveyard”. In: Geochemistry, geophysics, geosystems : G3 22.3 (2021).

[3]  John R. Baumgardner. “A Three-Dimensional Finite Element Model for Mantle Convection”. PhD thesis (1983).

How to cite: Récalde, N., Davies, J. H., Panton, J., Porcelli, D., and Andersen, M.: Investigating the stability and composition of LLSVP-like material in mantle convection models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13510, https://doi.org/10.5194/egusphere-egu24-13510, 2024.

Plate tectonics is the most prominent surface manifestation of mantle convection in Earth. Current observational results suggest that Earth is the only planet displaying plate tectonics. However, whether plate tectonics has accompanied the entire evolutionary history of Earth is a key question. If not, questions such as when plate tectonics began and what kind of tectonic mode prevailed before plate tectonics, have always been at the forefront and hot topics in the field of Earth science.

In this study, we employed three-dimensional spherical mantle convection numerical simulations to explore various mantle convection modes. Results indicate that, under different parameter frameworks, mantle convection modes can be categorized into five types: I) non-plate active lid convection mode, where the surface exhibits multiple concentrated weak zones, resulting in relatively fragmented plates; II) plate-like mobile lid convection mode, characterized by a higher number of subduction zones and mid-ocean ridges on the surface, which spontaneously form, develop and disappear over time, dividing the surface into about 10 plates; III) episodic plate-like mobile lid convection mode, where the surface experiences plate-like mobile lid mode for most of the time, interspersed with transient surface stagnation; IV) episodic stagnant lid convection mode, characterized by long periods of surface stagnation interspersed with short periods of surface movement with the surface mostly featuring only one subduction zone. V) stagnant lid convection mode, where the surface appears as a single rigid layer.

We mainly analyze the influence of lithospheric strength, i.e., yielding stress, Rayleigh number and internal heat rate on these five mantle convection modes. We can better explain the plate tectonics of the present Earth using mode Ⅱ. Because of the higher internal heat rate, higher mantle temperature and lower mantle viscosity, resulting in a larger Rayleigh number, our research suggests that the early Earth was in mode III or IV. Our results suggest that even if there was some type of plate tectonics in the early Earth, it is different from present plate tectonics. Before the onset of plate tectonics, the Earth might have experienced episodic lid convection. The results hold important scientific significance for understanding the evolution of the Earth's plate tectonics.

How to cite: Xiang, S. and Huang, J.: Mantle convection modes in 3D mantle convection simulations and its implications for the evolution of Earth’s plate tectonics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13588, https://doi.org/10.5194/egusphere-egu24-13588, 2024.

EGU24-15952 | ECS | PICO | GD3.2

Constraining Venus's interior with gravity and topography predictions from geodynamic models 

Julia Maia, Ana-Catalina Plesa, Nicola Tosi, and Mark Wieczorek

One of the most informative ways of studying the interior structure and geodynamics of terrestrial planets is the joint investigation of gravity and topography data. In the case of Venus, this is in fact one of the only sources of information about the planet's interior, along with estimations of the tidal Love number [1], moment of inertia factor [2], and the absence of an internally generated magnetic field [3].

Early gravity and topography studies that made use of Pioneer Venus and later Magellan data revealed unique properties of Venus's interior. They showed that Venus has a notably higher gravity-topography correlation for long wavelengths compared to Earth and a globally large apparent depth of compensation [4]. Considering these characteristics and analyzing the wavelength-dependent ratio between gravity and topography, the so-called spectral admittance, [5] concluded that the long-wavelength topography of the planet was supported dynamically, i.e., through convection in the mantle.

Since then, several studies have investigated the gravity and topography signature of Venus with the goal of understanding the planet’s interior by constraining geophysical properties of the mantle, such as the mantle viscosity. Some estimated the dynamic geoid contribution from three-dimensional geodynamic simulations [6,7]. Others adopted the analytical viscous flow model by [11] to study the viscosity structure of Venus's mantle [8,9,10]. The main advantage of the latter method is that it is computationally inexpensive, allowing for the performance of inversions. However, it is a simplified model which neglects lateral viscosity variations.

In this study, we estimate the dynamic topography and geoid signatures from the geodynamical models by [12], which include a strongly temperature-dependent viscosity, hence lateral viscosity variations, to evaluate the influence of different parameters such as the increase of viscosity with depth, the presence of viscosity jumps, and the ratio between intrusive and extrusive magmatism. In a second step, we plan to systematically evaluate the influence of lateral viscosity variations on the geoid and topography and thus to quantify the importance of the simplifications adopted in the analytical model.

Our first results show that the increase of viscosity with depth should be no more than 2 orders of magnitude, since larger values strongly decrease the spectral correlation and admittance at long wavelengths which is inconsistent with the observations. In addition, scenarios where extrusive magmatism dominates tend to overestimate the admittance due to the generation of thick thermal lithospheres in excess of 300 km thickness. These results underscore the importance of gravity and topography analyses for deciphering the geodynamical evolution and tectonic style of Venus.

[1] Konopliv and Yoder (1996) GRL, 23; [2] Margot et al. (2021) Nat Astron; [3] Phillips and Russel (1987) JGR, 92; [4] Sjogren et al. (1980) JGR, 85;  [5] Kiefer et al. (1986) GRL, 13; [6] Huang et al. (2013) EPSL, 362; [7] Rolf et al. (2018) Icarus, 313; [8] Pauer et al. (2006) JGR, 111; [9] Steinberger et al. (2010) Icarus, 207; [10] Maia et al. (2023) GRL, 50; [11] Hager & Clayton (1989) Mantle Convection; [12] Plesa et al. (2023) EGU.

How to cite: Maia, J., Plesa, A.-C., Tosi, N., and Wieczorek, M.: Constraining Venus's interior with gravity and topography predictions from geodynamic models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15952, https://doi.org/10.5194/egusphere-egu24-15952, 2024.

EGU24-16140 | ECS | PICO | GD3.2

Mantle hydration and implications for Earth and exoplanetary research 

Nickolas Moccetti Bardi, Paul J. Tackley, and Marla A. Metternich

So far, most numerical models focused on understanding different aspects of the Earth’s system, such as mantle convection, tectonics, or atmospheric dynamics, have typically adopted a limited perspective constrained to the specific region of interest. Recently, efforts have been made to couple these simulations, enabling them to interact seamlessly with one another. Abstaining from doing so may lead to results that don't accurately represent how the various systems interact.

Achieving the successful integration of the deep carbon cycle and water transport into our mantle dynamics code (StagYY) represents a crucial step towards this goal - a comprehensive, large-scale model of our planet, encompassing phenomena from the Earth's core to the uppermost layers of the atmosphere resulting from a collaborative effort between different research groups. We adopt a thermodynamic approach to quantify the H2O solubility of important water-carrying minerals within the mantle, with the goal of faithfully coupling geodynamic models and realistic transport/incorporation of water across the silicate part of our planet. The details of the numerical implementation are yet the subject of ongoing discussion; however, several crucial considerations must be thoroughly evaluated. These include the assessment of density variations resulting from water integration into nominally anhydrous minerals, the complex multi-stage degassing process of subducting slabs, and the inclusion of exotic phases that are currently absent from the thermodynamic databases being utilized.

The anticipated effects of a water-bearing mantle on the overarching dynamics are still under investigation. Nevertheless in-gassing, degassing, and the internal transport of water within the mantle exert a direct influence on various aspects. These include the governing viscosity field, the extent of H2O-induced melting, and atmospheric CO2 concentrations, among others. If water can, in fact, permeate deep into the mantle, it has the potential to introduce significant deviations in the dynamics of lower mantle convection compared to what current models predict. Furthermore, recent considerations of the stability regime of hydrous phases also point towards interesting implications in the study of water-rich exoplanets as stronger gravity profiles should result in colder geotherms, significantly expanding the thermodynamical stability of water-transporting phases across the P-T parameter space.

Quantifying this process will provide valuable insights for the geodynamic modeling community and help advance our understanding of the deep-Earth system. Furthermore, the distinct chemical exchange dynamics arising from our applications can be investigated further and prove advantageous for the study of exoplanetary atmospheres, especially those around bodies characterized by abundant water, such as water worlds and hycean planets.

How to cite: Moccetti Bardi, N., Tackley, P. J., and Metternich, M. A.: Mantle hydration and implications for Earth and exoplanetary research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16140, https://doi.org/10.5194/egusphere-egu24-16140, 2024.

Crystallization processes, a partial or complete overturn of the early mantle and other processes can lead to a compositionally stably stratified mantle which may hinder of even prevent convective currents. In the classical view, the layer will be stable if the restoring force, generated by the compositional stratification will exceed the driving force as provided by heating the layer from the core. The situation resembles the diffusive scenario of double diffusive convection, characterized by the fast diffusing component (heat) being the driving force, while the slowly diffusing component (composition) acts as the restoring force. If perturbed, subcritical convection can eventually take plain ce.  While in  pure thermal convection , subcritical flow only develops as localized patterns, in the double diffusive case, a perturbation can lead to a global destabilization (blue sky bifurcation) of the system, due to a sufficient finite  amplitude perturbation. . In this study we have investigated the influence of a finite amplitude perturbation of varying magnitudes , namely realze by an impact on a stably stratified mantle. Numerical experiments in 2- and 3D, cartesian and spherical simulations, based on a Finite Volume scheme  have been conducted to study the evolution of such a system. Key parameters  which characterize the evolution are the (1) initial stratification and the structure f the perturbation. The viscosity structure is a further influencing factor.

The experiments show that an impact into a stably stratified mantle can lead to a global destabilization, giving rise to complex flow patterns, including local and transient layering of the mantle flow. An evolutionary path of a planet from a stably stratified state to a complex layered period and/or to a full convection mode seems sensitive.

How to cite: Hansen, U. and Dude, S.: Spontaneous destabilization of a compositionally stably stratified mantle in the Early Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16401, https://doi.org/10.5194/egusphere-egu24-16401, 2024.

EGU24-16653 | PICO | GD3.2

Early formation of a water ocean as a function of initial CO2 and H2O contents in a solidifying rocky planet 

Helene Massol, Anne Davaille, Philippe Sarda, and Guillaume Delpech

We present a numerical model of a cooling magma ocean (MO) and the atmosphere degassing from it. The solidification of the MO leads to the enrichment of the silicate melt in volatiles, thus favoring degassing. Both reservoirs interact via heat and volatile exchange, where the volatiles are H2O and CO2. The aim of this model is to explore the influence of the atmosphere on the surface conditions after the MO stage, and especially the conditions required for the condensation of a water ocean to occur. For example, for an early Earth at 1 AU initially containing 1 Earth's water ocean mass, a water ocean could form for initial CO2 content as large as 1,000 bars. Moreover, a tenth of the actual Earth's water ocean mass would be sufficient to generate a water ocean on early Venus. Liquid water could also be present on the surface of the two exoplanets Trappist-1e and 1f. Comparing our results with other recent models, we discuss the relative influence of the model hypotheses, such as mantle composition, the treatment of the heat transfer in the atmosphere, and the treatment of the last stages of the MO solidification.

How to cite: Massol, H., Davaille, A., Sarda, P., and Delpech, G.: Early formation of a water ocean as a function of initial CO2 and H2O contents in a solidifying rocky planet, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16653, https://doi.org/10.5194/egusphere-egu24-16653, 2024.

 New high-pressure, high-temperature layered partial melting experiments have been performed to simulate the interaction between the last stage, dense Fe-Ti-rich cumulate layer that remained after about 99.5% crystallization of the lunar magma ocean (LMO), and the underlying solidified Mg-rich mantle. For this, a synthetic assemblage of an upper Fe-Ti-rich cumulate layer (6.1 wt.% TiO2 and 39.7 wt.% FeO) and a lower forsteritic olivine layer (Mg# = 92.8) has been taken in 1:4 weight ratio, respectively, and subjected to experiments at pressures ranging between 1 to 3 GPa and temperatures varying between 1100 ⁰C and 1525 ⁰C using a piston cylinder apparatus. In the top cumulate layer, phases such as Fe-rich clinopyroxene, Fe-poor clinopyroxene, pigeonite, orthopyroxene, rutile, ilmenite, quartz and melt were formed, depending upon different P-T conditions. The Fe-Ti-rich basaltic melts (5-18.5 wt.% TiO2, 13-28.6 wt.% FeO, and 35-59 wt.% SiO2) produced in this cumulate layer at different degrees of partial melting approach the lunar mare basalts in their compositions and can be used to explain the huge variation in TiO2 enrichment that is observed in lunar basalts (between 0 to ~17 wt. %). Following LMO crystallization, the last stage dense mineral-melt cumulate layer is expected to undergo a gravitational overturn due to density instability. This work aims to simulate the partial melting of the cumulates in this layer as a result of the overturn. The consequent compositional heterogeneity of the lunar mantle is used to justify the observed variation in Ti-rich basalt compositions on the lunar surface. The basaltic melts produced in these experiments are mostly Al, Mg-poor compared to available lunar basalt samples. However, this deficiency may be addressed by assimilation of these melts into low-Ti, Mg-rich basalt magmas that would have subsequently erupted from the underlying mantle. Simulations of such assimilation using thermodynamic modelling have also been done and the results support this theory. The possible fate of the last stage melt of the LMO has thus been studied and used to understand the variable compositions of lunar basalts.

How to cite: Moitra, H., Ghosh, S., Mukherjee, T., and Gupta, S.: Understanding the variability in the titanium contents of lunar basalts using high-pressure, high-temperature layered partial melting experiments and thermodynamic modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17525, https://doi.org/10.5194/egusphere-egu24-17525, 2024.

EGU24-17640 | PICO | GD3.2

Small-scale Structure of the Martian Mantle 

Constantinos Charalambous, Tom Pike, Benjamin Fernando, Henri Samuel, Carys Bill, Philippe Lognonné, and Bruce Banerdt

The InSight mission's SEIS instrument has provided a unique opportunity to probe the deep interior of Mars. This seismic exploration of the Martian interior has emerged as a promising avenue for revealing the enigmatic geophysical properties and dynamic processes within the planet's mantle.

In this study, we present an analysis of the seismic signature of marsquakes which transit deep into the mantle, providing crucial information on the seismic velocity profile and potential heterogeneities. The quakes show a characteristic late emergence of the first energy at higher frequencies which can be analysed as due to the scattering of seismic energy as it transits the mantle. From this we are able to quantify the size distribution of the mantle's small-scale heterogeneity as well as to constrain the rheological properties and convective vigor of the Martian mantle.

As unlike Earth, Mars has sealed its mantle contents under a stagnant lid, we use our observations to provide evidence about the early stages of planetary formation and differentiation on Mars. Our findings contribute to the better understanding of the Martian mantle's geodynamics and allow a comparative assessment of the evolution of planetary interiors that likely apply to other planets that lack plate tectonics.

How to cite: Charalambous, C., Pike, T., Fernando, B., Samuel, H., Bill, C., Lognonné, P., and Banerdt, B.: Small-scale Structure of the Martian Mantle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17640, https://doi.org/10.5194/egusphere-egu24-17640, 2024.

EGU24-19267 | PICO | GD3.2

Melting and Remelting in a Crystallizing Magma Ocean 

Antonio Manjon Cabeza Cordoba, Maxim D. Ballmer, and Oliver Shorttle

Geodynamic modelling is increasingly dependent on the initial conditions. Non-steady-state planetary evolution models are complex enough that several solutions can be achieved with small variations in the initial temperature, composition, etc. Models of magma ocean evolution predict an overturn of a layer enriched in iron and incompatible elements. The absence of this layer in any tomographic inversion of the Earth suggests that our models of magma ocean evolution are missing key phenomena. Since these models are the basis for the initial conditions of Earth-applied geodynamic planetary models, there is an urgency to find the origin of the discrepancies between our idea of magma ocean crystallization and the current state of the Earth.

To advance our understanding of the consequences of magma ocean crystallization, we carry out high resolution models of mantle flow coupled with (1D) magma ocean evolution (including melting and crystallization processes). We allow two different forms of topography to arise with a sticky air (sticky magma ocean) approximation: dynamic topography and thermodynamic topography. We explore how different equilibration times affect melt segregation and magma ocean composition, as well as how crystal settling influences solid state convection and differentiation. We calculate, as well, chemical exchange between the solid and liquid parts of our model by expanding on previous work, studying different equilibrium constants and allowing the system to self-regulate.

Preliminary results suggest a competition effect between the two forms of topography mentioned above. This competition implies that the equilibrium constant of chemical exchange, as well as melting segregation speed and crystal growth and settling, will have an essential role in the equilibration between the solid mantle and the liquid magma ocean. This and other results have implications for Earth, but also for other discovered magma oceans such as those on the Moon, Mars or even exoplanets.

How to cite: Manjon Cabeza Cordoba, A., Ballmer, M. D., and Shorttle, O.: Melting and Remelting in a Crystallizing Magma Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19267, https://doi.org/10.5194/egusphere-egu24-19267, 2024.

EGU24-22090 | ECS | PICO | GD3.2

Combined impact and interior evolution models in three dimensions indicate a southern impact origin of the Martian Dichotomy 

Kar Wai Cheng, Harry Ballantyne, Gregor Golabek, Martin Jutzi, Antoine Rozel, and Paul Tackley

The origin of the martian crustal dichotomy is a long-standing mystery since its discovery in the Mariner 9 era. Among various proposed hypotheses, a single giant impact origin (i.e. the Borealis impact) is the most well known, and the most studied. However, studies that include realistic impact models often adapt a simplified geological and geophysical model for predicting the final crustal distribution, while long-term mantle convection studies have mostly employed an over-simplified parametrization of the impact. Here we use a coupled SPH-thermochemical approach to first simulate an impact event, and then use the result of this realistic model as the initial condition for the long-term mantle convection model. We demonstrate that a giant impact collision results in a mantle-deep magma pond, which upon crystallisation leads to a thicker crust production on the impacted hemisphere. In other words, an impact-origin of Mars's southern highlands requires the giant impact to occur in the southern hemisphere. We find that both the impact scenario and the mantle properties affect the geometry of the impact-induced crust ("highlands'') and the subsequent state of the interior, and that the formation of "highlands'' extends beyond the initial magma pond.  We show that a near head-on (15o from the normal) impact event with impactor radius of 750 km, together with a mantle viscosity of 1020 Pa s, can best reproduce the southern highlands of Mars with a geometry similar to that of present-day observations.

How to cite: Cheng, K. W., Ballantyne, H., Golabek, G., Jutzi, M., Rozel, A., and Tackley, P.: Combined impact and interior evolution models in three dimensions indicate a southern impact origin of the Martian Dichotomy, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22090, https://doi.org/10.5194/egusphere-egu24-22090, 2024.

PS2 – Outer Planet Systems

EGU24-352 | ECS | Orals | PS2.1

Exploring the Collisionality of the Icy Galilean Moon Atmospheres. 

Leander Schlarmann, Audrey Vorburger, Shane R. Carberry Mogan, and Peter Wurz

In this study, we use the Direct Simulation Monte Carlo (DSMC) method [1] to investigate the collisional fraction of the atmospheres of Europa, Ganymede, and Callisto. The extent of the collisional atmosphere of the icy moons is still subject to ongoing debate. While Europa’s atmosphere is tenuous and effectively collisionless, the exobase for Ganymede and Callisto is expected to be located above a thin collision-dominated atmospheric layer [2].

In the 2030s, both ESA's Jupiter Icy Moons Explorer (JUICE) and NASA's Europa Clipper mission are set to explore Jupiter's icy moons from up close, using high-resolution mass spectrometers to sample their atmospheres. The Neutral gas and Ion Mass spectrometer (NIM) of the Particle Environment Package (PEP) onboard JUICE [3] and the MAss Spectrometer for Planetary EXploration (MASPEX) onboard Europa Clipper [4] will determine the atmospheric composition of the moons and potentially sample plume material on Europa. The collisional fraction of their atmospheres affects the abundances of the various species that will be measured, and hence also the deduction of the underlying surface composition. Therefore, obtaining a comprehensive understanding of atmospheric structures, including the collisional fraction, is imperative for both missions. This knowledge is essential to ensure the correct interpretation of the measured data once it becomes available.

The DSMC method is a computation technique, where rarefied gas flows are simulated by tracking the motion of individual particles, including their collisions and interactions, to provide insight into the macroscopic gas dynamics. Therefore, this method is ideal for studying thin atmospheres that transition from being collisional near the surface to ballistic at higher altitudes, such as the atmospheres of the icy Galilean moons. The model [5, 6] used herein includes different physical and chemical processes that create the atmospheres of the icy moons, such as sputtering due to interactions with Jupiter's magnetosphere, the sublimation of surface ice, and photochemical reactions.

[1] Bird, G. A. (1994). Molecular gas dynamics and the direct simulation of gas flows.
[2] Schlarmann, L., et al. (2024), in preparation.
[3] Grasset, O., et al. (2013). Planetary and Space Science, 78, 1-21.
[4] Phillips, C. B., and Pappalardo, R. T. (2014). Eos, Transactions AGU, 95(20), 165-167.
[5] Carberry Mogan, S. R., et al. (2021). Icarus, 368, 114597.
[6] Carberry Mogan, S. R., et al. (2022). Journal of Geophysical Research: Planets, 127(11).

How to cite: Schlarmann, L., Vorburger, A., Carberry Mogan, S. R., and Wurz, P.: Exploring the Collisionality of the Icy Galilean Moon Atmospheres., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-352, https://doi.org/10.5194/egusphere-egu24-352, 2024.

EGU24-1266 | Posters on site | PS2.1

The Plasma Instrument for Magnetic Sounding (PIMS): Measuring the Plasma Influence on Magnetic Induction on the Europa Clipper mission   

Adrienn Luspay-Kuti and the The PIMS Science and Engineering team

Characterizing Europa’s subsurface ocean is critical to assessing Europa’s habitability. Measurements of the magnetic field induced in the conducting Europan ocean in response to Jupiter’s magnetosphere is a proven technique that has successfully demonstrated the existence of subsurface oceans at Io (magma), Europa, and Callisto. In the case of Europa, the dynamic, magnetized plasma flow in the Jovian magnetosphere causes strong magnetic perturbations comparable to those of the induced field strength. Thus, accurate characterization of the ocean by magnetic sounding requires an accurate characterization of the plasma properties. The Plasma Instrument for Magnetic Sounding (PIMS) will launch on the Europa Clipper mission in October 2024 onboard a Falcon Heavy rocket and will measure the plasma properties in Jupiter’s magnetosphere and in Europa’s tenuous atmosphere. PIMS measurements will advance our understanding of the Jovian environment near Europa’s orbit and the interaction of Europa’s atmosphere and surface with Jupiter’s plasma and magnetic field. These scientific advances will, in turn, improve modeling efforts that will ultimately enable a highly accurate separation of the magnetic field due to induction in Europa’s interior from the highly variable magnetic perturbations due to the plasma interactions exterior to Europa. Thus, PIMS will enable the full potential of the induction technique in probing Europa’s interior to be realized, and will help constrain the average thickness of the ice shell and average thickness and salinity of the ocean, as well as characterize the composition and sources of the plasma and volatiles. In this presentation we will overview the PIMS instrument and its final calibration before it was integrated onto the spacecraft.

How to cite: Luspay-Kuti, A. and the The PIMS Science and Engineering team: The Plasma Instrument for Magnetic Sounding (PIMS): Measuring the Plasma Influence on Magnetic Induction on the Europa Clipper mission  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1266, https://doi.org/10.5194/egusphere-egu24-1266, 2024.

One of the most important realizations that planetary scientists have come to in the last 20 years is that in the search for potential habitability in our solar system, the focus need not only be on planetary bodies close to the Sun, where water on the surface is in liquid state. Based on Galileo and Cassini observations in the Jupiter and Saturn systems, there are many potential places in our solar system where sub-surface liquid water oceans may exist.

JUICE magnetometer (J-MAG) measurements (such as those made by the magnetometers on the Galileo and Cassini spacecraft) enable an understanding to be gained of the interior structure of the icy moons of Jupiter, specifically those of Ganymede, Callisto and Europa. Of particular interest are knowledge of the depth at which the liquid oceans reside beneath their icy surfaces, the strength of any internal magnetic fields such as at Ganymede and the strength of any induced magnetic fields arising within these oceans.

The primary science objectives of JUICE which will be constrained by the magnetic field observations and which drove the performance requirements of the J-MAG instrument include:

  • At Ganymede:
  • Characterization of the extent of the ocean and its relation to the deeper interior
  • Characterization of the ice shell
  • Characterization of the local environment and its interactions with the Jovian magnetosphere
  • Description of the deep interior and magnetic field generation
  • At Europa, further constrain the depth of the liquid ocean and its conductivity
  • At Callisto, characterize the outer shells, including the ocean

 

How to cite: Dougherty, M.: Using magnetic field observations from the Galilean moons to diagnose ocean properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1416, https://doi.org/10.5194/egusphere-egu24-1416, 2024.

EGU24-1750 | Posters on site | PS2.1

The J-MAG Magnetometer: Instrument design, performance, and initial in-flight results. 

Patrick Brown and the The J-MAG Instrument Team

JUICE is an ESA L-Class interplanetary mission to the Jupiter system that was launched on the 14th April 2023 from Kourou, French Guiana. It will make in-situ and remote sensing measurements of Jupiter and the Galilean moons during a three-year science operation phase starting in July 2031. The tour will include a high-latitude phase, fly-bys of Callisto and Europa culminating in elliptical and circular orbits of Ganymede down to an altitude of 200 km. Detection and characterization of potential sub-surface oceans on Europa and Ganymede are a key science goal of the mission as is the interaction between Ganymede’s internal magnetic field with the Jovian field.  Constraining the depth and conductivity of any subsurface ocean on Ganymede will be achieved through measurement of response to two magnetic inducing signals, one at Ganymede’s orbital period (171.7 hrs) and the other at Jupiter’s synodic period (10.5 hrs) which together drive a requirement for in-flight accuracy of 0.2nT. The combination of such low frequency and low amplitude scientific signals places a unique set of EMC cleanliness requirements on the spacecraft system and on the performance of the instrument configuration.

J-MAG is the DC magnetometer instrument on JUICE measuring the low frequency magnetic field vector in the range [0-64 Hz]. It is composed of a conventional dual fluxgate design together with a Coupled Dark State Magnetometer (CDSM) absolute scalar sensor and an electronics box accommodated within a vault on the main platform. All three sensors are mounted on the outer segment of a 10.6 m boom. The scalar sensor is included to enable calibration of the fluxgate sensors during the Ganymede phase where the magnetic field is highly variable and traditional techniques for fluxgate offset calibration (such as spacecraft rolls or analysis of incompressible waves in the solar wind) are not viable.  

We report on the instrument design and challenges presented by the mission environment and trajectory. We will present the performance of the magnetometer on ground and a summary of the initial results from the near-Earth commissioning phase that took place during May 2023.

 

How to cite: Brown, P. and the The J-MAG Instrument Team: The J-MAG Magnetometer: Instrument design, performance, and initial in-flight results., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1750, https://doi.org/10.5194/egusphere-egu24-1750, 2024.

EGU24-2170 | ECS | Posters on site | PS2.1

Understanding the interior magnetic fields of Ganymede using flybys of the Europa Clipper and JUICE missions 

Shivangi Sharan, Emma Bunce, Michele Dougherty, Xianzhe Jia, and Margaret Kivelson

The interiors of the icy moons of Jupiter hold a key to understanding habitability in the Solar System and beyond. They could serve as prototypes to comprehend similar bodies that might have the potential to sustain life. The magnetic field observations from the Galileo mission between 1996 and 2003 suggest large oceans below the icy crusts of Europa and Callisto and a probable subsurface ocean at Ganymede. It also discovered that Ganymede has an intrinsic magnetic field and a dynamic magnetosphere.

NASA’s Europa Clipper and ESA’s Jupiter ICy moons Explorer (JUICE) missions have been designed to better understand and characterise these icy moons. They aim to confirm the existence of a subsurface ocean at the three moons, in particular, Ganymede and Europa, and constrain their internal structure. The missions would also explore the magnetosphere of Jupiter and its interactions within the Jovian system. Ganymede is the largest moon of our Solar System, capable of producing its own dynamo field and possibly possessing an ocean beneath its surface. However, separating the intrinsic field from the induced field is a difficult problem. Galileo measurements provided two models for Ganymede’s overall internal field- a dipole and quadrupole model or a dipole and induction model. Both the quadrupole and induction signals are quite small and well represent the observations together with the dipole field.

Latest trajectory information for Europa Clipper assuming an October 2024 launch, and the predicted JUICE trajectory following the successful launch in April 2023 show initial close Ganymede flybys. In this study, we use them to understand their trajectories and highlight their importance in confirming the induced signal and thereby the ocean as well as for modelling the dynamo field. The first 2 Clipper and the first 3 JUICE flybys occur within an altitude of 500 km from Ganymede’s surface and are hence useful for overall internal field modelling. We predict the measurements that would be observed from the two internal sources as well as the external magnetospheric source to better understand the signals and decipher their differences. For the intrinsic and external fields, we use dynamo and magnetohydrodynamic models respectively while for the induced field, we use Jupiter’s background field along with the induction equation at the spacecraft locations.

The 5 flybys independently as well as together with the data from the Galileo flybys would enhance our understanding of the different magnetic sources at Ganymede and the fields they produce. These joint early flyby observations will enable us to be better equipped to model the magnetic field components near Ganymede in the orbital phase of the JUICE mission.

How to cite: Sharan, S., Bunce, E., Dougherty, M., Jia, X., and Kivelson, M.: Understanding the interior magnetic fields of Ganymede using flybys of the Europa Clipper and JUICE missions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2170, https://doi.org/10.5194/egusphere-egu24-2170, 2024.

EGU24-4522 | Orals | PS2.1

The Impact of Europa’s Deep Interior on the Electromagnetic Induction Signal from Europa’s Ocean 

Krishan Khurana, Hao Cao, and Lars Stixrude

Under low pressure and temperature, most rocks have extremely low electrical conductivities (< 10-9 S/m) which rise dramatically at temperatures encountered in deep interiors of solid bodies. The presence of ferric iron (Fe3+), whose abundance is related to the oxygen fugacity of the rock, lowers the activation energy of conduction and enhances rock conductivity further. Most models of the interior of Europa are consistent with the presence of a highly-conducting metallic iron core with a radius between 200 and 700 km (e.g., Kuskov and Kronrod, 2005). Thus, the mantle and the core of Europa are likely highly conducting and are expected to create measurable induction response. Accounting for this deep conductivity would not only improve the modeling of the physical parameters of the ocean but help further constrain the properties of Europa’s deeper interior.

Since the discovery of induction response from Europa’s ocean (Khurana et al., 1998), numerous studies have reexamined the electromagnetic induction signatures obtained by the Galileo spacecraft using increasingly sophisticated techniques to model the induction field and the moon/plasma interaction field (see e.g. Zimmer et al. 2000; Schilling et al. 2007; Vance et al. 2021). However, these studies have ignored the effect of induction from the deeper interior. Also, no studies have been performed for lower conductivities of the ocean and for longer period waves (such as the orbital period of Europa = 85.2 h) which can probe deeper even through a highly conducting ocean.

To address this problem, we have used the recursive method of Srivastava (1966) for a multiple layer model of Europa’s deep interior. The results from this preliminary exploration show that for a range of core radii and mantle conductivities, the deeper interior modifies the signal from the ocean by several nT at the two primary frequencies. The 85.2 h period penetrates through the ocean and elicits increasing response from the deep mantle as its conductivity is increased (from generation of stronger eddy currents). The 11.1 h period on the other hand produces a weaker response  with increasing mantle conductivity because the eddy currents are already at their highest level (100% induction from the ocean) but begin to follow a deeper path through the mantle and thus their magnetic response at the surface appears weaker.

Khurana, K.K., M.G. Kivelson, D. J. Stevenson, and others (1998) Induced magnetic fields as evidence for subsurface oceans in Europa and Callisto, Nature, 395, 777-780.

Kuskov O.L. and V.A. Kronrod (2005) Internal structure of Europa and Callisto, Icarus, 177, 550-569.

Srivastava, S.P. (1966) Theory of the magnetotelluric method for a spherical conductor, Geophys. J. Roy. Astro. Soc. 11, 373-387.

Vance, S. D., Styczinski, M. J., Bills, B. G., Cochrane, C. J., Soderlund, K. M., Gomez-Perez, N., & Paty, C. (2021). Magnetic induction responses of Jupiter's ocean moons including effects from adiabatic convection. J. Geophys. Res. : Planets, 126, e2020JE006418.

Zimmer, C., K.K. Khurana, and M.G. Kivelson (2000) Subsurface oceans on Europa and Callisto:  Constraints from Galileo magnetometer observations, Icarus, 147, 329.

How to cite: Khurana, K., Cao, H., and Stixrude, L.: The Impact of Europa’s Deep Interior on the Electromagnetic Induction Signal from Europa’s Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4522, https://doi.org/10.5194/egusphere-egu24-4522, 2024.

EGU24-4968 | Posters on site | PS2.1

Surface Deposition of Icy Dust Entrained in Europa’s Plumes 

Wei-Ling Tseng, Ian-Lin Lai, Wing-Huen Ip, Hsiang-Wen Hsu, and Yi-Shiang Tzeng

With its subsurface ocean, Europa raises intriguing possibilities about the potential for extraterrestrial life beneath its icy crust. Its unique surface features present a dynamic and complex geophysical landscape that offers valuable insights into its evolution. This study explores the plume dynamics and deposition of icy dust particles on Europa. Utilizing a Direct Simulation Monte Carlo (DSMC) modeling of Europa's gaseous plumes, we use a hybrid model to understand dust dynamics entrained in the plumes. This approach allows us to consider various parameters such as production rate, initial velocity of gas and dust, and size distribution of dust particles, providing a comprehensive view of plume dynamics and highlighting their impact on Europa's surface characteristics. The results showing distinct plume morphologies and dust deposition patterns offer clues to our understanding of Europa's ongoing geological activity and subsurface ocean.

How to cite: Tseng, W.-L., Lai, I.-L., Ip, W.-H., Hsu, H.-W., and Tzeng, Y.-S.: Surface Deposition of Icy Dust Entrained in Europa’s Plumes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4968, https://doi.org/10.5194/egusphere-egu24-4968, 2024.

EGU24-6113 | Orals | PS2.1

Impact of melt accumulation on tidal heat production in Europa’s mantle 

Mathilde Kervazo, Gabriel Tobie, Marie Behounkova, Caroline Dumoulin, and Gaël Choblet

Volcanic activity at Europa’s seafloor is one of the key questions regarding the habitability of its subsurface ocean. The suitable conditions for hydrothermalism on Europa’s seafloor are conditioned by the heat released from the underlying silicate mantle, supplied by both radiogenic and tidal heating. The orbital resonance between Io, Europa, and Ganymede forces their orbit and maintains non-zero eccentricities. Tidal heating due to eccentricity tides on Io is so extreme that it  produces intense volcanism.  Even though tidal heating  in Europa’s silicate mantle is expected to be much weaker than on Io due to its greater distance to Jupiter,   Běhounková et al. [1] showed that it may still be sufficient to maintain Europa’s mantle in a partially molten state  for several tens to hundred millions of years, particularly during periods of increased eccentricity. Due to inefficient melt transport through the thick lithosphere of Europa [2], melt produced during periods of enhanced eccentricity may accumulate and in turn affect the tidal heating, as it is the case for Io, implying a possible runaway melt process in the silicate interior of Europa.

 

In this context, the goal of this study is to evaluate the effect of melt accumulation on the tidal heat production of Europa’s silicate mantle. For that purpose, we follow the approach developed to model the solid tides in Io’s partially molten interior [3], taking into account the effect of melt on the viscoelastic properties of the mantle. We adapt it to the context of Europa, corresponding to a deeper and thinner asthenosphere than on Io. We show that, whatever the partially molten layer thickness, melt accumulation increases tidal heat production and tidal dissipation even exceeds radiogenic heating. For equivalent volume of accumulated melt, the thinner the layer, the more pronounced this effect is. Our results show that the accumulation of melt, over timescales consistent with the 3D model prediction of Běhounková et al. [1], may significantly affect the tidal dissipation amplitude and its pattern. The potential presence of such melt accumulations may be tested by future measurements by Europa Clipper and JUICE from the combined analysis of gravimetric, altimetric and magnetic data, which might reveal long-wavelength anomalies which could be confronted to our model prediction.

 

[1] Běhounková et al., GRL, 48(3), e2020GL090077 (2021),  [2] Bland and Elder, GRL, 49(5), e2021GL096939 (2022). [3] Kervazo et al., A&A, 650, A72 (2021)

 

How to cite: Kervazo, M., Tobie, G., Behounkova, M., Dumoulin, C., and Choblet, G.: Impact of melt accumulation on tidal heat production in Europa’s mantle, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6113, https://doi.org/10.5194/egusphere-egu24-6113, 2024.

EGU24-6262 | Posters on site | PS2.1

Exploring the Jupiter System through unique joint JUICE and Europa Clipper observations 

Louise Prockter, Emma Bunce, and Mathieu Choukroun and the JUICE-Clipper Steering Committee

Launched in April, 2023, ESA’s JUpiter ICy moons Explorer (JUICE) is en route to the Jupiter system. Upon arrival in 2031, the spacecraft will orbit Jupiter for 3.5 years, making 35 total encounters with Ganymede, Europa, and Callisto, before going into orbit about Ganymede for 1 year.  NASA’s Europa Clipper is scheduled to launch in October 2024, and arrives in the Jupiter system in 2030, a year before JUICE. Orbiting Jupiter, the Clipper spacecraft will spend a year in the system before focusing on ~52 flybys of Europa during a nominal four-year primary mission phase, while also making multiple serendipitous flybys of Ganymede and Callisto. Having two highly instrumented spacecraft in close proximity in time and space affords unprecedented opportunities for synergistic observations of Europa, Ganymede, Callisto, Io, Jupiter’s atmosphere, magnetosphere and environment, and Jupiter’s small satellites and rings, as well as opportunities for unique heliospheric and magnetosphere science during the JUICE and Clipper missions’ cruise and Jupiter-approach phases.

Analysis of potential joint science opportunities is underway by a small team of scientists from the JUICE and Clipper mission teams. Ideas have been collated from JCSC members as well as from three joint Clipper-JUICE workshops (2018, 2019, 2022), and the Science Traceability Matrix from a prior joint ESA-NASA study, the Europa Jupiter System Mission (EJSM). We recently produced a report on science that can be accomplished during the two spacecrafts’ cruise and Jupiter approach phases (Bunce et al., this meeting), and are now investigating potential opportunities once JUICE and Clipper are in orbit around Jupiter. Multiple opportunities exist for joint science at several different targets within the Jovian system, including two opportunities near Europa where the spacecraft are within 0.5Rj of each other and only a few hours apart. Scientific objectives may fall into one or more categories: (1) time dependent, in which both spacecraft must acquire data at same time, or one spacecraft’s observations inform the other’s observations; (2) space dependent, in which each spacecraft acquires data from specific parts of the Jovian system, or both observe the same target with similar, or different viewing geometries; and (3) an increase in science data (e.g. temporal or spatial coverage) made possible due to the availability of additional instrument types or data collection opportunities.

There are currently no firm commitments from NASA or ESA to accomplish science beyond that of each mission’s primary science objectives. However, discussions are ongoing and we are optimistic that our recommendations for the unprecedented opportunities afforded by the two missions’ alignment will enable funding support to be found. In this paper, we discuss some of the potential combined science from JUICE and Clipper that could further enhance understanding of the of the Jupiter system and the origin and habitability of the Galilean moons.

How to cite: Prockter, L., Bunce, E., and Choukroun, M. and the JUICE-Clipper Steering Committee: Exploring the Jupiter System through unique joint JUICE and Europa Clipper observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6262, https://doi.org/10.5194/egusphere-egu24-6262, 2024.

EGU24-6318 | Orals | PS2.1

Investigating the interior of Ganymede, Callisto and Europa with JUICE 

Tim Van Hoolst, Gabriel Tobie, and Claire Vallat and the JUICE WG1 SSR

On 14 April 2023, the JUpiter ICy moons Explorer (JUICE) of ESA was launched from Europe's Spaceport in French Guiana. It will arrive at Jupiter and its moons in July 2031. Here we describe how JUICE will investigate the interior of the three icy Galilean moons, Ganymede, Callisto and Europa. Best insights into their interior, such as from an induced magnetic field, tides, rotation variations, and radar reflections, will be obtained during close flybys of the moons with altitudes of about 1000 km or less and during the Ganymede orbital phase at an average altitude of about 500 km and less. The 9-month long orbital phase around Ganymede, the first of its kind around another moon than our moon, will allow an unprecedented and detailed insight into the moon’s interior, from the central regions where a magnetic field is generated to the internal ocean and outer ice shell. Multiple flybys of Callisto will constrain the density structure, clarify the differences in evolution compared to Ganymede and will provide key constraints on the origin and early evolution of the Jupiter system. JUICE will visit Europa only during two close flybys and will perform geophysical investigations on selected areas, complementary to those performed by Europa Clipper.

We emphasize the synergistic aspects of the different geophysical investigations, showing how different instruments will work together to probe the hydrosphere, internal differentiation, dynamics, and evolution of these icy moons. In situ measurements and remote sensing observations will support the geophysical instruments to achieve these goals by providing complementary information about tectonics, potential plumes, surface composition, and exchange processes between ocean, ice and surface. Additional insight into the dissipative processes in the Jupiter system will be provided by accurate tracking of the JUICE spacecraft.

 

How to cite: Van Hoolst, T., Tobie, G., and Vallat, C. and the JUICE WG1 SSR: Investigating the interior of Ganymede, Callisto and Europa with JUICE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6318, https://doi.org/10.5194/egusphere-egu24-6318, 2024.

EGU24-6577 | Posters on site | PS2.1

The Europa Clipper Flight System on its Path to Launch  

Haje Korth, Robert Pappalardo, and Bonnie Buratti and the Europa Clipper Flight System Engineering Team

At the beginning of the next decade, the Europa Clipper Flight System will enter orbit around Jupiter and, over a four-year period, will fly by Europa nearly 50 times to explore the habitability of this planet’s moon Europa. The Flight System comprises (1) the Propulsion Module, which provides the thermally-controlled spacecraft structure, propulsion subsystem, and solar array; (2) the Avionics Module, which enables spacecraft guidance, navigation, and control operations, provides power conditioning and computer resources which stores and prioritizes science data for downlink; (3) the Radio-Frequency Module, which provides telemetry uplink and science data downlink capabilities; and (4) a highly capable suite of remote-sensing and in-situ instruments to achieve the science objectives of the mission. The remote sensing payload consists of the Europa Ultraviolet Spectrograph (Europa-UVS), the Europa Imaging System (EIS), the Mapping Imaging Spectrometer for Europa (MISE), the Europa Thermal Imaging System (E-THEMIS), and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). The in-situ instruments comprise the Europa Clipper Magnetometer (ECM), the Plasma Instrument for Magnetic Sounding (PIMS), the SUrface Dust Analyzer (SUDA), and the MAss Spectrometer for Planetary Exploration (MASPEX). Gravity and radio science will be achieved using the spacecraft's telecommunication system, and valuable scientific data will be acquired by the spacecraft’s radiation monitoring system. The mission is presently in the assembly, testing, and launch operations (ATLO) phase. The Propulsion and RF Modules have been delivered from the Johns Hopkins Applied Physics Laboratory (APL) to the Jet Propulsion Laboratory (JPL). The flight system integration and environmental testing has been completed at the Jet Propulsion Laboratory. The flight system is presently undergoing a series of operations tests. In May 2024, it will be shipped to Kennedy Space Center, where it will be integrated with the solar array, which was delivered to the location earlier this year. The launch period begins on 10 October 2024, and once lifted off, the Europa Clipper will be cruising to the Jupiter System with gravity assists by Mars followed by Earth on the way. Go Europa Clipper!

How to cite: Korth, H., Pappalardo, R., and Buratti, B. and the Europa Clipper Flight System Engineering Team: The Europa Clipper Flight System on its Path to Launch , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6577, https://doi.org/10.5194/egusphere-egu24-6577, 2024.

EGU24-6579 | Orals | PS2.1

Can endogenic CO2 inflate radiolytic H2O2 in Europa’s Chaos? 

Ujjwal Raut, Silvia Protopapa, Bereket D Mamo, Geronimo Villanueva, Richard J Cartwright, Benjamin D Teolis, Kurt D Retherford, and Diana L Blaney

Recent JWST observations reveal a higher abundance of endogenic CO2 at Tara Regio, a prominent leading hemisphere chaos (Villanueva et al., 2023; Trumbo and Brown, 2023). Prior findings from Keck also show an excess of H2O2 in the same region (Trumbo et al., 2019). Could the emplacement of the ocean-derived CO2 onto Europa’s surface influence radiolytic chemistry to boost peroxide yields in these enigmatic chaos regions? Increased H2O2 at fractured chaos terrains where ocean-surface exchange is more likely is exciting from a habitability stance, as it may facilitate oxidant delivery to the subsurface ocean.

We present laboratory results that show H2O2 synthesis increases by 2-3 folds in the presence of trace amounts of CO2 (< 3 %) when compared to radiolysis of pure water ice. We also discuss correlations between CO2 and H2O2 abundances in the JWST datasets to determine whether Europa’s endogenous CO2 indeed conspires to inflate H2O2 at Tara Regio and possibly other chaos terrains. These JWST observations combined with emerging laboratory measurements set the stage for detailed mapping of CO2 (via its 2.7 and ~4.23-4.29 µm absorptions) and H2O2 (via its 3.5 µm absorption) with MISE (Europa Clipper) and MAJIS (JUICE) at unprecedented spatial resolution.

References:

  • Villanueva, G. L. et al., (2023) Science, 381, 1305–1308 
  • Trumbo, S. K and Brown, M. E. (2023) Science, 381, 1308–1311
  • Trumbo, S. K. et al. (2019) Astronomical Journal, 158, 127

How to cite: Raut, U., Protopapa, S., Mamo, B. D., Villanueva, G., Cartwright, R. J., Teolis, B. D., Retherford, K. D., and Blaney, D. L.: Can endogenic CO2 inflate radiolytic H2O2 in Europa’s Chaos?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6579, https://doi.org/10.5194/egusphere-egu24-6579, 2024.

EGU24-6809 | Orals | PS2.1

The Europa Clipper MASPEX Investigation 

J. Hunter Waite, James L. Burch, Tim Brockwell, David T. Young, Kelly Miller, Christopher R Glein, Danielle Y. Wyrick, Benjamin D. Teolis, Scott J. Bolton, Mathieu Choukroun, Melissa A. McGrath, William B. McKinnon, Olivier Mousis, Mark A. Sephton, Everett Shock, Mikhail Yu Zolotov, Steven C. Persyn, John M Stone, Rebecca Perryman, and Christine Ray and the MASPEX Science and Instrument Teams

The MAss Spectrometer for Planetary EXploration (MASPEX) is a multi-bounce time-of-flight neutral gas mass spectrometer with unprecedented spaceborne mass resolution and sensitivity. It is capable of measuring and identifying minor and trace gases requiring mass resolution of m/Δm ~ 25,000 at abundances of parts-per-million in Europa’s exosphere. Exospheric sources of gases include exsolved, sublimed, sputtered, and radiolytically produced volatiles from Europa’s surface and interior. These gases can be used to characterize surface composition and identify volatiles outgassed from Europa’s interior. Of particular relevance in characterizing Europa’s habitability are the ratios of organic compounds such as alkanes, alkenes, alkynes, alcohols, ethers, aldehydes, amides, amines, and nitriles that undergo chemical transformations, which can be used to determine oxidation states, pH, temperature, and free energy availability of an interior ocean, perched lake, or a gas source region in the ice shell (e.g., a diapir).

 

This paper presents: 1) the principles and ground-calibrated performance of the MASPEX instrument that is now integrated onto the Europa Clipper spacecraft and planned to be launched in October of 2024, 2) the planned scientific investigation and its critical role in the study of Europa’s habitability, 3) the operational plans, and 4) the anticipated data products from the MASPEX investigation. The paper will also discuss the complexity of the investigation and its requisite need for the acquisition of supporting geochemical, impact fragmentation, and sputtering/radiolytic data sets that help to characterize the geochemical reaction framework and the anticipated modification of chemical species due to impacts with the instrument’s thermalizing chamber, and from radiolysis and sputtering. In the latter context we present the science team’s efforts to generate the necessary data sets, and we encourage interested scientists to contribute to this important endeavor, which is essential for the maximum success of the MASPEX investigation.

How to cite: Waite, J. H., Burch, J. L., Brockwell, T., Young, D. T., Miller, K., Glein, C. R., Wyrick, D. Y., Teolis, B. D., Bolton, S. J., Choukroun, M., McGrath, M. A., McKinnon, W. B., Mousis, O., Sephton, M. A., Shock, E., Zolotov, M. Y., Persyn, S. C., Stone, J. M., Perryman, R., and Ray, C. and the MASPEX Science and Instrument Teams: The Europa Clipper MASPEX Investigation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6809, https://doi.org/10.5194/egusphere-egu24-6809, 2024.

EGU24-6850 | ECS | Posters on site | PS2.1

Ray tracing for Jupiter’s icy moon ionospheric occultation of Jovian auroral radio sources 

Rikuto Yasuda, Tomoki Kimura, Baptiste Cecconi, Hiroaki Misawa, Fuminori Tsuchiya, Yasumasa Kasaba, Shinnosuke Satoh, Shotaro Sakai, and Corentin Louis

The ionospheres of Jupiter’s icy moons have been observed by in situ plasma measurements and radio occultation. However, their spatial structures have not yet been fully characterized. To address this issue, we developed a new ray tracing method for modeling the radio occultation of the ionospheres using Jovian auroral radio sources. Applying our method to radio observations with the Galileo spacecraft, we derived the electron density of the ionosphere of Ganymede and Callisto. For Ganymede’s ionosphere, we found that the maximum electron density on the surface was 150 cm-3 in the open magnetic field line regions and 12.5 cm-3 in the closed magnetic field line region during the Galileo Ganymede 01 flyby. The difference in the electron density distribution was correlated with the accessibility of Jovian magnetospheric plasma to the atmosphere and surface of the moons. These results indicated that electron impact ionization of the Ganymede exosphere and sputtering of the surface water ice were effective for the producing Ganymede’s ionosphere. For Callisto’s ionosphere, we found that the densities were 350 cm-3 and 12.5 cm-3 on the night-side hemisphere during Callisto 09 and 30 flybys, respectively. These results combined with previous observations indicated that atmospheric production through sublimation controlled the ionospheric density of Callisto. This method is also applicable to upcoming Jovian radio observation data from the Jupiter Icy Moon Explorer, JUICE. 

How to cite: Yasuda, R., Kimura, T., Cecconi, B., Misawa, H., Tsuchiya, F., Kasaba, Y., Satoh, S., Sakai, S., and Louis, C.: Ray tracing for Jupiter’s icy moon ionospheric occultation of Jovian auroral radio sources, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6850, https://doi.org/10.5194/egusphere-egu24-6850, 2024.

EGU24-7724 | Orals | PS2.1

Energetic particle measurements near Ganymede: Galileo EPD data revisited and perspectives for Juice PEP 

Norbert Krupp, Elias Roussos, Markus Fränz, Peter Kollmann, George Clark, Chris Paranicas, Krishan Khurana, Stas Barabash, and Andre Galli

 

The Galileo spacecraft performed close flybys of the moon Ganymede between 1996 and 2001. We reanalysed data of the energetic particles detector EPD onboard Galileo and derived the particle fluxes, energy spectra, and pitch angle distributions in the energy range of several keV to MeV during Ganymede flybys G2, G7, G8, G28, and G29. We find sharp dropouts in ion and electron fluxes as signatures of the loss cones inside the Ganymede magnetosphere as well as trapped electron distribution. Additionally, bi-directional field-aligned and butterfly distributions were found as well. We discuss these findings compared with simulation results in charactering Ganymede’s magnetosphere and in the context of future measurements with the Particle Environment Package PEP onboard the Juice mission which will be in orbit around Ganymede in 2032.

How to cite: Krupp, N., Roussos, E., Fränz, M., Kollmann, P., Clark, G., Paranicas, C., Khurana, K., Barabash, S., and Galli, A.: Energetic particle measurements near Ganymede: Galileo EPD data revisited and perspectives for Juice PEP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7724, https://doi.org/10.5194/egusphere-egu24-7724, 2024.

Solid-state convection has been proposed to occur within Europa’s ice shell based both on the interpretation of observed geological activity during Galileo spacecraft exploration and theoretical investigations. Laboratory experiments have investigated the effect of grain size insensitive creep and grain size sensitive creep on the ductile behaviour of polycrystalline ice. The ice grain size and the ice impurities content and, consequently, the viscosity of the ice within Europa’s ice shell are poorly constrained, limiting the possibility to understand if solid-state convection can occur under Europa’s ice shell conditions. To investigate how diurnal tidal flexing and the internal dynamics of Europa’s ice shell influence the ice grain crystals’ evolution, we adopted a thermal-mechanical numerical model that uses finite differences and marker-in-cell techniques, implementing the dynamic recrystallization of the ice and the ice grain evolution in a self-consistent way with the numerical model. We found that solid-state convection within Europa’s ice shell can occur if it is diurnally tidally deformed, as the tidal stresses within the ice shell operate to reduce the ice grain sizes and the ice viscosity. We discuss future radio science experiments, in combination with radar sounder investigations, that will be capable of characterizing the possible presence of solid-state convection within Europa’s ice shell.

Acknowledgements: G.M. acknowledges support from the Italian Space Agency (2023-6- HH.0).

How to cite: Mitri, G.: Dynamic recrystallization within Europa’s ice shell: Implications for solid-state convection , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8353, https://doi.org/10.5194/egusphere-egu24-8353, 2024.

EGU24-8573 | ECS | Orals | PS2.1

Impact of Jupiter's heating and self-shadowing on the structure of its circumplanetary disk  

Antoine Schneeberger, Olivier Mousis, and Jonathan Lunine

At the very end of its growth, Jupiter became surrounded by a disk composed of gas and dust, where the Galilean moon presumably formed. It is supposed that satellitesimals formed by streaming instability and grew by pebble accretion. Once the satellitesimals reacedh a significant size, they undergone an inward type I migration by gravitational interaction with the disk. In the early stages of the circumplanetary disk, the migration of satellitesimals occurred over so short timescales that most bodies fell onto Jupiter, suggesting that the Galilean moons formed later during the disk’s evolution.  Other studies suggest that the moons sequentially formed and migrated inward. This suggests that the moons were trapped in mean motion resonances, halting their migration.  In the coming years, the ESA mission JUICE and NASA mission Europa-Clipper will study the Galilean moons composition and provide hints on their formation conditions.

In this context, we aim to model the evolution of a 2-dimensional circumplanetary disk around Jupiter. To do this, we have constructed a quasi-stationary circumplanetary disk model that considers viscous heating, accretion heating, and heating of the upper layers of the circumplanetary disk by Jupiter. The thermal structure is determined by a grey atmosphere radiative transfer model. We show that the heating by Jupiter of the upper layers of the disk induces flaring and disk self-shadowing effects, which locally increase and decrease the disk temperature, respectively. The resulting temperature variations can be up to 50 K relative to the surrounding disk temperature. Consequently, the circumplanetary disk can produce transient hotter and colder regions that can last up to 10 kyr. The alternance of hot and cold regions in the Jovian circumplanetary disk has then profound implications for the formation conditions of the Galilean moons.

How to cite: Schneeberger, A., Mousis, O., and Lunine, J.: Impact of Jupiter's heating and self-shadowing on the structure of its circumplanetary disk , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8573, https://doi.org/10.5194/egusphere-egu24-8573, 2024.

EGU24-9464 | Posters on site | PS2.1

The Jovian Electron and Ion Spectrometer (PEP-JEI) for the JUICE mission 

Markus Fränz, Patrick Bambach, Henning Fischer, Philipp Heumüller, Norbert Krupp, Wolfgang Kühne, Elias Roussos, Robert Labudda, and Stas Barabash

The magnetosphere of Jupiter is apart from the Sun the strongest source of charged particles in the Solar system. The interaction of these particles with the exospheres of the Jovian moons forms one of the most complex plasma laboratories encountered by human space flight. For this reason the plasma analyzer package forms a crucial experiment of the Jupiter Icy Moon Explorer (JUICE). As part of the Plasma Environment Package (PEP) we describe a combined electron and ion spectrometer which is able to measure the electron and ion distribution functions in the energy range 1 to 50000 eV with high sensitivity and time resolution. This instrument is called the Jovian Electron and Ion Analyzer, JEI. We report on the general performance of the instrument and on first observations of the solar wind during commissioning of the instrument in space.

How to cite: Fränz, M., Bambach, P., Fischer, H., Heumüller, P., Krupp, N., Kühne, W., Roussos, E., Labudda, R., and Barabash, S.: The Jovian Electron and Ion Spectrometer (PEP-JEI) for the JUICE mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9464, https://doi.org/10.5194/egusphere-egu24-9464, 2024.

EGU24-9753 | ECS | Orals | PS2.1

Tidal Dissipation in a Partially Molten Asthenosphere on Io 

Hamish Hay, Richard Katz, and Ian Hewitt

The rocky Jovian moon, Io, exhibits global volcanism that is driven by heat dissipated by tidal deformation. The large rate of heat exported by this volcanism, in conjunction with evidence in the form of magnetic induction, suggests that the mantle may contain a significant fraction of partial melt. This melt may be present in regions where both solid and liquid coexist at the macroscale. Nevertheless, existing models to investigate the location and magnitude of tidal heating consider an internal structure consisting of layers of pure solid or liquid. Such models are not appropriate for tidal deformation of partially molten materials. Building upon recent advancements in the theory of gravitational poroviscoelastic dynamics, we model tidal heating within Io, taking into account the effect of a two-phase, partially molten asthenosphere. 

The solid regions are modelled as a Maxwell viscoelastic material, and the top and bottom of the asthenosphere are treated as impermeable boundaries. We find that tidal dissipation within the fluid-filled pores depends on the ratio of the asthenosphere’s permeability to the melt’s viscosity. Thus, a low-viscosity melt and highly permeable pore-network favour enhanced tidal dissipation within the fluid. When this ratio, representing the Darcy drag, is large enough, fluid dissipation can exceed that within the solid grains when solid viscosity is high (> 1017 Pa s) or ultra-low (< 1011 Pa s). Tidal dissipation by the pore-hosted melt exhibits its own distinct tidal heating pattern, which always produces enhanced heating towards low latitudes.

How to cite: Hay, H., Katz, R., and Hewitt, I.: Tidal Dissipation in a Partially Molten Asthenosphere on Io, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9753, https://doi.org/10.5194/egusphere-egu24-9753, 2024.

EGU24-10327 | ECS | Posters on site | PS2.1

Accuracy of the Scalar Magnetometer aboard ESA's JUICE Mission 

Christoph Amtmann, Andreas Pollinger, Michaela Ellmeier, Michele Dougherty, Patrick Brown, Roland Lammegger, Alexander Betzler, Martín Agú, Christian Hagen, Irmgard Jernej, Josef Wilfinger, Richard Baughen, Alex Strickland, and Werner Magnes

The presentation discusses the accuracy of the scalar Coupled Dark State Magnetometer on board the Jupiter Icy Moon Explorer (JUICE) mission of the European Space Agency. The scalar magnetometer MAGSCA is part of the J-MAG instrument.

MAGSCA is an optical, omni-directional scalar magnetometer based on coherent population trapping, a quantum interference effect, within the hyperfine manifold of the 87Rb D1 line. The measurement principle is only based on natural constants and therefore, it is in principle drift free and no calibration is required. However, the technical realisation can influence the measurement accuracy.
The most dominating effects are heading characteristics, which are deviations of the magnetic field strength measurements from the ambient magnetic field strength.

The verification of the accuracy and precision of the instrument is required to ensure its compliance with the performance requirement of the mission: 0.2 nT (1-σ).
The verification is carried out with four dedicated sensor orientations in a Merritt coil system, which is located in the geomagnetic Conrad observatory. The coil system is used to compensate the Earth’s magnetic field and to apply appropriate test fields to the sensor. 

A novel method is presented which separates the heading characteristics of the instrument from residual (offset) fields within the coil system by fitting a mathematical model to the measured data. It allows verifying that the MAGSCA sensor unit does not have a measurable remanent magnetisation as well as that the desired accuracy of 0.2 nT (1-σ) is achieved by the MAGSCA flight hardware for the JUICE Mission.

How to cite: Amtmann, C., Pollinger, A., Ellmeier, M., Dougherty, M., Brown, P., Lammegger, R., Betzler, A., Agú, M., Hagen, C., Jernej, I., Wilfinger, J., Baughen, R., Strickland, A., and Magnes, W.: Accuracy of the Scalar Magnetometer aboard ESA's JUICE Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10327, https://doi.org/10.5194/egusphere-egu24-10327, 2024.

EGU24-10976 | ECS | Orals | PS2.1

Formation of chemically stratified layer in Ganymede’s ocean: implications for upcoming JUICE mission 

Mathis Pinceloup, Mathieu Bouffard, Steven Vance, Mohit Melwani Daswani, and Marshall Styczinski

Chemically stratified layers in the deep oceans of icy moons may strongly influence the oceans’ dynamics, thermal and chemical evolution, and therefore their habitability. Such layers can form during the differentiation of the refractory cores as they heat up due to the decay of long-lived radioactive elements. In the case of Ganymede, salts could be transported through the high-pressure ice layer to form a denser salt water layer at the base of the ocean. Such a layer would inhibit ocean convection, limiting chemical and thermal transport. It is therefore crucial to understand how these layers form and what specific signatures they may leave in geophysical observations of future space missions. The present work describes numerical simulations of the formation of stratified layers and the predicted observables that could be detected by instruments on the JUICE spacecraft.

3-D numerical simulations of Ganymede’s rotating ocean are performed with the PARODY code. Rayleigh-Bénard convection is imposed. We investigate the effect of either a constant flux of heavy salts or a fixed composition at the base of the ocean. Two regimes are identified by varying the dimensionless chemical Rayleigh (buoyancy over viscosity) and Schmidt numbers (viscosity over diffusivity). In the first regime, heavy salts are entrained and mixed in the convective region. In the second regime, the entrainment is too weak and a chemically stratified layer develops, eventually filling the entire ocean.

Extrapolation to Ganymede suggests the current existence of a chemically stratified layer at the base of the ocean with a thickness close to 30 km. By considering different stratifications in Ganymede’s ocean in the PlanetProfile and ForcedTides codes, we show that signatures of stratified layers might be detected in the gravity field, induced magnetic field, and tidal deformation responses. The problem of non-uniqueness in the individual observations points to the need to jointly invert these datasets from the JUICE mission to constrain the existence and properties of stratified oceanic layers.

How to cite: Pinceloup, M., Bouffard, M., Vance, S., Melwani Daswani, M., and Styczinski, M.: Formation of chemically stratified layer in Ganymede’s ocean: implications for upcoming JUICE mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10976, https://doi.org/10.5194/egusphere-egu24-10976, 2024.

EGU24-11349 | ECS | Posters on site | PS2.1

Extraction of topographic profiles of double ridges on Europa  

Caroline Haslebacher, Louise M. Prockter, Erin J. Leonard, Paul M. Schenk, and Nicolas Thomas

Double ridges are a common linear feature on Europa’s surface. They can be identified by a central trough accompanied by two ridge crests. Usually, the elevation of double ridge crests is not higher than 300 meters (e.g. [1]). Some double ridges run almost perfectly straight for hundreds of kilometers, while others are curved, for example into a cycloidal shape. Several double ridge formation hypotheses exist, which can be separated into cryo-volcanism/-sedimentation and brittle deformation (an overview can be found in [2]). Each proposed formation mechanism results in a unique topographic profile, which allows these hypotheses to be tested. 

We extract topographic profiles of more than 1000 mapped double ridges (perpendicular to their orientation) from a shape-from-shading topographic map. The shape-from-shading topographical map and the double ridge map are based on regional mosaics of Europa (data by [3]), two north-south covering swaths of the trailing and leading hemispheres at the regional scale (~230 m/px). The two regional mosaics were obtained under consistent illumination angles by the solid-state imager (SSI) on the Galileo spacecraft. We map double ridges in the regional mosaics with the help of the deep-learning tool LineaMapper [4]. We manually inspect, adjust, and verify LineaMapper’s predictions while respecting disruptions caused by other cross-cutting surface features.  

With this methodology, we analyze topographic profiles of double ridges in the regional mosaics and match them with unique profiles predicted by cryo-volcanism/-sedimentation and brittle deformation hypotheses. By assuming that, for any lineament, the number of disruptions per kilometer length is a proxy for relative age, we can assess the evolution of double ridge profiles over time, with potential implications for the upcoming space missions Europa Clipper and JUICE. 

[1] F. Nimmo, R. T. Pappalardo, B. Giese. (2003). On the origins of band topography, Europa. Icarus, 166(1), 21-32. 
[2] A.C. Dameron & D. M. Burr. (2018). Europan double ridge morphometry as a test of formation models. Icarus, 305(1), 225-249. 
[3] M. T. Bland, L. A. Weller, B. A. Archinal, E. Smith, B. H. Wheeler, (2021). Improving the Usability of Galileo and Voyager Images of Jupiter's Moon Europa. Earth and Space Science, 8(12). 
[4] C. Haslebacher, N. Thomas, V. T. Bickel, (2024). LineaMapper: A deep learning-powered tool for mapping linear surface features on Europa. Icarus, 410(1).

How to cite: Haslebacher, C., Prockter, L. M., Leonard, E. J., Schenk, P. M., and Thomas, N.: Extraction of topographic profiles of double ridges on Europa , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11349, https://doi.org/10.5194/egusphere-egu24-11349, 2024.

EGU24-11367 | ECS | Orals | PS2.1

Testing the penitente hypothesis on Europa via photometric roughness 

Ishan Mishra and Bonnie Buratti

Spiked, icy features, akin to the ‘penitentes’ on Earth [1], have been found on other airless bodies in the solar system as well, such as the 'bladed terrains' of Pluto [2] and the 'spires' of Callisto [3]. These features, thought to be formed due to sublimation erosion, are present in young, crater-less regions and hence represent an active response of the surfaces of these bodies to changing seasonal and climatic conditions. Interestingly, penitente formation has also been hypothesized on Europa [4], albeit the feasibility of that process on Europa has been questioned [5]. A fundamental limitation of testing this hypothesis for Europa is the lack of images at the resolution of the proposed penitente features (~ 15 m), unlike the images of the bladed terrains of Pluto from New Horizons and spires of Callisto from Galileo which clearly show these features. 

Photometric roughness models peer below the resolution limit of the camera to offer a glimpse of any surface roughness that is in the geometric optics limit.  Our roughness model [6], which has been successfully fit to a range of planetary bodies [7,8], will enable us to probe the surface roughness of Europa and test the penitente-hypothesis. We are locating Galileo images from the equatorial regions of Europa (within an equatorial zone restricted to ±24° where they are hypothesized to exist) and extracting scans of specific intensity (I/F) with backplanes of geometric coordinates. We will fit these I/F curves with our photometric model to derive roughness values, which will be compared to the proposed roughness of ~ 60° [4]. This predicted roughness is very high, so its effect on the light reflected from the surface should be easily detectable. To get a useful point of comparison for the roughness values we obtain for Europa, we will also perform a roughness analysis of the spires of Callisto, which are in a similar size regime of ~ 100 m. 

[1] Claudin, P. et al. (2015), Phys. Rev. E, 92(3), 033015; [2] Moore, J., et al. 2018, Icarus 300, 129-144, [3] Howard, A. D., & Moore, J. M. (2008). GRL, 35(3), L03203 [4] Hobley, D.E.J. et al. (2018). Nat. Geosci., 11(12), 901-904. [5] Hand, K.P. et al. ( 2020). Nat. Geosci., 13(1), 17-19. [6] Buratti, B. J., & J. Veverka (1985), Icarus 64, 320-328; [7] Buratti, B. J. et al. (2006). Planet. & Space Sci. 54, 1498-1509 [8] Lee, J. et al.  (2010), Icarus 206, 623-630.

How to cite: Mishra, I. and Buratti, B.: Testing the penitente hypothesis on Europa via photometric roughness, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11367, https://doi.org/10.5194/egusphere-egu24-11367, 2024.

EGU24-11664 | Posters on site | PS2.1

A detailed science and operations analysis of the first flyby of Europa by the Juice spacecraft 

Claire Vallat, Rosario Lorente, and Nicolas Altobelli and the The Juice Science Team

Juice is the first large mission chosen in the framework of ESA’s Cosmic Vision 2015-2025 program.

The focus of Juice is to characterize the conditions that might have led to the emergence of habitable environments among the Jovian icy satellites, in particular Ganymede, Europa and Callisto. Juice will also perform a multidisciplinary investigation of the Jupiter system as an archetype for gas giants.

The spacecraft payload consists of 10 state-of-the-art instruments (and one experiment that use the spacecraft telecommunication system with ground-based instruments) that will perform remote and in-situ measurements of Jupiter, its moons and their environment.

 

From a trajectory’s point of view, the mission calls for a three-year orbital survey of the Jupiter system followed by an additional 9 months in orbit around Ganymede for an in-depth characterization of Ganymede as a planetary object and possible habitat. During the Jupiter orbital phase, Juice will perform a sequence of 67 orbits of different periods and inclinations around the planet including several flybys of the Galilean moons, 2 of which as close as 400km altitude from Europa in July 2032.

The Juice top level Europa science goals are the determination of the composition of the non-ice materials and understanding their origin (deep interior vs exogenic), the search for liquid water under active sites and the study of the activity processes at play on the moon.

A representative detailed science operations plan has been developed by the science team covering a 24 hour-period around the first flyby of Europa in July 2032. The plan considers the latest knowledge on instrument and spacecraft resources and performances available at the time of the study.

This work presents the geometry and mission constraints associated to the flyby as well as the observation strategy chosen by the different payload; the remote sensing package’s strategy includes exosphere characterization (including potential plume detection) through limb observations and surface characterization at different scales and wavelengths, both on the inbound (dayside) and outbound (nightside) part of the flyby. At low altitude and centered around closest approach, the geophysics package will perform topography and surface roughness measurement using the laser altimeter as well as surface sounding down to a depth of up to ~ 9 km with the ice penetrating radar. Radio science range rate measurement will support the estimate of the main quadrupole coefficients and the testing of the hydrostatic hypothesis. The in-situ package will operate continuously to monitor the Europa plasma, neutral and electromagnetic wave environment. The resulting harmonized operations timeline, together with resources limitations and the assessment on the expected science return is discussed.

How to cite: Vallat, C., Lorente, R., and Altobelli, N. and the The Juice Science Team: A detailed science and operations analysis of the first flyby of Europa by the Juice spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11664, https://doi.org/10.5194/egusphere-egu24-11664, 2024.

EGU24-11772 | Orals | PS2.1

Ionospheric environment of Ganymede during the Galileo flybys 

Arnaud Beth, Marina Galand, Ronan Modolo, François Leblanc, Xianzhe Jia, Hans Huybrighs, and Gianluca Carnielli
The Galileo spacecraft flew by Ganymede, down to 0.1 RG from the surface for the closest, six times giving us insight into its plasma environment. Its ionosphere, made of ions born from the ionisation of neutrals present in Ganymede’s exosphere, represents the bulk of the plasma near the moon around closest approach. As it has been revealed by Galileo and Juno, near closest approach the ion population is dominated by low-energy ions from the water ion group (O+, HO+, H2O+) and O2+. However, little is known about their density, spatial distribution, and effect on the surface weathering of the moon itself. Galileo G2 flyby has been extensively studied. Based on a comparison between observations and 3D test-particle simulations, Carnielli et al. (2020a and 2020b) confirmed the ion composition (debated at the time), highlighted the inconsistency between the assumed exospheric densities and the observed ionospheric densities, and derived the contribution of ionospheric ions as an exospheric source. However, other flybys of Ganymede are also available (e.g. G1, G7, G8, G28, and G29) providing in-situ measurements at different phases of Ganymede around Jupiter or jovian magnetospheric conditions at the moon. We extend the original study by Carnielli et al. to other flybys, and compare our modelled ion moments (ion number density, velocity, and energy distribution) with Galileo in-situ data. We discuss our results and contrast them with those obtained for the G2 flyby.
 
 

How to cite: Beth, A., Galand, M., Modolo, R., Leblanc, F., Jia, X., Huybrighs, H., and Carnielli, G.: Ionospheric environment of Ganymede during the Galileo flybys, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11772, https://doi.org/10.5194/egusphere-egu24-11772, 2024.

EGU24-12178 | Orals | PS2.1

Energetic Neutral Atom (ENA) Imaging and In-Situ Energetic Particle Exploration of the Jovian Magnetosphere and Moon Environment from JUICE/PEP 

Pontus Brandt, George Clark, Peter Kollmann, Donald G. Mitchell, Malamati Gkioulidou, Dennis Haggerty, Stanislav Barabash, Peter Wurz, Norbert Krupp, Elias Roussos, Carol Paty, Xianzhe Jia, Krishan Khurana, Frederic Allegrini, Angele Pontoni, and H. Todd Smith

The Jovian Energetic Neutrals and Ions (JENI) Camera and the Jovian Energetic Electrons (JoEE) belong to the six-sensor suite Particle Environment Package (PEP) on board the JUICE mission. JENI is a combined ion and ENA camera with 90˚x120˚ Field-of-View and an energy range from a few keV to 110 keV for ENAs and 5 MeV for ions. Only one mission, Cassini, has captured ENA images of the Jovian system before during its distant flyby. Those images revealed emissions coming from the Europa neutral gas torus, but were too distant to resolve details on its spatial distribution and variability. The Juno mission has detected ENA emissions originating from both the Europa and also the Io torus, that indicate azimuthally asymmetric distributions. In ENA mode, JENI will image the Europa and Io tori, to investigate their spatial distribution and long-term variability providing global constraints to physical models of their sources. Although a predominant fraction of the ENAs from the tori originate from charge exchange between magnetospheric energetic ions and the neutral gas, a significant fraction may originate from charge exchange between the energetic ions and the ambient plasma in the tori. This opens up the intriguing possibility to also diagnose the plasma dynamics and distribution of the tori. JENI also targets the explosive recurrences of vast regions of heated plasma in the Jovian magnetotail (“injections”) that may be the engine behind the periodic radio emissions from rotating, magnetized planets, such as Saturn, Jupiter and perhaps even brown dwarfs. In ion mode, JENI will provide the detailed in-situ measurements of the energetic ion environment necessary to understand the physical heating and transport processes underlying the global context provided by the ENA images. JoEE is an electron spectrometer that near-simultaneously provide the energetic electron spectrum in multiple look directions over the energy range from 28 keV up to 2 MeV. JoEE’s prime objectives are to investigate the acceleration mechanisms of Jovian radiation belt electrons and their interaction with the Jovian moons. The Juno mission has recently made important electron measurements that provides useful guidance for deepening the JoEE objectives.

In this presentation an overview is given of JENI and JoEE, with emphasis on the ENA observations and their expected science return. This includes imaging of the Europa and Io tori distribution and variability, quasi-periodic magnetospheric injections, and their relation to rotationally periodic radio emissions from planets and brown dwarfs.

How to cite: Brandt, P., Clark, G., Kollmann, P., Mitchell, D. G., Gkioulidou, M., Haggerty, D., Barabash, S., Wurz, P., Krupp, N., Roussos, E., Paty, C., Jia, X., Khurana, K., Allegrini, F., Pontoni, A., and Smith, H. T.: Energetic Neutral Atom (ENA) Imaging and In-Situ Energetic Particle Exploration of the Jovian Magnetosphere and Moon Environment from JUICE/PEP, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12178, https://doi.org/10.5194/egusphere-egu24-12178, 2024.

EGU24-12317 | ECS | Posters on site | PS2.1

Monitoring the performances of MAJIS from ground to flight calibration measurements 

Paolo Haffoud, Yves Langevin, François Poulet, Mathieu Vincendon, Gianrico Filacchione, Giuseppe Piccioni, John Carter, Pierre Guiot, Benoit Lecomte, Cydalise Dumesnil, Alessandra Barbis, Leonardo Tommasi, Sébastien Rodriguez, Stefani Stefania, Federico Tosi, Cédric Pilorget, and Simone De Angelis

 

ESA’s Jupiter Icy Moons Explorer (JUICE) mission scientific payload includes a 2-channels (visible to near-infrared (VISNIR) and infrared (IR)) cryogenic imaging spectrometer instrument called the Moons And Jupiter Imaging Spectrometer (MAJIS). During its ground calibration campaign, this instrument was tested at different operative temperatures, and calibration measurements were acquired to derive the spatial, spectral, and radiometric performances. Following the launch of the JUICE mission to the Jovian System, the first in-flight measurements were acquired during the near-Earth commissioning phase (NECP). In flight, the internal calibration unit (ICU) was used to monitor the instrument’s response.  In particular, the ICU signal provides full illumination of the instrument's field of view. It exhibits several absorption bands thanks to a didymium and a polystyrene filter placed in front of the VISNIR and IR sources, respectively.

The performances of the instrument are evaluated through several metrics, including the absolute spectral calibration, the full width at half maximum of the response (spatial and spectral), the distortions (keystone and smile), and the impact of the optical head temperature.

The flight acquisitions will be presented and compared to the ground calibration analyses, and the current performances of the instrument will be discussed in the context of MAJIS main scientific goals.

How to cite: Haffoud, P., Langevin, Y., Poulet, F., Vincendon, M., Filacchione, G., Piccioni, G., Carter, J., Guiot, P., Lecomte, B., Dumesnil, C., Barbis, A., Tommasi, L., Rodriguez, S., Stefania, S., Tosi, F., Pilorget, C., and De Angelis, S.: Monitoring the performances of MAJIS from ground to flight calibration measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12317, https://doi.org/10.5194/egusphere-egu24-12317, 2024.

EGU24-13075 | ECS | Orals | PS2.1

Constraining Ion Precipitation onto Ganymede’s Surface with Backscattered Energetic Neutral Atoms 

Paul S. Szabo, Andrew R. Poppe, Andreas Mutzke, Lucas Liuzzo, and Shane R. Carberry Mogan

Ion precipitation onto Ganymede, shaped by interaction between the Jovian plasma and Ganymede’s magnetosphere, has been connected to brightness patterns and radiolysis products on its surface [1,2]. JUICE will measure ion fluxes in-situ at around 500 km altitude, leaving uncertainties for the precipitation patterns on the surface [3]. At Earth’s Moon, backscattered Energetic Neutral Atoms (ENAs) have been shown to be suitable for studying the ion-surface interaction from an orbiting spacecraft [4]. We now present the first modeling of ENAs created by backscattered H, O and S ions at Ganymede, which will enable JUICE to remotely observe the ion impacts. Using the SDTrimSP code [5], which has been verified for backscattered ENAs at the Moon [6, 7], we account for inputs of magnetospheric plasma precipitation from hybrid simulations [8] and Ganymede’s surface composition from telescopic observations [9].

Our simulation results support that backscattering is an important formation process mainly for atomic H and O populations, whose properties are directly related to the precipitation conditions. Especially backscattered H ENAs dominate over any sputtered ENAs [10] above at least around 1 keV, making them ideal candidates for observing the plasma-surface interaction at Ganymede. Compared to lunar ENAs, backscattering probabilities are lower, but extended high-energy tails occur due to energetic ion populations in the Jovian plasma. The backscattering process thus creates neutral atom contributions that are candidates for observation with both JUICE’s JNA and JENI instruments.

 

[1]          S. Fatemi, et al., Geophys. Res. Lett. 43 (2016), 4745.

[2]          S.K. Trumbo, et al., Sci. Adv. 9 (2023), eadg3724.

[3]          C. Plainaki , et al., Astrophys. J. 940 (2022), 186.

[4]          Y. Futaana, et al., Gephys. Res. Lett. 40 (2013), 262.

[5]          A. Mutzke, et al., IPP Report 2019-02 (2019).

[6]          P.S. Szabo, et al., Geophys. Res. Lett. 49 (2022), e2022GL101232.

[7]          P.S. Szabo, et al., J. Geophys. Res.: Planets 128 (2023), e2023JE007911.

[8]          A.R. Poppe, et al., J. Geophys. Space Phys. 123 (2018), 4614.

[9]          N. Ligier, et al., Icarus 333 (2019), 496.

[10]       A. Pontoni, et al., J. Geophys. Space Phys. 127 (2022), e2021JA029439.

 

 

How to cite: Szabo, P. S., Poppe, A. R., Mutzke, A., Liuzzo, L., and Carberry Mogan, S. R.: Constraining Ion Precipitation onto Ganymede’s Surface with Backscattered Energetic Neutral Atoms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13075, https://doi.org/10.5194/egusphere-egu24-13075, 2024.

EGU24-13816 | ECS | Orals | PS2.1

Cryovolcanism inside out: Signatures of past and present cryovolcanism on Europa 

Elodie Lesage, Samuel M. Howell, Julia W. Miller, Mariam Naseem, Justine Villette, Marc Neveu, Mohit Melwani Daswani, and Steven D. Vance

Introduction. Europa, the most visibly active icy moon of Jupiter, is a prime target for the search for life in the outer solar system. Two spacecraft missions, Europa Clipper from the National Aeronautics and Space Administration (NASA) and the Jupiter Icy Moon Explorer (JUICE) from the European Space Agency (ESA), will conduct extensive observations of its surface, gravity field and environment starting 2030. It has been proposed that liquid briny water reservoirs could be injected and stored in Europa’s ice shell, causing the formation of various geological features. In particular, these reservoirs could occasionally trigger eruptions [1], resulting in flows on the surface and vapor plumes in the atmosphere.

If shallow liquid brine reservoirs are indeed present in Europa's ice shell, they would leave surface evidence that future missions could detect, including local thermal anomalies, ice shell thickness change, and erupted briny solutions with time varying salinity. We present a novel simulation that models thermal, physical, and compositional ice shell and reservoir evolution and eruption, and that predicts the various signatures detectable by future robotic exploration.

Cryomagma chemistry. We conserve enthalpy to solve the coupled chemical evolution and pressurization of freezing brines stored in Europa’s ice shell using current best estimates of the oceanic composition [2] to predict the composition of erupted cryolava. This composition varies with time, as salts concentrate during freezing [3], which could lead to erupted brines of varying composition depending on the reservoir frozen fraction when the eruption is triggered. The equilibrium freezing of oceanic brines is modeled using the software PHREEQC to obtain the liquid and solid fraction of each component of the aqueous solution as a function of the temperature. 

Ice shell and reservoir modelling. We simultaneously model the ice shell and reservoir thermal, physical, and compositional evolution self-consistently building upon the framework of [4]. We solve for the conservation of enthalpy using conservative finite differences in a one-dimensional (1D) spherical shell, propagated explicitly forward in time. The thermophysical properties of the multiphase model are temperature-, pressure-, and composition dependant, thus the composition and physical state are consistently updated at every time step. Finally, modeled eruption frequency and eruptive characteristics are dependent on the properties and their gradients in ice surrounding the reservoir.

Results. Outputs of the model include the temporal evolution of the temperature in the ice shell, reservoir, and at the surface, and the time of eruptions and erupted cryomagma composition (Fig. 1).

Figure 1: Temporal evolution of signatures of a 1 km thick cryomagma reservoir located 1 km bellow the surface.

Acknowledgements. Portions of this research were carried out at the Jet  Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NASA). This work was supported by NASA’s Solar System Workings program (grants #80NM0018F0612 and #80NSSC20K0139)

References. [1] Lesage et al. (2022) PSJ 3(7), 170, [2] Melwani Daswani et al. (2021) GRL 48(18), [3] Naseem et al. (2023) PSJ 4(9), 181, [4] Howell, S. M. (2021) PSJ 2(4), 129.

How to cite: Lesage, E., Howell, S. M., Miller, J. W., Naseem, M., Villette, J., Neveu, M., Melwani Daswani, M., and Vance, S. D.: Cryovolcanism inside out: Signatures of past and present cryovolcanism on Europa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13816, https://doi.org/10.5194/egusphere-egu24-13816, 2024.

EGU24-14097 | Orals | PS2.1

The Europa Clipper Mission and its Final Stretch to Launch 

Kathleen L. Craft, Robert Pappalardo, Bonnie Buratti, Haje Korth, Ingrid Daubar, Cynthia Phillips, Rachel Klima, Sam Howell, Erin Leonard, Alexandra Matiella Novak, Trina Ray, Jennifer Kampmeier, and Brian Paczkowski and the Europa Clipper Science Team

Scheduled to launch in October 2024, NASA’s Europa Clipper will set out on a journey to explore the habitability of Jupiter’s icy ocean world Europa. After a 5.5 yr cruise that includes gravity assists at Mars and Earth, the spacecraft will enter orbit around Jupiter and will perform nearly 50 flybys of Europa over a four-year period. To explore Europa as an integrated system and achieve a complete picture of its habitability, the Europa Clipper mission has three main science objectives to characterize: (1) the ice shell and ocean including their heterogeneity, properties, and surface–ice–ocean exchange; (2) Europa’s composition including any non-ice materials on the surface and in the atmosphere, and any carbon-containing compounds; and (3) Europa’s geology including surface features and localities of high science interest. Additionally, several cross-cutting science topics will be investigated through searching for any current or recent activity in the form of thermal anomalies and plumes, performing geodetic and radiation measurements, and assessing high-resolution, co-located observations at select sites to provide reconnaissance for a potential future landed mission. These science objectives will be accomplished using a highly capable suite of remote-sensing and in-situ instruments. The remote sensing payload consists of the Europa Ultraviolet Spectrograph (Europa-UVS), the Europa Imaging System (EIS) consisting of a wide and a narrow angle camera (WAC, NAC), the Mapping Imaging Spectrometer for Europa (MISE), the Europa Thermal Imaging System (E-THEMIS), and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON). The in-situ instruments are the Europa Clipper Magnetometer (ECM), the Plasma Instrument for Magnetic Sounding (PIMS), the SUrface Dust Analyzer (SUDA), and the MAss Spectrometer for Planetary Exploration (MASPEX). Gravity and radio science will be obtained using the spacecraft's telecommunication system, and valuable scientific data will be acquired by the spacecraft’s radiation monitoring system.

Assembly, test, and launch operations (ATLO) of the Europa Clipper spacecraft are progressing well, and the flight system integration and environmental testing has been completed at the Jet Propulsion Laboratory. Currently, the flight system is undergoing operations testing, and in May 2024, the spacecraft will be shipped to NASA’s Kennedy Space Center at Cape Canaveral, Florida. There, the remaining integration activities will occur for the solar array and REASON antennas followed by final flight system tests. The launch period begins on 10 October 2024. To provide details on the mission’s instruments and planned investigations, the Europa Clipper science team is publishing manuscripts in a special issue of Space Science Reviews, and the team continues to work towards optimizing science return through preparation of the mission’s Strategic Science Planning Guide. As well, collaborative science opportunities with ESA’s JUpiter ICy moons Explorer (JUICE) mission, which will overlap in its tour period at Jupiter and make observations of Europa, are being discussed informally among the science teams. Onward to Europa!

How to cite: Craft, K. L., Pappalardo, R., Buratti, B., Korth, H., Daubar, I., Phillips, C., Klima, R., Howell, S., Leonard, E., Matiella Novak, A., Ray, T., Kampmeier, J., and Paczkowski, B. and the Europa Clipper Science Team: The Europa Clipper Mission and its Final Stretch to Launch, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14097, https://doi.org/10.5194/egusphere-egu24-14097, 2024.

EGU24-15429 | ECS | Posters on site | PS2.1

Modeling the Cassini States of large icy satellites with an angular momentum approach 

Alexis Coyette, Rose-Marie Baland, and Tim Van Hoolst

It is generally assumed that the large icy satellites of Jupiter and of Saturn are, like our Moon, in an equilibrium rotation state called a Cassini State. In this state, the rotation of the satellite is synchronous with the orbital motion and the precession rate of the rotation axis is equal to that of the normal to the orbit. Moreover, the spin axis of the satellite, the normal to its orbit and the normal to the inertial plane remain coplanar and the obliquity (the angle between the normal to the orbit and the spin axis) is constant over time. For satellites with a slow orbital precession rate like the large icy satellites, up to four Cassini states are possible, characterized by a (theoretically) constant obliquity close to 0 (CSI), ± π/2 (CSII and IV) and π (CSIII). From these four states, only two are stable: CSI and CSIII.

We here model these two stable Cassini States of triaxial satellites using an angular momentum approach. In our model, the motion of the spin motion in space is coupled with the polar motion of the satellite and, contrary to what is usually done in the classical Cassini States studies, we do not average the external gravitational torque over short period terms. We can therefore compute the mean obliquity value of the different satellites but also the nutations (small periodic variations) both in obliquity and in longitude, which are due to the periodic variations of the gravitational torque acting on the satellites. We identify and study two causes for the polar motion and their effects on the obliquity: the semi-diurnal polar motion due to the inclination and node precession and the long period polar motion due to the eccentricity and pericenter precession.

How to cite: Coyette, A., Baland, R.-M., and Van Hoolst, T.: Modeling the Cassini States of large icy satellites with an angular momentum approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15429, https://doi.org/10.5194/egusphere-egu24-15429, 2024.

EGU24-17407 | Posters on site | PS2.1

Analysis of the first data collected by the High Accuracy Accelerometer (HAA) onboard the JUICE spacecraft 

Umberto De Filippis, Paolo Cappuccio, Mauro Di benedetto, and Luciano Iess

The JUpiter ICy moons Explorer (JUICE) mission is a cornerstone of the European Space Agency (ESA). The mission was launched in April 2023 from Kourou with an Ariane V launcher and is expected to arrive at Jupiter in 2031. JUICE will investigate the gas giant planet Jupiter, its atmosphere, magnetosphere, and its icy moons, Ganymede, Europa and Callisto. The mission will focus on Ganymede, during the low altitude circular and polar orbital phase.

The spacecraft will carry a suite of scientific instruments, including a camera, a spectrometer, a radar system, a laser altimeter, and a suite of instrumentation dedicated to radio science experiments: the Ka-band Transponder (KaT), the Ultra Stable Oscillator (USO) and the High Accuracy Accelerometer (HAA).

The Gravity & Geophysics of Jupiter and Galilean Moons experiment (3GM) instrumentation will be used to study the gravity field up to degree and order 40 of Ganymede and the extent of internal oceans on the icy moons. Furthermore, during radio occultations, the 3GM experiment will investigate the structure of the neutral atmospheres and ionospheres of Jupiter and its moons.

The HAA accelerometer will play a fundamental role during the 3GM experiment even if it will not directly measure any of the physical quantities connected with the experiment scientific goals. It aims to measure the perturbations of non-gravitational forces that the JUICE spacecraft will undergo during 3GM measurements with an accuracy of  in the frequency band of  Hz. Such perturbations are mainly induced by the propellant sloshing within the tanks, especially during the moon flybys. These perturbing accelerations are included in the orbital determination algorithm. In this work we show the first inflight data collected by the HAA instrument during the cruise. We present the data collected after launch (April-June 2023) during the deployment of the spacecraft moving appendages such as the RIME antenna, the Langmuir probes and the magnetometer boom. The analysis of these data aims to preliminary characterize the instrument behaviour and the spacecraft dynamic environment. Additionally, we show the analysis of the HAA data collected during the first payload checkout (January 2024), with a focus on the preliminary assessment on the instrument in-flight scientific performances.  

How to cite: De Filippis, U., Cappuccio, P., Di benedetto, M., and Iess, L.: Analysis of the first data collected by the High Accuracy Accelerometer (HAA) onboard the JUICE spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17407, https://doi.org/10.5194/egusphere-egu24-17407, 2024.

EGU24-17570 | Orals | PS2.1

SUDA: A SUrface Dust Analyser for compositional mapping of the Galilean moon Europa 

Sascha Kempf and the SUDA Science Team

The Surface Dust Analyser (SUDA) is a dust impact mass spectrometer onboard of the Europa Clipper mission for investigating the surface composition of the Galilean moon Europa. The instrument is a Time--Of--Flight (TOF) impact mass spectrometer derived from previously flown dust compositional analyzers on Giotto, Stardust, and Cassini. SUDA uses the technology of the successful Cosmic Dust Analyzer (CDA) operating on Cassini and employs advanced reflectron-type ion optics for increased mass resolution. The instrument will measure the mass, speed, charge, elemental and isotopic composition of impacting grains.

 

Atmosphereless planetary moons such as the Galilean satellites are wrapped into a ballistic dust exosphere populated by tiny samples from the moon's surface produced by impacts of fast micrometeoroids. SUDA will measure the composition of such surface ejecta during close flybys at Europa to obtain key chemical constraints for revealing the satellite's composition, history, and geological evolution. Because of their ballistic orbits, detected ejecta can be traced back to the surface with a spatial resolution roughly equal to the instantaneous altitude of the spacecraft.

SUDA will detect a wide variety of compounds from Europa's surface over a concentration range of percent to ppm and connect them to their origin on the surface. This allows simultaneous compositional mapping of many organic and inorganic components, including both major and trace compounds, with a single instrument. Any recent tectonic activity, cryovolcanism, or resurfacing event is detectable by variations in the surface composition. This can be linked to corresponding geological features, including the analysis of compositional variations across large craters on Europa. SUDA will further the understanding of Europa's surface couples to its interior source regions.

In this presentation, we will discuss SUDA's unique capabilities to collect compositional ground truth from orbit and how SUDA contributes to the Europa Clipper science goals.

How to cite: Kempf, S. and the SUDA Science Team: SUDA: A SUrface Dust Analyser for compositional mapping of the Galilean moon Europa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17570, https://doi.org/10.5194/egusphere-egu24-17570, 2024.

EGU24-19302 | Posters on site | PS2.1

Studying the icy moons of Jupiter using a database framework 

Thomas Cornet, Guillaume Cruz-Mermy, Ines Belgacem, Francois Andrieu, and Frederic Schmidt

The NASA Galileo spacecraft explored the Jupiter system between 1995 and 2003. The spacecraft was equipped with the Near-Infrared Mapping Spectrometer instrument (NIMS), able to probe Jupiter’s atmosphere and the icy moons’ surface composition in the near-infrared with its 17 detectors operating between 0.7 to 5.2 microns [1]. The Galileo NIMS dataset was collected during flybys, which resulted in a series of very diverse data cubes, viewing geometries and spatial resolutions. In addition, depending on the instrument mode used to collect the data, and on the instrument’s own health status, the NIMS infrared spectra were collected with a varying spectral sampling (between 15 and 408 wavelengths), and an evolving absolute wavelength calibration over the course of the mission. Despite its heterogeneity and complexity of use, the Galileo/NIMS dataset is one of the most valuable resource to model and map the surface properties (composition, grain size, roughness, phase function) of Jupiter’s moons, which are the prime targets of the Europa Clipper [2] and ESA JUICE [3] missions in this decade.

We converted the Galileo/NIMS calibrated dataset publicly available on the PDS Imaging Node (as g-cubes) into a MySQL relational database, which allows to quickly select and extract radiance factors (I/F), geometry data, and metadata from the entire NIMS data set. The smallest element in the database is a spectrum (i.e. one pixel). Using SQL queries relying on the pixel viewing geometry (incidence, emission, phase, and azimuth) and the geographic pixel location (latitudes and longitudes on a target), phase curves and/or collections of spectra can be easily retrieved. Individual g-cubes data can also be accessed upon request. We used this database framework, together with Bayesian inversion methods and the Hapke model [4,5], to perform detailed compositional studies on Europa’s dark lineaments [6,7], and spectro-photometric modeling of broader regions of interest located in different hemispheres [8].

 

References

[1] Carlson et al., Space Science Reviews, 60, 457-502, 1992.

[2] Howell and Pappalardo, Nat Commun 11, 1311, 2020.

[3] Grasset et al., Plan Spac Sci 78, 1-21, 2013.

[4] Hapke, Icarus 221, 1079-1083, 2012.

[5] Hapke, Cambridge University Press, 1993.

[6] Cruz Mermy et al., Icarus 394, 115379, 2023.

[7] Andrieu et al., EPSC 2022.

[8] Belgacem et al., EPSC, 2022.

How to cite: Cornet, T., Cruz-Mermy, G., Belgacem, I., Andrieu, F., and Schmidt, F.: Studying the icy moons of Jupiter using a database framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19302, https://doi.org/10.5194/egusphere-egu24-19302, 2024.

EGU24-20110 | Posters on site | PS2.1

ESA JUICE and NASA Europa Clipper: Joint Science Opportunities during Cruise and Jupiter Approach 

Emma Bunce, Louise Prockter, and Mathieu Choukroun and the JUICE Clipper Science Committee

ESA’s JUpiter ICy moons Explorer (JUICE) launched on April 14, 2023, beginning an eight-year journey to the Jupiter system. Arriving in 2031, JUICE will make 35 total flybys of Ganymede, Europa, and Callisto before going into orbit about Ganymede. NASA’s Europa Clipper is scheduled to launch in October 2024, arriving in the Jupiter system in 2030, a year ahead of JUICE. Clipper will spend a year in the system before undertaking 49 flybys of Europa during a nominal three-year primary mission phase, while also making multiple serendipitous flybys of Ganymede and Callisto. Having two highly instrumented spacecraft in close proximity in time and space affords unprecedented opportunities for synergistic observations during the missions’ main orbital phases, and unique heliospheric and magnetosphere science during cruise and Jupiter approach.

While there are currently no firm commitments from NASA or ESA to accomplish science beyond that of each mission’s primary science objectives, discussions are ongoing and the task of the appointed JUICE-Clipper Steering Committee (JCSC) is to provide recommendation of compelling joint science opportunities between the two missions.

This paper will focus on the cruise and Jupiter approach phases. We have identified a number of potential opportunities for investigating the evolution of the solar wind plasma and interplanetary magnetic field and related structures such as monitoring Coronal Mass Ejections (CMEs) or Corotating Interaction Regions (CIRs) during times when the two spacecraft are radially aligned (i.e. at similar heliocentric longitudes) or at similar heliocentric distances, as well as radio science observations of the solar wind and/or Solar Energetic Particle (SEP) events that could be observed throughout interplanetary transfer. There is also potential for investigating the evolution of solar wind structures and disturbances when both spacecraft are “connected” through Parker Spiral field lines. The cruise science return from JUICE and Clipper could be further enhanced by data from other operational spacecraft (e.g., BepiColombo, Solar Orbiter, Parker Solar Probe, MAVEN, IMAP, Psyche), thus expanding the catalogue of opportunities for these identified configurations, as well as simultaneous observations by ground and space-based observatories (e.g., JWST, Keck, etc.). The >1 year Jupiter approach phase of the JUICE spacecraft while Clipper orbits within the jovian magnetosphere provides an unrivalled opportunity to study the complexity of the solar wind-magnetosphere interaction and aurora at Jupiter, a topic where there remain many open questions. This phase would provide a unique opportunity for preparatory joint observations to understand if and how the solar wind influences the moon’s local space environment, and the related interaction with Jupiter’s rapidly rotating magnetosphere.

How to cite: Bunce, E., Prockter, L., and Choukroun, M. and the JUICE Clipper Science Committee: ESA JUICE and NASA Europa Clipper: Joint Science Opportunities during Cruise and Jupiter Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20110, https://doi.org/10.5194/egusphere-egu24-20110, 2024.

EGU24-20679 | Orals | PS2.1

The JUICE mission - an overview, since launch and beyond  

Nicolas Altobelli, Olivier Witasse, Claire Vallat, Ignacio Tanco, Angela Dietz, and Christian Erd and the JUICE TEAMS

The JUICE mission has been launched by an Ariane 5 launcher on April 14, 2023 and is now on its way to reach Jupiter and its icy moons in 2031. The focus of JUICE is to characterise the conditions that may have led to the emergence of habitable environments among the Jovian icy satellites, with special emphasis on the internally active ocean-bearing worlds, Ganymede and Europa. Following a Jupiter Touring phase of 4 years, JUICE will become the first orbiter of a moon that is not our own, entering Ganymede orbit in 2034.

The spacecraft passed its commissioning review successfully on July 19, 2023, following the Near Earth Commissioning Phase (NECP), and, despite a few hickups, the ESA and multi-national instruments teams are now operating our interplanetary ship successfully. The preparation of the first combined flyby of the Earth and the Moon  in the history of space exploration (August 2024) is on-going. The first planning training exercise was completed by the Science Ground Segment, complementing the preparation of the strategic science planning of the Jupiter Tour.

How to cite: Altobelli, N., Witasse, O., Vallat, C., Tanco, I., Dietz, A., and Erd, C. and the JUICE TEAMS: The JUICE mission - an overview, since launch and beyond , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20679, https://doi.org/10.5194/egusphere-egu24-20679, 2024.

EGU24-20774 | Posters on site | PS2.1

Unique Heliospheric Measurement Opportunities with the ESA JUICE mission: Science Case for Particle Environment Package (PEP) 

Stas Barabash, Pontus Brandt, Peter Wurz, George Clark, Norbert Krupp, Elias Roussos, Gabriella Stenberg Wieser, Philipp Wittmann, Markus Fränz, Manabu Shimoyama, Martin Wieser, Peter Kollmann, and Donald Mitchell

The Jupiter bound JUICE mission (JUpiter ICy moons Explorer) was successfully launched on April 14, 2023 and is currently executing its 8-year interplanetary cruise phase. JUICE carries three comprehensive instrument suites to fully characterize particles, fields, and waves. The JUICE space plasma instrumentation constitutes the most comprehensive and capable heliophysics payload ever flown, or planned, in the important but not-well explored the solar system region between 1 and 5 au.

Science objectives that can be addressed by the JUICE payload include solar wind evolution, collisionless shock interactions and propagation, and particle acceleration, solar energetic particles, pick-up ion (PUI) origin and evolution, turbulent interactions, energetic neutral atom (ENA) imaging, and interplanetary hydrogen observations.

JUICE enables an expansion of inner heliospheric science, connecting to observations in the outer heliosphere and Very Local Interstellar Medium (VLISM) by NASA’s New Horizons, Voyager, and Interstellar Mapping and Acceleration Probe (IMAP) (to launch Feb 2025). New science opportunities are also enabled by the simultaneous observations from Europa Clipper in the same region. JUICE will spend the next six years between 0.7 au and 2.5 au, and in 2029-2031 it will explore the region out to Jupiter. JUICE has no thermal constraints past 1.34 au and the data volume from relevant sensors live well within the available data downlink through its weekly passes using the European Space Tracking (ESTRACK).

In this presentation, we discuss the unique heliophysics observations the six-sensor suite Particle Environment Package (PEP) on board can do in conjunction with other space physics measurements on board JUICE and Europa Clipper. The PEP-suite measures species-resolved energy and angular distributions of electrons (~ 1 eV to ~1.5 MeV), ions (~1 eV to > 10 MeV; energy rage is species dependent); and ENA (~ 5eV to 300 keV). In addition to the PEP instrument suite, JUICE also carries a radiation monitor (RADEM) that can provide complimentary energy and species resolved measurements of very energetic electrons and ions in the solar wind.

How to cite: Barabash, S., Brandt, P., Wurz, P., Clark, G., Krupp, N., Roussos, E., Stenberg Wieser, G., Wittmann, P., Fränz, M., Shimoyama, M., Wieser, M., Kollmann, P., and Mitchell, D.: Unique Heliospheric Measurement Opportunities with the ESA JUICE mission: Science Case for Particle Environment Package (PEP), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20774, https://doi.org/10.5194/egusphere-egu24-20774, 2024.

EGU24-762 | ECS | Orals | PS2.3

Experimental constraints on tidal dissipation in silicate cores of icy satellites 

Cassandra Seltzer, Hoagy O. Ghaffari, and Matěj Peč

The habitability of icy moons in the outer Solar System is linked to their ability to maintain warm subsurface oceans through time. While most heat generation in response to tidal forcing is thought to occur in icy crusts and water oceans, the actual response of silicic material to deformation under relevant planetary conditions has not previously been studied comprehensively in a laboratory setting. Similar meteoritic material is often studied at room pressure instead of at the 10s to 100s of MPas of pressure present at depth in moons, and subjected to dynamic forces to simulate impacts rather than observed under quasistatic loading and deformation. In the absence of laboratory constraints on peak strength and deformation behavior, large errors remain for estimates of heat contribution from the mantles, as well as in models of seismic and elastic properties of icy moon interiors.

We experimentally deformed samples of the Kilabo meteorite, an LL6 chondrite, under axial strain rates of 10-5 s-1 and confining pressures up to 100 MPa. We recorded the strength of the material, calculated energy dissipation through acoustic emission events, and measured how ultrasonic wavespeeds evolved as a function of confining pressure. Dissipative microcracking events occurred at all pressures, even at low stresses during isotropic pressurization and nominally “elastic” deformation. These events were most common at low confining pressures. The mechanical behavior of the meteoritic material also evolved as a function of confining pressure: peak strength occurred at 50 MPa laboratory confining pressure, and material continuously stiffened as pressure increased. These pressure-dependent properties indicate that larger icy planetary bodies may have stiffer, less deformable silicate layers than those found in small icy satellites. Rocky interior deformation could therefore contribute to the bulk heat budget required to maintain subsurface oceans in Ariel and Miranda, along with many other smaller icy moons in the outer Solar System.  

How to cite: Seltzer, C., O. Ghaffari, H., and Peč, M.: Experimental constraints on tidal dissipation in silicate cores of icy satellites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-762, https://doi.org/10.5194/egusphere-egu24-762, 2024.

EGU24-1905 | ECS | Orals | PS2.3

Convective storms and methane clouds on Uranus & Neptune: sporadicity and latitudinal variations revealed by a 3D cloud-resolving model 

Noe Clement, Jeremy Leconte, Aymeric Spiga, Sandrine Guerlet, Gwenael Milcareck, Arthur Le Saux, and Franck Selsis

Uranus and Neptune have atmospheres dominated by molecular hydrogen and helium. In the upper troposphere (between 0.1 and 10 bars), methane is the third main molecule and condenses, yielding a vertical gradient in methane. Because it is heavier than the H2/He background, methane condensation can inhibit convection and moist convective storms. Previous studies derived an analytical criterion on the methane vapor amount, above which moist convection is inhibited. In ice giants, this criterion yields a critical methane abundance of 1.2% at 80K (this corresponds approximately to the 1 bar level).

Using a 3D cloud-resolving model, we have shown (Clement et al. 2024, submitted in A&A) that this critical methane abundance governs storms inhibition and formation, concluding that the intermittency and intensity of storms depends on the methane abundance. Where methane exceeds this critical abundance in the deep atmosphere (at the equator and the middle latitudes on Uranus, and all latitudes on Neptune), frequent but weak storms form. Where methane remains below this critical abundance in the deep atmosphere (possibly at the poles on Uranus), storms are rarer but more powerful.

We use the insights of our 3D small-scale simulations to build a 1D parameterization of diffusion and convection for radiative-convective and global climate models. As 3D cloud-resolving simulations require long computation times, a radiative-convective model is needed to extrapolate heating tendencies. The combined use of these models should enable us to estimate more realistic periods between convective storms and explain the observed latitudinal sporadicity of methane clouds over a long period of time.

How to cite: Clement, N., Leconte, J., Spiga, A., Guerlet, S., Milcareck, G., Le Saux, A., and Selsis, F.: Convective storms and methane clouds on Uranus & Neptune: sporadicity and latitudinal variations revealed by a 3D cloud-resolving model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1905, https://doi.org/10.5194/egusphere-egu24-1905, 2024.

EGU24-3184 | Orals | PS2.3

Re-analysis of Uranus Data from Voyager 2 Plasma Science Experiment 

Georgios Xystouris, Fran Bagenal, and Robert Wilson

Both Voyager 1 and 2 are equipped with Plasma Science (PLS) instruments: four Faraday cups that measure the properties (density, temperature and flow) of low energy ions and electrons. During the Voyagers journey towards the interstellar space and the flybys from the gas giants PLS gave us the first in-situ data of the solar wind in such great distances, the magnetospheric plasma properties at the gas giants, and the extent of our heliosphere along with the conditions of the interstellar medium.

Voyager was particularly important for the study of the gas giants, as it was the first time we had in-situ plasma measurements from inside the magnetospheres, and PLS helped in studying not only the morphology of the magnetosphere, but also the plasma sources, dynamics, interaction with the moons, and ultimately its interaction with the solar wind plasma.

Jupiter and Saturn were visited from both Voyager 1 and 2, but only Voyager 2 visited Uranus and Neptune. The PLS data for Jupiter have been re-calibrated and archived by Bagenal+ [2017], Dougherty+ [2017], and Bodisch+ [2017]. They also developed an IDL package, VIPER (Voyager Ion PLS Experiment Response) for their analysis. For this work we re-analyzing the Voyager PLS data for Uranus and in this poster we present our methodology, the adaptation of VIPER for the Uranian conditions and the results of the re-analysis.

How to cite: Xystouris, G., Bagenal, F., and Wilson, R.: Re-analysis of Uranus Data from Voyager 2 Plasma Science Experiment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3184, https://doi.org/10.5194/egusphere-egu24-3184, 2024.

EGU24-5294 | Orals | PS2.3

Galactic cosmic ray cutoff rigidity and solar cycle variation at Neptune 

Martin Bødker Enghoff, Paul N. Romani, John E.P. Connerney, and John L. Jørgensen

Albedo changes of Neptune related to the 11-year solar cycle have been reported since the 1970s (Lockwood and Thompson, Nature 280, 1979). For nearly two decades a clear anti-correlation between solar activity and Neptune’s brightness was observed but the relationship appeared to break down between the late 1980s (Lockwood and Thompson, Nature 349, 1991) and mid 1990s (Lockwood and Jerzykieicz, Icarus 180(2), 2006) where signs of a direct correlation instead appeared. Recent results indicate a direct correlation sustained over two solar cycles (Chavez et al, Icarus 404, 2023) prompting renewed interest in attempting an explanation.

Several parameters vary with the solar cycle, one being UV light which has a much higher variation than that of visible light. This could affect the photochemistry of Neptune’s atmosphere which is rich in methane that photolyzes at wavelengths below 200 nm and can produce haze (Romani and Atreya, Icarus 74(3), 1988). Another parameter that varies is the flux of galactic cosmic rays (GCRs) which is modulated by the solar wind. GCRs can ionize molecules leading to ion-induced nucleation (Moses et al, GRL 16(12), 1989) but only for the energies of particles which are allowed entry to the planetary atmosphere by the magnetic field. Solar activity modulates GCRs of energies up to about 20 GeV so a solar variation due to GCRs is only possible if particles of those energies can enter the atmosphere. The parameter used to describe GCR entry is the cutoff rigidity (in GV).

In this work we have used the magnetic field model of Neptune (Connerney et al, ASR 12(8), 1992) and a particle trajectory program (the Geomagnetic Cutoff Rigidity Computer Program by Smart and Shea, 2001, Tech. Rep. No. 20010071975) to calculate a cutoff rigidity map for Neptune for vertical GCR entry. Since the magnetic field is very tilted compared to the rotational axis (by about 45 degrees) the cutoff rigidity map has interesting features as the GCRs are guided by the magnetic field lines. Thus, lower energies and therefore a higher GCR flux more susceptible to solar cycle changes are allowed to enter the atmosphere at mid latitudes, as opposed to most planets where this happens as the poles since their magnetic field is more closely aligned with the rotational axis.

Furthermore, we have used fitted GCR energy spectra in combination with the cutoff rigidity map to produce a map of solar cycle variations in GCR flux at a height of 49 km, which is at the pressure level where cosmic ray showers are initiated at Earth and also close to where Neptunian clouds are found. Where the cutoff rigidity is lowest the solar cycle variations of GCR are several tens of percents which could affect cloud formation significantly.

How to cite: Enghoff, M. B., Romani, P. N., Connerney, J. E. P., and Jørgensen, J. L.: Galactic cosmic ray cutoff rigidity and solar cycle variation at Neptune, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5294, https://doi.org/10.5194/egusphere-egu24-5294, 2024.

EGU24-9646 | ECS | Orals | PS2.3

Zonal Winds of Uranus: Analysis, Modelling and Prospects 

Deniz Soyuer, Ravit Helled, Benno Neuenschwander, and Luca Morf

Uranus is observed to have fast surface zonal winds with speeds reaching up to 200 ms−1 relative to its assumed bulk rotation. The exact decay behaviour of the winds is uncertain, but there is indirect evidence that they must decay rapidly in relatively shallow layers of Uranus. By analysing thousands of Uranus interior structure models our study investigates the Uranian zonal wind decay via past zonal gravitational harmonics measurements, as well as understanding our limitations of future zonal wind constraints with a prospective Uranus mission (as proposed by NASA’s Planetary Science and Astrobiology Decadal Survey 2023-2032). In addition, we explore the effect of zonal wind decay on planetary shapes, the relationship of zonal wind decay and planetary bulk rotation, and the effect of alternative surface zonal wind profile fits to surface wind measurements on aforementioned phenomena.

How to cite: Soyuer, D., Helled, R., Neuenschwander, B., and Morf, L.: Zonal Winds of Uranus: Analysis, Modelling and Prospects, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9646, https://doi.org/10.5194/egusphere-egu24-9646, 2024.

The international consortium GEPP has been set to conceptualize probe designs with appropriate payloads that would remain within the typical budget allocated for ESA M-class missions (currently 500 M€). The aims of the consortium are i) to conceptualize a line of generic planetary entry probes that could be targeted to the giant planets with very few modifications, ii) to make the international science community, ESA and its member states, conscious that there is an opportunity to supply a series of entry probes as part of future international collaborations, for example as part of the future NASA flagship mission towards Uranus (Uranus Orbiter Probe) or to any future NASA-led mission to the outer planets for an affordable budget, and iii) to demonstrate that an M-class budget could even fund several entry probes with well-prioritized science objectives. The model payload capabilities of each concept will be defined according to a carefully-designed science traceability matrix. Two extreme concepts shall be investigated by the GEPP Consortium, namely a highly capable parachute-descent probe including a typical payload of 30 kg of scientific instruments down to 10 bars, and a smaller parachute-descent probe designed to address top priority science objectives with selected key measurements that would address the ESA Cosmic Vision 2050 science objectives. This presentation will detail the scientific objectives for each entry probe design, as well as the content, organization and planning of the study, which is assumed to be completed by the end of 2025.

How to cite: Mousis, O. and the GEPP team: Generic Entry Probe Program (GEPP) – an international initiative promoting the development of European descent modules dedicated to the in situ exploration of giant planets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13379, https://doi.org/10.5194/egusphere-egu24-13379, 2024.

EGU24-16799 | Orals | PS2.3

Aerosol layers, clouds, spots and the colours of Uranus and Neptune 

Patrick Irwin, Jack Dobinson, Nicholas Teanby, Leigh Fletcher, Michael Roman, Amy Simon, Michael Wong, Glenn Orton, Daniel Toledo, and Santiago Perez-Hoyos

In the last twenty years, spectroscopic imaging observations of Uranus and Neptune, the solar system’s ‘Ice Giants’, have revolutionised our understanding of the atmospheres of these cold, distant worlds. In spectroscopic imaging observations, each pixel in the resolved image of the planet contains a continuous spectrum, which can be used to probe gaseous abundances as well as the precise vertical distribution of scattering particles, which is something that filter imaging alone cannot achieve. For example, observations made near 800 nm with the STIS instrument on Hubble Space Telescope have determined that the abundance of methane varies strongly with latitude in these atmospheres, with roughly a factor of two depletion at polar latitudes compared to the equator. At longer wavelengths (~1.5 μm), observations made with the NIFS instrument at Gemini-North have revealed not only the presence of hydrogen sulphide, but also hints of its latitudinal variation.

In this presentation we will highlight recent advances made with spectral imaging observations, using HST/STIS and also the MUSE instrument at the ESO Very large Telescope. On both planets the weight of evidence supports an atmospheric aerosol structure comprised of: 1) a deep layer of aerosol/H2S ice near the H2S condensation level at p > 5 bar;  2) a middle layer of aerosol/CH4-ice near the CH4 condensation level at p = 1 – 2 bar; and 3) an upper layer of photochemical haze. Variation in opacity and scattering properties of the middle aerosol layer near 1 – 2 bar are found to be responsible for the bulk difference in colour between Uranus and Neptune, and also for the seasonal cycle of Uranus’s colour. Meanwhile, variations in the reflectivity of the particles in the deep layer are found to be responsible for the dark spots seen in Neptune’s (and occasionally Uranus’s) atmosphere and in Neptune’s dark South Polar Wave near 60°S. In addition, a new class of deep bright cloud has been identified in Neptune’s atmosphere using VLT/MUSE, which hints at deep, vigorous convection.

While it is important that HST/STIS and VLT/MUSE monitoring observations will continue, the James Webb Space Telescope has recently observed both Uranus and Neptune using the NIRSpec instrument in Integral Field Unit (IFU) mode (i.e., spectroscopic imaging) at even longer wavelengths from 1.6 to 5.2 μm. These observations will advance even further our understanding of these distant worlds, although we note that extending such observations to NIRSpec’s shorter wavelengths would allow JWST to also recover the latitudinal variation of hydrogen sulphide, a key tracer of deep convection.

How to cite: Irwin, P., Dobinson, J., Teanby, N., Fletcher, L., Roman, M., Simon, A., Wong, M., Orton, G., Toledo, D., and Perez-Hoyos, S.: Aerosol layers, clouds, spots and the colours of Uranus and Neptune, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16799, https://doi.org/10.5194/egusphere-egu24-16799, 2024.

EGU24-18135 | Posters on site | PS2.3

Vortices in the magnetic tail of Uranus 

Filippo Pantellini and Léa Griton

Over the last twenty years, a still very limited number of extended numerical simulations of the Uranus magnetosphere, showed that large scale magnetic vortices form tailwards of the planet. Their structure is strongly time-dependent on daily and seasonal time scales, both,   because of both, the unusually large 59 deg angle between the magnetic axis and the rotation axis of the planet and the small angle (unique in the solar system) between the rotation axis and the orbital plane. Based on results from 3D magnetohydrodynamic simulations, we comment on the nature and the structure of the vortices at both solstice and equinox. 

How to cite: Pantellini, F. and Griton, L.: Vortices in the magnetic tail of Uranus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18135, https://doi.org/10.5194/egusphere-egu24-18135, 2024.

EGU24-18317 | ECS | Orals | PS2.3

Investigating Atmospheric Dynamics of Uranus and Neptune: A General Circulation Model Approach with a Parametrization of Convection 

Arthur Le Saux, Sandrine Guerlet, Aymeric Spiga, Jeremy Leconte, Noe Clement, and Gwenael Milcareck

Understanding the atmospheric dynamics of Uranus and Neptune remains a challenging endeavour due to the limited observational data available. In this study, we employ a sophisticated General Circulation Model (GCM), known as the Generic Planetary Circulation Model, to investigate the complex meteorological phenomena of the Ice Giants, with a focus on the role of convection in the troposphere Our attention is directed towards the parametrization of convection, a crucial driver of atmospheric circulation, as it significantly impacts the transport of energy and the distribution of chemical species throughout the atmosphere. One of the unique aspects of our study lies in the consideration of methane condensation in the convection parametrization scheme based on a thermal plume model initially developed for the Earth atmospheric boundary layer (Rio & Hourdin 2008). However, unlike for the Earth, the condensable species are heavier than the surrounding atmosphere mainly composed of hydrogen. This phenomenon is suggested to be a powerful driver of intermittent storms activity detected in the atmospheres of the Ice Giants (Guillot 2022). The improved fidelity of our GCM simulations offers valuable implications for interpreting observational data and refining our understanding of the atmospheric processes governing these enigmatic outer planets.

How to cite: Le Saux, A., Guerlet, S., Spiga, A., Leconte, J., Clement, N., and Milcareck, G.: Investigating Atmospheric Dynamics of Uranus and Neptune: A General Circulation Model Approach with a Parametrization of Convection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18317, https://doi.org/10.5194/egusphere-egu24-18317, 2024.

EGU24-20711 | Orals | PS2.3

The potential for neutral tori at Uranus and Neptune 

howard smith

Neutral Tori are generally a result of particles escaping from a planetary atmosphere, its rings or satellites through internal source mechanisms or interactions with the magnetosphere. These particles then form a population of co-orbiting neutral particles that provide a source of plasma to the magnetosphere as well as drive dynamics and chemistry. Thus, understanding neutral tori provides key (sometimes unique) insight into planetary magnetospheres, moon source characterization and understanding, and ultimately can provide insight to past, present and future of magnetospheres. Current increased neutral torus research had provided significant insight into Saturn and Jupiter’s magnetosphere and gas giants in general. These results indicated great potential for improving our understanding the magnetospheres of Uranus and Neptune whose orientations offer the possibility of magnetospheric configurations not previously observed. Here, we will discuss how the Gas Giant neutral torus state of understanding has signifcaintly increased and may provide an analogy for what we may expect from studying these features on Ice Giants. We also present some preliminary modeling to speculate on the possible presence of neutral tori at Uranus and Neptune.

How to cite: smith, H.: The potential for neutral tori at Uranus and Neptune, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20711, https://doi.org/10.5194/egusphere-egu24-20711, 2024.

EGU24-1243 | Posters on site | PS2.4

Ion cyclotron waves at Io: Pick-up rate and outgassing 

Martin Volwerk, Fran Bagenal, Vincent Dols, Margaret Kivelson, Krishan Khurana, Helmut Lammer, Daniel Schmid, Cyril Simon Wedlund, and XianZhe Jia

With its extended mission, JUNO is getting close to Io and performs moon flybys. It is therefore time to (re)analyse the already available magnetometer data from close flybys of Io by Galileo. Earlier studies of the J0 flyby showed the presence of ion cyclotron waves generated by the pick-up of SO2+ and determined the density of the picked-up ions. In this presentation we study all five Io flybys by Galileo and investigate the presence of ion cyclotron waves for three different species. SO2+, SO+ and S+. Through Fourier analysis and calculation of the cross-spectral matrix and strong criteria on power, polarization and ellipticity, we determine intervals of significant wave activity. Under the assumption of bi-spherical scattering of the pick-up ions in the velocity ring-distribution, an estimation of the pick-up ion density can be obtained. Through an assumption of the ionization frequency, this can be converted into a neutral density to obtain a value of the total neutral gas emitted per second and compare it to the usually assumed 1000 kg/s. Naturally, the five flybys will also give information about differences generated by local time, longitude and latitude.

How to cite: Volwerk, M., Bagenal, F., Dols, V., Kivelson, M., Khurana, K., Lammer, H., Schmid, D., Simon Wedlund, C., and Jia, X.: Ion cyclotron waves at Io: Pick-up rate and outgassing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1243, https://doi.org/10.5194/egusphere-egu24-1243, 2024.

EGU24-2578 | Orals | PS2.4

Modeling of Saturn’s radiation environment 

Alexander Drozdov, Peter Kollmann, Yixin Hao, and Dedong Wang

A common problem in space physics is how the energetic particles we observe in space are accelerated to high energies. In the magnetospheres and radiation belts of magnetized planets like the Earth and Saturn, we find electrons with up to MeV energies. There are two fundamental acceleration processes. Electrons can gain energy when they are transported closer to the planet (radial acceleration), where the magnetic field is stronger. The alternative is that the electrons are accelerated locally, through fluctuating electric or magnetic fields and wave-particle interaction. In this work, we use a modified version of the Versatile Electron Radiation Belts code to perform the simulations of the radiation belts at Saturn. Using convection terms of a modified Fokker-Planck equation, the zebra stripes and banana orbit signature is reproduced in the convection-diffusion code. Using the flexibility of our simulation framework, we explore the effects of radial diffusion, coulomb scattering and the local diffusion. Throughout the series of simulations, we aim to understand the role of the controlling processes of the radial transport acceleration (e.g., due to variable electric field) and the role of local acceleration, as well as any other processes needed to reproduce the observations.

How to cite: Drozdov, A., Kollmann, P., Hao, Y., and Wang, D.: Modeling of Saturn’s radiation environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2578, https://doi.org/10.5194/egusphere-egu24-2578, 2024.

EGU24-2951 | Orals | PS2.4

The roles of flux-tube entropy and effective gravity in the inward plasma transport at Saturn 

Simon Wing, Michelle Thomsen, Jay Johnson, Xuanye Ma, Donald Mitchell, Robert Allen, and Peter Delamere

The inward plasma transport at Saturnian magnetosphere is examined using the flux tube interchange stability formalism developed by Southwood and Kivelson (1987).  Seven events are selected.  Three cases are considered: (1) the injected flux-tube and ambient plasmas are nonisotropic; (2) the injected flux-tube and ambient plasmas are isotropic and (3) the injected flux-tube plasma is isotropic but the ambient plasma is nonisotropic.  Case (1) may be relevant for fresh injections while case (3) may be relevant for old injections.  For cases (1) and (2), all but one events have negative stability condition, suggesting that the flux-tube should be moving inward.  For case (3), the injections located at L > 11 have negative stability condition, while 4 out of 5 of the injections at L < 9 have positive stability condition.  The positive stability condition for small L suggests that the injection may be near its equilibrium position and possibly oscillating thereabouts---hence the outward transport if the flux tube overshot the equilibrium position.  The flux-tube entropy plays an important role in braking the plasma inward transport.  When the stability condition is positive, it is because the entropy term, which is positive, counters and dominates the effective gravity term, which is negative for all the events.  The ambient plasma and drift out from adjacent injections can affect the stability and the inward motion of the injected flux tube. The results have implications to inward plasma transport in Jovian magnetosphere as well as other fast rotating planetary magnetospheres.

How to cite: Wing, S., Thomsen, M., Johnson, J., Ma, X., Mitchell, D., Allen, R., and Delamere, P.: The roles of flux-tube entropy and effective gravity in the inward plasma transport at Saturn, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2951, https://doi.org/10.5194/egusphere-egu24-2951, 2024.

EGU24-3227 | Posters on site | PS2.4

Periodic narrowband radio wave emissions and inward plasma transport at Saturnian 

Xuanye Ma, Simon Wing, Pontus Brandt, Jay Johnson, Donald Mitchell, William Kurth, John Menietti, and Peter Delamere

The abrupt brightening of an Energetic Neutral Atom (ENA) blob or cloud has been interpreted as plasma injection in the Saturnian magnetosphere (termed ENA injection herein). Morphologically, there appears to be two types of abrupt ENA cloud brightening: (1) the brightening of a large cloud usually seen at distances > 10-12 Rs (Rs = 60,268 km) in the midnight or postmidnight region; (2) the brightening of a smaller cloud usually seen at distances < 10-12 Rs around 21-03 magnetic local time (MLT). Among many radio waves observed at Saturn, type 2 ENA injections correlate best with the 5 kHz narrowband waves. Using Cassini INCA and RPWS data, we examine the periodicities of the type 2 ENA injections and the 5 kHz narrowband emissions as well as their cross-correlations, which have been previously used to measure the lag times or phase differences. Because correlational analysis can only establish linear relationships, we also use mutual information to establish linear and nonlinear relationships. On average, the peak of the 5 kHz narrowband emission lags those of the type 2 ENA injection by about a few minutes to 2 hr. The injection of hot plasma into the inner magnetosphere can lead to temperature anisotropy, which can generate electrostatic upper hybrid waves, which upon encountering the high density gradient at the outer edge of the Enceladus density torus, can mode convert to the Z mode and then to O mode. The 5 kHz narrowband waves commonly propagate in the O mode.

How to cite: Ma, X., Wing, S., Brandt, P., Johnson, J., Mitchell, D., Kurth, W., Menietti, J., and Delamere, P.: Periodic narrowband radio wave emissions and inward plasma transport at Saturnian, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3227, https://doi.org/10.5194/egusphere-egu24-3227, 2024.

EGU24-3269 | Orals | PS2.4 | Highlight

New Extended Mission Results from Juno’s Stellar Reference Unit  

Heidi N Becker, Meghan Florence, Martin Brennan, Jonathan Lunine, Paul Schenk, Candice Hansen, Yasmina Martos, Scott Bolton, and James Alexander

Juno’s Extended Mission has expanded the scientific reach of Juno’s low-light Stellar Reference Unit (SRU) star camera to multiple new targets within the Jovian system. Close flybys of the dark sides of Ganymede and Europa (illuminated by Jupiter-shine) have yielded high-resolution SRU surface images that enabled significant improvements to the geomorphologic maps of these icy moons and revealed sites of potential present day surface activity on Europa (providing high quality baselines for Europa Clipper and JUICE). Close flybys of Jupiter’s dark side began in Spring 2023, launching the SRU’s Extended Mission study of lightning in the northern latitudes at resolutions as high as a few kilometers per pixel, and the geometry has also allowed the SRU to image Jupiter’s faint dust ring from vantage points inside the ring. The Mission’s planned flybys of Io in December 2023 and February 2024 will present additional opportunities for low-light high-resolution SRU surface imaging on the dark side of the volcanic moon. Our presentation will discuss new Extended Mission results from Juno’s SRU. 

How to cite: Becker, H. N., Florence, M., Brennan, M., Lunine, J., Schenk, P., Hansen, C., Martos, Y., Bolton, S., and Alexander, J.: New Extended Mission Results from Juno’s Stellar Reference Unit , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3269, https://doi.org/10.5194/egusphere-egu24-3269, 2024.

EGU24-4667 | Orals | PS2.4 | Highlight

Rapidly time-varying zonal flow in Jupiter's deep interior 

Jeremy Bloxham, Hao Cao, David Stevenson, John Connerney, and Scott Bolton

Recently, it has been shown that the secular variation of Jupiter's magnetic field, which has been observed by the Juno spacecraft, is in large part due to eastward advection of the Great Blue Spot (a localized, equatorial region of intense magnetic field) by fluid flow in the deep interior. More recent observations  by Juno suggest that the drift rate of the spot is varying rapidly in time. These time variations can be fit with a sinusoidal variation of the flow speed with a period of approximately four years.  Here, we discuss both the mechanism of this time variability and the constraints that its observability place on the structure and dynamics of the deep interior.

How to cite: Bloxham, J., Cao, H., Stevenson, D., Connerney, J., and Bolton, S.: Rapidly time-varying zonal flow in Jupiter's deep interior, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4667, https://doi.org/10.5194/egusphere-egu24-4667, 2024.

EGU24-5889 | ECS | Posters virtual | PS2.4

Delivery of organic matter to the Galilean moons 

Tom Benest Couzinou, Alizée Amsler Moulanier, and Olivier Mousis

The presence of carbonaceous matter is envisaged on the surface of many outer solar system bodies, including the Galilean moons. Density and moments of inertia of icy moons and dwarf planets also suggest the presence of this material in their refractory cores. The initial carbonaceous matter would have been composed of complex organic molecules (COMs) that possibly formed when the building blocks of the moons were in the forms of pebbles and icy grains in the protosolar nebula. Experimental studies indeed show that COMs can be formed from the UV irradiation of icy grains under nebular conditions.

A baseline scenario is the formation of the Galilean moons in a circumplanetary disk that was too cold to vaporize the solids originating from the protosolar nebula. In this scenario, only the thermodynamic conditions of the protosolar nebula play a crucial role in determining the composition of the building blocks of the moons. Here we aim to assess the thermodynamic conditions of the protosolar nebula that enable the formation and the delivery of COMs to the formation location of the Galilean moons in the context of the aforementioned scenario. To do so, we have developed a two-dimensional model that describes the transport of pebbles/dust particles during the evolution of the protosolar nebula, using a Lagrangian scheme. This allows us to calculate the interstellar flux received by the particles as they migrate through the nebula.

How to cite: Benest Couzinou, T., Amsler Moulanier, A., and Mousis, O.: Delivery of organic matter to the Galilean moons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5889, https://doi.org/10.5194/egusphere-egu24-5889, 2024.

EGU24-6024 | Orals | PS2.4

Influence of Ganymede's electron environment as measured by JADE on Ganymede's atmosphere 

Audrey Vorburger, Shahab Fatemi, Shane R. Carberry Mogan, André Galli, Lucas Liuzzo, Andrew R. Poppe, Lorenz Roth, and Peter Wurz

Ganymede’s atmosphere is one of the most complex among the moons of our solar system. As the only known satellite in our solar system to feature an intrinsic global magnetic field, Ganymede forms a small magnetosphere within the much larger magnetosphere of Jupiter. The interaction between the two magnetospheres makes Ganymede's plasma environment highly variable both in space and time. Consequently, the moon's atmosphere, predominantly shaped by the interplay between the plasma environment and Ganymede's surface, likely exhibits a corresponding high degree of variability.

The recent Juno spacecraft flyby of Ganymede has provided us with unprecedented insights into the moon's electron and ion environment. This study capitalizes on electron data collected by the Jovian Auroral Distributions Experiment (JADE) during Juno's traversal of Ganymede's magnetopause current layer, employing these measurements as a proxy for the electron conditions within Ganymede's auroral region. Our simulations reveal that these electrons play a pivotal role in governing Ganymede's H2 and O2 atmospheres, representing the predominant constituents of its atmospheric composition. Furthermore, the abundance of atomic O and H, crucial factors in Ganymede's atmospheric mass loss, is intricately influenced by these electrons, underscoring their significance in shaping the complex dynamics of Ganymede's atmospheric behavior.

Our current understanding of Ganymede's atmosphere predominantly stems from spectroscopic observations. However, it's crucial to acknowledge that the interpretation of spectroscopic data heavily relies on certain assumptions. Our analysis underscores the significance of acquiring a comprehensive understanding of Ganymede's atmosphere. To achieve this, it is imperative to conduct simultaneous observations encompassing the moon's surface, its atmospheric conditions, and the entirety of its plasma environment, including both thermal and energetic ions and electrons. 

How to cite: Vorburger, A., Fatemi, S., Carberry Mogan, S. R., Galli, A., Liuzzo, L., Poppe, A. R., Roth, L., and Wurz, P.: Influence of Ganymede's electron environment as measured by JADE on Ganymede's atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6024, https://doi.org/10.5194/egusphere-egu24-6024, 2024.

EGU24-6119 | ECS | Orals | PS2.4

Exploring the temperature profile of Jupiter's deep atmosphere 

Louis Siebenaler and Yamila Miguel

Our understanding of the giant planets in our solar system has been significantly advanced by the Juno and Cassini missions. These planets provide us with the unique opportunity to understand the interior structure of giant exoplanets. Recent insight into Jupiter’s atmospheric composition indicates a water concentration of 2-7 times solar in the equatorial region, surpassing the subsolar findings of the precursor Galileo mission. In this study, we conduct radiative transfer calculations for Jupiter's deep atmosphere including these enhanced water enrichment results and the presence of condensates predicted by chemical equilibrium models. Our primary focus is to derive a new temperature-pressure profile and assess the existence of potential radiative zones within the deep atmosphere. The presence of a radiative zone can have a profound impact on the internal structure of a planet and thus, a detailed analysis of Jupiter's temperature profile is essential for a comprehensive study of its interior structure.

How to cite: Siebenaler, L. and Miguel, Y.: Exploring the temperature profile of Jupiter's deep atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6119, https://doi.org/10.5194/egusphere-egu24-6119, 2024.

EGU24-6708 | Posters on site | PS2.4 | Highlight

Multi-wavelength Observations of Jupiter’s Northern Circumpolar Cyclones 

Scott Bolton, Shawn Brueshaber, Glenn Orton, Candy Hansen, Steve Levin, Alessandro Mura, Davide Grassi, Leigh Fletcher, John Rogers, Gerald Eichstädt, Mike Wong, Andy Ingersoll, Anton Ermakov, and Cheng Li

Juno arrived at Jupiter in 2016 and was inserted into a polar orbit with its closest approach (“perijove”) near Jupiter’s equator.  One of Juno’s first major discoveries was the existence of circumpolar cyclones covering both of Jupiter’s poles. Over the course of Juno’s prime and extended missions, the line of apsides of the orbit has experienced a constant northward migration due to Jupiter’s asymmetric gravity field. One result of this migration is the lowering the spacecraft’s altitude over Jupiter’s north pole.  Recently, the altitude over the north pole has reduced sufficiently to allow Juno’s microwave radiometer (MWR) to resolve Jupiter’s circumpolar cyclones.  The observations provide new insights into how the circumpolar cyclones evolve with depth.  We will present results from multi-wavelength observations of Jupiter’s polar cyclones including visible light images (JunoCam), the infrared images (JIRAM) and microwave images (MWR).  The combined data set reveals information on how the circumpolar cyclones compare and evolve with depth. 

How to cite: Bolton, S., Brueshaber, S., Orton, G., Hansen, C., Levin, S., Mura, A., Grassi, D., Fletcher, L., Rogers, J., Eichstädt, G., Wong, M., Ingersoll, A., Ermakov, A., and Li, C.: Multi-wavelength Observations of Jupiter’s Northern Circumpolar Cyclones, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6708, https://doi.org/10.5194/egusphere-egu24-6708, 2024.

EGU24-6795 | Posters on site | PS2.4

Probing the Depths of Spatial and Temporal Variability in Jupiter from Juno Microwave Radiometer Observations 

Glenn Orton, Zhimeng Zhang, Steven Levin, Leigh Fletcher, Fabiano Oyafuso, Cheng Li, Shawn Brueshaber, Michael H. Wong, Thomas Momary, Scott Bolton, Kevin Baines, Emma Dahl, and James Sinclair

    Juno’s Microwave Radiometer (MWR) is providing the unprecedented opportunity to explore the dynamical properties and composition of Jupiter’s deep atmosphere, which is arguably one of the most visibly heterogeneous and time variable in the solar system. Since its arrival on 27 August 2016, the MWR has observed variability in microwave emission at wavelengths between 1.3 and 50 cm, sensing from 0.7 bar to over 100 bars of atmospheric pressure at over 57 close approaches to the atmosphere, known as “perijoves”. There has been a concerted effort to collect contextual information from other Juno instruments, as well as ground- and space-based observations to help interpret the MWR results. The space-based observations have included those from Juno’s own visible camera (JunoCam) and its Jupiter Infrared Auroral Mapper (JIRAM), as well as the Hubble Space Telescope (HST). The ground-based observations have included images and spectra from both professional and citizen-science astronomers.

     We report here observations that are constrained to spatial resolutions of 2 degrees in latitude or better, and have been subject to recent improvements in the calibration drift for all MWR’s channels with an improved relative calibration uncertainty of 0.5% or better over the entire mission.  This has allowed us to evaluate zonal-mean temperatures and variability with improved confidence that these are real and not an artifact of receiver drift. The region that by far shows the greatest variability from a zonal mean is the North Equatorial Belt, (NEB: 12oN-16oN planetocentric) with a 2% standard deviation from the mean at all levels sensed by the MWR except for the 50-cm channel that senses variability in temperature and ammonia and water composition at pressures in excess of 100 bars of pressure. Among the strongest variability associated with discrete features in the atmosphere is a major upwelling and subsequent clearing of cloud cover in the North Temperate Belt (NTB: 20oN-26oN) in August-September of 2020.  In general, the microwave antenna temperature variability often but not always correlates with visible or near- to mid-infrared variability. In some regions, such as the Equatorial Zone (EZ: 3oS-6oN), substantial variability is detected not only in regions above the level of the water-condensate cloud (~10 bars) but also at great depth (>100 bars). An important part of our next steps will be to examine where variabilities in the zonal-mean microwave brightness are the result of zonally discrete features in the atmosphere, particularly the NEB.

How to cite: Orton, G., Zhang, Z., Levin, S., Fletcher, L., Oyafuso, F., Li, C., Brueshaber, S., Wong, M. H., Momary, T., Bolton, S., Baines, K., Dahl, E., and Sinclair, J.: Probing the Depths of Spatial and Temporal Variability in Jupiter from Juno Microwave Radiometer Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6795, https://doi.org/10.5194/egusphere-egu24-6795, 2024.

EGU24-6820 | ECS | Orals | PS2.4 | Highlight

Juno Microwave Radiometer Observations into the Subsurface of the Ice Shells of Io, Europa and Ganymede 

Anton Ermakov, Scott Bolton, Zhimeng Zhang, Steven Levin, Ryunosuke Akiba, Jonathan Lunine, Jianqing Feng, Kevin Hand, James Keane, Sidharth Misra, Paul Hartogh, David Stevenson, Matt Siegler, and Lea Bonnefoy

On June 7, 2021, and September 29, 2022, the NASA Juno spacecraft flew by Jupiter’s Galilean moons, Ganymede, and Europa, respectively.  The closest approach distance was only ~1000 km above Ganymede, and only ~350 km above Europa. More recently, on December 30, 2023, Juno passed by Io at a distance of 1500 km and is planned do so a second Io flyby on February 3, 2024 at a similar distance.  The close flybys were the first encounters with the moons in over two decades and provided the first opportunity to map the subsurface of the their shells at multiple microwave frequencies using Juno’s Microwave Radiometer (MWR).  The observations provided several swaths across the moons at six frequencies, ranging from 600 MHz to 22 GHz.  The ice transparency at microwave frequencies is dependent on its purity; assuming pure ice, the observations probe depths ranging from meters to kilometers. The MWR observations represent the first resolved interrogation of Ganymede and Europa’s subsurface ice shell revealing new constraints on porosity, fracturing, differences in terrain type and possibly the thickness of the ice shell. These unprecedented measurements of Io, Europa and Ganymede will allow comparative studies of the surfaces and subsurface structures of the Jovian satellites. The Juno MWR measurements complement previous ground-based radar and microwave radiometry observations, which provided early characterization of these surfaces.  A comparison of the microwave spectra for all three satellites will be presented, as well as a detailed analysis and interpretation of the Ganymede MWR data that provide new constraints on ice subsurface properties.

How to cite: Ermakov, A., Bolton, S., Zhang, Z., Levin, S., Akiba, R., Lunine, J., Feng, J., Hand, K., Keane, J., Misra, S., Hartogh, P., Stevenson, D., Siegler, M., and Bonnefoy, L.: Juno Microwave Radiometer Observations into the Subsurface of the Ice Shells of Io, Europa and Ganymede, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6820, https://doi.org/10.5194/egusphere-egu24-6820, 2024.

EGU24-6867 | Posters virtual | PS2.4

Io Torus Electron Densities inward of Io's M-shell 

William Kurth, George Hospodarsky, Jeremy Faden, John Douglas Menietti, Ali Sulaiman, Sadie Elliott, John E.P. Connerney, Frederic Allegrini, and Scott Bolton

Various characteristic frequencies observed in the plasma wave spectrum inward of Io have revealed a durable electron density profile that includes a localized relative maximum near M = 4.8 with a local minimum between this and the much greater densities closer to Io.  Scale heights relative to the centrifugal equator are of order one Jovian radius, thought to be too large for a cold heavy ion population leading to the conclusion that protons are likely responsible for the large scale height.  In this paper we show evidence of the low-frequency cutoff of the z-mode at the L=0 frequency, a polarization change at the local electron plasma frequency and low-frequency cutoff of ordinary mode waves.  The determination of the electron plasma frequency and electron cyclotron frequency from the measured magnetic field strength also allow the calculation of the upper hybrid resonance frequency and R=0 cutoff of the extraordinary mode.  Often, all of these spectral features can be found in the Juno plasma wave spectra obtained in the inner Io torus.

How to cite: Kurth, W., Hospodarsky, G., Faden, J., Menietti, J. D., Sulaiman, A., Elliott, S., Connerney, J. E. P., Allegrini, F., and Bolton, S.: Io Torus Electron Densities inward of Io's M-shell, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6867, https://doi.org/10.5194/egusphere-egu24-6867, 2024.

EGU24-7242 | Posters on site | PS2.4

The structure of Jupiter and Saturn's winds below the cloud level - insights from high harmonics gravity measurements 

Eli Galanti, Yohai Kaspi, Daniele Durante, and Luciano Iess

Strong and persistent zonal winds at the cloud level characterize both Jupiter and Saturn. Based on  Juno and Cassini's measurements of the low-order gravity harmonics up to J10,  it was shown that the observed cloud-level winds penetrate inward parallel to the planet's spin axis and decay at a depth of around 3,000 km and 9,000 km, respectively. However, because of the limited number of measured gravity harmonics, the latitudinal structure of the flows could not be uniquely determined, so only an overall estimate of their depth was obtained.

Here, we present new gravity analyses for both gas giants, based on the original Juno and Cassini measurements,  but in which the magnitude of harmonics higher than J10 is constrained at the less observable high latitudes. This enables resolving the gravity field up to J40 for Jupiter and J20 for Saturn, while being consistent with the previous gravity measurements.  We then use the high harmonics to better constrain the structure of the zonal flows below the observed cloud level, revealing the latitudinal variations in the depth of the flows. We show that for Saturn, the mid-to-high latitude jets must be shallower than the low-latitude winds, while in Jupiter, the low-latitude winds dominate the gravity signal. In the talk, we will review the similarities and differences between the two gas giants arising from our results and discuss their implications for our understanding of gas giant dynamics.

How to cite: Galanti, E., Kaspi, Y., Durante, D., and Iess, L.: The structure of Jupiter and Saturn's winds below the cloud level - insights from high harmonics gravity measurements, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7242, https://doi.org/10.5194/egusphere-egu24-7242, 2024.

The magnetospheres of gas giants are characterised by their strong magnetic fields, the fast rotation of the planet and the presence of embedded active moons (Io at Jupiter, Enceladus at Saturn), releasing neutral gas and, from there, plasma in the innermost regions of the systems. Their dynamics is believed to be controlled by a balance between the centrifugal force acting on cororating plasmas trapped in the planetary magnetic field, plasma pressure gradients and magnetic forces. This balance determines the rate of outward transport of mass, angular momentum and energy and has a strong influence on the global configuration and dynamics of the magnetospheres. It results in the formation of a magnetodisk of plasma at the planetary equator, and a global outward transport of plasma from the innermost source regions to the outer magnetosphere where it is lost through magnetospheric boundaries or downtail. 
    Until now, description of this transport has followed two different approaches in the literature. “Corotation enforcement” models focus on the description of angular momentum transport in a disk exchanging momentum with the planetary thermosphere/ionosphere via electric current systems transferring magnetic torques. They assume mass and conservation but do not explicitly describe the transport processes through the magnetodisk. On the contrary, radial diffusion models do not explicitly take into account angular momentum transport nor exchanges between the planet and the magnetospheric plasma, but they describe radial transport of mass and energy assuming a certain state of turbulence in the magnetodisk.
    We present a unifying approach of the radial transport of mass, angular momentum and energy, using turbulent diffusion and including sources and sinks of plasma of arbitrary radial distribution throughout the disk. Our set of coupled equations independently describes momentum exchange with the two conjugate ionospheres, thus allowing for the study of interhemispheric asymmetries, such as the ones revealed by Juno, in this coupling. We will present solutions of our coupled set of transport equations that explore the different possible causes and effects of interhemispheric asymmetries in magnetodisk/planet coupling, with emphasis on the cases of latitudinally thin and thick disks corresponding respectively to the cases of Jupiter and Saturn. We will compare the outputs of our models with recent observational constraints brought by the Juno and Cassini missions.

How to cite: Devinat, M., André, N., and Blanc, M.: A self-consistent model of radial transport in the magnetodisks of gas giants including interhemispheric asymmetries, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8604, https://doi.org/10.5194/egusphere-egu24-8604, 2024.

EGU24-8605 | ECS | Posters on site | PS2.4

What determines the strength and latitudinal extent of the equatorial zonal flows on Jupiter and Saturn?  

Keren Duer, Eli Galanti, and Yohai Kaspi

Jupiter's equatorial zonal flows reach wind velocities of ∼ 100 m/s, while on Saturn they are three times as strong and extend about twice as wide in latitude, despite the two planets being overall dynamically similar. Recent gravity measurements obtained by the Juno and Cassini spacecraft uncover that the depth of zonal jets on Saturn is about three times greater than on Jupiter. Here we reveal, using high-resolution 3D simulations, that the atmospheric depth is the determining factor controlling both the strength and latitudinal extent of the equatorial zonal flows, consistent with the measurements for both planets. We show that the atmospheric depth is proportional to the convectively-driven eddy momentum flux, which controls the strength of the zonal flows. These insights provide a comprehensive explanation for the observed differences in the equatorial regions of Jupiter and Saturn and offer new understandings into the dynamics of gas giants.

How to cite: Duer, K., Galanti, E., and Kaspi, Y.: What determines the strength and latitudinal extent of the equatorial zonal flows on Jupiter and Saturn? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8605, https://doi.org/10.5194/egusphere-egu24-8605, 2024.

The polar cyclones on Jupiter have been observed regularly since their discovery by the Juno mission in 2016. While the symmetrically spaced 9 and 6 cyclones at Jupiter's north and south pole (respectively) have largely maintained their locations, 5 years of Juno's observations showed oscillatory perturbations in their positions. In addition, an overall westward drift was measured for the cyclones at both poles. In this study, a mechanism for these motions is presented. This mechanism is driven by the known "beta-drift" effect, a poleward-westward acceleration experienced by cyclones under beta (the meridional gradient in planetary vertical vorticity). When considering the relative vorticity of other cyclones, in addition to beta, to evaluate beta-drift on each cyclone, the polar group of cyclones forms a dynamical system analogous to a system of springs. Using the Juno observations, we show that such a representation agrees well with the data describing the location and acceleration of the cyclones with time. In addition, a toy model, driven by such prescribed beta-drift forces, is able to reproduce motions similar to the observations.
To explain the mean westward motion exhibited by the circumpolar cyclones in the north and south poles (4° and 7. 5° degrees longitude per year, respectively), we propose a center-of-mass approach. Using simulations, we show that the motion of cyclones in a group can be primarily divided into a contribution from beta and a contribution from the interactions between cyclones. When considering the group as a whole, their center of mass is only subject to beta, manifesting in a polar orbit of the group, which precesses westward. This precession is proposed as the mechanism for the westward drift of the individual cyclones. We conclude by showing observational evidence for this interpretation.

How to cite: Gavriel, N. and Kaspi, Y.: Vorticity-gradient forces and a center-of-mass approach explain the mean and oscillatory motion of Jupiter's polar cyclones., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8890, https://doi.org/10.5194/egusphere-egu24-8890, 2024.

EGU24-9497 | ECS | Orals | PS2.4

Morphological Changes in Jupiter’s Northern Circumpolar Cyclones as Revealed by JunoCam and JIRAM.  

Shawn Brueshaber, Glenn Orton, Candice Hansen, Steven Levin, Alessandro Mura, Davide Grassi, Leigh N. Fletcher, John Rogers, Gerald Eichstadt, Michael H. Wong, and Scott Bolton

Juno has observed the circumpolar cyclones (CPCs) on Jupiter with the visible-light camera, JunoCam, and the 2-5 µm infrared JIRAM camera, since orbit insertion.  The CPCs have distinctive cloud features, and unique characteristics that broadly classify into two morphological forms, chaotic and filled.  As revealed by JunoCam, the filled CPCs typically appear with large bright cloud features on the periphery, similar in appearance to a circular saw blade.  Just inward of those, nearly uniform darker regions appear---probably stratiform clouds---occasionally displaying small hole-like openings, which appear bright at 5 μm. The overall appearance of the periphery and just inward is reminiscent of shear-like instability in the flow. Anticyclonic circulation has been witnessed in the center of several filled CPCs. Lightning has also been observed by JunoCam in one of the blade-like cloud features at perijove 31, and we occasionally observe thin, bright curvilinear cloud features and clusters of bright clouds with shadows indicating vertical structure. The chaotic CPCs, including the central cyclone, have a different morphology, however, appearing as a flocculent and tightly wrapped series of alternatively bright and dark spirals. Interestingly, CPC #2 has partially transformed from a chaotic morphology into a filled morphology, similar perhaps to how oval cyclones and barges in the low latitudes can sometimes transform into folded-filamentary cyclones (e.g., Clyde’s Spot).

Here, we discuss each CPC and the central cyclone throughout the course of the mission thus far. We primarily use images captured by JunoCam and JIRAM, but we note that the MWR is now resolving the CPCs (see separate abstract), providing additional clues on their vertical structure. This work is an attempt to document the morphology of the CPCs and their changes for future modeling attempts to replicate them in detail, which, in turn, may provide additional insight into their formation, evolution, and stability.

How to cite: Brueshaber, S., Orton, G., Hansen, C., Levin, S., Mura, A., Grassi, D., Fletcher, L. N., Rogers, J., Eichstadt, G., Wong, M. H., and Bolton, S.: Morphological Changes in Jupiter’s Northern Circumpolar Cyclones as Revealed by JunoCam and JIRAM. , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9497, https://doi.org/10.5194/egusphere-egu24-9497, 2024.

EGU24-10142 | Orals | PS2.4

Juno-UVS Observations of Io during the PJ58 Flyby 

Thomas Greathouse, Randy Gladstone, Vincent Hue, Maarten Versteeg, Joshua Kammer, Rohini Giles, Bertrand Bonfond, Denis Grodent, Jean-Claude Gerard, Scott Bolton, and Steven Levin

Currently in its first extended mission, NASA’s Juno spacecraft has made several close approaches to Jupiter’s Galilean satellites.  The final of these very close flybys will be of Io during the perijove (PJ) 58 orbit, scheduled to occur at 17:48:35 UTC on 3 Feb. 2024, about 3h59m prior to PJ58. Juno’s Ultraviolet Spectrograph (UVS) is a photon-counting far-ultraviolet (FUV) imaging spectrograph with a bandpass of 68-210 nm, which will be used to observe Io’s numerous FUV emissions during the flyby. The circumstances of the flyby are similar to that for Ganymede during PJ34 at 16:56 UTC on 7 June 2021, with the satellite only observable for a few minutes on either side of Juno’s closest approach. We plan to record data +/-5 min (at best 20 swaths of data) about the closest approach time hoping for a significant decrease in the high radiation background due to shielding provided by Io itself.  Our observations will range from an altitude of 1500 km (closest approach) to 7820 km, giving the UVS data an expected spatial resolution of 6 to 28 km at the sub-spacecraft point.  As with the similar close flyby of Ganymede (Greathouse et al. 2022; Molyneux et al. 2022), UVS will attempt to measure reflected FUV sunlight from the surface of Io and airglow emissions from oxygen and in this case sulfur atoms. These observations will be more challenging than at Ganymede, however, since the background due to penetrating (>10 MeV) electrons at Io is expected to be a factor of 10 or more larger than at Ganymede. In this talk we will present results from the initial reduction and analysis of the UVS data obtained during the flyby of Io.

How to cite: Greathouse, T., Gladstone, R., Hue, V., Versteeg, M., Kammer, J., Giles, R., Bonfond, B., Grodent, D., Gerard, J.-C., Bolton, S., and Levin, S.: Juno-UVS Observations of Io during the PJ58 Flyby, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10142, https://doi.org/10.5194/egusphere-egu24-10142, 2024.

EGU24-10549 | ECS | Posters on site | PS2.4

Electron to Light Ion Density Ratios During Cassini’s Grand Finale: Addressing Open Questions About Saturn’s Low-latitude Ionosphere 

Joshua Dreyer, Erik Vigren, Fredrik L. Johansson, Lina Hadid, Michiko Morooka, Jan-Erik Wahlund, and J. Hunter Waite

During Cassini's Grand Finale in 2017, the number densities of electron and light ions in Saturn's low-latitude ionosphere were measured in situ. This region is strongly influenced by the influx of ring material from Saturn's D ring.

The electron data from the onboard Langmuir probe (LP) and light ion densities from the Ion and Neutral Mass Spectrometer (INMS) correlate very well even on short timescales after correcting the INMS timestamps, whereas prior the correlation was limited to broader scales. We analyze the electron-to-ion ratios for the proximal orbits and identify three distinct regions in Saturn's ionosphere:

1) For altitudes above ∼2500 km and latitudes between -20° and 20°, the electron-to-light-ion ratios for the four analysed orbits are generally <1. This essentially suggests that either the INMS light ion densities are overestimated or the measured electron densities are underestimated. Our ongoing analysis may also provide additional constraints on the electron temperature profile by comparing changes between LP fixed-bias, RPWS wave, and INMS ion data.

2) At altitudes below ∼2500 km, we can further utilise the electron-to-light-ion ratios to estimate the abundance of heavier ions around closest approaches for orbits 288 and 292. Our results broadly match those of recent models.

3) At latitudes poleward of ±20° (altitudes >8000 km) the ratios increase rapidly. This may indicate the presence of heavier ions, such as O+ and water group species, spiralling in from the C ring.

How to cite: Dreyer, J., Vigren, E., Johansson, F. L., Hadid, L., Morooka, M., Wahlund, J.-E., and Waite, J. H.: Electron to Light Ion Density Ratios During Cassini’s Grand Finale: Addressing Open Questions About Saturn’s Low-latitude Ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10549, https://doi.org/10.5194/egusphere-egu24-10549, 2024.

EGU24-10938 | ECS | Orals | PS2.4

Jupiter's atmosphere through Juno's radio occultation experiments 

Andrea Caruso, Luis Gomez Casajus, Dustin Buccino, Edoardo Gramigna, Marzia Parisi, Drew Coffin, Paul Withers, Marco Zannoni, Maria Smirnova, Eli Galanti, Yohai Kaspi, Paolo Tortora, Ryan S. Park, Paul Steffes, and Scott Bolton

On July 31st, 2023 and September 9th, 2023, Juno performed the first studies of Jupiter’s atmosphere through radio occultation experiments since the Voyager and Galileo missions. These remote sensing experiments were conducted in a coherent two-way mode, where an uplink signal frequency was used as a reference for the downlink signals, at X and Ka band, transmitted back to the Earth.

During these experiments, the geometry of Juno's trajectory was such that the spacecraft was occulted by Jupiter as seen from Earth, therefore the radio signal, transmitted by the probe towards the DSN station, travelled through both Jupiter’s atmosphere and ionosphere. As a result, the radio signal underwent a phase shift due to the effect of refraction. Therefore, the Earth's antenna recorded a signal with a frequency different from what would have been observed if the signal had propagated through a vacuum. This difference, called Doppler residual frequency, has been used to infer the density, pressure, and temperature profiles of Jupiter’s neutral atmosphere and the electron number density of its ionosphere.

In the analysis of Jupiter’s atmosphere and ionosphere, where the assumption of spherical symmetry does not hold, the effect of oblateness cannot be neglected. Consequently, the radio data analysis cannot be performed by resorting to the traditional application of the Abel transform. Instead, a more suitable approach involves employing the ray-tracing technique.  This technique, based on the geometrical optics approximation, can also take into account the effects of zonal winds in retrieving the properties of Jupiter's atmosphere. Additionally, the use of multi-frequency link techniques allowed us to disentangle the contributions from dispersive and neutral media in the frequency shift.

This study presents an analysis of the data collected during the inaugural Juno radio occultation experiments of Jupiter. Specialized software has been developed to analyse the data acquired from these Juno-Jupiter two-way radio occultation experiments. Preliminary results of this analysis are given in terms of ionospheric electron density and atmospheric pressure-temperature profiles.

How to cite: Caruso, A., Gomez Casajus, L., Buccino, D., Gramigna, E., Parisi, M., Coffin, D., Withers, P., Zannoni, M., Smirnova, M., Galanti, E., Kaspi, Y., Tortora, P., Park, R. S., Steffes, P., and Bolton, S.: Jupiter's atmosphere through Juno's radio occultation experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10938, https://doi.org/10.5194/egusphere-egu24-10938, 2024.

EGU24-11864 | ECS | Posters virtual | PS2.4

Can Jupiter's atmospheric metallicity be different from the deep interior? 

Simon Müller and Ravit Helled

Updated formation and structure models of Jupiter predict a metal-poor envelope. This is at odds with measurements of the Galileo probe, which measured an enrichment of about two to three times solar. Additionally, Juno data imply that water and ammonia are enriched compared to a solar composition. Here we explore whether Jupiter can have a deep radiative layer that separates the upper atmosphere from the deeper interior. The origin of this radiative layer could be related to a hydrogen-transparency window or a depletion of alkali metals. 

We show that the accretion of heavy elements during Jupiter's evolution can lead to the desired atmospheric enrichment and that this configuration is stable over billions of years. The origin of the heavy elements could be due to cumulative impacts of small objects or from a large impact. We conclude that most of Jupiter's molecular envelope could have a solar composition while its uppermost atmosphere is enriched with heavier elements. The origin of this enrichment is likely the accretion of solid objects. This possibility resolves the long-standing mismatch between Jupiter's interior models and measurements of its atmospheric composition. Furthermore, our results imply that the measured atmospheric composition of exoplanets does not necessarily reflect their bulk compositions. 

We also investigate the possibility of the enrichment coming from the deeper interior and show that the observed enrichment is highly unlikely due to the erosion of a dilute core. This scenario is inconsistent with evolution calculations, the suggested deep radiative layer, and published interior models.

How to cite: Müller, S. and Helled, R.: Can Jupiter's atmospheric metallicity be different from the deep interior?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11864, https://doi.org/10.5194/egusphere-egu24-11864, 2024.

EGU24-12605 | Orals | PS2.4

Magnetic Field Observations During the Juno Spacecraft’s Close Passages of Io 

Jack Connerney, Daniel Gershman, john jorgensen, Matija Herceg, Stavros Kotsiaros, and Joachim Saur

The Juno spacecraft, in extended mission, explores the environments of the Galilean satellites as it passes through Jupiter’s equator plane prior to periJove. Two close passages of Io with a minimum altitude of ~1500 km were targeted to occur on orbits 57 and 58, providing a wealth of information on Io’s interior (gravity), geologic processes, atmosphere, and interaction with Jupiter’s magnetosphere. Juno’s magnetometer investigation samples the vector magnetic field in Io’s vicinity at 64 samples/s. Here we discuss Io’s interaction with the Jovian magnetosphere and the detection of ion cyclotron waves at ~0.5 Hz, ~1 Hz, and ~2 Hz, associated with Io-genic SO2, S, and O.

How to cite: Connerney, J., Gershman, D., jorgensen, J., Herceg, M., Kotsiaros, S., and Saur, J.: Magnetic Field Observations During the Juno Spacecraft’s Close Passages of Io, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12605, https://doi.org/10.5194/egusphere-egu24-12605, 2024.

EGU24-12950 | ECS | Posters virtual | PS2.4

Evidence of pure ammonia ice clouds from Juno/JIRAM infrared spectral data 

Francesco Biagiotti, Davide Grassi, Giuliano Liuzzi, Giuseppe Piccioni, Geronimo Villanueva, Fabrizio Oliva, Leigh Fletcher, Tristan Guillot, Emiliano D'Aversa, Alessandro Mura, Christina Plainaki, Giuseppe Sindoni, Alberto Adriani, and Elisa Di Mico

Ammonia is historically thought to be the main source of condensable species for Jupiter's main cloud layer (0.5-1 bar level). However, measurements from Galileo first [1] and Juno later [2] showed that the spectral features connected to ammonia clouds are rare (less than 2 % of the entire planetary disk) and not ubiquitous. Using infrared spectra collected by the JIRAM instrument on board the NASA Juno mission we investigated the possible presence of SIACs (spectrally identifiable ammonia clouds) in PJ1 data.

As a preliminary step, we used two spectral indicators sensible to the absorption of ammonia ice particles in the 2.97-3.01 micron range and ran a PCA+GMM (Principal Component Analysis + Gaussian Mixture Models) clustering analysis. The two indicators showed higher values in a high-latitude region in which cross-referenced JunoCam images highlight the presence of a Nautilus-shaped cloud, already noticed in PJ14 by previous work [3]. The PCA-GMM analysis identified the spectra in this region as belonging to a specific cluster, different from the surroundings. Performing optimal estimation atmospheric retrievals using the powerful NASA PSG (Planetary Spectrum generator) suite as the forward model, we tried to model all the spectra of this region (considering only the 2.5-3.1 micron range). We first used a toy model with a variable ammonia profile and parametrized pure reflecting hazes (complex refractive index 1.4+0i) and tholin clouds. It is important to stress that Titan’s like tholins must not be intended as a realistic candidate for Jupiter’s aerosol clouds but as an approximation of the real amorphous unknown material that exhibits an evident N-H-bond-like absorption. We found that the described toy model fits well the majority of the spectra outside the Nautilus, whereas the spectra near and inside the Nautilus require more complex assumptions on cloud compositions and so have been re-modeled.

As a result, we noticed that a total of 20 spectra are best fitted by a pure ammonia ice cloud model and so have been identified as SIACs. The SIACs are located at the center of the Nautilus-shaped cloud and in correspondence with the nearby swirls. In most cases, the SIACs are surrounded by spectra best fitted by a cloud deck composed of tholin particles coated with ammonia ice. Our results in correspondence with the Nautilus suggest: (I) higher altitude hazes and clouds, (II) higher values of ammonia relative humidity that also reach super-saturation conditions, and (III) smaller effective radii for the haze particles. Such results are compatible with the presence of pure ammonia ice clouds, formed at these latitudes as a consequence of an uplifting event from the lower troposphere that brought a large fraction of fresh ammonia up to reach super-saturation conditions, triggering condensation and/or coating of mixed particles.

[1] Baines K. H. et al. (2002) Icarus, 159, 1, 74-94. [2] Grassi D. et al. (2021) MNRAS, 503, 4, 4892-4907. [3] Guillot T. et al. (2023) EGU23, the 25th EGU General Assembly, EGU-17178.

How to cite: Biagiotti, F., Grassi, D., Liuzzi, G., Piccioni, G., Villanueva, G., Oliva, F., Fletcher, L., Guillot, T., D'Aversa, E., Mura, A., Plainaki, C., Sindoni, G., Adriani, A., and Di Mico, E.: Evidence of pure ammonia ice clouds from Juno/JIRAM infrared spectral data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12950, https://doi.org/10.5194/egusphere-egu24-12950, 2024.

EGU24-12983 | Orals | PS2.4 | Highlight

Juno Microwave Radiometer Observations of Europa’s Subsurface Ice Shell 

Steve Levin, Zhimeng Zhang, Scott Bolton, Shannon Brown, Anton Ermakov, Ryunosuke Akiba, Sidharth Misra, Paul Hartogh, and David Stevenson

Juno flew less than 360 km from the surface of Jupiter’s moon Europa on 29 September, 2022, and mapped part of the ice shell with the Microwave Radiometer (MWR) at frequencies of 0.6, 1.2, 2.5, 4.8, 9.6, and 22 GHz.  The partial map covers a latitude range from ~20oS to ~50oN and a longitude range from 70oW to 50oE.  At these frequencies, the emission originates well beneath the nearly-transparent surface, probing from as deep as 28 km (at 0.6 GHz) and less than 20 m (at 22 GHz), depending on the purity of the ice.  Microwave reflection plays an important role, and MWR data suggest the presence of small (radius a few cm) scatterers at depths of many meters.  Spatial variation is dominated by reflection, especially for the higher-frequency channels, and correlates with terrain type.  We present analysis of the data and discuss the implications. 

How to cite: Levin, S., Zhang, Z., Bolton, S., Brown, S., Ermakov, A., Akiba, R., Misra, S., Hartogh, P., and Stevenson, D.: Juno Microwave Radiometer Observations of Europa’s Subsurface Ice Shell, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12983, https://doi.org/10.5194/egusphere-egu24-12983, 2024.

EGU24-13056 | Orals | PS2.4 | Highlight

JIRAM's observations of Io during closest approaches 

Alessandro Mura, Federico Tosi, Francesca Zamboni, Rosaly M. Lopes, Julie Rathbun, Pete Mouginis-Mark, Heidi N. Becker, Candice Hansen-Koharcheck, Roberto Sordini, Madeline Pettine, Giuseppe Piccioni, Giuseppe Sindoni, Christina Plainaki, and Alberto Adriani

NASA’s Juno mission has been observing Jupiter since 2016 from a polar, highly elliptical orbit. Although not in the main scientific objectives, Juno took images and spectra of the Galilean moons from a very favourable position, using some of the cameras on board: JIRAM,  JunoCam and SRU. JIRAM, the Jovian InfraRed Auroral Mapper, is a dual-band imager and spectrometer in the infrared (2000-5000 nm); JunoCam is a visible color imager;  SRU is Juno's Stellar Reference Unit, a highly sensitive, visible  wavelength (450-1100 nm) camera.
JIRAM's imager channel is a single detector with 2D capability and with 2 different filters (L band, from 3.3 to 3.6 µm; M band, from 4.5 to 5 µm). The pixel angular resolution (0.01°) is fine enough for imaging the moons from Juno; the spatial resolution at the surface of the moons varies along the s/c distance and was of the order of 100 km/pixel at the beginning of the campaign, but it's now getting better, down to ~ 500 m. Here we focus on the study of JIRAM’s high resolution images, which can characterize the location, morphology, and some temperatures, of the volcanic thermal sources; comparison with images in the visible range is also performed.

How to cite: Mura, A., Tosi, F., Zamboni, F., Lopes, R. M., Rathbun, J., Mouginis-Mark, P., Becker, H. N., Hansen-Koharcheck, C., Sordini, R., Pettine, M., Piccioni, G., Sindoni, G., Plainaki, C., and Adriani, A.: JIRAM's observations of Io during closest approaches, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13056, https://doi.org/10.5194/egusphere-egu24-13056, 2024.

EGU24-13270 | ECS | Posters on site | PS2.4

A deep learning approach to study Jupiter's interior from Juno 

Maayan Ziv, Eli Galanti, Amir Sheffer, Saburo Howard, Tristan Guillot, and Yohai Kaspi
The interior structure of Jupiter holds information on its formation and evolution processes, with the two research fields highly related to one another. The range of plausible interior structures is constrained by the gravity field measured by the Juno mission, the atmospheric abundances measured by Galileo, and the 1 bar temperature estimated from radio occultation. Consequently, it is also affected by the surface winds and their internal structure, which significantly contribute to the gravity field. Inferring the range of plausible interior structures requires an intensive computational search of combinations of various planetary properties, such as the cloud-level temperature, compositions, core features, etc., matching the observations. This search requires computing ~10^8 interior models.
 Here, we propose an efficient deep learning method to generate unique interior models using the very accurate but computationally demanding concentric MacLaurin spheroid method. We train a neural network to predict interior model results accurately. This allows us to perform a broad parameter space search by computing only ~10^4 interior models, resulting in a large sample of plausible interior structures. The network can also be used to infer the non-linear relations between the physical features and the observable gravity field and mass.

How to cite: Ziv, M., Galanti, E., Sheffer, A., Howard, S., Guillot, T., and Kaspi, Y.: A deep learning approach to study Jupiter's interior from Juno, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13270, https://doi.org/10.5194/egusphere-egu24-13270, 2024.

EGU24-13536 | Orals | PS2.4 | Highlight

Observations of Io with the Juno Microwave Radiometer:  First Results and Implications for Global Heat Flow 

Shannon Brown, Scott Bolton, Steve Levin, Zhimeng Zhang, Matthew Siegler, and Jianqing Feng

The NASA Juno mission performed two close fly-bys of Jupiter’s moon Io on December 30, 2023 and February 3, 2024. Juno carries a 6-channel microwave radiometer (MWR) operating between 0.6-22 GHz. The first fly-by observed Io’s north pole and the 2nd pass mapped latitudes within +/- 45o on the Jovian facing hemisphere. The broad frequency range of the MWR probes successively deeper into the Io sub-surface with the 0.6GHz channel probing the deepest.  The sub-surface temperature, dielectric and surface roughness properties are encoded in the spectra obtained by the MWR. Here we report on the first spatially resolved observations of Io at frequencies below 22 GHz.  We find the brightness temperatures decrease with increasing latitude and are coldest at the north pole, consistent with prior infrared observations of the surface skin temperature. We observe a strong spectral gradient in the lowest frequency channels (increasing with depth) reflecting the sub-surface temperature profile from which we can infer endogenic heat flow. We will give an overview of the MWR observations and initial inferences about the sub-surface thermal and compositional properties.    

How to cite: Brown, S., Bolton, S., Levin, S., Zhang, Z., Siegler, M., and Feng, J.: Observations of Io with the Juno Microwave Radiometer:  First Results and Implications for Global Heat Flow, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13536, https://doi.org/10.5194/egusphere-egu24-13536, 2024.

The current Juno and recent Cassini missions have yielded unprecedented accuracy and resolution of the gravity fields of Jupiter and Saturn. The new observations of zonal harmonics through J12 have led to a new generation of interior models. Previously, interior models of two or three adiabatic layers were sufficient to satisfy gravity observations. However, to satisfy the Cassini and Juno observations, interior models require more complexity, with recent works proposing five layers, and the presence of gradients in composition and entropy. I describe the hydrostatic equations relevant to a rotating fluid planet with variable density, composition and entropy. Composition is formulated with a simple version of the additive volume law. Stability is described in terms of gradients in specific entropy and composition (mass fraction), which is assumed to be static (or slowly varying) . Relations between composition, entropy and diffusion parameters variation are described in terms of the density ratio, which is a prominent parameter of semiconvection (double diffusive convection). The resulting set of thermodynamic equations, along with gravity, are solved iteratively, calibrated by, and compared to the recent ab-initio EOS results of French et al. (2012) and Militzer et al. (2022).  To further simplify the thermodynamic formulation, non-adiabatic interior models that are polytropic where they are adiabatic are explored. Gravitational harmonics and moment of inertia of the resulting density profiles are calculated using the Theory of Figures to order 7 (Nettelman et al., 2021). Plausible and thermodynamically consistent interior models are shown to be relatively straightforward to obtain. Using the anelastic magnetohydrodynamics code MagIC (Gastine and Wicht, 2012), examples of these interior models are implemented as the background state for dynamo models of Jupiter and Saturn.   

How to cite: Heimpel, M.: Thermodynamically consistent background state and dynamo models constrained by Juno and Cassini gravity harmonics, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13983, https://doi.org/10.5194/egusphere-egu24-13983, 2024.

EGU24-14359 | Posters virtual | PS2.4 | Highlight

Super-adiabatic Temperature Gradient at Jupiter’s Equatorial Zone and Implications for the Water Abundance 

Cheng Li, Michael Allison, Sushil Atreya, Leigh Fletcher, Andrew Ingersoll, Tristan Guillot, Liming Li, Jonathan Lunine, Yamila Miguel, Glenn Orton, Fabiano Oyafuso, Paul Steffes, Hunter Waite, Michael Wong, Zhimeng Zhang, Steven Levin, and Scott Bolton

The temperature structure of a giant planet was traditionally thought to be an adiabat because convective mixing homogenizes entropy. The only in-situ measurement made by the Galileo Probe detected a near-adiabatic temperature structure within one of Jupiter’s 5 hot spots with small but definite local departures from adiabaticity. We analyze Juno’s microwave observations near Jupiter’s equator (0 ~ 5 oN) and find that the equatorial temperature structure is best characterized by a stable super-adiabatic temperature profile rather than an adiabatic one. Water is the only substance with sufficient abundance to alter the atmosphere's mean molecular weight and prevent dynamic instability if a super-adiabatic temperature gradient exists. Thus, from the super-adiabaticity, our results indicate a water concentration (or the oxygen to hydrogen ratio) of about 4 times solar with a possible range of 2 ~ 7 times solar in Jupiter’s equatorial region.

How to cite: Li, C., Allison, M., Atreya, S., Fletcher, L., Ingersoll, A., Guillot, T., Li, L., Lunine, J., Miguel, Y., Orton, G., Oyafuso, F., Steffes, P., Waite, H., Wong, M., Zhang, Z., Levin, S., and Bolton, S.: Super-adiabatic Temperature Gradient at Jupiter’s Equatorial Zone and Implications for the Water Abundance, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14359, https://doi.org/10.5194/egusphere-egu24-14359, 2024.

EGU24-14393 | Posters on site | PS2.4

Energetic charged particle observations of Europa’s near-space environment during the Juno PJ45 flyby and anticipations for the JUICE mission  

George Clark, Barry Mauk, Chris Paranicas, Pontus Brandt, Peter Kollmann, Todd Smith, Frederic Allegrini, Scott Bolton, Don Mitchell, Matina Gkioulidou, Stas Barabash, Peter Wurz, Norbert Krupp, Elias Roussos, Hans Huybrighs, Carol Paty, Xianzhe Jia, Krishan Khurana, and Angele Pontoni

Jupiter’s moon Europa is of high scientific interest because it is an ocean world with a tenuous atmosphere and may also harbor sporadic water plumes. Europa is also embedded deep within Jupiter’s magnetosphere and resides in a harsh environment of radiation comprised of energetic-to-relativistic electrons and ions. Understanding the interplay between Europa and its near-space environment is key to unlocking the mysteries on how energetic particles contribute to surface weathering processes and how the moon itself and the neutral gasses that surround its orbital region contribute to energetic charged particle dynamics (e.g., acceleration and losses). In this presentation, we report on energetic particle observations made by Juno/JEDI during the PJ45 close flyby of Europa and discuss implications for the Particle Environment Package (PEP) instrument suite onboard ESA’s JUICE mission.

How to cite: Clark, G., Mauk, B., Paranicas, C., Brandt, P., Kollmann, P., Smith, T., Allegrini, F., Bolton, S., Mitchell, D., Gkioulidou, M., Barabash, S., Wurz, P., Krupp, N., Roussos, E., Huybrighs, H., Paty, C., Jia, X., Khurana, K., and Pontoni, A.: Energetic charged particle observations of Europa’s near-space environment during the Juno PJ45 flyby and anticipations for the JUICE mission , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14393, https://doi.org/10.5194/egusphere-egu24-14393, 2024.

EGU24-14431 | Posters on site | PS2.4

Io's topography on the basis of JunoCam images 

Gerald Eichstädt, Glenn S. Orton, Candice Hansen-Koharcheck, Tristan Guillot, Heidi Becker, and Scott J. Bolton

Juno's close approach of Io, during the inbound branch of the Perijove-57 Jupiter flyby, allowed Juno's visible light imager, JunoCam, to take a short sequence of close-up Io images at a cadence of about one minute. Consecutive images cover overlapping areas on Io from different angles. The parallax effect is definitely perceptible for several of the highest mountains. The images also show shadows cast by some of the mountains onto their much flatter surroundings. Varying shading, to be distinguished from albedo and color variability, returns small-scale inclination data.  Mountains imaged near Io's limb reveal distinctive silhouettes.  We use all these ingredients to retrieve relative elevation data from JunoCam's close-up Io images.  We will summarize  the available data, the applied methods, and our derived digital terrain results.

How to cite: Eichstädt, G., Orton, G. S., Hansen-Koharcheck, C., Guillot, T., Becker, H., and Bolton, S. J.: Io's topography on the basis of JunoCam images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14431, https://doi.org/10.5194/egusphere-egu24-14431, 2024.

EGU24-15158 | ECS | Posters on site | PS2.4

Prospects for Jovian seismology with the Lenghu planetary telescope 

Yiqing Zou, Fei He, Zhonghua Yao, Zhaojin Rong, and Yong Wei

Abstract: Jupiter is one of the top priorities for deep space exploration in China and other countries. A crucial and remaining unclear scientific topic in Jupiter exploration is depicting the structure of its interior. This paper discusses the current understanding of Jupiter's interior, based on the current development of Jupiter exploration and research history. The present space-based and ground-based observation methods are reviewed, and their feasibility is analyzed. To gain insight into the internal structure of Jupiter, we propose to study Jupiter’s innards by planetary seismology. The ground-based observation, namely the Jupiter Seismologic Interferometer Polarization Imager (SIPI) in Lenghu, will be developed to obtain the Doppler velocity distribution on the surface of Jupiter and identify the oscillation signals. Lenghu has good observation conditions in China and even the world, providing a novel insight into studying the interior of Jupiter. This will also be the first study of the interior of Jupiter by using asteroseismology in China, which has significant implications for the exploration mission of Jupiter.

Keywords: Jupiter seismology; Jupiter's interior; Jupiter model; Jupiter Seismologic Interferometer Polarization Imager (SIPI)

How to cite: Zou, Y., He, F., Yao, Z., Rong, Z., and Wei, Y.: Prospects for Jovian seismology with the Lenghu planetary telescope, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15158, https://doi.org/10.5194/egusphere-egu24-15158, 2024.

EGU24-15196 | ECS | Posters on site | PS2.4

Simulations of Io plasma torus around Jupiter: Predictions for Lenghu Observatory 

Xiaoyi Tan, Fei He, Masato Kagitani, Yong Zhao, Zhonghua Yao, Zhaojin Rong, and Yong Wei

Characterizing the temporal evolution of the three-dimensional structure of the Io plasma torus is essential to understand the dynamics of the Jovian magnetosphere. Optical imaging is a powerful tool to uncover the global torus structure. Currently, two ground-based optical telescopes with diameters of 0.8 m and 1.8 m, respectively, are under construction at the Lenghu Observatory for Planetary Science on the Tibetan Plateau of China, to systematically observe the Io plasma torus at wavelengths between 392 nm and 1100 nm. These telescopes will begin to operate in the end of 2023. In order to support the inversion and scientific interpretation of the Io plasma torus images, we perform systematic simulations of the Io plasma torus in this work. First, a three-dimensional model of electron and ion densities and electron temperature is constructed first. Then the emissions of O 372.7 nm, O 372.9 nm, S 406.9 nm, S 671.8 nm, S 673.1 nm, and S 953.2 nm are simulated from the perspective of observing from the Earth. The simulated emission intensities and distributions are consistent with previous observations. This work provides a state-of-the-art convenient tool for groundbased telescope observation of the Io plasma torus at a specific site and time, and also benefits future inversion of images to obtain physical parameters of Io plasma torus.

How to cite: Tan, X., He, F., Kagitani, M., Zhao, Y., Yao, Z., Rong, Z., and Wei, Y.: Simulations of Io plasma torus around Jupiter: Predictions for Lenghu Observatory, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15196, https://doi.org/10.5194/egusphere-egu24-15196, 2024.

EGU24-16258 | ECS | Posters virtual | PS2.4

Investigation of ion flux response to magnetic dipolarization events in the Jovian magnetotail using Juno/JEDI data 

Georgia Moutsiana, George Clark, Matina Gkioulidou, Ioannis Daglis, and Barry Mauk

The acceleration and energization processes of charged particles in planetary magnetotails are commonly associated with magnetic dipolarization events and are thought to share similarities among the various magnetospheres of our solar system. In the present study, we focus on Jupiter’s extensive and massive magnetosphere, characterized by multispecies plasma in diverse charge states, resulting in a varied set of acceleration-relevant factors that can be examined. During Juno’s prime mission, we utilize magnetic field data from the MAG instrument, and energetic ion data from JEDI-090 and JEDI-270 identical instruments, which provide measurements for the energy, angular, and compositional distributions of hydrogen (∼50 keV to ∼1 MeV), oxygen (∼170 keV to ∼2 MeV) and sulfur (∼170 keV to ∼4 MeV) ions. In particular, we examine and present the typical response of hydrogen, oxygen and sulfur ion fluxes, as well as pitch angle distributions, to local magnetic field dipolarizations in Jupiter’s magnetotail, focusing on observations at radial distances beyond 30 RJ. As part of our ongoing work, we plan to conduct a comparative analysis of energization processes around dipolarization events in the magnetotails of both Earth and Jupiter, in an attempt to discern similarities and differences in the associated mechanisms for these two planets.

How to cite: Moutsiana, G., Clark, G., Gkioulidou, M., Daglis, I., and Mauk, B.: Investigation of ion flux response to magnetic dipolarization events in the Jovian magnetotail using Juno/JEDI data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16258, https://doi.org/10.5194/egusphere-egu24-16258, 2024.

EGU24-17351 | Orals | PS2.4 | Highlight

How high are Jupiter’s clouds? From high-resolution JunoCam images to a multi-wavelength analysis 

Tristan Guillot, Francesco Biagiotti, Grassi Davide, Wong Mike, Fletcher Leigh, Orton Glenn, Gerald Eichstaedt, Marylyn Rosenqvist, Shawn Brueshaber, Candy Hansen, Caleb Keaveney, Kevin Kelly, Tom Momary, Jonathan Lunine, and Scott Bolton

Last year, we showed that JunoCam images, acquired in the visible, have the resolution necessary to measure the height of clouds from their projected shadows. We focused our analysis on the “Nautilus”, a 3000-km cyclonic vortex seen during Juno’s 14th periojove. That structure consists mainly of a spiraling counter clockwise white cloud that casts a shadow onto a reddish cloud deck∼20 to 30 km below. Small individual clouds also pop out of the white cloud deck, towering about ~10 to 20 km above it. An analysis of near-simultaneous HST images of the Nautilus confirms that the white region is higher than its surrounding darker, reddish cloud deck. These respective elevations are consistent with the white clouds being made of fresh ammonia ice while most of the reddish clouds underneath are made of ammonium hydrosulfide NH4SH, as predicted by equilibrium cloud models.

An analysis by F. Biagiotti of a similar region observed by JIRAM during Juno’s 1st perijove identifies the presence of elusive ammonia ice crystals, either pure or mixed with a nitrogen-bearing species similar to Titan’s tholins. In addition, these clouds have altitudes that are consistent with the above interpretation. However, the surrounding material is not much deeper and incompatible with NH4SH. We discuss a possible solution to the corundum: At least in the gas, the atmosphere's optical thickness is much larger at the wavelengths used for the JIRAM study (2 to 3.2 micron)  than in the visible. The effect of scattering by cloud particles is to be evaluated, but it appears likely that altogether, infrared observations at these wavelengths cannot penetrate as deep as visible ones.

An interpretation of these observations, consistent with spectroscopic observations in the visible, is therefore that, at least in this region close to ~40°N, most of Jupiter's visible cloud deck is made of NH4SH, that updrafts can locally deliver fresh ammonia ice but that these ammonia ice crystals remain only for a short time either because of downwelling and evaporation or because of coating.

How to cite: Guillot, T., Biagiotti, F., Davide, G., Mike, W., Leigh, F., Glenn, O., Eichstaedt, G., Rosenqvist, M., Brueshaber, S., Hansen, C., Keaveney, C., Kelly, K., Momary, T., Lunine, J., and Bolton, S.: How high are Jupiter’s clouds? From high-resolution JunoCam images to a multi-wavelength analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17351, https://doi.org/10.5194/egusphere-egu24-17351, 2024.

EGU24-20547 | Orals | PS2.4

A detailed map of the Jovian high-energy radiation belts 

John Jørgensen, Troelz Denver, Matija Herceg, Julia Sushkova, Peter Jørgensen, Jack Connerney, and Scott Bolton

High energy particle fluxes (>15MeV e- and 120MeV p+) throughout the Jovian magnetosphere have been continuously measured by the MAG investigation’s ASC instrument. Juno’s highly elliptical polar orbit has effectively traversed almost all of the Jovian magnetosphere with most regions sampled multiple times over time. Pronounced variations in the observed flux for comparable regions of the magnetosphere are observed in association with the positions of the Galilean moons and their associated dust and plasma tori, while global variations appear to be coupled to magnetic compression due to corona mass ejections. Oversampling of specific regions affords the opportunity to compile a quiet time map of the energetic trapped particle environment despite variations in solar activity and satellite-related effects. Subtracting this quiet time flux from that observed yields detailed information on the impact of solar activity, the Galilean moons, and the gossamer rings on the high-energy trapped particle environment of Jupiter. We present the observed quiet time map and show the impact on the trapped high-energy flux from the abovementioned local sources and sinks, and compare these results to those observed by Pioneer 10 and 11.

How to cite: Jørgensen, J., Denver, T., Herceg, M., Sushkova, J., Jørgensen, P., Connerney, J., and Bolton, S.: A detailed map of the Jovian high-energy radiation belts, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20547, https://doi.org/10.5194/egusphere-egu24-20547, 2024.

EGU24-1458 | Orals | PS2.5 | Highlight

Constraining the Thickness of the Conductive Portion Europa's Ice Shell using Sparse Radar Echoes 

Dustin Schroeder, Natalie Wolfenbarger, and Gregor Steinbrügge

Ice penetrating radars are intuitively appealing for probing ice shells because it is perceived as a way to directly imaging the ice/ocean interface or as a way to "picture" and interpret visually the structural  cross-section of the ice. While this approach is significant and can lead to substantial discoveries, it's also likely that many radar sounding measurements will not exhibit these obvious, intuitive features.

Here, we address the potential of more subtle radar echoes (or the absence thereof) in providing valuable information. These echoes can impose constraints on ice temperature and thickness, offering insights similar to those obtained from other planetary geophysical methods like gravity science or magnetic induction measurements.

In our study, we examine four potential radar signatures: pore-closure, eutectic melt, isolated echo detection, and attenuation horizons. We demonstrate that each of these signatures, by providing observational constraints on either the temperature or the integrated two-way attenuation at a given depth, can help determine the thickness of the conductive portion of Europa's ice shell.

By integrating these findings with other geophysical approaches (e.g., gravity, magnetics), radar sounding data can significantly enhance studies and models of the ice-shell interior, even without the direct detection of the ice/ocean interface.

 

How to cite: Schroeder, D., Wolfenbarger, N., and Steinbrügge, G.: Constraining the Thickness of the Conductive Portion Europa's Ice Shell using Sparse Radar Echoes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1458, https://doi.org/10.5194/egusphere-egu24-1458, 2024.

EGU24-2392 | Posters on site | PS2.5

Titan in Late Northern Summer from JWST and Keck Observations 

Conor Nixon, Bruno Bézard, Thomas Cornet, Brandon Coy, Imke de Pater, Maël Es-Sayeh, Heidi Hammel, Emmanuel Lellouch, Juan Lora, Nicholas Lombardo, Manuel López-Puertas, Pascal Rannou, Sébastien Rodriguez, Nicholas Teanby, and Elizabeth Turtle and the Titan JWST and Keck Observation Team

Titan is an object of fascination for scientists researching the solar system, as a ‘terrestrial-like’ world with active meteorology and fluvial and lacustrine formations based on methane chemistry and condensation. The Cassini-Huygens mission explored Titan extensively from 2004 to 2017, but since that time further observation of its slow seasonal cycle has been possible only via telescopes positioned on or close to the Earth. Titan’s unique characteristics led to a concerted post-Cassini observational campaign, with many of the most powerful telescopes available to astronomy. In this work we report on observations from 2022 & 2023 with three instruments on the James Webb Space Telescope (JWST), NIRCam, NIRSpec and MIRI, also in coordination with imaging from Keck II. In November 2022 and July 2023, Titan was the subject of multi-spectral filter imaging with JWST NIRCam and Keck II NIRC2, revealing tropospheric clouds at mid-northern latitudes, in line with climate modeling predictions for this season (late northern summer). In filters sensitive to the upper troposphere, we observed clouds growing and apparently ascending in altitude during a Titan day. JWST NIRSpec spectroscopy yielded for the first time a high resolution (R=2700) spectrum of Titan across the entire near-infrared (1-5 microns) unobscured by telluric absorption. This, among other things, enabled measuring the detailed structure of the CO 4.7 micron non-LTE emission, including the fundamental, the first two overtone bands and two isotopic bands. It is also the first time that CO2 emission has been resolved in the NIR and the first time it has been seen on Titan’s dayside.  Finally, very sensitive spectroscopy with JWST MIRI in the mid infrared (5-28 microns) confirmed the many stratospheric gases seen by Cassini CIRS, but also added a new detection of methyl (CH3) in the middle atmosphere, a product of methane photochemistry that was expected but not previously seen. We modeled parts of the spectra to find a global mean temperature profile and profiles of minor gases. Soon we hope to extract yet more results from the NIRSpec and MIRI spectra as our understanding of the calibration and modeling progresses. In this presentation we summarize our results to date and describe planned future observations of Titan with JWST and Keck cycles.

How to cite: Nixon, C., Bézard, B., Cornet, T., Coy, B., de Pater, I., Es-Sayeh, M., Hammel, H., Lellouch, E., Lora, J., Lombardo, N., López-Puertas, M., Rannou, P., Rodriguez, S., Teanby, N., and Turtle, E. and the Titan JWST and Keck Observation Team: Titan in Late Northern Summer from JWST and Keck Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2392, https://doi.org/10.5194/egusphere-egu24-2392, 2024.

EGU24-5965 | Posters on site | PS2.5

Ground-based monitoring of atmospheric species on Titan and a search for new nitriles with IRTF/TEXES 

Athena Coustenis, Therese Encrenaz, Thomas K. Greathouse, David Jacquemart, Rohini Giles, Conor A. Nixon, Panayotis Lavvas, Nicholas Lombardo, Sandrine Vinatier, Bruno Bezard, Krim Lahouari, Pascale Soulard, Benoit Tremblay, Antoine Jolly, and Brendan Steffens

The atmosphere of Titan is known to be a laboratory of complex organic chemistry. (Coustenis, 2021) From the Voyager missions, and later the Cassini-Huygens mission, several hydrocarbons and nitriles have been detected and their seasonal variations have been monitored during a period of one Titan season (30 years). Other minor species have been detected from the ground mainly in the millimeter range or using space-borne observatories like ISO. These results have been included in photochemical models that have also predicted the presence of other minor species, among which some have infrared transitions in the 5-25-µm spectral range where propane (C3H8) and allene (CH2CCH2) have already been detected. We have started an observing program using the TEXES thermal infrared imaging spectrometer at the Infrared Telescope Facility (Mauna Kea Observatory) to monitor the infrared signatures of hydrogen cyanide (HCN) and cyanoacetylene (HC3N), along with acetylene (C2H2 and C2HD). In addition, we have been searching for cyanopropyne (C4H3N) and isobutyronitrile (C4H7N) in the 20-micron region. High-resolution spectra of Titan with TEXES were recorded before where Lombardo et al. (2019) measured HNC (hydrogen isocyanide) in Titan’s lower stratosphere (1 ppb around 100 km), which is the first time HNC has been measured at these altitudes.  In September 2022 we obtained spectra of Titan in the following spectral ranges: (1) 498-500 cm-1 (C2HD, HC3N, search for C4H3N); (2) 537-540 cm-1 (C2HD, search for C4H7N); (3) 744-749 cm-1 (C2H2, HCN); (4) 1244-1250 cm-1 (CH4). Observations are presently being processed. In 2023, laboratory spectra of cyanopropyne and isobutyronitrile have been recorded at Sorbonne Université in the 495-505 cm-1 and 510-570 cm-1 spectral ranges, respectively, with a spectral resolution of 0.01 cm-1 and 0.056 cm-1 (Coustenis et al., 2023). Cross sections have been derived for these two molecules and upper limits will be derived for these two molecules in the atmosphere of Titan. TEXES data will also be used for a study of the variations of HCN and HC3N since the end of the Cassini mission, and for a retrieval of D/H from C2HD/C2H2.

References

  • Coustenis, A., 2021. “The Atmosphere of Titan”. In Read, P. (Ed.), Oxford Research Encyclopedia of Planetary Science. Oxford University Press. doi:https://doi.org/10.1093/acrefore/9780190647926.013.120
  • Lombardo, N.A., Nixon, C.A., Greathouse, T.K., Bézard, B., Jolly, A., Vinatier, S., Teanby, N.A.A, Richter, M.J., Irwin, P.J.G., Coustenis, A., Flasar, F.M., 2019. Detection of propadiene on Titan. Astroph. J. Lett. 881, Issue 2, article id. L33, 6 pp.
  • Coustenis, A., Nixon, C. A., Encrenaz, Th., Lavvas, P., 2023. Titan’s chemical composition from Cassini and ground-based measurements. IUGG 2023, Berlin, Germany, 11-20 July.

How to cite: Coustenis, A., Encrenaz, T., Greathouse, T. K., Jacquemart, D., Giles, R., Nixon, C. A., Lavvas, P., Lombardo, N., Vinatier, S., Bezard, B., Lahouari, K., Soulard, P., Tremblay, B., Jolly, A., and Steffens, B.: Ground-based monitoring of atmospheric species on Titan and a search for new nitriles with IRTF/TEXES, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5965, https://doi.org/10.5194/egusphere-egu24-5965, 2024.

EGU24-6159 | ECS | Posters on site | PS2.5

The effects of an icy porous layer on the two-way radar attenuation on Enceladus 

William Byrne, Ana-Catalina Plesa, Tina Rückriemen-Bez, Andreas Benedikter, and Hauke Hussmann

Saturn's moon, Enceladus is considered a priority target for future planetary missions due to its high astrobiological potential [1]. Water jets presumably originating from a subsurface ocean have been observed at the south pole of Enceladus by NASA’s Cassini mission [2], and their analysis provides a direct window into the ocean composition [3] that, in turn, can help to understand the nature and amount of impurities that may exist within the ice shell.

Enceladus’ jet activity generates a highly porous material that affects the thermal state of the ice shell. The thickness of that layer and its distribution are poorly constrained, but local thicknesses of up to 700m have been reported from the analysis of pit chains on the surface of Enceladus [4]. Such a thick porous layer can strongly attenuate the signal of radar sounders that have been proposed to investigate the Enceladus’ subsurface [5].

Here, we use numerical simulations to determine the effects of a porous layer on the two-way radar attenuation. We generate a variety of steady-state one-dimensional thermal models based on proposed parameters for Enceladus’ ice shell thickness (5 - 35 km, [6]), porous layer thickness (0 - 700 m [4]) and its thermal conductivity (0.1 - 0.001 W/mK [7,8]). In addition to systematically testing parameter combinations, we use two ice shell thickness maps [6] together with local thermal profiles to provide a global spatial distribution of potential penetration depths that could be achieved by radar measurements. We use two material models ("high" and "low" loss) to identify the impact of chemical impurities on attenuation [9]. While the “low” loss scenario considers an ice shell composed of pure water ice, the “high” loss case is characterized by a homogeneous mixture of water ice and chlorides in concentrations extrapolated from the particle composition of Enceladus’ plume [5].

Our results show that the presence of a porous layer has a first-order effect on the two-way radar attenuation. For regions covered by porous layers with thicknesses larger than 250 m and a thermal conductivity lower than 0.025 W/(mK) the two-way radar attenuation reaches a threshold value of 100 dB before reaching the ice-ocean interface in the low loss scenarios. In the high loss cases, for similar porous layer thicknesses and thermal conductivity, the two-way attenuation remains below 100 dB for at most 48% of the ice shell. Depending on the local ice shell thickness and properties of the snow deposits, as little as a few percent of the ice shell can be penetrated before the 100 dB limit is reached. We note, however, that the presence of a porous layer leads to high subsurface temperatures and promotes the formation of brines at shallow depth that can be detected by future radar measurements.

 

References:

[1] Choblet et al., 2021. [2] Hansen et al., 2006. [3] Postberg et al., 2008. [4] Martin et al., 2023. [5] Soucek et al., 2023. [6] Hemingway & Mittal, 2019. [7] Seiferlin et al., 1996. [8] Ferrari et al., 2021. [9] Kalousova et al., 2017.

How to cite: Byrne, W., Plesa, A.-C., Rückriemen-Bez, T., Benedikter, A., and Hussmann, H.: The effects of an icy porous layer on the two-way radar attenuation on Enceladus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6159, https://doi.org/10.5194/egusphere-egu24-6159, 2024.

EGU24-7948 | ECS | Orals | PS2.5

The role of ammonia in the primordial distribution of volatiles in the hydrosphere of Europa 

Alizée Amsler Moulanier, Olivier Mousis, and Alexis Bouquet

The presence of hydrospheres within the Galilean moons raises the question of whether or not they could provide habitable environments. The study of nowadays’ volatiles inventory on those moons is indicative of their formation processes and their effects on this inventory. However, for the ability to disentangle between the possible scenarios, it is necessary to examine the post-accretion processes that could impact the volatile inventory of the hydrospheres. Especially, an “open-ocean” phase which took place shortly after accretion, before the icy crust formation, must be considered, in view of its influence on the volatile inventory. More specifically, the abundance of ammonia in Europa’s building blocks is a key constrain, both on the habitability conditions of the ocean and the volatile distribution in the primordial thick atmosphere of the moon.

Our work focuses on modelling the ocean-atmosphere equilibrium which took place over this period, based on different formation scenarios of Europa. To do so, we compute the vapor-liquid equilibrium between water and volatiles, as well as the chemical equilibria happening within the ocean to investigate the primitive hydrosphere of Europa. Our model allows for an assessment of the impact of the initial distribution of volatiles resulting from the thermodynamic equilibrium between Europa’s primordial atmosphere and ocean. In particular, we show the correlation between the ratio of dissolved CO2 and NH3 and the distribution of partial pressures in the primordial atmosphere of Europa.

Navigating between two endmembers for the composition of the building blocks (nitrogen delivered by hydrated rocks or cometary ices), and varying the proportion of ammonia incorporated into the ocean after accretion, we obtain a range of primordial volatile distributions, to be linked to nowadays inventory. We also find ammonia abundance thresholds above which CO2 content is significantly depleted by NH2COO-  formation.

How to cite: Amsler Moulanier, A., Mousis, O., and Bouquet, A.: The role of ammonia in the primordial distribution of volatiles in the hydrosphere of Europa, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7948, https://doi.org/10.5194/egusphere-egu24-7948, 2024.

EGU24-9751 | ECS | Posters on site | PS2.5

Icy Moon Surfaces Microstructure through Multiphysics Simulations 

Cyril Mergny and Frédéric Schmidt

Water ice has a microstructure shaped by a complex interplay of coupled multi-physics processes. Among them, ice sintering—also referred to as metamorphism or annealing—transports material from ice grains into their neck region, resulting in changes in the mechanical and thermal properties of the ice. Understanding sintering is essential to investigate the properties and microstructure of ice. While the sintering process of snow on Earth has been extensively studied, there is a scarce amount of information regarding the alteration of ice in planetary surface environments characterized by low temperatures and pressures.

Here we present a multiphysics simulation model designed to study the evolution of planetary ice microstructure.  Coupled to a heat transfer solver, we have built a new model for the sintering of ice grain  with mathematical refinement to the diffusion process. As changes in ice microstructure affect the thermal properties we have expressed the heat conductivity with a formulation that consider microstructure and porosity which enables a two coupling between sintering and heat transfers.

Our simulations of Europa's icy surface spanned a million years, allowing us to thoroughly explore the evolution of ice microstructure. Results show that the hottest regions experience significant sintering, even if high temperatures are only reached during a brief portion of the day. This process takes place on timescales shorter than Europa's ice crust age, suggests that these regions should currently have surface ice composed of interconnected grains. Accurately simulating these highly coupled processes, plays a crucial role in accurately determining the microstructure and quantitative composition of Europa's surface, a key objective for upcoming missions such as JUICE and Europa Clipper.

How to cite: Mergny, C. and Schmidt, F.: Icy Moon Surfaces Microstructure through Multiphysics Simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9751, https://doi.org/10.5194/egusphere-egu24-9751, 2024.

EGU24-13407 | ECS | Posters on site | PS2.5

From Sea Ice to Icy Shells: Modeling the Dielectric Properties of Ice-Brine Mixtures 

Natalie Wolfenbarger, Dustin Schroeder, and Donald Blankenship

The search for habitable worlds within our solar system is guided by liquid water. Evidence for global, salty oceans hidden beneath the icy shells of moons in the Jovian system has motivated two upcoming missions: ESA’s Jupiter Icy Moons Explorer (Juice), launched April 2023, and NASA’s Europa Clipper, launching October 2024. Both spacecraft are equipped with ice-penetrating radar instruments, the Radar for Icy Moon Exploration (RIME) and the Radar for Europa Assessment and Sounding: Ocean to Near-surface (REASON), that will transmit radio waves into the subsurface and record energy reflected from interfaces defined by contrasts in dielectric properties, such as the ice-ocean interface.

The ocean is presumed to be the most extensive liquid water reservoir beneath the surface. However, various ice-water interfaces could exist throughout the ice shell. Dynamic processes such as impacts, convection, tidal heating, strike-slip faulting, and basal fracturing have been hypothesized to influence melt generation or inject ocean water in the ice shell interior. Even in the absence of these dynamic processes, impurities within the ice allow liquid water to be thermodynamically stable as brine at temperatures below the freezing point. In ice shells with non-zero bulk salinity, transitions from solid ice to ice-brine mixtures, or eutectic interfaces, invariably precede the ice-ocean interface. Understanding the detectability and radiometric character of eutectic interfaces is therefore a critical step towards interpreting the data collected by these ice-penetrating radar instruments.

In this work, we review measurements and models of the dielectric properties of sea ice and marine ice on Earth. We use these measurements and models as a foundation to propose a path forward for modeling the dielectric properties of eutectic interfaces within an ice shell. We assess how the ice shell's bulk salinity and the thickness of the thermally conductive layer impact the detectability and radiometric characteristics of eutectic interfaces. Our discussion includes how future laboratory measurements of existing terrestrial ice samples coupled to measurements of proxy samples consistent with off-world ocean sources can inform and refine our proposed framework.

How to cite: Wolfenbarger, N., Schroeder, D., and Blankenship, D.: From Sea Ice to Icy Shells: Modeling the Dielectric Properties of Ice-Brine Mixtures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13407, https://doi.org/10.5194/egusphere-egu24-13407, 2024.

EGU24-13575 | ECS | Orals | PS2.5

Supercooling and Glass Formation upon Freezing of Enceladus-relevant Salt Solutions 

Fabian Klenner, Lucas M. Fifer, Ardith D. Bravenec, Baptiste Journaux, and David C. Catling

Analysis of ice grains emitted from Saturn’s moon Enceladus revealed that the moon’s subsurface ocean represents a potentially habitable place in the Solar System [1-4].

The emitted ice grains could be crystalline, glassy, or a mixture of both [5,6]. These phase states of the grains are ultimately linked to their formation, i.e. liquid-solid phase transitions. Recent work indicates that emitted plume material does not directly reflect ocean composition [7]. However, even a small fraction of glass within the grains may be favorable for the preservation of organics or even cells [8,9], potentially present in Enceladus’s ocean.

Supercooling, vitrification (glass formation) and heat capacities of aqueous solutions can be measured with or derived from Differential Scanning Calorimetry (DSC). This technique was recently used to study Mars-relevant brines [10]. For Enceladus-relevant salt systems (described below), liquid-solid phase transitions remain an open area of research with limited thermodynamic data.

Here, we present results from DSC experiments with aliquots of aqueous solutions of NaCl, KCl, Na2CO3, NaHCO3, NH4OH, Na2HPO4, K2HPO4, as well as mixtures thereof. Measured salt concentrations covered the range of estimated concentrations of these compounds in Enceladus’s ocean [3,7,11]. We analyzed samples (volumes from 4 to 40 μL) over a wide range of cooling rates, from as low as 10 K/min up to ~1000 K/min via drop-quenching into liquid nitrogen (flash freezing). We then modeled the freezing process of these solutions and associated mineral formation using the aqueous chemistry package PHREEQC and compared the modeling results with our DSC experiments.

Our preliminary results show that at least 60 K supercooling is possible to occur during freezing of salty ice grains from Enceladus. Between 0.5 – 15 percent of the grain’s total volume form a glassy state, with salt-rich grains containing more glass than salt-poor grains. Flash freezing leads to a significantly higher degree of vitrification and lower glass transition temperatures (Tg) than other cooling rates.

Our work is an important step toward understanding the formation and structure of ice grains from Enceladus as well as their capability for cryopreservation of organics and cells. Thermodynamic and kinetic data derived from our experimental results, such as heat capacities and Tg, help inform future models. Our results are also relevant to Jupiter’s moon Europa where a potential plume might also be sourced from the moon’s underlying water ocean.

 

References

[1] Postberg et al. (2018) Nature 558, 564–568.

[2] Khawaja et al. (2019) Mon. Not. R. Astron. Soc. 489, 5231–5243.

[3] Postberg et al. (2023) Nature 618, 489–493.

[4] Hsu et al. (2015) Nature 519, 1098–1101.

[5] Newman et al. (2008) Icarus 193, 397–406.

[6] Fox-Powell & Cousins (2021) J. Geophys. Res.: Planets 126, e2020JE006628.

[7] Fifer et al. (2022) Planet Sci. J. 3, 191.

[8] Fahy & Wowk (2015) in Cryopreservation and freeze-drying protocols, pp.21–82.

[9] Berejnov et al. (2006) J. Appl. Cryst. 39, 7848–7939.

[10] Bravenec & Catling (2023) ACS Earth Space Chem. 7, 1433–1445.

[11] Postberg et al. (2009) Nature 459, 1098–1101.

How to cite: Klenner, F., Fifer, L. M., Bravenec, A. D., Journaux, B., and Catling, D. C.: Supercooling and Glass Formation upon Freezing of Enceladus-relevant Salt Solutions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13575, https://doi.org/10.5194/egusphere-egu24-13575, 2024.

EGU24-15222 | Orals | PS2.5

Titan’s surface chemical composition: what we learnt after 13 years of Cassini exploration 

Anezina Solomonidou, Alice Le Gall, Paul Hayne, and Athena Coustenis

The Cassini spacecraft spent 13 years in the Saturnian system and performed observations of Titan through 127 flybys, along with the in situ observations of the surface by Huygens. This led to the detailed investigation of Titan’s surface composition at both local and global scale. However, due to the complexity of Titan’s atmosphere and surface, the surface composition is only partially unveiled and is still considered to be one of Titan’s largest mysteries. Titan is resembling Earth like no other body in our solar system even though its mean surface temperature in -180 ºC (~93 K), and instead of silicate rocks like on Earth, water ice is abundant in the crust. Sedimentary deposits in the form of hydrocarbon grains cover the top layer of the surface, while liquid hydrocarbons are found in the polar lakes. Titan’s active geology with its resurfacing processes creates a surficial topography where exposed materials from the underlying ‘old’ crust along with new atmospheric sediments are present. After Cassini and Huygens with their several instruments investigated Titan for more than a decade one of the prevailing questions that still remains unanswered is whether and where water ice is exposed on the surface. Additionally, advanced knowledge with regards to the mixtures and the materials that create and cover the surface is yet to be gained from future missions and ground/space telescopes that would carry advanced technology. Here, we present an overview of what we have learnt so far about the composition as well as its correlation and constraints with regards to Titan’s astrobiology.

How to cite: Solomonidou, A., Le Gall, A., Hayne, P., and Coustenis, A.: Titan’s surface chemical composition: what we learnt after 13 years of Cassini exploration, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15222, https://doi.org/10.5194/egusphere-egu24-15222, 2024.

EGU24-16084 | ECS | Posters on site | PS2.5

Towards biosignature detection on Icy Moons with ORIGIN 

Nikita Jennifer Boeren, Peter Keresztes Schmidt, Marek Tulej, Peter Wurz, and Andreas Riedo

In the search for life beyond Earth, the icy moons Europa and Enceladus have been brought forward as the most promising targets within our Solar System. Recently, the Enceladus Orbilander mission has gained significant interest as it has been selected as a NASA flagship mission1. This emphasises the need for reliable in-situ instrumentation capable of biosignature detection and identification.

In-situ instrumentation must not only meet flight-capability requirements, but the detection capabilities should extend beyond single molecules or compound groups. Various groups of compounds are listed to be of astrobiological interest, such as amino acids, lipids, and nucleobases1–3. Ideally, instruments should be capable of simultaneously detecting several different compound groups, in varying abundances from major components down to trace level. Therefore, to successfully detect both trace abundances and highly abundant compounds, a high sensitivity and wide dynamic range coverage are essential as well.

This contribution will provide a comprehensive overview of the ORIGIN (ORganics Information Gathering INstrument) space-prototype, a Laser Desorption Ionisation Mass Spectrometer (LDI-MS), designed for the in-situ detection of molecular biosignatures. ORIGIN's light-weight and robust design, includes a nanosecond pulsed laser system (λ=266 nm, 20 Hz, τ=3 ns) and a miniature reflectron-type Time-Of-Flight mass analyser (RTOF) (160 mm x Ø 60 mm)4. The instrument is designed to address the challenges of flight-capability, sensitivity, and dynamic range coverage, which are all essential for reliable biosignature detection on exploration missions.

ORIGIN's analytical capabilities have been demonstrated for amino acids and lipids, and have recently been extended to nucleobases4-6. We will discuss results of the recent experiments to give an overview of ORIGIN’s detection capabilities including sensitivity and dynamic range, which are crucial for future space exploration missions. The determined limit of detection for three lipids (∼7×10−13 mol μL−1) aligns with the specified requirements in the Enceladus Orbilander mission concept (1×10−12 mol μL−1)3,6. The application of ORIGIN towards the detection of biosignatures on icy moons and the envisioned concept of ice sample handling will also be discussed.

1. National Academies of Sciences, Engineering, and Medicine. Origins, Worlds, Life: A Decadal Strategy for Planetary Science and Astrobiology 2023-2032. 26522 (The National Academies Press, 2022). doi:10.17226/26522.
2. Hand, K. P. et al. Report of the Europa Lander Science Definition Team. (Jet Propulsion Laboratory, 2017).
3. MacKenzie, S. et al. Enceladus Orbilander: A Flagship Mission Concept for the Planetary Decadal Survey. vol. 2020 (John Hopkins Applied Physics Laboratory, 2020).
4. Ligterink, N. F. W. et al. ORIGIN: a novel and compact Laser Desorption – Mass Spectrometry system for sensitive in situ detection of amino acids on extraterrestrial surfaces. Sci. Rep. 10, 9641 (2020).
5. Boeren, N. J. et al. Detecting Lipids on Planetary Surfaces with Laser Desorption Ionization Mass Spectrometry. Planet. Sci. J. 3, 241 (2022).
6. Boeren N.J. et al. Laser Desorption Ionization Mass Spectrometry of Nucleobases for Future Space Exploration Missions, Planet. Sci. J., to be submitted.

How to cite: Boeren, N. J., Keresztes Schmidt, P., Tulej, M., Wurz, P., and Riedo, A.: Towards biosignature detection on Icy Moons with ORIGIN, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16084, https://doi.org/10.5194/egusphere-egu24-16084, 2024.

EGU24-17310 | ECS | Orals | PS2.5

Reflectance properties of analogues for the surfaces of icy moons 

Rafael Ottersberg, Antoine Pommerol, Linus Leo Stöckli, and Nicolas Thomas

Spectrometers and colour imagers on past and future space missions, as well as ground-based telescopes, help us to improve our understanding of the composition of icy surfaces in the outer solar system. To help interpret these datasets, we study the VIS-NIR (0.4-2.5 µm) reflectance properties of granular (salty) ice particles exposed to simulated space environments.

We further developed an original experimental chamber (SCITEAS-2) to study the evolution of samples at temperatures representative of icy planetary surfaces in the outer solar system. We built a new cooling/heating stage to precisely control the sample’s temperature, allowing us to decouple the effects of temperature and time on the sublimation process. The surface temperature of the ice is monitored by measuring IR-emission using Thermopile sensors. To study the reflectance of the sample, we use a hyperspectral imaging system consisting of a Halogen light source, a monochromator, and two cameras (CCD and MCT). We produce granular ice particles with a broad size distribution (d≈1-400µm) by flash-freezing dispersed droplets in LN2. These particles can be made from pure water or salty solutions.

We observe that the VIS-spectrum of pure water ice is flatter than the one of the ice produced from a 10wt% NaCl solution, which has a blue slope. The most prominent feature of granular 10wt% NaCl-ice is a narrow absorption feature at 1.98 µm, attributed to hydrohalite (NaCl · 2H2O), which is not present in the pure ice sample. However, it only appears after some sublimation of the sample. While the spectra of pure water ice and 10wt% NaCl ice match well for the pristine samples, sublimation strongly increases the albedo of salty ice. Sublimation forms a crust atop the sample, affecting the reflectance and strongly influencing other thermo-physical properties. Therefore, we propose that sublimation is an important ingredient in interpreting spectral data of the Jovian Moon Europa because the timescales of the effects of sublimation are smaller than surface renewal by micrometeorite gardening or sputtering.

These datasets will help to interpret high-resolution colour images and spectra acquired by the EIS and MISE instruments on Europa Clipper as well as similar instruments on JUICE.

How to cite: Ottersberg, R., Pommerol, A., Stöckli, L. L., and Thomas, N.: Reflectance properties of analogues for the surfaces of icy moons, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17310, https://doi.org/10.5194/egusphere-egu24-17310, 2024.

EGU24-17359 | ECS | Orals | PS2.5

Microwave scattering in the Antarctic megadunes region: reconciling radar and radiometry 

Lea Bonnefoy, Catherine Prigent, Ghislain Picard, Clément Soriot, Lise Kilic, and Carlos Jimenez

Icy surfaces across the solar system display unusual microwave radar and radiometry properties, including very high backscattering cross-sections and polarization ratios. At low temperature, snow and ice are very transparent to microwaves, leading to long path lengths and multiple scattering. Yet despite the large volume of available passive and active microwave satellite observations over the Earth cryosphere, physical interpretation of the co-variability of the multi-frequency observations is still challenging, especially when trying to reconcile radiometry and radar observations. To shed light on microwave scattering in icy regoliths, we focus on the Antarctic megadunes region, the coldest and driest area on Earth, which we propose as a new analog for icy satellites due to its very low precipitation (net zero snow accumulation) and temperature (averaging -50°C), combined with the highest microwave backscatter in Antarctica. We assemble a dataset consisting of 5.2 GHz ASCAT and 13.4 GHz QuikSCAT and OSCAT scatterometry, as well as AMSR2 radiometry at 6.9 to 89 GHz. Using the Snow Microwave Radiative Transfer (SMRT) model with a simplified snowpack with constant temperature and continuously increasing grain size and density with depth, we simulate simultaneously radar and radiometry. For the first time, we show that scatterometry and 6.9 to 37 GHz radiometry at V polarization can be successfully simulated with a unique simple snowpack model, indicating that incoherent volume scattering on subsurface heterogeneities dominates both the active and passive signal. The success of our approach encourages further work to analyze and simulate jointly active and passive microwave observations, both in the Earth cryosphere and on icy moons.

How to cite: Bonnefoy, L., Prigent, C., Picard, G., Soriot, C., Kilic, L., and Jimenez, C.: Microwave scattering in the Antarctic megadunes region: reconciling radar and radiometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17359, https://doi.org/10.5194/egusphere-egu24-17359, 2024.

EGU24-17668 | ECS | Posters on site | PS2.5

Numerical analysis of polar orbits for future Enceladus missions 

Taruna Parihar, Hauke Hussmann, Kai Wickhusen, Gabriel Caritá, Alexander Stark, Jürgen Oberst, Andreas Benedikter, Eduardo Rodrigues Silva Filho, Jalal Matar, and Roman Galas

Saturn's moon Enceladus gained limelight with the discovery by the Cassini spacecraft of plumes of ejected gas and ice particles from pronounced linear structures in its South Pole region called “Tiger Stripes". The small (500 km) satellite is believed to have a porous rocky core and an ice shell, separated by a global subsurface saltwater ocean. The tidal heating potentially aids in driving chemical reactions in the moon’s interior which makes it a very promising candidate where the right conditions for life formation may exist. This makes Enceladus a prime target for a future spacecraft remote sensing mission. Due to the strong gravitational perturbations caused by Saturn, the higher gravitational moments of Enceladus and additional perturbations by the other moons of Saturn, the dynamic environment for artificial satellites around Enceladus is extremely complex. As a consequence, the search for natural stable orbits is far from trivial. We carried out comprehensive numerical integrations of spacecraft orbits, with the aim to find suitable candidate orbits for a remote sensing mission. A polar orbit is desirable to further investigate the tiger stripes region, and for mapping of the global subsurface ocean. Also, the orbit should provide repeated coverage for various instruments on board the satellite. All the relevant perturbations caused by the Sun, Jupiter, Saturn and its other moons, the higher degrees and order of Enceladus’ gravity field and solar radiation pressure are taken into account. We searched for suitable orbits in inertial space by varying orbital parameters such as semi-major axis (350 to 450 km), inclination (40° to 120°) and longitude of ascending node. Moderately inclined orbits (inclination between 45° and 60°) covering the equatorial and mid-latitude regions of Enceladus were found to be stable from several months up to years. In contrast, the more useful polar mapping orbits were found to be extremely unstable due to the so-called “Kozai mechanism”, due to which a spacecraft would impact the moon’s surface within a few days. However, an example of a highly inclined orbit was found with inclination of approximately 79°, which had an orbital life time of 13 days. A longer mission in this orbit would require correction maneuvers every approximately 10 days. This would provide coverage of the tiger stripes region and allow for a global characterization of the ocean. We also determined the delta-v that would be necessary to maintain such an orbit over a mission of several months. Also, special attention was paid to satellite formation flying in this orbit to maintain a stable baseline for a distributed radar sounder system (across-track formation of multiple satellites).

How to cite: Parihar, T., Hussmann, H., Wickhusen, K., Caritá, G., Stark, A., Oberst, J., Benedikter, A., Rodrigues Silva Filho, E., Matar, J., and Galas, R.: Numerical analysis of polar orbits for future Enceladus missions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17668, https://doi.org/10.5194/egusphere-egu24-17668, 2024.

EGU24-18102 * | Orals | PS2.5 | Highlight

JUICE flybys at Europa: context for MAJIS observations 

Emiliano D'Aversa, Nicolas Ligier, François Poulet, Yves Langevin, John Carter, and Giuseppe Piccioni

We report here about the currently foreseen scientific activity of the MAJIS instrument during the two planned JUICE flybys of Europa in 2032. MAJIS [1] (Moon and Jupiter Imaging Spectrometer) is a two-channel imaging spectrometer onboard JUICE, covering the spectral range 0.5-5.55 μm, splitted in a VISNIR channel (0.5-2.36 μm, <4.6 nm sampling) and a IR channel (2.27-5.55 μm, <7 nm sampling). This work has been developed in the framework of an inter-instrumental planning exercise carried on by ESA in 2022/23 to establish the best scientific and technical strategy to be adopted by the JUICE spacecraft during its low-altitude encounters with the Jovian satellite. Although the final JUICE trajectory is still subject to change (version Crema 5.0 [2] has been used), and several details of the actual observations are pending, the overall framework of the operations is well established and able to give an idea of the possible scientific constraints and outcomes for MAJIS.

The two Europa flybys are expected to be rather similar in terms of overall geometry, but almost specular about equator, enabling a good complementary coverage of both northern and southern hemispheres. Only the first one has been studied in detail and discussed here.

Due to favorable illumination conditions, the flyby inbound leg is mainly devoted to surface studies. A first almost full coverage of the trailing hemisphere for all latitudes below 45°N, including some slant view of the southern polar cap, can be obtained at lower resolutions (3-10 km/px), during the initial flyby phase.A wider surface coverage can then be achieved at medium spatial resolution (1-2 km/px), encompassing a wide portion of Europa’s darker trailing hemisphere. The 150 μrad IFOV will also enable MAJIS to acquire multispectral images of the Europa surface at high resolution (110-300 m/px) in small postage stamps distributed along narrow tracks (about 80 x 1800 km), near the closest approach. While current evaluations make them cover mid latitudes linear features (a region around Cadmus and Minos Lineae, ~160°E,45°N), the precise location of these high-res tracks might change significantly as a consequence of trajectory adjustments. 

A search for thermal anomalies can be performed during the outbound flyby leg, when the spacecraft mostly flies over the night (leading) hemisphere. The rest of the outbound is devoted to limb observations at different latitudes, with vertical resolution changing from 1.1 to 10 km/px. The high solar phase angle encountered in this section (~140°) is optimal for searching eventual active plumes thanks to the high forward scattering efficiency of small ice particles in the MAJIS spectral range. The region covered by such limb observations should also be compatible with the location of plumes reported in literature [3,4,5].

 

References

[1] Poulet et al., 2023, Submitted to Space Science Review.

[2] ESA SPICE Service, JUICE Operational SPICE Kernel Dataset, DOI: 10.5270/esa-ybmj68p.

[3] Roth et al.,2014, Science, 343, 171, DOI: 10.1126/science.1247051.

[4] Sparks et al.,2016, ApJ,829,121, DOI: 10.3847/0004-637X/829/2/121.

[5] Jia et al.,2018, Nature Astronomy, 2, 459, DOI: 10.1038/s41550-018-0450-z.

 

Acknowledgments

This work has been developed under the ASI-INAF agreement n. 2023-6-HH.0.

How to cite: D'Aversa, E., Ligier, N., Poulet, F., Langevin, Y., Carter, J., and Piccioni, G.: JUICE flybys at Europa: context for MAJIS observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18102, https://doi.org/10.5194/egusphere-egu24-18102, 2024.

EGU24-18178 | ECS | Posters on site | PS2.5

Microphysics of Europa’s surface with Galileo/NIMS data 

Guillaume Cruz Mermy, Frederic Schmidt, François Andrieu, Thomas Cornet, and Ines Belgacem

Europa’s surface is one of the youngest in the solar system. The Jovian moon is believed to hide a global liquid water ocean under its icy crust [1] and is exposed to intense space weathering due to the continuous bombardment by electrons and ions from Jupiter’s magnetosphere [2]. To understand the processes governing the evolution of the surface it is necessary to finely characterize the microphysics of the ice (composition via endmember volume abundance, grain size and surface roughness). However, the majority of the previous studies [3,4] do not allow to constrain precisely these parameters.

 

Here we report the use of a radiative transfer model [5] in a Bayesian MCMC inference framework [6,7] to retrieve microphysical properties of Europa's surface using the Galileo Near-Infrared Mapping Spectrometer (NIMS) hyperspectral data [8]. We present the analysis of a calibrated spectrum of a dark lineament from the trailing Anti-jovian hemisphere. The estimated signal-to-noise ratio (SNR) is between 5 and 50, we mainly focus on the 1.0-2.5 µm region for which the SNR is higher with an uncertainty on the absolute calibration up to 10% [8].

 

A first work has allowed us to test all combinations of 3, 4 and 5 endmembers from a list of 15 relevant compounds [9]. We were able to test over 5,000 combinations and show that some compounds appear necessary to reproduce the observation, such as water ice and sulfuric acid octahydrate, in agreement with previous studies [3,4,10]. However, adding either hydrated sulfates or chlorine salts produces results substantially similar [9]. Here we present a follow-up study in which we focus on the few acceptable combinations identified by our Bayesian inversions and we analyze the results in terms of grain size and surface roughness. We show that the grain size of the mandatory endmembers is well constrained and similar from one combination to another [11]. The macroscopic roughness is however poorly constrained [11], as expected. Thanks to numerical optimizations we are able to invert independently every spectel of a NIMS hyperspectral cube with the bayesian MCMC algorithm. From this result, we present maps of microphysical properties on an entire hyperspectral image of a dark lineament. 


References: [1] Pappalardo, R. et al. (1999) JGR. [2] Carlson, R. W. et al. (2005) Icar. [3] Ligier, N. Et al. (2016) The Astr. Jour. [4] King, O. Et al. (2022) PSS. [5] Hapke, B. (2012). Cambridge Univ. Press. [6] Cubillos, P. et al. (2016), The Astr. Jour. [7] Braak, C. J. F. (2008), Stat & Comp. [8] Carlson, R. et al. (1992) ed. C. T. Russell. [9] Cruz-Mermy, G. (2022) Icarus. [10] Mishra, I. et al. (2021) Planet. Sci. [11] Cruz-Mermy, G. (2024) In prep.

How to cite: Cruz Mermy, G., Schmidt, F., Andrieu, F., Cornet, T., and Belgacem, I.: Microphysics of Europa’s surface with Galileo/NIMS data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18178, https://doi.org/10.5194/egusphere-egu24-18178, 2024.

EGU24-18532 | ECS | Posters on site | PS2.5

The thermal and dynamic state of Europa’s ice shell: Revealed by global-scale convection models 

Tina Rückriemen-Bez, Ana-Catalina Plesa, William Byrne, Hauke Hussmann, and Andreas Benedikter

Europa’s hydro- and cryosphere is of primary interest in the quest for habitable environments in the solar system (e.g., [1]). The ice shell, which connects the potential subsurface ocean to the surface, may itself provide niches for life if liquid brine pockets can form and exist for extended periods of time. It is thus crucial to understand the thermal and dynamic state of the ice shell in order to characterize the existence and transport of liquid brines within the ice shell.

Recent work by [2] and [3] investigated the effects of temperature dependent thermal conductivity (k) as well as heat capacity (cp) and a complex composite rheology on convection in the ice shell. In this work, we build upon these previous efforts by combining the influence of both - varying thermodynamic parameters and complex rheology - in geodynamic simulations performed with the convection code GAIA [4]. Instead of a temperature-dependent heat capacity, we investigate the effect of a temperature- and depth-dependent thermal expansivity (α), which is a crucial term in determining the buoyancy induced by temperature differences.

 

We study the dynamic state (Nu-Ra scaling), the mechanical state (elastic thickness, brittle-to-ductile transition, deformation maps), and the thermal state (bottom and top boundary heat flux, occurrence of brines) of the ice shell for various setups (using both constant and variable α and k) and input parameters (ice shell thickness and grain size). For selected models, i.e. distinct thermal and dynamic states, we calculate the local two-way attenuation based on [5], [6]. The resulting two-way attenuation patterns will offer initial insights into the radar's ability to penetrate to the ice-ocean interface. If attenuation proves excessive due to the presence of hot thermal plumes, making the sampling of the ice-ocean interface unlikely, the patterns can still provide valuable insights into the dynamic state of Europa's ice shell. This includes parameters such as the thickness of the conductive layer (the so-called stagnant lid) that forms in the top part of the ice shell or the wavelength of convective structures deeper in the ice shell.

References:

[1] Coustenis & Encrenaz et al., 2013. [2] Carnahan et al. 2021. [3] Harel et al. 2020. [4] Hüttig et al., 2013. [5] Kalousova et al., 2017. [6] Soucek et al., 2023.

How to cite: Rückriemen-Bez, T., Plesa, A.-C., Byrne, W., Hussmann, H., and Benedikter, A.: The thermal and dynamic state of Europa’s ice shell: Revealed by global-scale convection models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18532, https://doi.org/10.5194/egusphere-egu24-18532, 2024.

EGU24-20219 | ECS | Posters on site | PS2.5

The Leaky Cauldron; an experimental study of the icy plumes of Enceladus 

Yael Bourgeois, Fabrizio Giordano, Stephanie Cazaux, and Ferry Schrijer

The discovery of vast subsurface oceans hidden under kilometers of ices on icy moons in our Solar System has sparked worldwide interests in ascertaining their potential habitability. In the case of Saturn’s moon Enceladus, supersonic plumes of water vapour and icy grains have been observed by the Cassini mission spewing from the surface, giving us indirect knowledge of the composition of this subsurface ocean. The exact mechanisms of the plumes however, and their effect on the composition of the ejected matter has yet to be clearly understood. The focus of this study is to experimentally investigate physical characteristics of the plumes located at the South Polar Terrain (SPT) of Enceladus. Using facilities at TU Delft faculty, we simulate experimentally the topology of the ice crevasses and the subsurface ocean with a narrow channel mounted atop a liquid water reservoir placed inside a vacuum chamber. We inquire upon the dependence of the channel walls temperature on the plume’s exhaust velocity. Using a straight channel, our results show that colder wall temperatures enable a saturated water vapour flow with a minima 1.5-3 % solid fraction and vent velocities reaching around 400-500 m/s. The data ranges for velocities and solid fraction extrapolated from the Cassini data (550-2000 m/s and 7-70 %) thus cannot be explained by straight channel models. Using a channel with an expansion ratio of 1.73 however, the measured supersonic plume velocity becomes comparable to some of the in situ Mach number determined at Enceladus. Using a method based on the energy conservation law, it is possible to extrapolate from our experimental data some plausible geometries of the ice crevasses of Enceladus. This work lays the ground work for a coming comprehensive parametric study of the channel geometry and its effect on exhaust Mach number, temperature and solid fraction.

How to cite: Bourgeois, Y., Giordano, F., Cazaux, S., and Schrijer, F.: The Leaky Cauldron; an experimental study of the icy plumes of Enceladus, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20219, https://doi.org/10.5194/egusphere-egu24-20219, 2024.

EGU24-20872 | ECS | Orals | PS2.5

Optimising Thermal Mapping Instrument Filters to Unveil Enceladus' Subsurface Secrets 

Duncan Lyster, Carly Howett, Neil Bowles, Rory Evans, Tristram Warren, and Keith Nowicki

Introduction: Enceladus is a key target for astrobiological study, with its subsurface ocean and cryovolcanism focused at the South Pole’s 'tiger stripe' fractures; understanding temperature variations is essential to decipher the moon's geological activity and potential for life. Blending heritage from TechDemoSat-1, Mars Climate Sounder, and Lunar Trailblazer, the University of Oxford’s Enceladus Thermal Mapper (ETM) faces new opportunities and challenges in observing this active icy moon of Saturn. This high heritage thermal instrument will characterise Enceladus’ activity and surface properties by measuring its day, night, and polar-night temperatures, with particular focus on the tiger stripes. The winter temperatures are the most challenging, as they plunge as low as 45 K. This cold temperature regime is driving adaptations to sensor design and operations, for example requiring long exposure times and meticulous noise control.

High-Resolution Multi-Band Radiometric Thermal Mapping vs Spectroscopy: Cassini's Composite Infrared Spectrometer (CIRS) achieved high spectral and spatial resolution, with its highest spatial-resolution detectors (focal planes 3 and 4) having 10 pixels, each with an instantaneous field of view (iFOV) of 0.273 mrad [1]. However, due to the limited flyby nature of Cassini much of Enceladus was left without high-resolution thermal mapping. In contrast, the University of Oxford's multi-band radiometric instrument operates 384 cross-track line scanning pixels, each with an iFOV of 0.540 mrad. The instrument has space for 15 wavelength bands and operates as a 384 x 288 pixel push-broom sensor. Preliminary mission concepts anticipate flying this instrument in orbit around Enceladus at an altitude of 150 km. This would mean ETM could globally map Enceladus at 80 m/pixel resolution, with a track 31 km wide (Fig. 1).

Digital Twin Instrument for Optimised Filter Selection: We will discuss the newly developed digital model of the instrument, which creates a framework for comparing and selecting various bandpass filters and sensor geometries. Strategically chosen filter profiles will facilitate the determination of black body emission curves, allowing for precise temperature measurements with a goal of improving constraints on global thermal emission due to tidal heating. The suitability of different filter profiles for NASA’s science goals will be discussed.

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Figure 1: Fractures at Enceladus’ South Pole – Cassini’s CIRS compared to Enceladus Thermal Mapper Warm fractures at Enceladus’ South Pole vary in temperature along their length. (Left) One of the highest resolution thermal maps captured by Cassini. [2] (Right) Artistic impression: Orbiting at 150 km, ETM’s ground track would be 31 km, and it would be capable of resolving 80 m features at nadir.

References: [1] Howett, C. J. A., Spencer, J. R., Pearl, J., and Segura, M. (2011) J. Geophys. Res., 116, E03003. [2] NASA/JPL/GSFC/SWRI/SSI (2010) "Zooming in on heat at Baghdad Sulcus", Cassini-Huygens, https://saturn.jpl.nasa.gov/

How to cite: Lyster, D., Howett, C., Bowles, N., Evans, R., Warren, T., and Nowicki, K.: Optimising Thermal Mapping Instrument Filters to Unveil Enceladus' Subsurface Secrets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20872, https://doi.org/10.5194/egusphere-egu24-20872, 2024.

EGU24-21117 | Posters on site | PS2.5 | Highlight

 Compiling analysis-ready ice data across cryosphere disciplines  

Julia Kowalski, Ana-Catalina Plesa, Marc Boxberg, Jacob Buffo, Klara Kalousova, Johanna Kerch, Maria Gema Llorens, Maurine Montagnat, Tina Rückriemen-Bez, Dustin Schroeder, Anna L. Simson, Christophe Sotin, Katrin Stephan, Benjamin Terschanski, Gabriel Tobie, and Natalie S. Wolfenbarger

Ice is omnipresent in our Solar System: on Earth, on different planetary bodies, and on moons in the outer Solar System. In the past, terrestrial and extraterrestrial cryosphere science mostly developed as independent research fields whereas synergies may shed light on both fields. In fact, close cooperation across different cryosphere research communities is a necessary prerequisite for designing future planetary exploration missions. An in-depth knowledge of similarities and differences between ice regimes on Earth and beyond paves the way for a mission preparation that optimally orchestrates terrestrial analogue field test, lab experiments, and simulation-based extrapolation to hypothesized ice regimes at the target body.


The authors of this contribution constitute the International Space Science Institute (ISSI) team Bridging the gap: from terrestrial to icy moons cryospheres, which started in 2023 and brings together scientists of different focus in terrestrial and extra-terrestrial cryosphere research. The overall goal of our project is to make knowledge hidden in the vast amounts of existing data from different research groups accessible by consolidating it into a comprehensive meta-data enriched compilation of ice properties including uncertainty margins if available. This extends to relevant physical regimes and different scales on both Earth, and icy moons including data from field campaign measurements, laboratory experiments, and planetary missions. A particular focus of our work will be to increase the analysis readiness of the data for subsequent data-driven or simulation-based analysis. This approach will provide us with the unique opportunity to transfer and extrapolate the information from the Earth to the outer Solar System bodies.


Here, we will introduce the project and its rationale, describe our approach to selecting and compiling the data, as well as how we will make them accessible, and present first results.

How to cite: Kowalski, J., Plesa, A.-C., Boxberg, M., Buffo, J., Kalousova, K., Kerch, J., Llorens, M. G., Montagnat, M., Rückriemen-Bez, T., Schroeder, D., Simson, A. L., Sotin, C., Stephan, K., Terschanski, B., Tobie, G., and Wolfenbarger, N. S.:  Compiling analysis-ready ice data across cryosphere disciplines , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21117, https://doi.org/10.5194/egusphere-egu24-21117, 2024.

PS3 – Small bodies: dwarf planets, asteroids, comets, KBOs, TNOs, meteors, and interplanetary dust

EGU24-1027 | ECS | Orals | PS3.1

Constraining the mass of meteoroids entering the atmosphere 

Simon Anghel, Mirel Birlan, and Dan-Alin Nedelcu

Cosmic objects, predominantly small meteoroids, frequently interact with Earth's atmosphere, and often go undetected due to their small size. Thus, to better understand the nature of these objects, we need to deploy networks of detectors which track their atmospheric disintegration [1]. This study delves into techniques for measuring the pre-atmospheric mass of meteoroids with known trajectories, some of which were the subject of successful meteorite recovery campaigns. Among the studied methods, we found that the radiated light of the meteoroid disintegration is the most reliable method of estimating its kinetic energy and pre-atmospheric mass [2]. This relation in combination with currently expanding fireball networks [3] can be used to calibrate other methods of estimating the objects mass (e.g. radio, infrasound). Ultimately, by constraining the size and frequency of small meteoroids, we can make inferences about the formation, evolution, and distribution of small objects and debris in the Solar System.

 

References:

[1] Colas F. et al. (2020) Astronomy & Astrophysics 644:A53.  [2] Anghel S. et al. (2021) Monthly Notices of the Royal Astronomical Society 508:571. [3] Vida D. et al. (2021) Monthly Notices of the Royal Astronomical Society 506:5046.

 

How to cite: Anghel, S., Birlan, M., and Nedelcu, D.-A.: Constraining the mass of meteoroids entering the atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1027, https://doi.org/10.5194/egusphere-egu24-1027, 2024.

EGU24-2629 | Posters on site | PS3.1

Highly collisional regions determined by interplanetary magnetic field structures 

Hairong Lai, Lin Pan, Yingdong Jia, Christopher Russell, Martin Connors, and Jun Cui

Submicron debris released in interplanetary collisions gets charged in the solar wind and generates disturbances to the magnetic field environment. The unique magnetic field disturbances, named interplanetary field enhancements (IFEs) are recorded by many spacecraft. In this study, we have developed a novel model to trace the IFEs to their origins. By employing this model, we can pinout regions with highly collision frequencies, thereby identifying regions of intense collisional activity. We can also determine the long-term variation of these highly collisional regions with interplanetary magnetic field observations over decades. The model can help constrain interplanetary magnetic disturbances and our results can be used to guide part of the interplanetary-object survey.

How to cite: Lai, H., Pan, L., Jia, Y., Russell, C., Connors, M., and Cui, J.: Highly collisional regions determined by interplanetary magnetic field structures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2629, https://doi.org/10.5194/egusphere-egu24-2629, 2024.

EGU24-2750 | ECS | Orals | PS3.1

The Mineralogy and Unique Widmanstatten Pattern in Iron Meteorites 

Salma Subhi and Aisha Alowais

This research aims to investigate iron meteorites samples, in terms of their elemental composition, distinguished structure, and their role in enhancing our understanding of the early solar system astrophysical processes. Iron meteorites represent a distinctive category of extraterrestrial materials, provide valuable insights into the formation and composition of asteroids, and the historical evolution of the early solar system around 4.6 billion years ago. Physical tests, including magnetism, fusion crust, density, and the window test, were performed on 140 samples from 2017 to 2023, with 161 analyses being carried out.  In addition to that, the study sheds light on the metallic phases of an oriented intergrowth of kamacite and taenite bands, revealing their occurrence in a unique Widmanstatten pattern. This pattern is visible on the studied samples that have been cut, polished, and etched with a weak, nitric acid. This remarkable pattern provides essential information for unraveling the thermal and cooling histories of these celestial bodies. Advanced analytical techniques such as X-ray fluorescence (XRF), and X-ray diffraction (XRD), were employed to identify the mineralogy and chemical composition of a diverse array of specimens. Iron-nickel minerals such as Kamacite are commonly found in the studied samples as well as the presence of troilite (FeS) inclusions, and traces of other elements. Of the 140 samples, three samples from different countries were identified as iron meteorites, allowing for a nuanced exploration of their unique characteristics. The chemical composition and mineralogy of the samples, revealed by the mentioned techniques, lead us to conclude that these samples formed at the core of asteroids or fragmented planets. This research contributes significantly to the UAE’s planetary science program and enriches meteoritic studies for university students and researchers in this field.

How to cite: Subhi, S. and Alowais, A.: The Mineralogy and Unique Widmanstatten Pattern in Iron Meteorites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2750, https://doi.org/10.5194/egusphere-egu24-2750, 2024.

EGU24-3147 | ECS | Orals | PS3.1

Unraveling the Origins of JFC-like Bodies: A Comparative Study of Comets and Meteoroids 

Patrick Shober, Jeremie Vaubaillon, Gonzalo Tancredi, Hadrien Devillepoix, Eleanor Sansom, Sophie Deam, Simon Anghel, Francois Colas, and Silvia Martino

Jupiter-family comets (JFCs) originate from the Kuiper belt and scattered disk, characterized by short orbital periods and frequent interactions with Jupiter. Their icy composition and a chaotic transition to the inner solar system result in short dynamic and physical lifetimes. These features make JFCs key subjects for understanding the migration of celestial bodies and possibly the delivery of organic materials to the early Earth. Numerous studies of fireballs have historically posited a substantial contribution of large objects from JFC orbits, suggesting a significant presence of cometary material in the near-Earth environment. However, this prevalent belief necessitates a thorough re-examination, as the physical evolution of comets and the mechanisms governing their disintegration remain subjects of debate. Understanding the population of meteoroids and comets is crucial for evaluating this population's physical breakdown and evolution. Current dust models suggest that fragmentation and disintegration of comets play a significant role in populating the zodiacal cloud. However, the larger centimeter-meter scale debris observed by fireball networks has been shown to resemble more asteroidal sources dynamically, indicating that comets might be breaking down directly only into dust-sized fragments. 

This study extends the scope of existing research by conducting a detailed analysis of both JFCs and comet-like fireball observations, aiming to elucidate the origins and dynamics of objects on JFC-like orbits across varying size scales. Utilizing extensive data from four major fireball networks (DFN, EFN, FRIPON, MORP) and ephemeris data of JFCs, the research comprises 646 fireball orbits and 661 JFCs. Methods include orbital stability analysis over 10,000 years, Lyapunov lifetime estimation, debiased NEO model source region estimation, meteorite fall identification, and meteor shower analysis.

The analysis reveals that most meteoroids on JFC-like orbits do not align dynamically with typical JFCs. Instead, they predominantly originate from stable orbits in the outer main asteroid belt, challenging the notion that centimeter-to-meter scale meteoroids on JFC-like orbits primarily derive from JFCs. Furthermore, a subset of 24 JFCs in near-Earth orbits displayed unexpected orbital stability, suggesting a presence of asteroidal interlopers from the outer main belt within the JFC population.

Our study demonstrates significant dynamical differences between kilometer-scale JFCs and smaller meteoroids. While the larger JFCs frequently encounter Jupiter and have dynamic, transient orbits, the smaller meteoroids detected by fireball networks originate primarily from stable orbits, indicating a predominant influence of asteroidal material from the outer main belt. This finding challenges conventional assumptions about the origins of JFC-like debris observed on Earth and highlights the complexity and diversity of the small-body environment in our solar system.

 

How to cite: Shober, P., Vaubaillon, J., Tancredi, G., Devillepoix, H., Sansom, E., Deam, S., Anghel, S., Colas, F., and Martino, S.: Unraveling the Origins of JFC-like Bodies: A Comparative Study of Comets and Meteoroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3147, https://doi.org/10.5194/egusphere-egu24-3147, 2024.

EGU24-3854 | ECS | Posters on site | PS3.1

Image-based small body shape modeling using the neural implicit method 

Hao Chen, Jürgen Oberst, Konrad Willner, Xuanyu Hu, Friedrich Damme, Ramona Ziese, and Philipp Gläser

One of the objectives of cameras on spacecraft for exploration of asteroids and comets is to perform shape modeling of the small bodies. Stereo-photogrammetry (SPG) and stereo-photoclinometry (SPC) stand out as the two main image-based methods for shape modeling, used in both previous and ongoing missions. In recent years, machine learning technology has experienced rapid development and demonstrated great promise for planetary topographic modeling. However, applications to small bodies have been limited so far. In this work, we present a neural implicit shape modeling method designed specifically for small body images characterized by rapid model convergence. We select 25143 Itokawa, explored by the Hayabusa mission, as a demonstration.  The method uses a sparse set of 52 images captured by the Asteroid Multi-band Imaging Camera (AMICA). The results are consistent with models previously produced using the SPC method in terms of overall size and shape. Also, our method can effectively capture fine-scale terrain features on the surface of Itokawa. This suggests that the neural implicit method can provide a new option and insight for the 3D reconstruction of small bodies.

How to cite: Chen, H., Oberst, J., Willner, K., Hu, X., Damme, F., Ziese, R., and Gläser, P.: Image-based small body shape modeling using the neural implicit method, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3854, https://doi.org/10.5194/egusphere-egu24-3854, 2024.

EGU24-4652 | ECS | Orals | PS3.1

Discovery of Rubble-Pile Asteroid Dynamics through Sparse Symbolic Regression 

Iosto Fodde and Fabio Ferrari

Current evidence shows that most asteroids are rubble piles, which are defined to be aggregates of loosely consolidated material bound by gravity and likely a small amount of cohesive strength. Rubble-pile asteroids are granular systems, which can be reshaped through external excitation like meteoritic impacts, the YORP effect, and planetary encounters. Universal modelling of granular systems is one of the major unsolved topics in physics, as these systems are chaotic, multi-scale, and highly dependent on the non-linear interactions between its constituent particles. These difficulties are exacerbated as the low gravity invalidates some terrestrial observations and scaling laws.

Most analytical models are based on continuum mechanics, like the Mohr-Coulomb or Drucker–Prager criterion, fitted to specific sets of observations. These models are able to explain certain aspects of the asteroid population well, but are not able to accurately describe all their critical properties and are furthermore not dynamical. On the other hand, numerical simulations have shown a great potential to predict the evolution of these systems, down to properties of their individual fragments. However, their high computational burden and sensitive dependency on initial conditions make it harder to generalise conclusions made from them.

This work tries to bridge the gap between numerical and analytical modelling of rubble pile asteroids, by using the data produced by numerical simulations to derive a set of analytical equations of motion. Machine learning based system identification methods like genetic programming or neural networks have been shown to work well in predicting complex non-linear dynamical systems. However, key properties of good analytical models, like interpretability and generalizability, are often neglected by these methods. For this reason the sparse identification of non-linear dynamics (SINDy) method was developed, which avoids this problem by applying a sequential thresholding least-squares algorithm on a set of mathematical functions to obtain a sparse representation of the dynamics. 

In this work, first a set of time series data is obtained from the numerical code GRAINS, which is an N-body code that takes into account the complex shape of the individual particles, as they interact through self gravity and contact. A set of macroscopic state and environment variables are selected, which can either be physical values like the moments of inertia and/or spin-up rate, or numerically derived optimal coordinates (using e.g. proper orthogonal decomposition). This time series data is then used by SINDy to obtain a symbolic representation of the time derivative of the state variables. The thresholding parameter of SINDy can be tuned to obtain either a simpler model that mainly qualitatively describes the system, or a more complex model that also has a good quantitative performance. These analytical models are then used to obtain various dynamical properties of the systems, e.g. equilibrium points, bifurcations, etc.

This research shows how the data obtained from simulations can be used to obtain a parsimonious model for the dynamics of rubble pile asteroids. These models can further improve our understanding of the origin and evolution of rubble-pile asteroids, and help inform and interpret future observations.

How to cite: Fodde, I. and Ferrari, F.: Discovery of Rubble-Pile Asteroid Dynamics through Sparse Symbolic Regression, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4652, https://doi.org/10.5194/egusphere-egu24-4652, 2024.

EGU24-6055 | ECS | Posters on site | PS3.1

Searching for a concentration of olivine-rich bodies in asteroid collisional families in the main belt 

Marjorie Galinier, Marco Delbo, Chrysa Avdellidou, and Laurent Galluccio

It is understood that large asteroids that were (partially) melted by the heat produced by the decay of radioactive elements at the beginning of our Solar System, differentiated into layers of distinct compositions: an iron core, an olivine-rich mantle and a basaltic crust (Šrámek et al. 2012; Kruijer et al. 2014; Elkins-Tanton & Weiss 2017). Traces of material corresponding to each of these layers have been identified by studying the composition of asteroids in the current main asteroid belt. In addition, the collisional break-up of a differentiated asteroid is expected to produce fragments of different compositions representative of each layer. However, no family with a clear abundance of olivine-rich mantle-like asteroids has been found to date (DeMeo et al. 2019). There is a scarcity of olivine-rich asteroids in the main belt compared to other compositions, known as the ’missing mantle problem’. DeMeo et al. (2019) states that, up to now, there is no statistical concentration of olivine-rich objects in any asteroid family, and that these objects are evenly distributed throughout the main belt.

Using the Gaia DR3 dataset, which contains more than 60 000 Solar System small bodies with reflectance spectra in the visible wavelength range (Gaia Collaboration et al. 2023), we analysed the collisional families of Nesvorny et al. (2015) to search for a potential concentration of olivine-rich asteroids in any family. This composition corresponds to the A-type spectroscopic class in several taxonomic schemes (Bus & Binzel 2002; DeMeo et al. 2009; Mahlke et al. 2022). We found from the study of literature data that the family (36256) 1999 XT17 (FIN 629 in Nesvorny et al. 2015) was the most probable to show a concentration of potential olivine-rich objects. This family is located in the ’pristine zone’ of the main belt (Brož et al. 2013), and it contains 58 members in Nesvorny et al. (2015), 15 of which show a spectrum in the Gaia DR3 dataset.

We classified these 15 members with a χ2 procedure, using a combination of their Gaia DR3 spectra and their literature data, when available. We used the Bus-DeMeo (DeMeo et al. 2009) taxonomic templates to perform this classification, following the methods of Avdellidou et al. (2022). We obtained 12 objects classified as A-types out of the 15. We analysed the spectra of these objects and their position in the proper orbital elements space, and we concluded that a cluster of objects within the collisional (36256) 1999 XT17 family might show homogeneous olivine-rich compositions. This cluster could have once been part of a completely or partially-differentiated body, or could have been formed from nebular processes.

We will present the implications of our findings, including the possibility that despite being rare, A-type asteroids might be better revealed by large-scale spectroscopic surveys, such as ESA Gaia DR3/DR4 and the future NASA’s SPHEREx mission.

How to cite: Galinier, M., Delbo, M., Avdellidou, C., and Galluccio, L.: Searching for a concentration of olivine-rich bodies in asteroid collisional families in the main belt, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6055, https://doi.org/10.5194/egusphere-egu24-6055, 2024.

EGU24-7979 | Posters on site | PS3.1

VNIR Spectral comparison between S-Type asteroids and brachinites and ungrouped brachinites-like, in support of the HERA mission 

Alessandra Migliorini, Cristian Carli, Enrico Bruschini, Tiberio Cuppone, Stefania Stefani, Giovanni Pratesi, Alice Stephan, Fiorangela La Forgia, and Monica Lazzarin

The Didymos-Dimorphos binary system, target of the DART mission that successfully impacted the small moon Dimorphos in September 2022, is classified as an S-type asteroid. It shows spectral properties that well fit with the regions that are closer to high olivine abundances in the Band Area Ratio (B.A.R.) versus Band Center at 1 μm (BCI) plane. Further investigation of the Didymos-Dimorphos system will be performed with the HERA mission, to be launched in October 2024. S-type asteroids are characterized by spectral properties that span from low-Ca pyroxene, up to high-Ca pyroxene and olivine content, with possible different abundances of those phases. Different potential types of meteorites can overlap this region as suggested in different works. High interest is generally attributed to those objects with spectral properties that are in between pyroxene and olivine composition to better understand the potential detection limit of olivine and so clarify the olivine-paradox. Here, we investigate the spectral properties of 12 brachinites and ungrouped achondrites brachinite-like (UBAs), that have olivine abundance between 57% and 94% (and fayalite, Fa, between 17.5% and 34%) with some minor variation in mineral association, abundance, and composition. We study the Visible to Near Infrared (VNIR) reflectance properties to evidence how they change in a spectral range suitable to investigate S-types and compare with Didymos spectral properties. In the VNIR spectral range these samples clearly show a systematic trend between the BCI and the B.A.R. that correlate with the olivine abundance and slightly with iron content on olivine. In fact, meteorites with high olivine amounts but a very low Fa content (i.e. low iron) have positions of the absorptions coherent with the associated pyroxene. Clearly the samples investigated in this work moved from the portion of S (III) type with higher BCI up to the region defined by the S (I) type as defined by Gaffey et al. (1993), with VNIR mainly dominated by olivine. We can notice how Didymos nicely fit within this domain defined by brachinites-UBAs and it is slightly out from the OC boot defined by the S (IV) type.

This research was supported by ASI-INAF n.2018-16-HH.0 (Ol-BODIES project) and by ASI (agreement n. 2022-8-HH.0) for ESA’s Hera mission.

How to cite: Migliorini, A., Carli, C., Bruschini, E., Cuppone, T., Stefani, S., Pratesi, G., Stephan, A., La Forgia, F., and Lazzarin, M.: VNIR Spectral comparison between S-Type asteroids and brachinites and ungrouped brachinites-like, in support of the HERA mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7979, https://doi.org/10.5194/egusphere-egu24-7979, 2024.

EGU24-8518 | Orals | PS3.1

Continuous monitoring of dust impacts across the inner heliosphere by the Solar Orbiter RPW/TDS Maximum Amplitudes 

David Píša, Jan Souček, Samuel Kočiščák, Andreas Kvammen, Jakub Vaverka, Tomáš Formánek, Ondřej Santolík, Michiko Morooka, Milan Maksimovic, and Arnaud Zaslavsky

Hypervelocity (>1 km/s) dust grains orbiting in the inner heliosphere can collide with a spacecraft and create a plasma cloud that changes electrical conditions in the surrounding plasma. These changes can be detected by the onboard radio and plasma wave receivers acting as efficient dust impact detectors. Estimated dust impact rates depend on the observation time window and they are commonly extrapolated. Our study presents the RPW/TDS Maximum Amplitudes (MAMP) data that continuously monitors signals from up to four RPW antenna configurations (monopole or dipole, and HF Search Coil) onboard the Solar Orbiter satellite. The signal is sampled in the high cadence (2.091 Msps) and stored in a buffer as the absolute maximum amplitude. MAMP values are then provided with a cadence between 32 and 128 sps, giving us a time resolution between 8 and 31 ms. Individual dust impacts detected by the onboard algorithm evaluating 62ms-long waveform snapshots every second are compared with the MAMP observations and show a very good match. After corrections for the high amplitude plasma waves or non-standard operational modes, and together with the TDS Statistics, the MAMP observations are used for the individual dust impact identification and corrected impact rates during the entire Solar Orbiter mission.

How to cite: Píša, D., Souček, J., Kočiščák, S., Kvammen, A., Vaverka, J., Formánek, T., Santolík, O., Morooka, M., Maksimovic, M., and Zaslavsky, A.: Continuous monitoring of dust impacts across the inner heliosphere by the Solar Orbiter RPW/TDS Maximum Amplitudes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8518, https://doi.org/10.5194/egusphere-egu24-8518, 2024.

EGU24-8629 | ECS | Posters on site | PS3.1

Laboratory reflectance spectra of enstatite and oldhamite mixtures for comparison with Earth-based reflectance spectra of asteroid 2867 Šteins 

Kathrin Markus, Gabriele Arnold, Lyuba Moroz, Daniela Henckel, and Harald Hiesinger

2867 Šteins is a main belt asteroid and was a fly-by target of ESA’s Rosetta mission [1]. It has been previously studied by ground-based observations (e.g., [2,3,4,5,6,7]). It has been classified as an E[II]-type asteroid. E-type asteroids are characterized by flat or slightly reddish and featureless reflectance spectra in the VIS and NIR and high geometric albedos and are generally associated with aubrites, enstatite achondrites [8]. E[II]-type asteroids additionally show an absorption band at 0.49 µm, which has been attributed to oldhamite [9]. The depth of the absorption band at 0.49 µm in Šteins’ spectra has been reported to be 9-13 % [3,5,6,7]. Oldhamite usually only occurs as an accessory phase while the abundance required to produce the absorption band is much higher.

We present 0.3 to 16 µm reflectance spectra of synthetic enstatite (Mg2Si2O6), synthetic oldhamite (CaS), and of their mixtures for comparison with spectra of E[II]-type asteroids such as Šteins, and investigate the spectral behavior of the mixtures with respect to their oldhamite content.

All reflectance spectra were collected using a Bruker Vertex 80v FTIR spectrometer at the Planetary Spectroscopy Laboratory (PSL) of the Institute of Planetary Research at DLR, Berlin [10]. The synthesis of the enstatite sample with the composition En99.6Fs0.0Wo0.4 has been described in [11]. The oldhamite sample was purchased from abcr GmbH. Mixtures containing 1, 3, 5, 10, 20, 30, 40, 50, 60, 70, 80, and 90 vol% oldhamite were prepared.

The spectrum of synthetic oldhamite shows an absorption band at 0.41 µm with a relative depth of 11.4 % instead of the absorption band at 0.49 µm. This band is visible in the spectra of all mixtures, even in the spectrum of the mixture with only 1 vol% oldhamite. In the MIR, the spectra with ≤10 vol% oldhamite are very similar to the spectrum of the pure enstatite and are generally dominated by the Christiansen feature and the Reststrahlen bands. The pure oldhamite is significantly brighter than the enstatite spectrum in the MIR. Changes in the band depth and reflectance do not occur as a single trend, but follow two distinct trends. One for mixtures with ≤10 vol% of oldhamite where changes occur rapidly and another trend for mixtures with ≥20 vol% of oldhamite where changes occur more slowly.

The differences in the oldhamite absorption band do not allow for an estimation of the oldhamite content on Šteins but an overall comparison between the laboratory spectra and Earth-based spectra of Šteins gives an upper limit for the oldhamite content on the surface of Šteins of 40 vol%. 

[1] Keller et al. (2010) Science, 327, 190-193. [2] Barucci et al. (2005) A&A, 430, 313-317. [3] Nedelcu et al. (2007) A&A, 473, L33-L36. [4] Dotto et al. (2009) A&A, 494, L29-L32. [5] Fornasier et al.  2007) A&A, 474, L29-L32. [6] Fornasier et al. (2008) Icarus 196, 119-134. [7] Weissman et al. (2008) Met. Planet. Sci., 43, 905-914. [8] Gaffey et al.  1993) Meteoritics 28, 161-187. [9] Burbine et al. (2002) Met. Planet. Sci., 37, 1233-1244. [10] Maturilli and Helbert. (2019) LPSC, 1846. [11] Markus et al. (2018) Planet. Space Sci., 159, 43-55.

How to cite: Markus, K., Arnold, G., Moroz, L., Henckel, D., and Hiesinger, H.: Laboratory reflectance spectra of enstatite and oldhamite mixtures for comparison with Earth-based reflectance spectra of asteroid 2867 Šteins, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8629, https://doi.org/10.5194/egusphere-egu24-8629, 2024.

3D models of asteroids provide their physical properties, such as shape, size, and surface features, which are of great importance to asteroid exploration missions and scientific research. The stereo photoclinometry (SPC) technique retrieves detailed surface topography of asteroids based on the reflectance information embedded in the image intensity of each pixel, thus the assessment of its performance is essential before the launch of the mission spacecraft. This work presents a laboratory experiment to evaluate the high-resolution and high-precision 3D surface models of asteroids reconstructed through an integrated photogrammetric and photoclinometric approach using simulation images. The whole experiment involves 3 steps. Firstly, construct the scaled-down experimental fields to simulate real in-situ conditions of the space probe with 3D printed models of asteroids, which represent the target asteroids of future missions. Then, collect simulation data according to various scenarios that might be encountered in a real on-orbit mission. Finally, reconstruct detailed asteroid models through the SPC refinement approach on the basis of stereo photogrammetry (SPG) models. Our previous studies indicate that SPC performance is influenced by both the azimuth and the incidence angles of illumination, as well as the image's general intensity. The experiment takes all these factors into account, as a reference for improving the image-acquiring plan during the in-situ detailed survey phase. The integrated approach will be tested for pixel-wise surface reconstruction of 3D-printed asteroid models of different shapes, i.e., Itokawa and Bennu. According to initial experimental results, the developed approach demonstrates the capability to attain high geometric accuracies and capture fine small-scale topographic details, which fulfills the requirement of the asteroid exploration missions.

How to cite: Li, H., Wu, B., and Liu, Y.: Detailed 3D Surface Reconstruction of Asteroids by Integrating Stereo Photogrammetry and Stereo Photoclinometry, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8725, https://doi.org/10.5194/egusphere-egu24-8725, 2024.

EGU24-8902 | ECS | Posters on site | PS3.1

Laboratory study of dust impact ion free expansion 

Libor Nouzak, John Fontanese, Kathryn R. Edwards, Mihaly Horanyi, and Zoltan Sternovsky

This study presents the investigation of the angular and velocity distribution of ions expanding freely from a dust impact generated plasma plume. The characteristic angular and velocity distributions are relevant for the design of dust detector and analyzer instrument, or for the interpretation of electric field antenna signals generated by dust impacts on the spacecraft body.  Iron dust particles of micron and sub-micron size are accelerated to velocities 2–40 km/s using the electrostatic dust accelerator operated at the University of Colorado. A unique experimental setup with a delay line detector (DLD) is used to measure the properties of the expanding ion cloud. The DLD provides the position and the time of impact for individual ions originating from the tungsten impact plate. The angular distribution of ions with respect to target normal is calculated from these positions. The velocity distribution is determined from arrival times of the ions on the detector. The experimental results show that the impact-generated ions expand in the form of a plume with angular distribution following a cosine law and half angle 25°. The velocity distribution consists from different parts which correspond to expansion of a distinct plasma components. The slowest component of the distribution has the most probably speed around 5 km/s and the fastest component around 30 km/s. The contribution of the components changes according to velocity of dust.

How to cite: Nouzak, L., Fontanese, J., Edwards, K. R., Horanyi, M., and Sternovsky, Z.: Laboratory study of dust impact ion free expansion, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8902, https://doi.org/10.5194/egusphere-egu24-8902, 2024.

EGU24-9078 | Posters on site | PS3.1

On the question of when to settle for a target in the Comet Interceptor mission 

Erik Vigren, Anders I. Eriksson, Niklas J. T. Edberg, and Colin Snodgrass

The Comet Interceptor (CI) mission, planned for launch in 2029, will ideally involve a flyby of a dynamically new long period comet or an interstellar object passing through the inner solar system. Powerful ground based facilities like the Vera C. Rubin Observatory Legacy Survey of Space and Time will aid in the search for a potential target. The CI mission includes a parking phase at the Sun-Earth L2 point and the target may in fact still be unknown by the time of launch. The question on when to settle for a target is complex. For instance may arise the question of how long time it is motivated to await with a final decision given the chance that a better target may show up if just waiting a little bit longer. We present expectation value-based formalism that could aid in decision making of such kind.

How to cite: Vigren, E., Eriksson, A. I., Edberg, N. J. T., and Snodgrass, C.: On the question of when to settle for a target in the Comet Interceptor mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9078, https://doi.org/10.5194/egusphere-egu24-9078, 2024.

EGU24-9663 | ECS | Posters on site | PS3.1

Massive Micron Meteoroids in the near-Sun Space as Observed by Parker Solar Probe 

Tianhang Chen, Jiansen He, Ziqi Wu, and Rui Zhuo

The interplanetary dust, together with solar wind plasma, forms the space environment of the inner heliosphere. There are two main particle populations of dust, α-meteoroids in bound orbits with micron size and β-meteoroids in hyperbolic orbits with sub-micron and nano size. Collisions between dust particles and dynamical evolution of their orbits greatly shape the grain size and heliocentric distance distributions of dust cloud, yet the specific mechanism still remains unknown. After Parker Solar Probe (PSP) successfully performed more than 10 encounter missions, plenty of dust impact events have been recognized, providing a glimpse of the complex. In this work, we analyze the geometry feature of streaks captured by the Wide-field Imager for Parker Solar Probe (WISPR) and try to locate the impact origins. In addition, we translate the results of streak storms in WISPR images to dust impact rates so as to compare with those recorded by the PSP FIELDS Experiment (FIELDS). We find there is evidence for the α-meteoroids impact. The debris products are directly observed by WISPR. We also find that the dust impact rates determined by the two methods are in good agreement. A pure α-meteoroid model is used to fit the observed impact rates within about 0.3 AU (~67 solar radii) and the fit is pretty well, especially for the rates near perihelion of PSP. Based on these results, we suggest that α-meteoroids can take a significant proportion of zodiacal dust near the Sun and this may lead to a different size distribution of dust cloud and a different mechanism of meteoritic evolution from what they are observed as at 1 AU.

How to cite: Chen, T., He, J., Wu, Z., and Zhuo, R.: Massive Micron Meteoroids in the near-Sun Space as Observed by Parker Solar Probe, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9663, https://doi.org/10.5194/egusphere-egu24-9663, 2024.

EGU24-9846 | ECS | Orals | PS3.1

Planar dynamics of non-spherical close tidally locked binaries asteroids  

Gabriel Caritá, Hauke Hussmann, Antonio Fernando Bertachini de Almeida Prado, Nelson Callegari, Maria Helena Moreira Morais, and Ricardo Egydio de Carvalho

Asteroids are originated by the evolution of the disk in the Solar System and, in general, do not have spherical and symmetrical shapes. The reason for those irregular shapes is the small mass of the bodies, such that gravity is not sufficient to make them reach a spherical shape. Those irregular shapes make the study of spacecraft orbits to investigate those objects  complex. Adding this to the fact that their weak gravitational field allows forces that are usually negligible or of second order  for spacecraft near a massive body (e.g.,  solar radiation pressure) to be comparable to the gravitational forces, provides an interesting and important problem to be studied in terms of astrodynamics. The study of asteroids is important because they carry essential scientific information about the origin and evolution of the Solar System. For all these points, it is important to understand their motion and investigate the motion of a spacecraft close to the asteroid. Asteroids may exist alone or in groups of two or three. Recent observations show that binary asteroids could be even more common than we think. In that sense, the present research focused on studying the orbital evolution of a binary asteroid system with almost equal masses composed of two non-spherical asteroids tidally locked that are close to each other, and the dynamical evolution of spacecraft orbiting the system. Since Keplerian orbital elements are not always a good approach for spacecraft in high mass ratio binary systems, to study this problem, we consider the mathematical models of the planar full two-body-problem for the binary asteroid, and the circular restricted three-body problem for the spacecraft, adding ellipsoidal geometry to represent the non-spherical shapes of the binary in order to find natural stable solutions. We also analyzed the structure of the phase space and the importance of the effect of solar radiation pressure on this dynamics. We studied the dynamics and the effect of the gravitational shape of close binary systems in their mutual orbits, as well as the existence of spacecraft circular and resonant orbits. As an application of this research, we studied the binary system Antiope 90. We found stable, close direct and retrograde orbits for the jacobi constants between -1.1 and -0.5; and internal resonant retrograde orbits within the primary and the secondary for the energy -0.7. The majority of the dynamical structure has survived over 90 days assuming the effects of solar pressure radiation.

How to cite: Caritá, G., Hussmann, H., Prado, A. F. B. D. A., Callegari, N., Morais, M. H. M., and de Carvalho, R. E.: Planar dynamics of non-spherical close tidally locked binaries asteroids , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9846, https://doi.org/10.5194/egusphere-egu24-9846, 2024.

EGU24-10569 | Posters on site | PS3.1

Influence of ambient environment on dust grains detection by electric field instruments 

Jakub Vaverka, Jiří Pavlů, Jana Šafránková, Zdeněk Němeček, and Samia Ijaz

Dust grain impacting the spacecraft body can be either partly or totally evaporated and ionized as well as a small part of spacecraft material. A cloud of charged particles (impact cloud) generated by such impact can consequently influence the spacecraft potential and/or measurements of on-board scientific instruments. Electric field instruments are sensitive to these disturbances and typically register signals generated by dust impacts as short transient pulses. This method is commonly used for the detection of dust grains even without dedicated dust detectors.

The presented study is focused on the influence of the ambient environment on dust detection for various designs of electric field instruments (probes/antennas) operating in the monopole and dipole configurations. An ambient plasma influences the spacecraft potential, which is crucial for charge separation and consequent propagation of the impact cloud. The plasma and solitary waves also affect dust detection by the presence of other pulses in the measured data. It is important to understand these effects to compare results obtained by various spacecraft in different environments.

How to cite: Vaverka, J., Pavlů, J., Šafránková, J., Němeček, Z., and Ijaz, S.: Influence of ambient environment on dust grains detection by electric field instruments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10569, https://doi.org/10.5194/egusphere-egu24-10569, 2024.

EGU24-10656 | ECS | Posters on site | PS3.1

Study of Dust Impact Signals around Mars using MAVEN/LPW Observations 

Samia Ijaz, Jakub Vaverka, Zdeněk Němeček, and Jana Šafránková

Electric field instruments can detect dust impacts on a spacecraft body as transient pulses in the measured electric field. Our study investigates these transient (millisecond) pulses detected by the Langmuir Probe and Waves (LPW) instrument onboard the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft. We present a statistical analysis of 360,000 medium frequency burst electric field waveforms recorded in 2015; the study aims to identify and analyze the characteristics of these transient pulses. An automatic routine is used to detect waveforms with rapid fluctuations in the electric field data; this comprises over 12,000 events in the dipole and nearly 5,000 in the monopole configurations. Our findings reveal that most of the pulses in monopole configuration are likely the result of interference rather than dust impacts. Our analysis mainly focuses on dipole observations, which predominantly consist of bipolar events typically associated with dust impacts. These events are mainly detected in the Martian ionosphere, where the spacecraft is negatively charged. Fewer events are recorded when the spacecraft is positively charged, with a maximum at an altitude of 1200 km. The low detection rate of dust impact signals outside the ionosphere suggests that the planet is the most probable source of these dust particles. However, the physical processes by which dust grains are lifted from the surface of the planet to high altitudes are not clear, and thus a possibility that the signals observed might not be generated by dust impacts remains for further investigations.

How to cite: Ijaz, S., Vaverka, J., Němeček, Z., and Šafránková, J.: Study of Dust Impact Signals around Mars using MAVEN/LPW Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10656, https://doi.org/10.5194/egusphere-egu24-10656, 2024.

EGU24-11065 | ECS | Orals | PS3.1

Spectral ratioing of Afρ to constrain the particle size distributions of comets 

Nico Haslebacher, Nicolas Thomas, and Raphael Marschall

Introduction: Afρ is a measure for the brightness of a cometary coma [1]. In the past, Afρ has been commonly used as a proxy for the activity of comets [2]. In later studies it was found that the brightness of a coma (Afρ) is dominated by the particle size distribution [3] and that Afρ on its own is a poor predictor for the activity of a comet [4]. In this work we use a numerical model of cometary dust environments to get a better understanding of the relationship of Afρ and the particle size distribution and show how spectral ratioing of Afρ could provide constraints for the particle size distributions of comets.

Methods: A numerical dust model is used to calculate the expected Afρ at two different wavelengths for a wide range of different parameters. Specifically, we calculate the ratio Afρ (425 nm) / Afρ (900 nm) in dependence to the power-law index of the particle size distribution. It is implicitly assumed that the particle size distribution follows a simple power-law. We use particles sizes in the range of 0.01 µm to 10 cm and choose  logarithmic particle size bins that are small enough to have a converging result. The scattering properties of each particle size are calculated for three different dust compositions. We use water ice to model bright particles, enstatite to model silicate particles and amorphous carbon to model dark particles. The scattering properties are calculated based on Mie-theory. Further, we studied day-night asymmetries, parameters related to the outflow velocity of the dust and phase angle effects.

Results: We show that the spectral ratio of Afρ modelled at 425 nm and 900 nm correlate with the power-law index of the particle size distribution. Large particle dominated comas can be distinguished from small particle dominated comas. For small particle dominated coma the specral ratio of Afρ can be used to further constrain the power-law index.

Acknowledgments: This work has been carried out within the framework of the National Centre of Competence in Research PlanetS supported by the Swiss National Science Foundation under grants 51NF40_182901 and 51NF40_205606. Additional financial support from the European Space Agency is also acknowledged.

References: [1] A’Hearn, M. F. et. al. (1984), AJ, 89, 579 [2] Weiler, M. et. Al. (2003), A&A, 403, 313 [3] Fink, U. and Rubin, M. (2012), Icarus, 221, 721 [4] Marschall, R. et. al. (2022), A&A, 666, A151

 

How to cite: Haslebacher, N., Thomas, N., and Marschall, R.: Spectral ratioing of Afρ to constrain the particle size distributions of comets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11065, https://doi.org/10.5194/egusphere-egu24-11065, 2024.

An increasing number of small extraterrestrial objects in the Solar System are found to have bilobed shapes, which could have resulted from the merger of two independently formed bodies. It is both natural and justified to treat the lobes separately to account for, or discern, any potential difference between them (Andert, et al., 2015). Gravity provides a crucial constraint on the interior mass distribution of the body and is among the key scientific objectives in most space missions. Most often, the gravitational field is modeled as a spherical harmonic (SH) series, whose coefficients are then used along with other constraints to interpret the interior structure.

In this study, a double harmonic-series approach for the bilobed bodies is presented. Namely, a harmonic series is established for each lobe to facilitate the investigation of their interior structures separately. The focus of the analysis is on comet 67P/Churyumov-Gerasimenko, the rendezvous target of the Rosetta mission with an exemplary bilobed shape and variable gravity field (Sierks et al. 2015; Pätzold et al. 2016, 2019). We employ the ellipsoidal harmonic (EH) series, whose coefficients are fully analogous to those of the SH and whose reference surfaces fit more closely the triaxial shapes of the individual lobes (Hu 2016).

We develop the double EH model for 67P via simulations and assess the model performance around the body. Additionally, we discuss the equivalence of the double EH model to the SH model as well as the conditions for direct model transformation from the latter. We revisit the physical meaning of the EH coefficients and demonstrate how their known relationship to the body's mass density moments can be leveraged to interpret different mass distributions of the comet. Importantly, there should be no restriction on the applicability of the method to other bilobed objects.

 

Reference

Andert, T., et al. (2015), The Gravity field of Comet 67 P/Churyumov-Gerasimenko Expressed in Bispherical Harmonics, in: AGU Fall Meeting Abstracts. pp. P31E-2109.

Hu, X. (2016), The exact transformation from spherical harmonic to ellipsoidal harmonic coefficients for gravitational field modeling, Celest. Mech. & Dyn. Ast. 125, pp. 195-222, https://doi.org/10.1007/s10569-016-9678-z.

Pätzold, M., et al. (2016), A homogeneous nucleus for comet 67P/Churyumov-Gerasimenko from its gravity field, Nature, vol. 530, pp. 63-65, https://doi.org/10.1038/nature16535.

Pätzold, M., et al. (2019), The Nucleus of comet 67P/Churyumov-Gerasimenko - Part I: The global view - nucleus mass, mass-loss, porosity, and implications. Monthly Notices of the Royal Astronomical Society, 483, 2337–2346, https://doi.org/10.1093/mnras/sty3171.

Sierks H., et al. (2015), On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko, Science, vol. 347, no. 6220, https://doi.org/10.1126/science.aaa1044.

How to cite: Hu, X. and Andert, T.: Double harmonic-series gravitational field model for bilobed small bodies: example for 67P/Churyumov-Gerasimenko, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12458, https://doi.org/10.5194/egusphere-egu24-12458, 2024.

EGU24-12996 | ECS | Posters on site | PS3.1

Simulating NASA DART impact: Insights into the interior of asteroid Dimorphos 

Cem Berk Senel, Ozgur Karatekin, Robert Luther, Grégoire Henry, and Philippe Claeys

Impacts are commonplace in our Solar System, constituting one of the key mechanisms that regulate the evolution of asteroids and comets. From small-scale Martian meteorites to large biosphere-forming collisions, e.g., the Chicxulub catastrophe at the end of the Cretaceous Period, impact events are essential to understanding the dynamic history of planetary bodies. In recent years, asteroid missions have made major advancements in characterizing the Near-Earth Objects (NEOs), from JAXA's Hayabusa2 sample-return mission on asteroid Ryugu to NASA’s recent DART space mission that performed the first kinetic deflection on asteroid Dimorphos [1]. The upcoming Hera mission by the European Space Agency (ESA) will characterize the DART impact during a rendezvous with Dimorphos in 2026. Meanwhile, numerical simulations have studied the potential impact cratering and ejecta plume outcomes in response to the DART-scale impactor [2]. Yet, interior features of near-Earth asteroids remain unknown. Understanding what lies inside Dimorphos, various interior scenarios are tested by combining shock physics modeling with the outputs of ejecta observations. The observed ejecta outcome makes it possible to groundtruth modeled ejecta. Therefore, a series of hypervelocity impact simulations are performed through the iSALE2D shock physics code [3-5], incorporating recent mechanical and material parameters [6,7]. Additionally, the DART spacecraft is approximated to be a porous aluminum sphere. The impactor vertically collides at a speed of 6.145 km/s, with Dimorphos taken as an axisymmetric ellipsoid. We test the DART impact within the low-to-intermediate strength regime (1 Pa - 1 kPa) with a wide porosity range (10 - 50%) for a homogeneous interior. This process is iterated for heterogeneous interiors consisting of multiple weak or strong inner layering with or without core formation and boulders. The model results provide new predictions for the plausible cratering formation, thus key insights into the interior of Dimorphos.
References
[1] Daly et al. (2023). Nature, 616(7957), 443-447.
[2] Stickle et al. (2022). The Planetary science journal, 3(11), 248.
[3] Amsden et al. (1980). LANL Report, LA-8095:101p., New Mexico.
[4] Collins et al. (2004). Meteoritics & Planetary Science, 39(2), 217-231.
[5]​​ Wünnemann et al. (2006). Icarus, 180(2), 514-527.
[6] Luther et al. (2022). The Planetary science journal, 3(10), 227.
[7] Raducan et al. (2022). The Planetary science journal, 3(6), 128.

How to cite: Senel, C. B., Karatekin, O., Luther, R., Henry, G., and Claeys, P.: Simulating NASA DART impact: Insights into the interior of asteroid Dimorphos, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12996, https://doi.org/10.5194/egusphere-egu24-12996, 2024.

EGU24-13303 | Orals | PS3.1

Space Weathering Provides a Lower Limit on the Age of Saturn’s Rings 

Larry W. Esposito, Joshua P. Elliott, and E. Todd Bradley

Cassini observations of the micrometeoroid bombardment flux, ring mass and fractional pollution constrain the origin and history of Saturn’s rings. In the simplest model, the age of the rings can be estimated by assuming the rings are a closed system with constant bombardment at the current rate. Observations during the Cassini Grand Finale orbits provide some challenges for this assumption. Further, the remote sensing of the rings shows a red slope, with higher pollution at the shortest wavelengths, consistent with reddening due to space weathering of atmosphereless bodies. If processes at the time of the micrometeorite impacts or subsequent chemical and physical weathering can degrade the original pollutants, this means that laboratory spectra are not appropriate to determine the total extrinsic material that has struck the rings over its lifetime. Rosetta data on the dust composition and surface reflectivity of Comet P67 provide our starting point for the composition of the bombarding material. Laboratory results for irradiation of icy outer solar system analogues indicate oxidation of organics and other pollutants over time. It is now generally agreed that the radiolysis of ice by energetic ions, electrons and solar UV photons produces the oxygen, ozone and peroxide seen at many icy satellites. The porosity of ice provides sufficient space for chemical reactions and mobility (Li 2022). The ring particle surfaces are in addition continually gardened by particle collisions and meteoritic impacts. Because of these loss processes, the current fractional pollution provides only a lower limit on the total integrated pollution flux, and thus a lower limit for the ring age. Two independent analyses of Cassini UVIS spectra of Saturn’s rings give fractional pollution in the outer B ring of 2-3%. This provides a lower limit of 400 to 1600 million years for the most opaque parts of Saturn’s B ring, depending on whether we use the maximum or minimum values for the bombardment rate reported by Cassini CDA (Kempf 2023). The A and C rings, as well as other ring structures, may be younger, having formed more recently.

How to cite: Esposito, L. W., Elliott, J. P., and Bradley, E. T.: Space Weathering Provides a Lower Limit on the Age of Saturn’s Rings, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13303, https://doi.org/10.5194/egusphere-egu24-13303, 2024.

EGU24-14995 | ECS | Orals | PS3.1

Advanced Meteorite Identification through YOLO Object Detection Algorithms 

Aisha Alowais, Munya Alkhalifa, Salma Subhi, and Ilias Fernini

This study addresses the challenge of visually identifying meteorites from terrestrial rocks, traditionally a task for experts followed by chemical analysis. We propose a transformative approach using computer vision and machine learning, employing YOLO (You Only Look Once) object detection algorithms (versions 5, 6, 7, and 8), to overcome the bottleneck in expert availability for instantaneous classification. Leveraging a curated selection from the Sharjah Academy for Astronomy, Space Sciences, and Technology (SAASST) unique meteorite collection, we aim to differentiate meteorites from terrestrial rocks based on their surface features and characteristics. The collection comprises a diverse assemblage of approximately 8,000 objects such as iron meteorites, Martian meteorites, tektites, fulgurites, and more. Our methodology includes a comparative analysis of YOLO versions, focusing on precision, recall, and F1 scores to assess each algorithm's adaptability to the unique features of meteoritic material. Preliminary results indicate YOLOv5 as the most efficient compared to its previous versions, achieving a maximum mAP of 0.995 and correctly classifying 93% of test samples. This study aims to determine the optimal YOLO version for enhancing the accuracy and efficiency of meteorite classification. In addition, the selected optimal model will be deployed on a Jetson Nano processor aboard a drone, significantly enhancing onsite meteorite detection capabilities.

How to cite: Alowais, A., Alkhalifa, M., Subhi, S., and Fernini, I.: Advanced Meteorite Identification through YOLO Object Detection Algorithms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14995, https://doi.org/10.5194/egusphere-egu24-14995, 2024.

EGU24-15462 | ECS | Posters on site | PS3.1

Lake Zapovednoe's Molten Fragments of Tunguska Airburst in 1908 

Lucie Smrčinová, Gunther Kletetschka, Richard Štorc, Eva Švecová, Viktor Goliáš, and Daniel Vondrák

The Tunguska airburst occurred on June 30, 1908 and it was most likely caused by the impact of the Tunguska cosmic body (TCB). It is not clear what the origin of the TCB was as no impact craters or possible body remains have been found to date. We studied the possible molten fragments of the TCB found in lacustine sediments of Zapovednoe Lake, a water body which is located ~60 km west from the airburst epicentre. Lake sediment cores which were retrieved from the lake contained an event layer dated to 1908–1910 CE. This layer included microscopical molten fragments and anomalous composition.

 

Three short cores (ZP1, ZP2, ZP3) were extracted in the central part of Zapovednoe Lake using a Kajak gravity corer. We used an X-ray fluorescence spectroscopy (XRF) and Scanning Electron Microscopy (SEM) for lake sediment characterization. Magnetic spherules (MSPs) and other magnetic grains were extracted from ZP1 by standard magnetic separation technique and all MSPs were identified with SEM and characterized using elemental microanalysis. We performed XRF analyses of 2 or 5 mm thick slices of the sediment cores and evaluated the concentrations and ratios of individual elements. Sediment samples of ZP2 were used for core dating, using gamma spectrometry for the specific activity of 210Pb, 137Cs, and 226Ra isotopes similar to the record from nearby Suzdalevo Lake.

 

Radioisotope activities revealed the age consistent with the year 1908 CE. The gamma spectrometry results were in good agreement with the XRF measurements, where the event layer had increased concentrations of lithogenic elements, such as Mg, Al, Si, S, K, Ca, Ti, Fe, Cu and Mn. The SEM analysis revealed that molten fragments were indeed found among the potential MSPs extracted from the event layer and adjacent layers. These spherical melts were rich in iron and most of them were found at depth corresponding to the event layer. Only a small portion of MSPs was found in the adjacent layers.

 

Our results revealed the presence of the TCB airburst event layer. The anomalous event layer resulted from increased erosion in the Zapovednoe Lake catchment. However, massive tree falls and subsequent wildfires from the airburst likely contributed to the anomalous elemental composition of the lake sediment as well. We found for the first time in lake sediments preserved MSPs which come from the melts produced by the TCB airburst and may contain an extraterrestrial material.

How to cite: Smrčinová, L., Kletetschka, G., Štorc, R., Švecová, E., Goliáš, V., and Vondrák, D.: Lake Zapovednoe's Molten Fragments of Tunguska Airburst in 1908, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15462, https://doi.org/10.5194/egusphere-egu24-15462, 2024.

EGU24-15528 | Posters on site | PS3.1

The influence of sputtering and sublimation on Kuiper belt dust trajectories 

Ingrid Mann, Andrew Poppe, Amalie Gjelsvik, and Aigen Li

NASA’s New Horizons spacecraft is currently exploring the outer solar system and passes the Kuiper Belt. The Student Dust Counter (SDC) onboard New Horizons has measured the flux of interplanetary dust grains throughout nearly the entire mission so far. The observed dust flux around 50 AU at the expected edge of the the Kuipe belt is higher than predicted. A possible explanation could lie in the trajetcries of the dust particles that can be pushed out to large distances by radiation pressure force. We investigate the trajectories of ice particles in the Kuiper belt which are more strongly influenced by radiation pressure when their sizes are reduced, due to mass loss caused by sublimation, solar wind sputtering and photo sputtering. The results suggest that the changing size of the particles may lead to a more stable and confined dust ring in the Solar System's Kuiper Belt. 

How to cite: Mann, I., Poppe, A., Gjelsvik, A., and Li, A.: The influence of sputtering and sublimation on Kuiper belt dust trajectories, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15528, https://doi.org/10.5194/egusphere-egu24-15528, 2024.

EGU24-15837 | ECS | Orals | PS3.1

Studying gas flow on cometary surfaces with diffusivity variations using flow simulations and experiments 

Stephan Zivithal, Günter Kargl, Wolfgang Macher, Carsten Güttler, Bastian Gundlach, Holger Sierks, and Jürgen Blum

Comet surfaces have a complex morphology on large scales (such as pits, depressions, scarps and faults) as well as on small scales (such as particle size, porosity distribution and roughness of the comet surface). Little is known about the influence especially of small-scale structures on the gas-flow and the ability to lift off dust particles. Focusing on small-scale structures, we simulate diffusion processes applying Fick's law. For the upper and lower boundary of the simulated box, a flat sublimation front with constant pressure below the inactive surface layer and a perfect vacuum on the surface is assumed. By applying periodic boundary conditions in the planar direction, we mimic an infinite surface with periodic inhomogeneity. We performed the simulation with different variations of diffusivity. In one example, the simulation shows that a region of high porosity within a region of low porosity experiences an increase in the flow rate, as would be expected according to Fick's Law. Nevertheless, it also significantly changes the flow rate in the surrounding region due to lateral flows in the vicinity of the high diffusivity region. We analyze the results qualitatively and compare them with 3D Monte Carlo simulations in a similar setting, which shows a general agreement.

In addition, we conduct experiments with a dedicated vacuum-chamber to measure the viscous permeability and Knudsen diffusion of granular materials by applying the binary friction model. The design allows measurements in different gas-flow regimes, with most samples mainly covering the free molecular flow and the transition region. In the last measurement campaign, bi-disperse samples of spherical particles were measured and the results show a good agreement with generalized models depending on the specific surface area of the sample. The current measurement campaign focuses on angular materials and the influence of shape properties on diffusivity. The results show that packings of highly porous hollow cylinders have a lower diffusivity than expected compared to more compact packings of spherical particles. A comparison with Monte Carlo simulations (from [1,2]) of packings of highly porous spherical particles also shows a higher diffusivity compared to the same measurements. Further measurements will show whether a dependence on a particular shape property could explain this discrepancy.

[1] Macher, Wolfgang, et al. "Transmission probability of gas molecules through porous layers at Knudsen diffusion." Journal of Engineering Mathematics 144.1 (2024): 1-26.

[2] Güttler, Carsten, et al. "Simulation and experiment of gas diffusion in a granular bed." Monthly Notices of the Royal Astronomical Society 524.4 (2023): 6114-6123.

How to cite: Zivithal, S., Kargl, G., Macher, W., Güttler, C., Gundlach, B., Sierks, H., and Blum, J.: Studying gas flow on cometary surfaces with diffusivity variations using flow simulations and experiments, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15837, https://doi.org/10.5194/egusphere-egu24-15837, 2024.

EGU24-17927 | ECS | Orals | PS3.1

Numerical inference of viscoelastic properties in tidal models of rubble pile asteroids 

Ethan Burnett, Iosto Fodde, and Fabio Ferrari

Tidal theory in binary asteroids is in a low state of development in comparison to that of planetary satellites. The dissipative processes within binary secondaries are divergent from the processes at work in planetary satellites, and also the evolutionary timescales are drastically shortened. To study the tidal torques and the spin evolution of the smaller secondaries in binary asteroid systems, it is believed to still be possible to apply a viscoelastic theory somewhat analogous to the models used for planetary satellites (see e.g. Murray & Dermott 1999). If this is true, then there should exist body-averaged “bulk” material properties, such as rigidity and viscosity, applicable for these models. Importantly, it should be possible to compute effective k2 (tidal potential Love number) and Q (quality factor) values for these tiny worlds.

Some pioneering works have derived first-order tidal laws for binary asteroids via analytic and semi-analytic methods. Nimmo & Matsuyama (Icarus 2019) derive a friction-driven effective quality factor Q which decreases (i.e. more dissipation) with stronger friction. Goldreich & Sari (The Astrophysical Journal 2009) argue that effective rigidity is dynamically dominant, deriving an important law for effective k2 for asteroids that scales linearly with the asteroid radius. They also argue that effective Q could be quite low for asteroids, lower than prior estimates of Q ~102. By contrast, Efroimsky (The Astronomical Journal 2015) argues that effective viscosity is dominant and rigidity doesn’t matter. Recently, Pou and Nimmo (Icarus 2024) showed that k2/Q values implied by the ages of some binary asteroids are much lower than the values predicted by Goldreich & Sari (2009), suggesting that the theory of the latter is incomplete.

In this work, we follow up on the aforementioned theoretical works with numerical experiments of binary asteroid tidal evolution, which have strong scientific motive to be carried out. This is accomplished using the massive N-body simulation architecture of GRAINS (Ferrari et al, MNRAS 2019), wherein gravitational, contact, and frictional effects are modeled in the interaction of thousands of non-spherical mass elements. We initialize a simplified binary system analogous somewhat to the scenarios employed in Agrusa et al (PSJ, 2022). To facilitate tidal locking, the static moment-of-inertia asymmetry is made sufficiently large, the secondary is initialized in a state of slightly super-synchronous rotation, and inter-element friction is enhanced, if needed, to yield a dissipation timescale in line with our numerical capabilities (a move inspired by the approach of Goldreich, The Astronomical Journal 1966). From our simulation results, we perform the following analysis:

  • A simple regression analysis infers the effective k2/Q from the computed rotational energy dissipation rate, via parallel application of the classical 1D MacDonald tidal dissipation model.
  • Previously derived scaling laws for effective k2 and Q are tested.
  • The accuracy of the MacDonald tidal torque model for binary rubble pile asteroids is tested.
  • With time permitting, if the (unimodal) MacDonald tidal model is shown to be inaccurate, we'll explore computation of an appropriate multimodal tidal potential, as in Darwin-Kaula theory.

How to cite: Burnett, E., Fodde, I., and Ferrari, F.: Numerical inference of viscoelastic properties in tidal models of rubble pile asteroids, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17927, https://doi.org/10.5194/egusphere-egu24-17927, 2024.

EGU24-18373 | ECS | Orals | PS3.1

Comet 12P/Pons-Brooks' Dust Fate 

Gabriel Borderes Motta, Daniel Kastinen, Johan Kero, and Maria Gritsevich

Gritsevich et al. (2022) studied the evolution of a dust trail from the massive outburst of comet 17P/Holmes in October 2007. They predicted that ground-based telescopes could observe this dust trail in 2022 and the subsequent observations were successfully conducted. The observations of the dust trail provide a valuable opportunity to study many peculiarities of the comet, including its activity, structure, and characteristics of the released dust particles. In the present work, we study dynamic evolution of the particles after a long period of time. We investigate the potential for a collision with Earth, Moon, and other celestial bodies; instants of high concentration of particles in the dust trail, and how the solar radiation pressure affects the dynamics of the dust. Recently, comet 12P/Pons-Brooks has experienced a series of well-documented outbursts during its current approach to perihelion, making it an exciting case for investigation. We simulate the evolution of dust particles released by the outbursts of comet 12P/Pons-Brooks during 2023. We use the software REBOUND for the simulations, integrating with the IAS15 numerical integrator. We initiate a system with the Sun, Venus, Earth, Moon, Mars, Jupiter, Saturn, Uranus, and the comet itself at the outburst date for the simulation. The results of the simulations are detailed and analyzed throughout the work.

 

References

Maria Gritsevich, Markku Nissinen, Arto Oksanen, Jari Suomela, Elizabeth A Silber, Evolution of the dust trail of comet 17P/Holmes, Monthly Notices of the Royal Astronomical Society, Volume 513, Issue 2, June 2022, Pages 2201–2214, https://doi.org/10.1093/mnras/stac822

How to cite: Borderes Motta, G., Kastinen, D., Kero, J., and Gritsevich, M.: Comet 12P/Pons-Brooks' Dust Fate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18373, https://doi.org/10.5194/egusphere-egu24-18373, 2024.

We have a long-term goal of creating a holistic and cross-disciplinary approach to meteor research where we connect together topics such as meteor measurements, ablation simulations, meteoroid stream simulations, and sensor simulations. Here, we present the most recent work on developing an automated radar data analysis algorithm able to calculate probability distributions of meteor- and meteoroid parameters for head echoes measured using interferometric high-power large-aperture radars. The algorithm utilizes direct Monte Carlo simulations of uncertainties, with Bayesian Markov-chain Monte Carlo estimation of meteor model parameters. The algorithm also employs N-body propagation of distributions to perform orbit determination, estimating the galactic background noise temperature for absolute-calibration and an statistical approach using many high signal-to-noise ratio meteors for phase calibration. This analysis algorithm has been applied to data from the Middle and Upper atmosphere (MU) radar in Shigaraki, Japan. As a first case study, we have re-analysed a part of the MU radar meteor head echo data set collected during 2009-2010. As a result we have confirmed the existence of a rare high-altitude radar meteor population with initial altitudes reaching up to ~150 km. Out of the total amount of 106 000 events, only 74 had an initial altitude >130 km, while four of those had an initial altitude >145 km.

How to cite: Kastinen, D. and Kero, J.: High-altitude radar meteors detected using a new analysis algorithm for interferometric meteor head echoes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18828, https://doi.org/10.5194/egusphere-egu24-18828, 2024.

EGU24-19273 | Orals | PS3.1

Near-Earth Objects’ Forecast of Collisional Events (NEOForCE). Impact monitoring system 

Dmitrii Vavilov and Daniel Hestroffer

Estimating the probability of a collision of asteroids with the Earth is an important task for planetary defense. There are systems that compute impact probabilities of near-Earth asteroids with the Earth on a regular basis: Sentry (Nasa, Jet Propulsion Laboratory) and CLOMON-2 (originally University of Pisa, now ESA). Here we present NEOForCE (Near-Earth Objects Forecast for Collisional Events) a new monitoring system developed at Institut de mécanique céleste et de calcul des éphémérides (IMCCE, Paris Observatory). This system is original and independent. As ephemeris of major planets and the Moon we use INPOP [1]. The asteroids’ orbits and covariance matrices are taken from DynAstVO database [2]. For computing the impact probability we use the Line Of Variation (LOV) sampling method [3] but with significant modifications. The longest axis of the confidence ellipsoid is chosen to be sampled obtaining virtual asteroids. Each virtual asteroid’s orbit is propagated from the time of discovery 100 years ahead with variational equations. Each virtual asteroid is a representative of its small vicinity and we apply the Partial Banana Mapping method (PBM) [5] for each of this vicinity to look for possible collisions. Then the results are combined and the procedure to find explicitly the initial conditions of the collisional trajectory is launched.

The main differences with the existing monitoring systems are: usage of INPOP ephemeris of major planets instead of DE, having our own orbit fitting and propagation procedure of asteroids from DynAstVO, and implementation of Partial Banana Mapping method. Hence the system provides an independent assessment of the impact probability, which in case of risks is crucial.

 

[1] Fienga, A., et al. (2020) INPOP new release: INPOP19a. Astrometry, Earth Rotation, and Reference Systems in the GAIA era. p. 293-297.

[2] Desmars J., et al. (2017) DynAstVO: a Europlanet database of NEA orbits. European Planetary Science Congress. 2017. p. EPSC2017-324.

[3] Milani A., et al. (2005) Nonlinear impact monitoring: line of variation searches for impactors. ICARUS, V. 173, p. 362-384.

[4] Vavilov D.E. (2020) The partial banana mapping: a robust linear method for impact probability estimation. MNRAS, V. 492, p. 4546–4552.

How to cite: Vavilov, D. and Hestroffer, D.: Near-Earth Objects’ Forecast of Collisional Events (NEOForCE). Impact monitoring system, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19273, https://doi.org/10.5194/egusphere-egu24-19273, 2024.

EGU24-19491 | Orals | PS3.1

Superresolution color images from the sparse data cubes of the Hyperscout-H hyperspectral imager aboard the Hera mission 

Björn Grieger, Julia de León, Hannah Goldberg, Tomas Kohout, Gábor Kovács, Michael Küppers, Balázs Vince Nagy, and Marcel Popescu

On 26 September 2022, NASA's Double Asteroid Redirection Test (DART) mission impacted Dimorphos, the moonlet of near-earth asteroid (65803) Didymos, performing the world's first planetary defence test. ESA's Hera mission will be launched in October 2024 and rendezvous with the Didymos system end of 2026 or beginning of 2027. It will closely investigate the system and in particular the consequences of the DART impact.  

Hera carries the hyperspectral imager Hyperscout-H. Its sensor consists of 2048 x 1088 pixels which are arranged in macro pixel blocks of 5 x 5 pixels. The 25 pixels of each block are covered with filters in 25 different wavelengths where the center response ranges from 657 to 949 nm. Therefore, each of the 2048 x 1088 pixels provides only the brightness information for one wavelength and hence the theoretical 2048 x 1088 x 25 data cube is only sparsely populated. 

A simple straight forward approach to replenish the sparse data cube would be to move a 5 x 5 pixel window with one pixel steps horizotally and vertically over the whole frame and assign the obtained 25 wavelength spectrum to the center pixel of the window. Besides reducing the image resolution to the quite coarse macro pixels, the accuracy of this method is limited by pixel to pixel variations of the spectra and even more by varying albedo and shading effects caused by varying surface inclination. This makes the resultant spectra very noisy. 

In order to retrieve more accurate spectra with higher spatial resolution, we separate the spectrum at each micro pixel into a normalized spectrum and a brightness scaling factor. We assume the normalized spectra to be spatially smooth, but not necessarily the scaled spectra. Ratios of measured values are used to iteratively compute the normalized spectral value from adjacent pixels. After convergence, the spectra are brightness scaled to reproduce the measured values. This approach allows to replenish the complete data cube with full micro pixel resolution. The application to test images shows that spectra are recovered much more accurately than with the direct approach and that only very little spatial detail is lost. 

Having replenished the complete data cube allows us to construct color images at full micro pixel resolution. The three colors are sufficient to capture most of the spatial variation of the spectra of asteroid surfaces and hence the constructed color images provide a concise visualization of the respective full data cubes. 

How to cite: Grieger, B., de León, J., Goldberg, H., Kohout, T., Kovács, G., Küppers, M., Nagy, B. V., and Popescu, M.: Superresolution color images from the sparse data cubes of the Hyperscout-H hyperspectral imager aboard the Hera mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19491, https://doi.org/10.5194/egusphere-egu24-19491, 2024.

EGU24-19956 | Posters on site | PS3.1

Characterization of dust impact spots on various materials 

Jiří Pavlů, Libor Nouzák, Jan Wild, Libor Juha, Zoltan Sternovsky, Jana Šafránková, and Zdeněk Němeček

Understanding the interaction between dust grains and spacecraft materials is crucial for spacecraft dust observations. This study focuses on the characterization of hypervelocity space dust impact spots on a variety of materials commonly used in spacecraft construction. Utilizing laboratory-based experiments, we investigate the spots created by hypervelocity impacts.

Experimental setups involve subjecting different materials, including polymers, metals, and composites, to controlled impacts by accelerated micro-sized dust particles. We employ advanced imaging techniques, such as scanning electron microscopy (SEM), to analyze impact spots at micro and nanoscales. Energy-dispersive X-ray spectroscopy (EDS) is employed to assess compositional changes induced by impact events.

Preliminary results reveal unique impact signatures on diverse materials, showcasing variations in crater morphology, size distribution, and material response. The identification of surface modifications, including fractures, melting, and the formation of ejecta, provides valuable insights into the underlying physics of hypervelocity impacts on different materials. We attempt to extend our observations towards the ejecta creation efficency by various materials.

How to cite: Pavlů, J., Nouzák, L., Wild, J., Juha, L., Sternovsky, Z., Šafránková, J., and Němeček, Z.: Characterization of dust impact spots on various materials, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19956, https://doi.org/10.5194/egusphere-egu24-19956, 2024.

EGU24-20327 | Orals | PS3.1

Enstatite chondrite meteorites date the giant planet instability 

Chrysa Avdellidou, Marco Delbo, David Nesvorny, Kevin Walsh, and Alessandro Morbidelli

The identification of meteorite parent bodies provides the context for understanding planetesimal formation and evolution as well as the key solar system dynamical events they have witnessed. We identified that the family of asteroid fragments whose largest member is asteroid (161) Athor is the unique source of the rare EL enstatite chondrite meteorites (Avdellidou et al. 2022), the closest meteorites to Earth in terms of their isotopic ratios. The Athor family was created by the collisional fragmentation of a parent body 3 Gyr ago in the inner main belt (Delbo et al. 2019), however the diameter of the Athor family progenitor was much smaller than the putative size of the EL original planetesimal (Triellof et a. 2022). Therefore, we deduced that the EL planetesimal that accreted in the terrestrial planet region underwent a first catastrophic collision in that region, and one of its fragments suffered a more recent catastrophic collision in the main belt, generating the current source of the EL meteorites. 

We investigated the possible ways that could have brought the Athor family progenitor in its current position in the inner main belt. To do so, we used an interdisciplinary methodology where we combined laboratory meteorite thermochronometric data, thermal modelling, and dynamical simulations. 

We showed that planetesimal fragments from the terrestrial zone must have been implanted into the main asteroid belt at least 60 Myr after the beginning of the solar system. We concluded that the giant planet instability is the only dynamical process that can enable such implantation so late in the solar system timeline. 

Acknowledgements. We acknowledge support from the ANR ORIGINS (ANR- 18-CE31-0014). This work is based on data provided by the Minor Planet Physical Properties Catalogue (MP3C) of the Observatoire de la Côte d’Azur (mp3c.oca.eu).

References:

Avdellidou, Delbo, A. Morbidelli, Walsh, Munaibari, Bourdelle de Micas, Devogèle, Fornasier, Gounelle, & van Belle. Athor asteroid family as the source of the EL enstatite meteorites, 2022, A&A, 665, id.L9, 13 pp.

Delbo, Avdellidou, & Morbidelli, Ancient and primordial collisional families as the main sources of X-type asteroids of the inner main belt, 2019, A&A, 624, A69 

Trieloff, Hopp & Gail. Evolution of the parent body of enstatite (EL) chondrites, 2022, Icarus, 373, 114762

How to cite: Avdellidou, C., Delbo, M., Nesvorny, D., Walsh, K., and Morbidelli, A.: Enstatite chondrite meteorites date the giant planet instability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20327, https://doi.org/10.5194/egusphere-egu24-20327, 2024.

EGU24-22216 | Orals | PS3.1

Activities of the Comet Interceptor Comet Environment and Target Identification Working Groups 

Geraint Jones, Colin Snodgrass, Aurelie Guilbert-Lepoutre, Jean-Baptiste Vincent, Charlotte Goetz, Elena Martellato, Seiji Sugita, and Kueppers Kueppers

Comet Interceptor is an European Space Agency (ESA) mission in cooperation with the Japan Aerospace Exploration Agency (JAXA). It aims to characterise through a close flyby a long period comet, preferably dynamically new, or an interstellar object. The main spacecraft will be accompanied in its encounter with the target comet’s nucleus by two small probes, one provided by Europe, and the other by Japan. The mission is planned for launch in 2029. Its Science Working Team (SWT) is supported in specific scientific and science operation areas by Working Groups (WGs). These are the Target Identification WG and Comet Environment WG. The latter comprises three sub-WGs, covering the Nucleus, Near-Environment, and Far-Environment. Here, we provide a brief overview of the mission, and present and describe the aims and activities of the working groups. The search is already underway for potential comets to encounter, and preparations are being made for the scientific exploitation of the data from the mission’s three spacecraft.

How to cite: Jones, G., Snodgrass, C., Guilbert-Lepoutre, A., Vincent, J.-B., Goetz, C., Martellato, E., Sugita, S., and Kueppers, K.: Activities of the Comet Interceptor Comet Environment and Target Identification Working Groups, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22216, https://doi.org/10.5194/egusphere-egu24-22216, 2024.

PS4 – Space weather and space weathering

EGU24-1981 | Posters on site | PS4.1

Solar wind controls on Martian proton aurora brightening and atmospheric ion loss intensifying 

Fei He, Kai Fan, Andrea Hughes, Yong Wei, Jun Cui, Nicholas Schneider, Markus Fraenz, Xiao-Xin Zhang, Qingyu Meng, and Xiaodong Wang

Charge exchange between solar wind protons and local hydrogen atoms generates hydrogen energetic neutral atoms (H-ENAs) in the extended neutral hydrogen corona surrounding Mars. The following collisions between H-ENAs and atmospheric molecules generate a distinct proton aurora. How the solar wind influences the proton aurora activity in the short term is not well unknown. We found that there are synchronized proton aurora brightening and atmospheric ion loss intensifying on Mars, both controlled by solar wind dynamic pressure, using observations by the Mars Atmosphere and Volatile Evolution spacecraft. Significant erosion of the Martian ionosphere during periods of high dynamic pressure indicates at least five-to-tenfold increase in atmospheric ion loss. An empirical relationship between ion escape rate and auroral emission enhancement is established, providing a new proxy of Mars’ atmospheric ion loss with optical imaging that may be used remotely and with greater flexibility.

How to cite: He, F., Fan, K., Hughes, A., Wei, Y., Cui, J., Schneider, N., Fraenz, M., Zhang, X.-X., Meng, Q., and Wang, X.: Solar wind controls on Martian proton aurora brightening and atmospheric ion loss intensifying, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1981, https://doi.org/10.5194/egusphere-egu24-1981, 2024.

EGU24-2004 | Posters on site | PS4.1

Ion escape processes in the solar system and beyond  

Iannis Dandouras and Masatoshi Yamauchi

Understanding the evolution of planetary atmospheres, and particularly the evolution of their composition and eventual habitability, is a major challenge. The evolution of an atmosphere is driven by its interactions with the planetary surface and interior, the influx from space (e.g. meteors), and the atmospheric escape to space in the form of neutral or ionised atoms/molecules, upwelling from the atmosphere and escaping to space.
For a planet like Earth, atmospheric escape in the form of neutrals concerns essentially hydrogen whereas heavier species, such as oxygen and nitrogen which constitute 99% of the mass of the terrestrial atmosphere, need to be accelerated as ions in order to reach escape velocities. The ions that outflow from the ionosphere are successively accelerated through a series of energisation mechanisms and can eventually reach velocities above the gravitational escape velocity.
Missions like Cluster, MAVEN and Cassini and associated modelling efforts have advanced our understanding of the ion acceleration, circulation in the magnetosphere and escape mechanisms operating on different planetary objects of our solar system, magnetised or unmagnetised.
However, several questions remain open, as:
(i) What is the exact composition of the escaping populations and how does it change in response to the different driving conditions?  How does it affect the long-term evolution of the composition of a planetary atmosphere and its habitability?
(ii) What is the exact degree of plasma recirculation for each ion species, after it has left the ionosphere, versus direct or indirect escape, and what is its dependence on the solar and geomagnetic activity conditions?
(iii) What is the effect of a planetary magnetic field on the different escape mechanisms, particularly in view of the conjugate effect of different magnetospheric size / solar wind dynamic pressure / exobase altitude / solar irradiance?
(iv) The discovery in recent years of a large number of exoplanets, several of them in the "habitable" zone, raises the question of atmospheric escape mechanisms operating in these environments. Could exoplanets orbiting active K-M stars undergo massive atmospheric escape, removing the constituents of water from their atmospheres under XUV irradiation and making them uninhabitable within a few tens to hundreds of Myr, as some models suggest? 

 

 

How to cite: Dandouras, I. and Yamauchi, M.: Ion escape processes in the solar system and beyond , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2004, https://doi.org/10.5194/egusphere-egu24-2004, 2024.

EGU24-2078 | ECS | Posters on site | PS4.1

Theory and fluid simulations of ion and electron acoustic instabilities in Parker Solar Probe observations close to the Sun. 

Mahmoud Saad Afify, Jürgen Dreher, and Maria Elena Innocenti

Multiple electron and ion beams have been observed by the Parker Solar Probe (PSP) in the low solar atmosphere (Sun et al. 2021; Liu et al. 2023). In the presence of two resonant counter-steaming ion and electron populations, we expect the development of ion and electron acoustic instabilities, respectively (Mozer et al. 2020; Chen et al. 2020; Verscharen et al. 2022). Ion acoustic waves have indeed been observed by PSP (Mozer et al. 2021 a,b, 2023a) with characteristics that differ from previous observations. The latter is a coupled pair of high and low frequencies. Moreover, they have an electrostatic nature and a long duration of several hours. Their importance comes from the absence of whistler waves very close to the Sun, which seem to play a major role in heat flux regulation further away from the Sun (Halekas et al. 2021; Micera et al. 2021) and the recent observations that ensure the heating of core electrons and ions during the existence of such electrostatic waves (Kellogg 2020; Cattell et al. 2022; Mozer et al. 2022, 2023b). Employing the theory and multi-fluid simulations for both ion and electron acoustic instabilities (Kakad et al. 2013; Kakad & Kakad 2019; Afify et al. 2023) in plasma regimes compatible with PSP observations gives reasonable results. However, this study will be complemented by kinetic simulations with a fully kinetic code that implements solar wind plasma expansion self-consistently, EB-iPic3D (Innocenti et al. 2019), since the fluid analysis is unable to address the contribution of resonant electrons when the wave phase velocity is close to the electron thermal velocity. Indeed, the fluid simulations can capture decently the linear stage of these instabilities while becoming less accurate in the nonlinear stage (Kakad et al. 2014). This study highlights many phenomena, such as the mechanism behind the onset and propagation of different time domain structures such as electron and ion acoustic waves, how they modify the electron-ion velocity distribution functions, and the heating of the core electrons and ions.

How to cite: Afify, M. S., Dreher, J., and Innocenti, M. E.: Theory and fluid simulations of ion and electron acoustic instabilities in Parker Solar Probe observations close to the Sun., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2078, https://doi.org/10.5194/egusphere-egu24-2078, 2024.

EGU24-4846 | ECS | Posters on site | PS4.1

Variation Martian proton aurora in different timescales 

Jingyi Wu, Fei He, Yong Wei, and Andrea Hughes

The aurorae on Mars are divided into diffuse aurora, discrete aurora and proton aurora. Proton aurora is the most common type of aurora on Mars. The proton aurora on Mars is formed when protons in the solar wind pass through the Martian hydrogen corona and undergo charge exchange to form energetic neutral atoms, which deposit energy in the Martian atmosphere. Previous research results showed that the main external factors that affect the occurrence rate, emission enhancement, intensity and peak height of proton aurora are the solar wind particle flux and velocity, solar zenith angle and solar longitude. Here, we extend the previous proton aurora database compiled by Hughes et al. [2019], which was in the descending phase of the last solar cycle between 2014-2018, to present with similar algorithm. Using this new database covering almost one solar cycle, we investigated the long-term variations of the proton aurora on Mars in three timescales, including the solar rotation cycle, Martian season, and solar cycle. The results will help us understand the solar wind-Mars interactions.

How to cite: Wu, J., He, F., Wei, Y., and Hughes, A.: Variation Martian proton aurora in different timescales, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4846, https://doi.org/10.5194/egusphere-egu24-4846, 2024.

EGU24-5648 | Posters on site | PS4.1

Very minor ions in the magnetosphere: a hub of the mesospheric, ionospheric, magnetospheric, solar wind, lunar, and meteoroid sciences. 

Masatoshi Yamauchi, Iannis Dandouras, Peter Würz, Daniel Kastinen, John Plane, Leonard Schulz, Andrew Yau, Lynn Kistler, Steve Christon, Stein Haaland, Yoshifumi Saito, Satonori Nozawa, Ingrid Mann, Shigeto Watanabe, and Tinna Gunnarsdottir

This is the summary of findings by ISSI topical team on the molecular and metallic ions in the magnetosphere.

Heavy molecular and metallic ions with mass ≥ 27 (Al+, N2+, NO+, O2++, Fe+, Cu+, Ti+, etc) in the magnetosphere provide independent information on the ion sources and entry route to the magnetosphere from traditional four components (H+, He++, He+, O+). There are four ultimate sources of these heavy molecular and metallic ions: the solar wind (high charge-state metallic ions), the ionosphere (mainly molecular ions), the atmospheric metal layers (low charge-state metallic ions and metal-rich molecular ions that ultimately originating from ablation of meteoroids and possibly space debris), and the surface and exosphere go the Moon (low charge-state metallic and molecular ions). 

The lunar origin low charge-state metallic ions, if separated from the ionospheric origin, give independent information on the entry route into the magnetosphere for ions of much larger gyroradius than the solar wind ions. The atmospheric-origin molecular ions are essential in understanding energization, ionization altitudes, and upward transport in the ionosphere during various ionospheric and magnetospheric conditions. These ions are also important when considering the evolution of the Earth's atmosphere on the geological timescale. 

So far, we cannot dismiss any of four possible sources with the existing data because only a few terrestrial missions have been equipped with instrumentation dedicated to separate these molecular and metallic ions, within only a limited energy range (cold ions of < 50 eV and energetic ions of ~100 keV or more) and a limited mass range (mainly ≤ 40 amu). This is far too limited to make any quantitative discussion on the very heavy ions in the magnetosphere.  Under this circumstance, it is worth to re-examine, using available tools, the existing data from the past and on-going missions, including those not designed for the required mass separation, to search for these ions.  

We synthesised these patchy observations and combining all sources with updated models. With such knowledge, we re-examined available data and model that actually provided important indications of the sources of these heavy ions and their amounts that have been overlooked to date.  Finally, we note the possible future contamination of specific masses by ablated space debris (Al, but also Li, Fe, Ni, Cu, Ti, and Ge) in the coming decades.

How to cite: Yamauchi, M., Dandouras, I., Würz, P., Kastinen, D., Plane, J., Schulz, L., Yau, A., Kistler, L., Christon, S., Haaland, S., Saito, Y., Nozawa, S., Mann, I., Watanabe, S., and Gunnarsdottir, T.: Very minor ions in the magnetosphere: a hub of the mesospheric, ionospheric, magnetospheric, solar wind, lunar, and meteoroid sciences., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5648, https://doi.org/10.5194/egusphere-egu24-5648, 2024.

EGU24-5907 | Orals | PS4.1

Study of magnetosphere dynamics combing geospace and planetary missions 

Rumi Nakamura, James Slavin, Daniel Schmid, and Weijie Sun and the Bepicolombo Earth-Flyby Interval Substorm Study Team

Solar system missions studying the sun and the planets in the inner and outer heliosphere use gravity assists of the planets to reach the target orbit of the missions. If such a maneuver happens around Earth, these observations enable us a unique multipoint observation of the magnetosphere together with other existing geospace missions as was the case of the Bepicolombo in April 2020 and the Solar Orbiter in November 2021 and is expected for JUICE in August 2024. Although the spacecraft during flybys are usually not operated in a full science mode, a new constellation with other fleet of spacecraft in Geospace can provide important information in particular for studying large-scale magnetospheric dynamics.

In this presentation we discuss the three-dimensional evolution of the magnetotail current of a substorm on April 10, 2020 that took place during the Earth-flyby interval of Bepicolombo. Magnetotail disturbances are observed by GOES 17 and Cluster in the midnight region, while BepiColombo spacecraft traversed the premidnight region duskward at 9-11 RE downtail. The four Cluster satellites, which were separated mainly in north-south direction, crossed the inner magnetosphere successively from north to south. They enable us to monitor the vertical (latitudinal) structure and the sequential changes of the magnetotail current sheet until the end of the recovery phase of the substorm. Multiple dipolarizations and multiple transient field-aligned currents (FAC) were observed by Cluster. Using the unique dataset from these multi-point observations, we examine the structure of the large-scale current sheet and analyze the embedded transient intense field-aligned current disturbances. By also comparing the observations with an empirical magnetic field model, we obtain the changes of the near-Earth magnetotail structure during the multiple dipolarization event.

How to cite: Nakamura, R., Slavin, J., Schmid, D., and Sun, W. and the Bepicolombo Earth-Flyby Interval Substorm Study Team: Study of magnetosphere dynamics combing geospace and planetary missions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5907, https://doi.org/10.5194/egusphere-egu24-5907, 2024.

Space weather, i.e. the conditions in space driven by the dynamic solar activity, is a terminology that has been traditionally used to refer to the Sun’s effects on the near-Earth environment. This is because of a rather obvious reason, namely that most of the technological systems susceptible to space weather conditions and all human beings are currently on Earth or in near-Earth space. Hence, space weather research and forecasting efforts have focussed for decades mainly on our own neighbourhood. Nevertheless, in more recent years there has been a paradigm shift, due to which the field of space weather science has been gradually evolving into a heliosphere-wide discipline. This has been motivated by two main factors: (1) a growing interest in human exploration outside the Earth–Luna system, with efforts centred especially on Mars, and (2) an increasing endeavour from the research community to view the solar system as a Sun–heliosphere–planets integrated environment.

In this presentation, we will first provide a brief overview of the more “traditional” approach of space weather science to studying the Sun and its transient phenomena—e.g., the structured solar wind, coronal mass ejections, and solar energetic particles. We will then showcase more recent efforts that have been centred on taking advantage of data from missions scattered throughout the solar system to analyse space weather events at multiple points in the heliosphere and their effects on different planetary environments. Finally, we will highlight current and future opportunities for advancing our knowledge of the Sun and space weather-driving phenomena across the heliosphere. Particular emphasis will be given to possible synergies between different subjects of solar system science—i.e. solar, heliospheric, and planetary—and to ideas for the future in terms of multi-disciplinary space missions that can improve our understanding of space weather phenomena from a fundamental physics standpoint and, at the same time, that can expand our knowledge of space weather drivers and effects at other locations than Earth.

How to cite: Palmerio, E.: Space weather today: From an Earth-centred discipline to a heliosphere-wide field of research, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7037, https://doi.org/10.5194/egusphere-egu24-7037, 2024.

Open magnetic flux (OMF) emanating from the Sun permeates the entire interplanetary space and plays an important role in all physical processes throughout the heliosphere that involve magnetic fields. It has been a topic of investigation based on both observational and numerical model analysis. And yet, there are still unresolved debates surrounding the OMF, considered to be among the big open questions in the field of solar and space physics. One of these is the “missing” open flux problem, according to which photospheric open flux estimates do not match measurements made in situ at 1 au. These photospheric estimates are obtained based on two different methods. According to the first, extreme ultraviolet (EUV) observations of coronal holes (CHs), that are considered as primary sources of OMF, are overlaid over global magnetic maps (Carrington maps), and the magnetic flux they enclosed is summed up. The second method is based on areas of open flux determined by coronal models and the summation of the magnetic flux they enclose. However, regardless of the complexity of coronal models, current research has shown that modelled open flux strongly underestimates that determined by the first method, and both underestimate the flux measure in situ at 1 au, by at least a factor of 2. These comparisons with values measured at 1 au are based on the conclusion made by Ulysses’ observations of the latitudinal invariance of the magnitude of the radial interplanetary magnetic field, which lead to the consensus that the total heliospheric open flux can be calculated by a single point in situ measurements. The aforementioned discrepancies have raised many questions. Are observational limitations responsible for the missing open flux? Are model limitations, such as the complexity of the model, the numerical implementation, and uncertainties in input data, contributing to the problem? How can we constrain and validate coronal models? Do we fully understand the sources of open flux? During this presentation we will navigate through research contributing to answering these questions and the direction of current and future efforts both in modelling and observations.

How to cite: Asvestari, E.: Exploring the heliospheric open flux problem from multiple perspectives, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7959, https://doi.org/10.5194/egusphere-egu24-7959, 2024.

EGU24-9364 | ECS | Posters virtual | PS4.1

Serverless Computing Architecture for Enhanced Martian Aurora Detection in the Emirates Mars Mission 

David Pacios, José Luis Vázquez-Poletti, Dattaraj B. Dhurri, Dimitra Atri, Rafael Moreno Vozmediano, Robert J. Lillis, Nikolaos Schetakis, Jorge Gómez-Sanz, Alessio Di Iorio, and Luis Vazquez

This work introduces a novel serverless computing architecture designed to analyze Martian auroras for the Emirates Mars Mission (Hope probe). Utilizing OpenCV and machine learning algorithms, the architecture offers efficient and scalable image classification, object detection, and segmentation. It leverages cloud computing's scalability and elasticity, handling large volumes of image data and adapting to varying workloads. Our study highlights the system's capacity to process and analyze images of Martian auroras swiftly while maintaining cost-effectiveness. The application of this technology within the HOPE Mission not only addresses the complexities involved in detecting Martian auroras but also sets a precedent for future remote sensing applications. Our results demonstrate the potential of serverless computing in enhancing the analysis of extraterrestrial phenomena and contributing significantly to planetary science.

This contribution has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No.101007638 (Project EYE - Economy bY spacE) .

How to cite: Pacios, D., Vázquez-Poletti, J. L., Dhurri, D. B., Atri, D., Moreno Vozmediano, R., Lillis, R. J., Schetakis, N., Gómez-Sanz, J., Di Iorio, A., and Vazquez, L.: Serverless Computing Architecture for Enhanced Martian Aurora Detection in the Emirates Mars Mission, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9364, https://doi.org/10.5194/egusphere-egu24-9364, 2024.

Aurora has been detected on a few occasions on the Venus nightside with the Pioneer Venus UltraViolet Spectrometer (PVO-UVS). The main characteristics are the presence of the OI 130 and 136 nm emissions, a lack of discrete structure (diffuse aurora) and correlation with interplanetary shocks. Ground-based observations in the visible have shown that the [OI] green line at 557.7 nm is also observed following periods of the solar wind intensification. Although no concurrent measurement of auroral particle precipitation has been made, numerical simulations of the UV emissions have indicated that precipitation of soft auroral electrons (15-20 eV) and low energy fluxes is a likely candidate.

A discrete aurora was first observed in the middle ultraviolet on the Martian nightside limb from the Mars Express orbiter in a region of strong crustal field in the southern hemisphere. Prominent emissions included the CO Cameron bands and the CO2+ UV doublet.  Limb observations have been made from Mars Express and MAVEN during the last 10 years. Recently, global auroral images have been collected with the UltraViolet Spectrometer (EMUS) on board the Emirates Mars Mission (EMM). These observations reveal a wide variety of auroral morphologies including discrete, diffuse, proton and sinuous aurora, each one bearing the signature of the interaction between the solar wind, the induced (or crustal) magnetic field and the atmosphere.

In this presentation, we compare the characteristics of the Venus and Mars diffuse aurora observed by Pioneer Venus and MAVEN respectively. We focus on the determination of the charged particles characteristics (mean energy, flux, energy distribution) based on the brightness and intensity ratio of spectral emissions. Following recent laboratory measurement of the efficiency of the Cameron bands excitation by electron impact, we re-examine the dependence of the Cameron/CO2+ UVD intensity ratio on the auroral electron energy. Similarly, the different shapes of the electron excitation cross sections of the OI emissions at 130 and 136 nm induces an intensity ratio that depends on the energy of the precipitation. This dependence can be used to map the mean electron energy, based on FUV spectral observations with the EMUS. Finally, we discuss the expected brightness of the Mars visible aurora and set an upper limit on the intensity of the OI green line based on attempts to detect it with the UVIS spectrometer on board the Trace Gas Orbiter. We show that global observations with the M-AC visible camera on board the M-MATISSE orbiters will generate considerable progress in our understanding of the morphology, time variations and energetics of the Martian aurora.

 

How to cite: Gérard, J.-C. and Soret, L.: Spectroscopy of Mars and Venus aurora: a remote sensing tool for similarities and differences, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9791, https://doi.org/10.5194/egusphere-egu24-9791, 2024.

EGU24-10912 | Orals | PS4.1

Magnetosheath jets: an interdisciplinary perspective 

Ferdinand Plaschke

Earth’s magnetosheath, particularly its region downstream of the quasi-parallel bow shock, is permeated by plasma jets. These are local enhancements in the dynamic pressure, bubbles of plasma that are typically faster and denser in comparison to the ambient plasma. While jets emanate from the patchy and rippled quasi-parallel bow shock or upstream foreshock region, they are able to cross the entire magnetosheath and impact on the magnetopause. There, they may trigger magnetic reconnection and magnetopause surface waves, thereby coupling into large-scale magnetospheric dynamics. Consequently, the effects of jets can be observed inside the magnetosphere and also from ground. Jets are conceptually highly interesting phenomena as they can be interpreted as coupling elements between different regions and vastly different scales. Interdisciplinary research has led to significant advances in our understanding of jets over the past decade. However, despite all the efforts, many basic and fundamental questions remain unanswered. We review some latest results and open questions in jet research, emphasizing the benefit of interdisciplinary approaches.

How to cite: Plaschke, F.: Magnetosheath jets: an interdisciplinary perspective, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10912, https://doi.org/10.5194/egusphere-egu24-10912, 2024.

EGU24-13286 | Posters on site | PS4.1

Unveiling the Mysteries of Multiscale Magnetotail Dynamics with the CINEMA Constellation 

Sasha Ukhorskiy and Robyn Millan and the CINEMA Science Team

Planetary magnetospheres are among the most dynamic and complex systems studied in heliophysics. Driven by their stellar environment and internal sources (e.g., planetary rotation or moons), these vast reservoirs of magnetic energy exhibit a range of dynamical states. Energy circulation (convection) through the system can be steady or explosive, triggering fast plasma flows, global current systems, and spectacular auroral displays. Understanding the response of magnetospheres to their stellar environment is essential for understanding the nature of our home in space, a key heliophysics goal. In Earth’s solar wind–driven magnetosphere, the magnetotail is a key region through which energy is circulated. How the magnetotail maintains steady convection, and when and how it decides to explosively release stored energy, are major unsolved mysteries of space physics. A significant challenge is the intrinsically multiscale nature of magnetotail convection, which is difficult to capture with the sparse measurements available so far. The CINEMA (Cross-Scale INvestigation of Earth’s Magnetotail and Aurora) SMEX Phase A Mission Concept will provide a new cross-scale view of the magnetotail, revealing its large-scale configuration and its influence on dynamics at smaller scales. With a constellation of 9 spacecraft in low-earth orbit all equipped with a full complement of high-resolution energetic particle sensor, auroral imagers, and magnetometers, CINEMA will capture the plasmasheet structure and evolution key for unveiling the mysteries of multiscale magnetospheric convection.  

How to cite: Ukhorskiy, S. and Millan, R. and the CINEMA Science Team: Unveiling the Mysteries of Multiscale Magnetotail Dynamics with the CINEMA Constellation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13286, https://doi.org/10.5194/egusphere-egu24-13286, 2024.

EGU24-13384 | Orals | PS4.1

Mars Aurora: A Comparison of MAVEN/IUVS and EMM/EMUS Observations 

Nicholas Schneider, Robert Lillis, Sonal Jain, Justin Deighan, Julianna Cessna, Michael Chaffin, Andrea Hughes, Krishnaprasad Chirakkil, Jean-Claude Gérard, and Lauriane Soret

Mars' lack of a global magnetic field led to initial expectations of minimal auroral activity. Mars Express's SPICAM instrument nonetheless discovered an unusual form of aurora in 2005. The ultraviolet emissions were confined near Mars' strong crustal field region, showing that even weak magnetic fields can be responsible for aurora. These discrete aurora emissions were identified in 19 observations over SPICAM's decade of observations. 

The MAVEN spacecraft arrived at Mars in 2014 carrying the Imaging UltraViolet Spectrograph (IUVS). Thanks to its high sensitivity and observing cadence, IUVS increased detections of discrete aurora twenty-fold. IUVS also discovered two new widespread forms of aurora. Diffuse aurora is a planet-engulfing phenomenon, caused by solar energetic protons and electrons directly impacting the entire unshielded planet. Proton aurora is caused by solar wind protons charge-exchanging into the atmosphere and causing Lyman alpha emission across the dayside. IUVS studies the aurora at mid- and far-UV wavelengths in both limb scans and nadir imaging.

The Emirates Mars Mission (EMM) arrived in 2021 carrying the Emirates Mission UltraViolet Spectrometer (EMUS). EMUS quickly added to the menagerie of auroral phenomena thanks to its high far-UV sensitivity. Discrete aurora emissions were seen in a substantial fraction of nightside observations, and appear to take on new forms not seen by IUVS (sinuous"non-crustal field", among others). Furthermore, EMUS detected a spatially-variable form of proton aurora called patchy proton aurora. EMUS studies the aurora through nadir imaging at far- and extreme-UV wavelengths.

The net result of the tremendous influx of new observations is a lag in cataloguing and cross-comparing the types of observations made with different instruments at different wavelength ranges in different observing modes. We now have the perspective to identify the causes of these auroral phenomena, which gives a more physics-based nomenclature:

  • suprathermal electron aurora: hot electrons from the Mars environment appear to be responsible for most forms of discrete aurora
  • solar energetic particle aurora: SEP electrons and protons from the Sun cause the planet-wide diffuse aurora 
  • solar wind aurora: solar wind protons charged-exchange into the atmosphere to cause dayside aurora

This presentation seeks to give that broader context, highlighting

  • what phenomena IUVS and EMUS observe, depending on their distinct instrumental capabilities
  • whether they’re actually seeing the same phenomena or different ones, 
  • how can one type of observation can complement the other, 
  • where one’s capabilities are unique, and 
  • what are the best directions for collaboration;
  • how in situ measurements of particles and fields can contribute to the next stage of understanding of the conditions for particle precipitation

A more coherent observational perspective, as outlined above, may grant a framework for developing a deeper physical understanding of Mars unexpected diverse auroral processes.

How to cite: Schneider, N., Lillis, R., Jain, S., Deighan, J., Cessna, J., Chaffin, M., Hughes, A., Chirakkil, K., Gérard, J.-C., and Soret, L.: Mars Aurora: A Comparison of MAVEN/IUVS and EMM/EMUS Observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13384, https://doi.org/10.5194/egusphere-egu24-13384, 2024.

EGU24-13610 | Orals | PS4.1 | Highlight

Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS 

Robert Lillis, Krishnaprasad Chirakkil, Justin Deighan, Matthew Fillingim, Sonal Jain, Michael Chaffin, Susarla Raghuram, Gregory Holsclaw, Hoor Almazmi, David Brain, Nick Schneider, Shaosui Xu, Jasper Halekas, Jared Espley, Jacob Gruesbeck, and Shannon Curry

Benefiting from a large orbit and high sensitivity, the Emirates Mars mission EMUS instrument has provided the first opportunity to synoptically and regularly image Mars’ discrete FUV auroral oxygen emission at 130.4 and 135.6 nm.  Over 15-20 minutes, EMUS produces a) images by slewing its aperture slit across the disk or b) “movies” of narrow regions by staring continuously.

Discrete aurora are observed primarily where the magnetic topology is open (i.e. connected to the collisional atmosphere at one end), which occurs where Mars’ crustal magnetic fields are either very weak or primarily vertical.  Discrete aurora show a strong local time dependence, with occurrence % decreasing with increasing solar zenith angle.  The highest occurrences are generally found in the post-dusk sector, before 10 PM SLT, though a few regions (e.g. 60°-70° S, 120°-150° E) are brightest between midnight and 3 AM.   

Sinuous discrete auroras (SDA) are enigmatic, sharply-defined filamentary emissions identified in approximately 3% of observations. These emissions intersect Mars' UV terminator, aligning generally away from the Sun, tending to cluster into groups oriented to the north, south, east, and west. The occurrence of SDAs increases with higher solar wind pressure. SDAs have a tendency to form toward the direction of the solar wind convection electric field (i.e., forming in the +E hemisphere). Depending on whether they originate near dusk or dawn, there is a moderate clockwise or counterclockwise "twist" observed in the average orientation of SDAs, respectively. Based on these characteristics, we infer a connection between SDAs and Mars' magnetotail current sheet, suggesting that the emission may be a result of energized electrons within this sheet.

Lastly, near the dawn and dusk terminators, discrete aurora often display a preference for formation in regions of either positive or negative crustal magnetic field, depending on IMF direction.  This preference can be used to determine whether a dayside (magnetosheath or photoelectron) or nightside (magnetotail) source of electrons is dominant.  Overall, nightside sources dominate over dayside by 20-40%, although individual radial crustal fields can show strong preferences for day or night sources.  This tells us that local magnetic geometry plays a role in global precipitation patterns.

With more than 3000 nightside images and 400 aurora movies collected (totaling more than 12 million pixels) since April 2021, we now have a powerful tool to understand Martian aurora morphologies, variability, and dependence on internal and external drivers. 

How to cite: Lillis, R., Chirakkil, K., Deighan, J., Fillingim, M., Jain, S., Chaffin, M., Raghuram, S., Holsclaw, G., Almazmi, H., Brain, D., Schneider, N., Xu, S., Halekas, J., Espley, J., Gruesbeck, J., and Curry, S.: Exploring Mars discrete aurora with synoptic images and movies from EMM EMUS, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13610, https://doi.org/10.5194/egusphere-egu24-13610, 2024.

EGU24-14121 | ECS | Orals | PS4.1

Application of machine learning for modeling and characterizing electron and proton auroras on Mars 

Dattaraj Dhuri, Dimitra Atri, and Sonya Hseih

Auroras on Mars are known since their first discovery in 2005 by Mars Express and subsequently have been observed by Mars Atmosphere and Volatile Evolution (MAVEN) since 2014. Since 2021, Emirates UV spectrometer (EMUS) onboard the Emirates Mars Mission (EMM) has been observing Martian auroras with an unprecedented frequency. These auroras are seen as FUV and EUV emissions of H, O, CO, and CO2 and are categorized based on their morphologies and the particles that are responsible for these emissions. Electron precipitation on the nightside causes discrete and diffuse auroras whereas solar wind protons penetrating the Mars atmosphere cause proton auroras on the dayside. EMUS also detected new discrete auroras extending thousands of km into the nightside with a sinuous morphology. The variety and abundance of Mars aurora occurrences make them an important tool for gaining new insights into solar wind interaction with Mars's magnetosphere. Mars aurora research therefore involves characterizing aurora occurences in terms of solar activity, seasonal variability, IMF orientation, crustal magnetic fields, and energies of precipitating particles. In this work, we present applications of machine learning for modeling proton auroras as well as automatically detecting discrete electron auroras, leveraging a plethora of MAVEN and EMUS observations. We also focus on explainability of these ML models, commonly perceived as “black-boxes”, and approaches to analyze and validate correlations learned by these models. We discuss in detail the characteristics of proton and electron auroras thus revealed by these models and present future directions for such applications on Mars and other planets.

How to cite: Dhuri, D., Atri, D., and Hseih, S.: Application of machine learning for modeling and characterizing electron and proton auroras on Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14121, https://doi.org/10.5194/egusphere-egu24-14121, 2024.

EGU24-14406 | ECS | Posters on site | PS4.1

The Solar Wind: A net source or sink for terrestrial mass? 

Parker Hinton, David Brain, Neesha Schnepf, Riku Jarvinen, and Fran Bagenal

Shortly after the solar wind was first measured by the Second Soviet Cosmic Rocket (Luna 2) in 1959, planetary scientists immediately began wondering if it might be a source of mass for terrestrial atmospheres; perhaps even providing the Earth with all of the hydrogen needed for its oceans (De Turville 1961). This particular idea has been shown not to hold water, moreover, it is now known that the solar wind can drive escape from planetary atmospheres in the form of pick up ions. This presentation highlights an unresolved question: does the solar wind represent a net source or sink of mass for the terrestrial planets? We approach the problem using an ion-kinetic quasi-neutral hybrid (QNH) particle-in-cell (PIC) code called Rhybrid. We simulate the interaction of the solar wind with non-magnetized and weakly-magnetized terrestrial-type planets ranging in size from Mars to super Earth (1.5 RE). We also vary the ion production rate and dipole moment strength in order to explore the relevant parameter space. We quantify the escape rate of planetary ions (H+ and O+), as well as the accretion rate of solar hydrogen, and present the net mass flux for the different modeled scenarios.

How to cite: Hinton, P., Brain, D., Schnepf, N., Jarvinen, R., and Bagenal, F.: The Solar Wind: A net source or sink for terrestrial mass?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14406, https://doi.org/10.5194/egusphere-egu24-14406, 2024.

Auroral emissions have been observed throughout the Solar System. They are the photo-manifestation of the interaction of energetic, extra-atmospheric particles (typically electrons or ions) with an atmosphere. As the source of energy comes from the space environment (e.g., solar wind or magnetosphere if applicable), the auroral emissions are a tracer of plasma bombardments in an atmosphere. They are also a fingerprint of plasma source and atmospheric species. They are an invaluable, remote-sensing probe of plasma interaction in the Solar System.

Through a multi-instrument analysis of gas, particle and spectroscopic dataset from Rosetta, we have established that the atomic emissions observed in the coma of comet 67P at large heliocentric distances (> 2 astronomical units) are of auroral origin [Galand et al., Nature Astronomy, https://doi.org/10.1038/s41550-020-1171-7, 2020; Stephenson et al.., A&A, https://doi.org/10.1051/0004-6361/202039155, 2021]. We will discuss the source of the energetic particles responsible for the Far UltraViolet (FUV) emissions and will highlight the relevance of observing some of them from Earth. We will contrast these emissions with those observed at comets in the soft X-rays and extreme ultraviolet and with the FUV emissions observed at Earth, Mars and Ganymede.

How to cite: Galand, M.: Far Ultraviolet atomic emissions at comet 67P: What have we learned? , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16001, https://doi.org/10.5194/egusphere-egu24-16001, 2024.

EGU24-19005 | ECS | Orals | PS4.1

The Balance of Internal and External Drivers in Gas Giant Magnetospheres 

Matthew J. Rutala, Caitriona M. Jackman, Alexandra R. Fogg, Sophie A. Murray, Mathew J. Owens, and Chihiro Tao
The magnetospheres of the gas giants are characterized by strong planetary magnetic fields, rapid rotation, and an intriguing, but not fully characterized, mix of external (solar wind) and internal driving of magnetospheric processes, including the aurorae. Determining the balance between these internal and external drivers is made difficult by the limitations of single-spacecraft measurements, which represent the vast majority of all in-situ magnetospheric measurements and upstream solar wind measurements at the giant planets. Simultaneous in-situ measurements, upstream solar wind monitoring, and remote sensing (e.g. multi-wavelength auroral imaging), gives the best chance to characterize internal and external drivers. Such data have only been taken once, during the brief coordination of the Galileo and Cassini spacecraft at Jupiter. In lieu of a large dataset of simultaneous measurements, advances in our statistical understanding of the balance between these internal and external drivers have been made by leveraging models of either the solar wind, giant planet magnetospheres, or both.

In the coming years, additional in-situ data, upstream monitoring, and remote observations coordinated either between space- or earth-based observatories will provide more context for understanding the giant planet magnetospheres, including potential coordination between JUICE and Europa Clipper. In the meantime, improved statistical analysis of both models and data are our best tools to better understand these systems. To this end, we will present the Multi-Model Ensemble System for the outer Heliosphere (MMESH)-- a suite of analysis tools designed to improve the accuracy of solar wind propagation models at the outer planets by self-consistently quantifying modeling uncertainties and biases and forming ensemble models with estimated error. Robust ensembles models allow statistically meaningful analyses of the effects of various solar wind drivers on planetary magnetospheres and quantification of the extent of external control over giant planet magnetospheres. We will conclude by demonstrating the usefulness of these statistical techniques by showing early results of an investigation into external control over Jupiter's overall auroral power and discussing future applications and improvements of this technique.

How to cite: Rutala, M. J., Jackman, C. M., Fogg, A. R., Murray, S. A., Owens, M. J., and Tao, C.: The Balance of Internal and External Drivers in Gas Giant Magnetospheres, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19005, https://doi.org/10.5194/egusphere-egu24-19005, 2024.

We combine the electromagnetic fields from a hybrid plasma model with a particle tracing tool to study the spatial distribution of energetic neutral atoms (ENAs) emitted from Titan's atmosphere when the moon is exposed to different magnetospheric upstream regimes. These ENAs are generated when energetic magnetospheric ions undergo charge exchange within Titan's atmosphere. The spatial distribution of the emitted ENA flux is largely determined by the parent ions' trajectories through the draped fields in Titan's interaction region. Since images from the ENA detector aboard Cassini captured only a fraction of the ENA population, we provide context for such observations by calculating maps of the ENA flux through a spherical detector concentric with Titan. We determine the global distribution of ENA emissions and constrain deviations between the locations of ENA production and detection. We find that the ENA flux is highest in a band that encircles Titan perpendicular to the ambient magnetospheric field, which was strictly perpendicular to the moon's orbital plane during only one Cassini flyby. The field line draping strongly attenuates the emitted ENA flux, but does not alter the overall morphology of the detectable flux pattern. The majority of detectable ENAs leave Titan's atmosphere far from where they are produced, that is, even a spacecraft located directly above the moon's atmosphere would detect ENAs generated beyond its immediate environment. Some energetic parent ions produce ENAs only after they are mirrored by the field perturbations in Titan's wake and return to the moon, demonstrating the complex histories of detectable ENAs.

How to cite: Simon, S., Tippens, T., and Liuzzo, L.: Influence of Titan's Variable Electromagnetic Environment on the Global Distribution of Energetic Neutral Atoms, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6, https://doi.org/10.5194/egusphere-egu24-6, 2024.

EGU24-1237 | ECS | Orals | PS4.2

Steady-state of the Martian induced magnetosphere and its rapid response to interplanetary magnetic field rotation 

Rentong Lin, Shiyong Huang, Zhigang Yuan, Honghong Wu, Kui Jiang, Yuming Wang, Tielong Zhang, Sibo Xu, Yue Dong, Qiyang Xiong, and Huxing Huang

The induced magnetosphere in non-magnetized planets or moons, formed by the interaction between their atmosphere and stellar wind or planetary wind, is generally modulated by external magnetic field.

 

The magnetic field in the induced magnetosphere is believed to be dominated by the draped field. The direction of such draped field is theoretically expected to align with the y-z direction of the interplanetary magnetic field. However, observations show the opposite direction of magnetic field in the induced magnetospheres from the interplanetary magnetic field direction. Using joint observations from Tianwen-1 and MAVEN, we obtain the averaged magnetic field map of the Martian induced magnetosphere in the accurate MSE coordinate system and calculated its standard deviation. The standard deviation confirms that the averaged magnetic field distribution is consistent with the steady state assumption. The magnetic field map illustrates a clockwise rotation of the averaged magnetic field in the y-z plane, occurring in both the dayside and nightside in the Martian induced magnetosphere. According to the magnetic induction equation, this clockwise rotation of the magnetic field occurs when a difference in the speed of plasma flow exists within the magnetosphere. It should be noted that the induced magnetospheres of the other non-magnetized planets exhibit similar qualitative properties to that of Mars, suggesting that they share comparable magnetic field characteristics.

 

Observations of the response process of induced magnetosphere to external magnetic field are significant for understanding global dynamical processes in non-magnetized planets, and yet such observations are quite scarce. Using simultaneous observations from Tianwen-1 and Mars Atmosphere and Volatile EvolutioN (MAVEN), we report for the first time the dynamic response of the Martian induced magnetosphere to the rotation of interplanetary magnetic field from the Sun. The magnetic field in the Martian induced magnetosphere deflected as the interplanetary magnetic field rotated suddenly, and eventually stabilized (< 3.5 minutes). The convective electric field rotated in response to the interplanetary magnetic field rotation, and the pick-up oxygen ion plume emerged in minutes (< 3 minutes). These quite short recovery timescales indicate that the induced magnetosphere is a rapidly dynamic system, and is highly sensitive to external magnetic field. It cautions us that change of interplanetary magnetic field should be considered as one of the general types of space weather on Mars, and it is essential of monitoring and short-term forecasting of interplanetary magnetic field upstream of Mars.

How to cite: Lin, R., Huang, S., Yuan, Z., Wu, H., Jiang, K., Wang, Y., Zhang, T., Xu, S., Dong, Y., Xiong, Q., and Huang, H.: Steady-state of the Martian induced magnetosphere and its rapid response to interplanetary magnetic field rotation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1237, https://doi.org/10.5194/egusphere-egu24-1237, 2024.

EGU24-1710 | ECS | Orals | PS4.2

Characterizing the current systems in the Martian ionosphere 

Jiawei Gao, Anna Mittelholz, Zhaojin Rong, moa persson, Zhen Shi, Chi Zhang, Xiaodong Wang, and Yong Wei

When the solar wind encounters the ionosphere of an unmagnetized planet, it induces currents, forming an induced magnetosphere. These currents, along with their associated magnetic fields, play a crucial role in controlling the movement of charged particles, and are essential for understanding the escape of planetary ions. Unlike the well-documented magnetospheric current systems, the ionospheric current systems on unmagnetized planet remain less understood, limiting our ability to quantify electrodynamic energy transfer. Here, using 8 years of data from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we provide the first global map of the Martian ionospheric currents. We identified two current systems coexist within the ionosphere: one aligning with the solar wind electric field, with asymmetries between the west-east electric hemispheres and driven by the solar wind; and one characterized by two current vortices on the dayside, powered by the atmospheric neutral winds. Our findings indicate that the Martian ionospheric dynamics are influenced by both the neutral winds from below and the solar wind from above, emphasizing the intricate nature of current systems on unmagnetized planets.

How to cite: Gao, J., Mittelholz, A., Rong, Z., persson, M., Shi, Z., Zhang, C., Wang, X., and Wei, Y.: Characterizing the current systems in the Martian ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1710, https://doi.org/10.5194/egusphere-egu24-1710, 2024.

EGU24-2228 | ECS | Orals | PS4.2 | Highlight

Observations of a Mini-Magnetosphere Above the Martian Crustal Magnetic Fields 

Kai Fan, Yong Wei, Markus Fraenz, Jun Cui, Fei He, Limei Yan, Lihui Chai, Jun Zhong, Zhaojin Rong, and Eduard Dubinin

Mars is typically regarded as a non-magnetic planet. Currents in the Martian ionosphere generate a Venus-like induced magnetosphere which deflects the solar wind flows and piles up the interplanetary magnetic fields. However, crustal magnetic fields in the southern hemisphere influence local plasma properties. Using observations from the MAVEN mission, we characterize the distinguishing plasma characteristics of a mini-magnetosphere that forms on the Martian dayside. We establish three criteria to differentiate this mini-magnetosphere from the induced magnetosphere. Notably, the mini-magnetosphere exhibits higher plasma beta (values near 1), with a balance between planetary ions, crustal magnetic fields, and the solar wind at the magnetopause. Observations show that the crustal magnetosphere reaches an altitude of 1,300 km, larger than one-third of the Martian radius, indicating a dichotomy between the induced northern and the crustal southern magnetospheres. These findings offer novel insights into the distinctive properties of hybrid magnetospheres in the near-Mars space.

How to cite: Fan, K., Wei, Y., Fraenz, M., Cui, J., He, F., Yan, L., Chai, L., Zhong, J., Rong, Z., and Dubinin, E.: Observations of a Mini-Magnetosphere Above the Martian Crustal Magnetic Fields, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2228, https://doi.org/10.5194/egusphere-egu24-2228, 2024.

EGU24-2891 | ECS | Orals | PS4.2

The response of Martian photoelectron boundary to the 2018 global dust storm 

Yuqi Wang, Yong Wei, and Kai Fan

Extensive research efforts have revealed that the Martian dust storms can perturb the upper atmospheric condition and as a consequence, enhance plasma density and photoelectron flux in the ionosphere. However, previous observational studies of the Martian dust storm impacts have been restricted to regions below 400 km, which limits our understanding of the Martian dust storm effects in the upper ionosphere and magnetosphere. Here, based on the suprathermal electron measurements made by the Solar Wind Electron Analyzer onboard the Mars Atmosphere and Volatile Evolution, we identify with an automatic procedure the occurrences of all photoelectron boundary (PEB) crossings at solar zenith angle below 120° (with a dust-free median altitude of about 600 km). Using the dayside PEB as a proxy of the upper ionospheric and magnetospheric condition, we analyze the variations of the PEB altitude during the 2018 global dust storm (GDS) of Mars Year 34 (MY34) and compare them with the period in MY33 when there was no global dust storm. We conclude that the column dust optical depth (CDOD) emerges as one of the main driving factors for PEB altitude variations during the GDS. Our analysis implies that the GDS can affect the Martian upper atmosphere and ionosphere over considerable distances and extended time scales.

How to cite: Wang, Y., Wei, Y., and Fan, K.: The response of Martian photoelectron boundary to the 2018 global dust storm, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2891, https://doi.org/10.5194/egusphere-egu24-2891, 2024.

EGU24-2924 | ECS | Orals | PS4.2

Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars 

Neesha Schnepf, Yaxue Dong, David Brain, Gwen Hanley, William Peterson, Robert Strangeway, Ed Thiemann, Jasper Halekas, Jared Espley, Frank Eparvier, and James McFadden

Mars once had a dense atmosphere enabling liquid water existing on its surface, however, much of that atmosphere has since escaped to space. We examine how incoming solar and solar wind energy fluxes drive escape of atomic and molecular oxygen ions (O+ and O2+) at Mars. We use MAVEN data to evaluate ion escape from February 1, 2016 through May 25, 2022. We find that Martian O+ and O2+ have increased escape flux with increased solar wind kinetic energy flux. Increased solar wind electromagnetic energy flux also corresponds to increased O+ and O2+ escape flux. Increased solar irradiance (both total and ionizing) does not obviously increase escape of O+ and O2+. Together, these results suggest that the solar wind electromagnetic energy flux should be considered along with the kinetic energy flux, and that other parameters should be considered when evaluating solar irradiance’s impact on O+ and O2+ escape.

How to cite: Schnepf, N., Dong, Y., Brain, D., Hanley, G., Peterson, W., Strangeway, R., Thiemann, E., Halekas, J., Espley, J., Eparvier, F., and McFadden, J.: Solar and solar wind energy drivers for O+ and O2+ ion escape at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2924, https://doi.org/10.5194/egusphere-egu24-2924, 2024.

EGU24-3755 | ECS | Posters on site | PS4.2

Effects of solar wind density and velocity variations on the Martian ionosphere and plasma transport 

Yihui Song, Haoyu Lu, Jinbin Cao, Xiaoshu Wu, Yang Liu, Shibang Li, Siqi Wang, James A. Wild, Chenling Zhou, Jianxuan Wang, and Nihan Chen

Solar wind dynamic pressure, consisting solar wind density and velocity, is an important external driver that controls Martian plasma environment. In this study, a 3D magnetohydrodynamic model is applied to investigate the separate influences of solar wind density and velocity on the Martian ionosphere. The spatial distributions of ions in the dayside and near nightside ionosphere under different solar wind density and velocity conditions are analyzed, as well as the ion transport process. We find that for the same dynamic pressure condition, the ionosphere extends to higher altitudes under higher solar wind density, indicating that a solar wind velocity enhancement event is more efficient at compressing the Martian ionosphere. A higher solar wind velocity will result in a stronger induced magnetic field, shielding the Martian ionosphere, preventing the penetration of solar wind particles. For the same dynamic pressure, increasing solar wind density (decreasing velocity) leads to a higher horizontal ion velocity, facilitating day-to-night plasma transport. As a result, the ionosphere extends farther into the nightside. Also, the ion outflow flux is larger for high solar wind density, which may lead to a higher escape rate. Moreover, the strong crustal fields in the southern hemisphere also cause significant effect to the ionosphere, hindering horizontal ion transport. An additional outflow channel is also provided by the crustal field on the southern dayside, causing different responses of flow pattern between local and global scale while the solar wind condition is varied.

How to cite: Song, Y., Lu, H., Cao, J., Wu, X., Liu, Y., Li, S., Wang, S., Wild, J. A., Zhou, C., Wang, J., and Chen, N.: Effects of solar wind density and velocity variations on the Martian ionosphere and plasma transport, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3755, https://doi.org/10.5194/egusphere-egu24-3755, 2024.

EGU24-4015 | Orals | PS4.2 | Highlight

Tianwen-1 MINPA in-flight operation and first science results 

Wenya Li, Linggao Kong, and Jijie Ma

The Mars Ion and Neutral Particle Analyzer (MINPA), one of the seven scientific payloads onboard the Tianwen-1 orbiter, was specifically designed to investigate the interaction between the solar wind and Mars by analyzing ions and energetic neutral atoms (ENAs). Commencing its scientific data collection in November 2021, MINPA successfully completed its first far-magnetotail survey during the summer of 2022. Our presentation will provide a comprehensive overview of MINPA's in-flight operations and its initial scientific findings. Regarding ENA observations, MINPA achieved successful data collection during solar wind, magnetosheath, and nightside observations. An algorithm has been developed to convert ENA count rates into intensity. A statistical analysis of solar wind ENAs revealed a neutralization rate of the solar wind at the flanks of the Mars magnetosphere. We also performed a collaborative analysis using MINPA data and numerical modeling to gain a deeper understanding of the ENA spectrum and its properties. In the ion component, MINPA observed hydrogen and heavy ions across various regions at Mars. With a far apoapsis, MINPA measured heavy ion escape in the far magnetotail, showcasing significant enhancements during periods of coronal mass ejection (CME) impacts. To enhance our understanding of the Martian space environment, an interdisciplinary team, comprising scientists from the Tianwen-1, Emirates Mars Mission (EMM), Mars Atmosphere and Volatile Evolution (MAVEN), and Mars Express missions, has been assembled within the ISSI framework.

How to cite: Li, W., Kong, L., and Ma, J.: Tianwen-1 MINPA in-flight operation and first science results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4015, https://doi.org/10.5194/egusphere-egu24-4015, 2024.

A three-dimensional, four-species multi-fluid magnetohydrodynamic (MHD) model was developed to simulate the global interaction between the solar wind and Venus during the solar maximum and solar minimum periods. The model was augmented to incorporate the production and loss of the significant ion species in the Venusian ionosphere, i. e. H+, O2+, O+, CO2+, taking into account chemical reactions among all species. Results of simulated Venusian induced magnetosphere, which were validated by comparing with the observations from Venus Express, suggest that the shock locations are closer to the planet during the solar minimum condition, because the magnitude of electromagnetic forces in the minimum increased to counterbalance the heightened solar wind dynamic pressure. The Venusian ionosphere simulation results show that the ionospheric density profile is more condensed during solar minimum which are consistent with previous observations and simulations. Moreover, by taking advantage of our model, functions of electromagnetic forces acting on various ion species were analyzed to explore potential mechanisms behind the differences between these two solar wind conditions. The estimated ions escape rate is much higher for the minimum condition due to increased J×B forces within the magnetotail which are cause by the compressed magnetic field lines under higher solar wind dynamic pressures. This multi-fluid MHD model could serve as an efficient tool for exploring the fine structures of the Venusian space environment system and could also find applications in the future study of distinguishing impacts caused by the variation of a single parameter.

How to cite: Chen, N., Lu, H., and Li, S.: Solar Wind - Venus Interaction During the Solar Maximum & Solar Minimum Periods: A Newly Developed Multi-Fluid MHD Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4026, https://doi.org/10.5194/egusphere-egu24-4026, 2024.

EGU24-4227 | ECS | Orals | PS4.2

The Impact and Mechanism of Magnetic Fields on Plasma Dynamics in the Martian Space Environment 

Shibang Li, Haoyu Lu, Jinbin Cao, Jun Cui, Nihan Chen, Yihui Song, and Jianxuan Wang

The absence of a global magnetic field at Mars results in a direct interaction between the solar wind and the ionosphere, leading to ion escape from its atmosphere to space. However, the existence and asymmetric distribution of crustal fields introduce significant complexity into the plasma dynamics within the Martian environment, resulting from a disordered magnetic field topology characterized by its orientation parallel, directed towards, and away from the Martian surface. Based on three-dimensional multifluid magnetohydrodynamic simulations, we investigated the impact of the magnetic inclination angle on the Martian ionospheric plasma dynamics under the typical solar wind conditions. Numerical results showed that ions can be effectively diffuse upwards along vertical magnetic fields driven by the electron pressure gradient and the motional electric force, leading to a strong outward flux escaped through plume and the magnetotail eventually. In addition, due to the Hall electric force, there is a tendency for ion flow to be deflected in the horizontal plane. These results provide valuable insights into the influence of magnetic fields on ion motion in the Martian space environment.

How to cite: Li, S., Lu, H., Cao, J., Cui, J., Chen, N., Song, Y., and Wang, J.: The Impact and Mechanism of Magnetic Fields on Plasma Dynamics in the Martian Space Environment, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4227, https://doi.org/10.5194/egusphere-egu24-4227, 2024.

Using global magnetohydrodynamics simulations, we investigate the effects of the solar wind magnetosonic Mach number and the interplanetary magnetic field (IMF) on the bow shock of Venus.  Our results reveal the following findings:  (1) The size of the Venusian bow shock is primarily determined by Mach number. An increase in Mach number results in the bow shock moving closer to Venus and a reduction in its flaring angle. (2) Both the subsolar standoff distance and the bow shock's flaring angle increase with the strength of the IMF components that are perpendicular to the solar wind flow direction (By and Bz in the VSO coordinate system), whereas the parallel IMF component (Bx) has a limited impact on the subsolar standoff distance but affects the flaring angle. (3) The cross-section of the bow shock is elongated in the direction perpendicular to the IMF on the Y-Z plane, and the elongation degree is enhanced with increasing intensities of By and Bz. (4) The quasi-parallel bow shock locates closer to the planet as compared to the quasi-perpendicular bow shock. These findings are in alignment with prior empirical and theoretical models. The influences of Mach number and IMF on the bow shock's position and geometry are attributed to the propagation of fast magnetosonic waves, showing the nature of the formation of a collisionless bow shock under the interaction of magnetized flow with an atmospheric object.

How to cite: Xu, Q.: The effects of Mach number and IMF on the location of Venus bow shock: an MHD study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4901, https://doi.org/10.5194/egusphere-egu24-4901, 2024.

EGU24-5382 | Posters virtual | PS4.2

MAVEN Observations of the Interloop Magnetic Reconnections at Mars 

Guo Chen, Can Huang, Ying Zhang, Yasong Ge, Aimin Du, Rongsheng Wang, Lei Wang, Lican Shan, Christian Mazelle, and Hao Luo

Magnetic reconnection between neighboring magnetic field loops, so-called inter-loop reconnection, is a common process to drive flares in the solar atmosphere. However, there is no direct evidence that a similar but less explosive process can take place on planets. The strong crustal fields on Mars are capable of generating plenty of magnetic loops in the near Mars regions, which provides a unique environment to research the inter-loop reconnection on a planet. Here, we report magnetic reconnection events between crustal field loops in the Martian ionosphere observed by MAVEN for the first time. During the current layer crossing, signatures including Hall magnetic field, Alfvénic outflow, and electron energization were recorded, and the energized electrons exhibited auroral-like peaked electron distributions. This finding implies that the inter-loop reconnection in the Martian ionosphere could contribute to the localized energy deposition and particle energization, which provides the seed source for aurora in the Martian atmosphere.

How to cite: Chen, G., Huang, C., Zhang, Y., Ge, Y., Du, A., Wang, R., Wang, L., Shan, L., Mazelle, C., and Luo, H.: MAVEN Observations of the Interloop Magnetic Reconnections at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5382, https://doi.org/10.5194/egusphere-egu24-5382, 2024.

EGU24-5481 | ECS | Orals | PS4.2

Constraining ion transport in the diamagnetic cavity of comet 67P 

Zoe Lewis, Arnaud Beth, Marina Galand, Pierre Henri, Martin Rubin, and Peter Stephenson

Comets are small icy bodies originating from the outer solar system that produce an increasingly dense gas coma through sublimation as they approach perihelion. Photoionisation of this gas results in a cometary ionosphere, which interacts with the impinging solar wind, leading to large scale plasma structures. One such structure is the diamagnetic cavity: the magnetic field-free inner region that the solar wind cannot penetrate. This region was encountered many times by the ESA Rosetta mission, which escorted comet 67P/Churyumov-Gerasimenko for a two-year section of its orbit.

Within the diamagnetic cavity, high ion bulk velocities have been observed by the Rosetta Plasma Consortium (RPC) instruments. The fast ions are thought to have been accelerated by an ambipolar electric field, but the nature and strength of this field are difficult to determine analytically. Our study therefore aims to model the impact of various electric field profiles on the ionospheric density profile and ion composition. The 1D numerical model we have developed includes three key ion species (H2O+, H3O+, and NH4+) in order to assess the sensitivity of each to the timescale of plasma loss through transport. NH4+ is of particular interest, as it has been previously shown to be the dominant ion species at low cometocentric distances near perihelion. It is only produced through the protonation of NH3, a minor component of the neutral gas, and we show that this makes it particularly sensitive to the electric field.

We also compare the simulated electron density to RPC datasets, to find the electric field strength and profile which best recreate the plasma densities measured inside the diamagnetic cavity near perihelion. From this, we also constrain the radial bulk ion speed that is required to explain the observations with the model.

How to cite: Lewis, Z., Beth, A., Galand, M., Henri, P., Rubin, M., and Stephenson, P.: Constraining ion transport in the diamagnetic cavity of comet 67P, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5481, https://doi.org/10.5194/egusphere-egu24-5481, 2024.

Based on magnetic field and plasma measurements from the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission, we present the first observation of magnetic reconnection occurring between the closed crustal magnetic field and the Ion Composition Boundry(ICB) at the dayside of Mars. Notably, distinctive typical features typical of reconnection, such as the Hall magnetic field and plasma outflow, have been unambiguously detected. Our findings robustly support the occurrence of reconnection at Mars, specifically highlighting the interaction between the interplanetary magnetic field in the induced magnetosphere and the closed crustal magnetic field. This reconnection event induces significant alterations in the magnetic field topology, exerting a profound influence on the escape dynamics of ions.

How to cite: Qiu, X. and Yu, Y.: Observations of magnetic reconnection between the crustal magnetic field and the ICB at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5676, https://doi.org/10.5194/egusphere-egu24-5676, 2024.

EGU24-6135 | Orals | PS4.2

Interaction between non-linear plasma structures and collisionless shocks: magnetic holes vs cometary shock 

Cyril Simon Wedlund, Francesco Pucci, Luis Preisser, Pierre Henri, Etienne Behar, Giulio Ballerini, Francesco Califano, Thierry Passot, Pierre-Louis Sulem, and Adriana Settino

Linear Magnetic Holes (LMHs) are magnetic field depressions generated in the solar wind upstream of planetary and cometary shock. Some of those structures are reminiscent of mirror modes, thus possibly linked to the mirror mode instability driven by a temperature anisotropy in a large plasma beta environment. LMHs have also been found downstream of the shock, which suggests that they can survive its crossing (Karlsson et al. 2022). Using the new GPU-intensive kinetic hybrid model Menura (Behar et al. 2022), we present two-dimensional (2D 3V) simulations of individual solar-wind LMHs impacting a shock in quasi-perpendicular conditions. First, we feed an analytical model of stable LMHs of various size and depth with magnetic field and density variations in antiphase, oriented along the solar wind magnetic field, into the simulation. The LMHs are then left to propagate with and into the plasma flow, eventually impacting the shock, where they may cross into the induced magnetosheath. We look at the global and local effects of such crossings and how the structures' characteristics and their immediate vicinity change over time. We apply this setup to (i) a local quasi-perpendicular shock structure created by one reflecting boundary and (ii) a global simulation of a cometary environment, and compare with observational findings. This work is part of preliminary modelling efforts preparing for the upcoming ESA/JAXA Comet Interceptor mission.

How to cite: Simon Wedlund, C., Pucci, F., Preisser, L., Henri, P., Behar, E., Ballerini, G., Califano, F., Passot, T., Sulem, P.-L., and Settino, A.: Interaction between non-linear plasma structures and collisionless shocks: magnetic holes vs cometary shock, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6135, https://doi.org/10.5194/egusphere-egu24-6135, 2024.

EGU24-7269 | ECS | Posters on site | PS4.2

Solar Wind Energetic Neutral Atom Observation at Mars by MINPA Onboard the Tianwen-1 Orbiter 

Jijie Ma, Wenya Li, Linggao Kong, André Galli, Peter Wurz, Binbin Tang, Yiteng Zhang, Lianghai Xie, Limin Wang, and Fuhao Qiao

The Mars Ion and Neutral Particle Analyzer (MINPA), one of the seven scientific payloads onboard the Tianwen-1 orbiter, was designed to measure ions and energetic neutral atoms (ENAs) at Mars. Here, we present MINPA's first results of the solar-wind ENAs, which are produced through the charge exchange process between the solar wind hydrogen ions and the neutral atoms of the Martian exosphere. We perform a comprehensive comparison between the inflight ENA data and ground calibration results to understand the energy and angular distributions of the solar-wind ENA signals by MINPA, and an algorithm is developed to convert the ENA count rate to intensity. The contamination by solar extreme ultraviolet (EUV) and the observation independency between ENAs and ions are both evaluated. We will present several cases and statistic results of the solar wind ENA observations, and their intensities are estimated to be 10^5~10^6 cm^-2 sr^-1 s^-1, which is in good agreement with previous model attempts.

How to cite: Ma, J., Li, W., Kong, L., Galli, A., Wurz, P., Tang, B., Zhang, Y., Xie, L., Wang, L., and Qiao, F.: Solar Wind Energetic Neutral Atom Observation at Mars by MINPA Onboard the Tianwen-1 Orbiter, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7269, https://doi.org/10.5194/egusphere-egu24-7269, 2024.

EGU24-7998 | ECS | Orals | PS4.2

Ion chemistry in the Martian dayside ionosphere 

Moa Persson and Erik Vigren

The ion composition of the Martian ionosphere is controlled by the ionisation of the neutral species (mainly CO2, CO and O) in the upper atmosphere and the chemical reactions that follow. The primary ions, CO2+ and O+, are reactive with O and CO2, respectively, as to produce O2+, which is the dominant ion species in the ionosphere. We apply a variety of simple chemical schemes to model the ion chemistry in the Martian dayside ionosphere using data from deep dip campaigns of the MAVEN mission. As model input we use concentrations of neutral species, as measured by the Neutral and Gas Ion Mass Spectrometer (NGIMS) onboard MAVEN, and solar EUV spectra measured by TIMED/SEE; extrapolated in distance and phase to Mars. We reach an adequate agreement between the calculated ion densities of the main ion species and those measured by NGIMS. However, the calculated ion composition does not fully match the measurements and deviations of up to a factor of 3-4 do prevail for some of the considered ion species. Several previous studies have solved similar issues by adjusting the input parameters to the calculations, such as increasing the neutral O density, reducing the neutral CO2 density or decreasing the solar irradiance. We present results from a thorough exploration of the involved parameter space and discuss possible reasons for still persisting model-observation discrepancies.

How to cite: Persson, M. and Vigren, E.: Ion chemistry in the Martian dayside ionosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7998, https://doi.org/10.5194/egusphere-egu24-7998, 2024.

EGU24-9328 | ECS | Posters on site | PS4.2

Study of Martian Ionospheric Plasma Depletion Events using MAVEN and Mars Express Spacecraft 

Praveen Basuvaraj, František Němec, Christopher Fowler, Leonardo Regoli, Zdeněk Němeček, and Jana Šafránková

Plasma Depletion Events (PDEs), characterized by a significant reduction (at least tenfold) in ion number density, are known to occur in the Martian ionosphere. Since its launch in September 2014, the MAVEN spacecraft has spotted around 1000 PDEs, primarily located in the nightside ionosphere and regions with strong crustal magnetic fields. We show that dayside PDEs are associated with an increased level of electrostatic fluctuations and suggest their formation through ambipolar diffusion triggered by the sudden escape of suprathermal electrons. We further investigate possible concurrent detections of PDEs by MAVEN and Mars Express. For this purpose, local electron density measurements from Mars Express near the MAVEN-identified PDEs are systematically checked. We present the first multi-spacecraft observations of PDEs, and we use them to discuss their spatio-temporal extents.

How to cite: Basuvaraj, P., Němec, F., Fowler, C., Regoli, L., Němeček, Z., and Šafránková, J.: Study of Martian Ionospheric Plasma Depletion Events using MAVEN and Mars Express Spacecraft, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9328, https://doi.org/10.5194/egusphere-egu24-9328, 2024.

EGU24-10518 | Orals | PS4.2

The Martian Surface Radiation Environment: Zenith Angle Dependence of Fluxes of Different Secondary Particle Species Produced in the Mars Atmosphere 

Salman Khaksarighiri, Robert F. Wimmer-Schweingruber, Timothy J. stubbs, Phillip H. Phipps, Mark D. Looper, Jingnan Guo, Bent Ehresmann, Donald M. Hassler, Daniel Matthiä, Cary Zeitlin, Jan Leo Löwe, Thomas Berger, Sven Löffler, and Günther Reitz

Understanding the zenith angle dependence of the Martian surface radiation environment is crucial for planning future human exploration missions to Mars. In our previous research (Wimmer et al. 2015; Guo et al. 2021; Khaksarighiri et al. 2023) we extensively studied the zenith-angle dependence of the Martian surface radiation dose rate. Leveraging the same validated radiation model, calibrated with data from the Radiation Assessment Detector (RAD) on Mars, we calculated the flux of secondary downward particles reaching to the surface of Mars from various zenith angles resulting from the interaction of primary particles with the Martian atmosphere. 

These flux of secondary particles, coming from different zenith angles, can be integrated into a comprehensive topographic map of Mars, providing a detailed depiction of the global radiation landscape.
The construction of this radiation map requires careful consideration of various factors, including atmospheric column density, local and large-scale topography offering potential shielding effects, and the input spectrum is affected by heliospheric modulation. Additionally, accounting for seasonal pressure cycles and daily atmospheric surface pressure due to thermal tides is essential. Our model specifically focused on the influence of zenith angle on atmospheric column depth and simulations tailored to the Gale Crater region, a region explored by the Curiosity rover. 

Applying this methodology allows us to create lookup tables of all secondary particles reaching the Martian surface from various zenith angles and evaluate the atmospheric impact. Employing these matrices alongside the incident spectrum enables the calculation of secondary particle flux from all zenith angles on the Martian surface.

This method provides valuable insights into the fluctuations in radiation flux on Mars, facilitating thorough assessments of potential radiation hazards. Mission planners can leverage these data, obtaining vital information to identify secure landing areas and sheltered regions for astronauts on the Martian surface.

How to cite: Khaksarighiri, S., Wimmer-Schweingruber, R. F., stubbs, T. J., Phipps, P. H., Looper, M. D., Guo, J., Ehresmann, B., Hassler, D. M., Matthiä, D., Zeitlin, C., Löwe, J. L., Berger, T., Löffler, S., and Reitz, G.: The Martian Surface Radiation Environment: Zenith Angle Dependence of Fluxes of Different Secondary Particle Species Produced in the Mars Atmosphere, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10518, https://doi.org/10.5194/egusphere-egu24-10518, 2024.

EGU24-10573 | ECS | Orals | PS4.2

4000 Sols on Mars - A Long-term Study of Radiation Variations 

Jan Leo Löwe, Robert Wimmer-Schweingruber, Salman Khaksarighiri, Donald Hassler, Jingnan Guo, Bent Ehresmann, Cary Zeitlin, Daniel Matthiä, Thomas Berger, Günther Reitz, and Sven Löffler

The Radiation Assessment Detector (RAD) onboard the Mars Science Laboratory's Curiosity rover is the first-ever instrument continuously monitoring energetic particles on the surface of Mars. Since the rover's landing on August 6, 2012, RAD has accumulated valuable data, providing an unprecedented opportunity to assess the radiation environment across a solar cycle on an another planet.
Understanding the radiation environment on Mars is crucial for a more accurate assessment of the risks posed to manned future space missions. Moreover, it also serves to further investigate planetary conditions, properties of the Sun, and galactic cosmic rays (GCRs). 
 
The radiation field on the surface of Mars primarily consists of charged particles, including primary GCRs propagating to the Martian surface and secondary particles generated through the interaction of primary GCRs with the Martian atmosphere or soil. 
Furthermore, it undergoes temporal changes caused by factors such as atmospheric pressure variations due to thermal tides, seasonal changes, geographical and topographical shielding effects, heliospheric modulation of GCRs, as well as Martian soil and subsurface conditions. Considering all these factors is essential for a comprehensive description of the radiation environment.
 
 Here we utilize the extensive RAD dataset spanning the last 11 years to delve into the intricate variations in particle flux. Our analysis encompasses a diverse array of particle species, providing a comprehensive understanding of how particle flux evolves over the course of one complete solar cycle. This extended time frame allows us to capture and analyze long-term trends, offering valuable insights into the dynamic nature of particle interactions within the Martian environment. By exploring the temporal patterns of particle flux across different species, we aim to contribute to a more nuanced comprehension of the complex radiation dynamics on Mars and its implications for future space missions and potential habitation. 
 
Additionally, we endeavored to understand the impacts of subsurface composition on the Martian surface radiation field, particularly in generating additional upward particles. This investigation is significant as it contributes to the exploration of potential subsurface water content on the surface of Mars.

How to cite: Löwe, J. L., Wimmer-Schweingruber, R., Khaksarighiri, S., Hassler, D., Guo, J., Ehresmann, B., Zeitlin, C., Matthiä, D., Berger, T., Reitz, G., and Löffler, S.: 4000 Sols on Mars - A Long-term Study of Radiation Variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10573, https://doi.org/10.5194/egusphere-egu24-10573, 2024.

EGU24-10671 | Posters on site | PS4.2

Science goals of the COMPASS instrument consortium on M-MATISSE 

David Andrews, Yoshifumi Futaana, Pierre Henri, Johan De Keyser, David Píša, Ferdinand Platschke, Hanna Rothkaehl, and Štěpán Štverák

Mars–Magnetosphere ATmosphere Ionosphere and Space-weather SciencE (M-MATISSE) is a candidate for the ESA M7 mission opportunity, currently being studied by ESA in Phase A.  It consists of two spacecraft with largely identical scientific payloads that will be placed into orbit around Mars in 2037.  On inclined elliptical orbits they will encounter all relevant regions of the Mars-induced magnetosphere and upper atmosphere for further refining our understanding of the exchange of material, energy and momentum between the solar wind and space environment, and the Martian system. The Combined Magnetic and Plasma Sensor Suite, COMPASS, consists of dual Fluxgate Magnetometers (MAG), dual Langmuir Probes (LP), a Mutual Impedance eXperiment (MIX) (composed of an electronic card Mutual Impedance Board (MIB) that supplies driving electric signals to the Mutual Impedance Probe (MIP)) and a 3D Velocity of Ion (3DVI) instrument (composed of Ion Drift Meter (IDM) and a Retarding Potential Analyzer (RPA) in a combined instrument package), with redundant integrated Wave Analyzer Processing Unit (WAPU) for handling digital data processing and redundant Low Voltage Power Supply (LVPS). Design heritage for COMPASS is derived from the Dust and Fields Package to be flown on Comet Interceptor and from the Radio And Plasma Wave Investigation on the Jupiter Icy Moons Explorer. By sharing physical and electrical resources where possible, COMPASS provides an integrated suite of sensors and data handling systems that will provide highly configurable measurements of plasma properties (density, temperature, velocity and basic composition), as well as the vector magnetic field, a single component of the electric field, and the spacecraft potential. In this presentation, we will review the initial design, expected performance and scientific goals of the COMPASS consortium within the M-MATISSE mission.

How to cite: Andrews, D., Futaana, Y., Henri, P., De Keyser, J., Píša, D., Platschke, F., Rothkaehl, H., and Štverák, Š.: Science goals of the COMPASS instrument consortium on M-MATISSE, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10671, https://doi.org/10.5194/egusphere-egu24-10671, 2024.

EGU24-10733 | ECS | Posters on site | PS4.2

Tianwen-1 and MAVEN Observed Multiple Ion Escape Channels of Mars during an Interplanetary Coronal Mass Ejection 

Fuhao Qiao, Lei Li, Lianghai Xie, Wenya Li, Linggao Kong, Binbin Tang, Taifeng Jin, Yiteng Zhang, Aibing Zhang, Limin Wang, and Jijie Ma

Interplanetary coronal mass ejections (ICMEs) are solar transients that have significant effects on the Martian space environment. The simultaneous spacecraft observations from Tianwen-1 and Mars Atmosphere and Volatile Evolution (MAVEN) are used to study the planetary ion escape for a dramatic ICME. MAVEN passes through the upstream solar wind, +E hemisphere, and -E hemisphere in one orbital period at 20:00 UT -24:00 UT on 2022 April 24. During this period, the interplanetary magnetic field (IMF) remained stable and dominated by the +Y component. In addition to the well-known “plume” escape channels located in the +E hemisphere, MAVEN also observed one ion escape channel in each hemisphere. The additional escape channel located in the +E hemisphere was easily identified as ionized atoms originating from the exosphere, which became significant during CME and was first reported. These ions are observed in both the solar wind and the magnetosheath, and the observed flux of these ions is strongest when MAVEN is very close to the upstream of the bow shock. In this event, ion density of this channel is up to 0.03 cm-3, which is 10 % ~ 30 % of the observed plume. The escape channel structure in the -E hemisphere is complex, and MAVEN has insufficient observation of this channel due to its orbital inclination. Tianwen-1 provided a powerful supplement based on the 1.5 hr observation of this structure, revealing many characteristics of this escape channel. The channel in the -E hemisphere also shows a narrow band in the energy spectrum, similar to the plume. Moreover, its density is between the ion densities of the two +E hemispherical channels. Interestingly, it is more likely to be observed near the magnetic pileup boundary rather than the entire -E hemisphere magnetosheath. These new channels reveal more details of Martian ion escape. The solar wind conditions similar to the early solar system during the ICMEs also help to study the early evolution of Mars.

How to cite: Qiao, F., Li, L., Xie, L., Li, W., Kong, L., Tang, B., Jin, T., Zhang, Y., Zhang, A., Wang, L., and Ma, J.: Tianwen-1 and MAVEN Observed Multiple Ion Escape Channels of Mars during an Interplanetary Coronal Mass Ejection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10733, https://doi.org/10.5194/egusphere-egu24-10733, 2024.

EGU24-10951 | ECS | Orals | PS4.2

The response of Martian magnetotail to interplanetary coronal mass ejection events: joint observations of Tianwen-1 and MAVEN 

Limin Wang, Lei Li, Wenya Li, Lianghai Xie, Yiteng Zhang, Binbin Tang, Linggao Kong, Aibing Zhang, Fuhao Qiao, and Jijie Ma

The Martian magnetotail serves as an important channel for the escape of planetary ions, with abundant dynamic processes. After Tianwen-1 successfully entered the scientific orbit around Mars, the sun is becoming increasingly active. With the orbital apoapsis ~10,760 km, Tianwen-1 completed its first magnetotail phase from March to July 2022, providing a good opportunity to investigate the response of the Martian far magnetotail to interplanetary coronal mass ejections (ICMEs). We made a preliminary analysis of the dynamic tail under an ICME impact on 16 May 2022, with Tianwen-1 monitoring magnetotail and Mars Atmosphere and Volatile EvolutioN (MAVEN) providing upstream measurements. Based on MAVEN observations, the arrival of the ICME was determined to be around 05:10 UT on 16 May 2022. Subsequently, a significant increase in the energy levels of H+ and O+ ions was seen when Tianwen-1 entered the magnetotail about one and a half hours later. Tianwen-1 continuously detected a subset of O+ ions with energies exceeding 1 keV. Accordingly, the escape rate of O+ became ~6.2 times greater during this ICME, and the highest O+ enhancement happened between 1 keV and 3 keV. The disturbance lasted 39 hours before returning to a quiet level. Furthermore, we conducted a statistical analysis on the escape rate of O+ in the far magnetotail (attitude higher than 2 Mars radius) during 11 ICME events from March to July 2022. The ion loss rates substantially increased during ICME events, especially for O+ with energy above several keV. This observation suggests the presence of effective acceleration processes in the Martian tail under ICME conditions.

How to cite: Wang, L., Li, L., Li, W., Xie, L., Zhang, Y., Tang, B., Kong, L., Zhang, A., Qiao, F., and Ma, J.: The response of Martian magnetotail to interplanetary coronal mass ejection events: joint observations of Tianwen-1 and MAVEN, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10951, https://doi.org/10.5194/egusphere-egu24-10951, 2024.

EGU24-12682 | Posters on site | PS4.2

Analysis of Two Selected Solar Events in 2011 and 2015 With Mars Express Radio Occultation Data 

Ananya Krishnan, Ozgur Karatekin, Sebastein Verkercke, Gregoire Henry, Beatriz Sánchez-Cano, and Olivier Witasse

Martian ionosphere has a stratified structure with two main layers in its electron density profile (Ne). The primary layer (M2 layer) is formed by solar EUV radiation (~20-90 nm) and has a peak electron density at around 120-140 km altitude with a peak density of ~1011 m-3. The second layer (M1 layer) occurs at a lower altitude with a peak electron density of ~109 m-3 and is formed by solar X-ray and electron impact ionization. The electron densities and the altitudes at which these peaks occur vary with space weather activities. Radio Occultation (RO) experiments provide vertical electron density profiles that span the entire ionosphere. Therefore, RO experiments are ideal for understanding the variabilities of Martian ionospheric parameters (peak density, peak altitude, and Total Electron Content (TEC)).

Here, we study the effect of solar flares and interplanetary coronal mass ejections (ICMEs) on the Martian ionosphere for two selected solar events in 2011 and 2015, using the publicly available Mars EXpress (MEX) radio occultation (RO) data (MaRS). The 2011 event was associated with a single flare and ICME1 while the 2015 event includes a series of ICMEs and flares2. The MaRS residual Doppler data for the selected periods were processed to obtain the electron density profiles using RO data processing pipeline developed at the Royal Observatory of Belgium3. For both events, the temporal variations of total electron content (TEC) and electron density profiles are retrieved to analyze and quantify the ionospheric response due to solar flares and CMEs.

The analysis showed that the effects of solar events were observable in Mars upper atmosphere for up to several weeks, with the influence gradually decaying following the peak intensity at the arrival of CME. The overall electron density structure showed no evident changes in both events, but a gradual decrease in M2 peak altitude was observed for the 2011 event. An abrupt change in scale height was also observed for some of the profiles in 2011 and 2015, following a high-impact flare or CME. The overall trend of the measured TEC showed a good agreement with the predictions, however, no clear signs of variation due to solar events were observed. All the RO measurements available for this study were 1-4 days earlier or later than the peak events. Thus, this study also points to necessity of having more frequent RO measurements and multi-instrument monitoring of the ionosphere.

Figure 1: The electron density profiles shifted 0.5 units along the x-axis, showing the gradual decrease in M2 peak altitude following the 2011 solar event.

Figure 2:  The SZA, M2 peak density, and M2 peak altitude obtained from MaRS data (black) with 2015 solar events (vertical-coloured lines). The M2 peak density and M2 peak altitude are compared with the NeMars model predictions (green). The NeMars gives these parameters without considering the solar event.

References:

1. Morgan, D. D., et al.,2014, JGR: Space Physics, 119(7), 5891–5908. 

2. Jakosky, B. M., et al., 2015, Science, 350(6261). 

3. Krishnan, A., et al.,2023, Radio Science, 58, e2023RS007784.

 

How to cite: Krishnan, A., Karatekin, O., Verkercke, S., Henry, G., Sánchez-Cano, B., and Witasse, O.: Analysis of Two Selected Solar Events in 2011 and 2015 With Mars Express Radio Occultation Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12682, https://doi.org/10.5194/egusphere-egu24-12682, 2024.

EGU24-13783 | Orals | PS4.2

Inversion of Upstream Solar Wind Parameters from Tianwen-1 H-ENA Observations at Mars 

Yiteng Zhang, Lei Li, Lianghai Xie, Linggao Kong, Wenya Li, Jijie Ma, Binbin Tang, Fuhao Qiao, Limin Wang, Taifeng Jin, and Aibing Zhang

An algorithm has been developed to invert the solar wind parameters from the hydrogen energetic neutral atom (H-ENA) measured in near-Mars space. Supposing the H-ENA is produced by change exchange collision between protons that originated in the solar wind and neutrals in the exosphere, an H-ENA model is established based on the magnetohydrodynamic (MHD) simulation of the solar wind interaction with Mars, to study the H-ENA characteristics. It is revealed that the solar wind H-ENAs are high-speed, low-temperature beams, just like the solar wind, while the magnetosheath H-ENAs are slower and hotter, with broader energy distribution. Assuming Maxwellian velocity distribution, the solar wind H-ENA flux is best fitted by a Gaussian function, from which the solar wind velocity, density, and temperature can be retrieved. Further investigation, based on the ENA flux simulated by the H-ENA model, reveals that the accuracy of inversed solar wind parameters is related to the angular and energy resolutions of the ENA detector. Finally, the algorithm is verified using the H-ENA observations from the Tianwen-1 mission. The upstream solar wind velocity when inversed is close to that of the in situ plasma measurement. Our result suggests the solar wind parameters inversed from H-ENA observation could be an important supplement to the dataset supporting studies on the Martian space environment, where long-term continuous monitoring of the upstream SW condition is lacking.

How to cite: Zhang, Y., Li, L., Xie, L., Kong, L., Li, W., Ma, J., Tang, B., Qiao, F., Wang, L., Jin, T., and Zhang, A.: Inversion of Upstream Solar Wind Parameters from Tianwen-1 H-ENA Observations at Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13783, https://doi.org/10.5194/egusphere-egu24-13783, 2024.

EGU24-14568 | Posters on site | PS4.2

Magnetosheath turbulence and intermittency at Venus, Earth and Mars observed during space weather events 

Marius M. Echim, Luciano Rodriguez, Giovanni Lapenta, Daria Shukhobodskaia, Harikrishnan Aravindakshan, Eliza Teodorescu, and Costel Munteanu

We investigate the effects of space weather events on the properties of turbulence and intermittency detected in the magnetosheath of Venus and Mars and compare with properties detected  in the Earth’s magnetosheath when impacted by the same interplanetary event. We select two Interplanetary Coronal Mass Ejection (ICME) events in 2012 which hit Venus and Earth and one ICME in 2018 which hit Earth and Mars. We use magnetic field and plasma data  provided by Venus Express, Cluster, MMS and MAVEN on which we apply a full set of analysis methods including computation of  Power Spectral Density (PSD), Probability Density Functions (PDFs) and the flatness. We compare the spectral index and the intermittent range of scales (where we observe scale dependent/increasing flatness) obtained for the non-magnetized planets with the same turbulence descriptors obtained for the Earth. We also compare planetary magnetosheath turbulence and intermittency  properties observed during space weather events with quiet times results, for each planetary system.

How to cite: Echim, M. M., Rodriguez, L., Lapenta, G., Shukhobodskaia, D., Aravindakshan, H., Teodorescu, E., and Munteanu, C.: Magnetosheath turbulence and intermittency at Venus, Earth and Mars observed during space weather events, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14568, https://doi.org/10.5194/egusphere-egu24-14568, 2024.

Venus and Mars, our two neighboring planets, have no global intrinsic magnetic fields, and the induced magnetospheres are formed in their solar wind interactions through mass loading of magnetic flux tubes carried by the solar wind and draping around the highly conducting ionosphere. Although they have similar global magnetic environments in their induced magnetosphere controlled by the interplanetary magnetic field and the solar wind motional electric field, their differences in planetary size, solar wind conditions, crustal magnetic fields, etc. also have measurable impacts. We comparatively study the magnetic field structures in the Venusian and Martian induced magnetospheres near the terminator via observations. The nature of their current systems and the features of magnetic structures such as flux ropes are examined in the near-terminator space and the effects of solar activity, interplanetary magnetic field, and crustal fields are explored. The results reveal the solar wind interaction with unmagnetized planets near the terminator, and a simulation provides a three‐dimensional view.

How to cite: Xiao, S.: Magnetic Field Structures in the Near-terminator Induced Magnetospheres of Venus and Mars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14776, https://doi.org/10.5194/egusphere-egu24-14776, 2024.

EGU24-16773 | ECS | Posters on site | PS4.2

Modeling Solar Wind Interaction with Mars through a Ten-ion-species Multifluid MHD Approach 

Jianxuan Wang, Haoyu Lu, and Shibang Li

The configurations of the Martian ionosphere and magnetosphere play a crucial role in the process of ion escape, given that the ionosphere serves as an important source of Martian ion escape and the magnetosphere is closely associated with the escape channels. In this study, we introduced a recently developed three-dimensional multifluid magnetohydrodynamic (MHD) model involving ten ionospheric ion species prevalent on Mars, Ar+, CO2+, CO+, C+, N2+, N+, NO+, O+, O2+, and H+. We solved control equations for each species integrated with their self-consistent chemical reactions. The model successfully reproduced the large-scale structure of bow shock (BS), magnetic pile-up boundary (MPB), and induced magnetosphere consistent with observational statistical results. Benefiting from the consideration of more species and relevant chemical reactions, the model calculated ionospheric profiles are in good agreement with existing studies derived from observations. Moreover, the presence of the crustal magnetic field concentrated in the southern hemisphere of Mars tends to elevate the boundary position of MPB by tens to hundreds of kilometers and impact ion escape processes. Therefore, our model, by calculating ion density and velocity for individual species, can reveal diverse effects of the crustal magnetic field on each ion species.

How to cite: Wang, J., Lu, H., and Li, S.: Modeling Solar Wind Interaction with Mars through a Ten-ion-species Multifluid MHD Approach, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16773, https://doi.org/10.5194/egusphere-egu24-16773, 2024.

EGU24-18658 | ECS | Posters virtual | PS4.2

The response of the cometary ionosphere to space weather forcing 

Aniko Timar, Zoltan Nemeth, and Jim Burch

The Rosetta spacecraft, traversing the inner magnetosphere of comet 67P/Churyumov-Gerasimenko, observed medium-energy ions of cometary origin. These ions, moving in the direction of the cometary nucleus, are likely accelerated in the outer regions of the comet's magnetosphere. Emerging from the low-energy ion background, their signal can reach energies between 50 and 1000 eV over a few hours or days in the ion spectrum measured by the RPC IES sensor of Rosetta. Over a similar time scale, they gradually lose their energy before disappearing again from the measurements. During these medium-energy ion events, the low-energy ion background is depleted. To explain the observed temporal characteristics of the ion spectrum, we investigated the effects of the dynamic pressure of the solar wind surrounding the comet on the medium-energy ions. We demonstrated that there is a very good correlation between the solar wind pressure and the quantity of medium-energy ions detected by Rosetta: when the solar wind pressure increases, the measured amount of medium-energy ions also increases. Additionally, we observe a significant correlation between ion energy and dynamic pressure as well, although the ion energy is also influenced by other parameters, such as cometary activity and the distance from the nucleus.

How to cite: Timar, A., Nemeth, Z., and Burch, J.: The response of the cometary ionosphere to space weather forcing, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18658, https://doi.org/10.5194/egusphere-egu24-18658, 2024.

EGU24-420 | ECS | Orals | ESSI1.5

Neural Networks for Surrogate Models of the Corona and Solar Wind 

Filipa Barros, João José Graça Lima, Rui F. Pinto, and André Restivo

In previous work, an Artificial Neural Network (ANN) was developed to automate the estimation of solar wind profiles used as initial conditions in MULTI-VP simulations. This approach, coupled with profile clustering, reduced the time previously required for estimation by MULTI-VP, enhancing the efficiency of the simulation process. It was observed that generating initial estimates closer to the final simulation led to reduced computation time, with a mean speedup of 1.13. Additionally, this adjustment yielded a twofold advantage: it minimized the amplitude of spurious transients, reinforcing the numerical stability of calculations and enabling the code to maintain a more moderate integration time step.

However, upon further analysis, it became evident that the physical model inherently required a relaxation time for the final solution to stabilize. Therefore, while refining initial conditions offered improvements, there was a limit to how much it could accelerate the process. Consequently, attention turned towards the development of a surrogate model focused on the upper corona (from 3 solar radii to 30 solar radii). This range was chosen because the model can avoid learning the initial phases of wind acceleration, which are hard to accurately predict. Moreover, in order to connect the model to heliospheric models and for space weather applications, more than 3 radii is more than sufficient and guarantees that the physics remain consistent within the reproducible domain.

This surrogate model aims at delivering faster forecasts, with MULTI-VP running in parallel (eventually refining the solutions). The surrogate model for MULTI-VP was tested using a heliospheric model and data from spacecraft at L1, validating its efficacy beyond Mean Squared Error (MSE) evaluations and ensuring physical conservation principles were upheld.

This work aims at simplifying and accelerating the process of establishing boundary conditions for heliospheric models without dismissing the physical models for both extreme events and for more physically accurate results. 

How to cite: Barros, F., Lima, J. J. G., F. Pinto, R., and Restivo, A.: Neural Networks for Surrogate Models of the Corona and Solar Wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-420, https://doi.org/10.5194/egusphere-egu24-420, 2024.

we show the evolutions of the separated strands within the apparent single coronal loops observed in Atmospheric Imaging Assembly (AIA) images. The loop strands are detected on  the upsampled AIA 193 equation.pdf images, which are   generated using a super-resolution convolutional neural  network, respectively. The architecture of the network is designed to map the AIA images to unprecedentedly high spatial resolution coronal images taken by  High-resolution Coronal Imager (Hi-C) during its brief flight. At some times, pairs of individual strands appeared to braid with each other and subsequently evolved to become pairs of almost parallel ones with their segments having exchanged totally.  These evolutions provide  morphological evidence supporting occurrences of magnetic reconnections between the braiding strands, which are further confirmed by  the occurrences of the transient hot emissions (>5 MK)  located at the footpoints of  the braiding structures. 

How to cite: Bi, Y.: The coronal braiding structures detected in the machine-learning upscaled SDO/AIA images, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1494, https://doi.org/10.5194/egusphere-egu24-1494, 2024.

EGU24-1604 | ECS | Orals | ESSI1.5

Machine Learning Synthesis and inversion method for Stokes Parameters in the solar context 

Juan Esteban Agudelo Ortiz, Germain Nicolás Morales Suarez, Santiago Vargas Domínguez, and Sergiy Shelyag

The arrival of new and more powerful spectropolarimetric instruments such as DKIST, the development of better magnetohydrodinamic (MHD) simulation codes and the creation of newly inversion methods, are coming with the demands of increasing amounts of computational time and power. This, with increasing generation of data, will come with even years of processing that will stop the advance of scientific investigations on mid-late stages. The arrival of Machine Learning models able to replicate patterns in data come with the possibilites of them to adapt to different types of datasets, such as those for classification or for creation of sequences like the seq2seq models, that once trained, they are able to give results according to previous methods that differ on order of magnitude in time processing, being a lot faster. Some work has been done within this field for creating machine learning inversion methods using data obtained from actual inversion codes applied on observational data, and using data from radiative transfer codes for synthesis, reducing both computational demands and time processing. This work attempts to follow onto this steps, using in this case datasets obtained from simulation codes like MURaM and their correspondent Stokes parameters obtained from non-lte radiative transfer codes like NICOLE, training forward (synthesis) and backward (inversion) some neural network models to test whether or not they can learn their physical behaviours and at what accuracy, for being used in the future to process actual data obtained from newly simulation codes and for real solar observations, being another step into the future for creating a new paradigm on how to invert and sunthesize quantities in Physics in general.

How to cite: Agudelo Ortiz, J. E., Morales Suarez, G. N., Vargas Domínguez, S., and Shelyag, S.: Machine Learning Synthesis and inversion method for Stokes Parameters in the solar context, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1604, https://doi.org/10.5194/egusphere-egu24-1604, 2024.

EGU24-2046 | ECS | Posters on site | ESSI1.5

Comparative Analysis of Random Forest and XGBoost in Classifying Ionospheric Signal Disturbances During Solar Flares 

Filip Arnaut, Aleksandra Kolarski, and Vladimir Srećković

In our previous publication (Arnaut et al. 2023), we demonstrated the application of the Random Forest (RF) algorithm for classifying disturbances associated with solar flares (SF), erroneous signals, and measurement errors in VLF amplitude data i.e., anomaly detection in VLF amplitude data. The RF algorithm is widely regarded as a preferred option for conducting research in novel domains. Its advantages, such as its ability to avoid overfitting data and its simplicity, make it particularly valuable in these situations. Nevertheless, it is imperative to conduct thorough testing and evaluation of alternative algorithms and methods to ascertain their potential advantages and enhance the overall efficiency of the method. This brief communication demonstrates the application of the XGBoost (XGB) method on the exact dataset previously used for the RF algorithm, along with a comparative analysis between the two algorithms. Given that the problem is framed as a machine learning (ML) problem with a focus on the minority class, the comparative analysis is exclusively conducted using the minority (anomalous) data class. The data pre-processing methodology can be found in Arnaut et al. (2023). The XGB tuning process involved using a grid search method to optimize the hyperparameters of the model. The number of estimators (trees) was varied from 25 to 500 in increments of 25, and the learning rate was varied from 0.02 to 0.4 in increments of 0.02. The F1-Score for the anomalous data class is similar for both models, with a value of 0.508 for the RF model and 0.51 for the XGB model. These scores were calculated using the entire test dataset, which consists of 19 transmitter-receiver pairs. Upon closer examination, it becomes evident that the RF model exhibits a higher precision metric (0.488) than the XGB model (0.37), while the XGB model demonstrates a higher recall metric (0.84) compared to the RF model (0.53). Upon examining each individual transmitter-receiver pair, it was found that XGB outperformed RF in terms of F1-Scores in 10 out of 19 cases. The most significant disparities are observed in cases where the XGB model outperformed by a margin of 0.15 in terms of F1-Score, but conversely performed worse by approximately -0.16 in another instance for the anomalous data class. The XGB models outperformed the RF model by approximately 6.72% in terms of the F1-score for the anomalous data class when averaging all the 19 transmitter-receiver pairs. When utilizing a point-based evaluation metric that assigns rewards or penalties for each entry in the confusion matrix, the RF model demonstrates an overall improvement of approximately 5% compared to the XGB model. Overall, the comparison between the RF and XGB models is ambiguous. Both models have instances where one is superior to the other. Further research is necessary to fully optimize the method, which has benefits in automatically classifying VLF amplitude anomalous signals caused by SF effects, erroneous measurements, and other factors.

References:

Arnaut, F., Kolarski, A. and Srećković, V.A., 2023. Random Forest Classification and Ionospheric Response to Solar Flares: Analysis and Validation. Universe9(10), p.436.

How to cite: Arnaut, F., Kolarski, A., and Srećković, V.: Comparative Analysis of Random Forest and XGBoost in Classifying Ionospheric Signal Disturbances During Solar Flares, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2046, https://doi.org/10.5194/egusphere-egu24-2046, 2024.

EGU24-4181 | Posters on site | ESSI1.5

Prediction of sunspot number using Gaussian processes 

Everton Frigo and Italo Gonçalves

The solar activity has various direct and indirect impacts on human activities. During periods of high solar activity, the harmful effects triggered by solar variability are maximized. On a decadal to multidecadal time scale, solar variability exhibits a main cycle of around 11 years known as the Schwabe solar cycle, leading to a solar maximum approximately every 11 years. The most commonly used variable for measuring solar activity is the sunspot number. Over the last few decades, numerous techniques have been employed to predict the time evolution of the solar cycle for subsequent years. Recently, there has been a growing number of studies utilizing machine learning methods to predict solar cycles. One such method is the Gaussian process, which is well-suited for working with small amounts of data and can also provide an uncertainty measure for predictions. In this study, the Gaussian process technique is employed to predict the sunspot number between 2024 and 2050. The dataset used to train and validate the model comprises monthly averages of sunspots relative to the period 1700-2023. According to the results, the current solar cycle, currently at its maximum, is anticipated to last until 2030. The subsequent solar maximum is projected to occur around the end of 2033, with an estimated maximum sunspot number of approximately 150. If this prediction holds true, the next solar cycle's maximum will resemble that observed in the current one.

How to cite: Frigo, E. and Gonçalves, I.: Prediction of sunspot number using Gaussian processes, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4181, https://doi.org/10.5194/egusphere-egu24-4181, 2024.

EGU24-4471 | ECS | Orals | ESSI1.5

Solar Wind Speed Estimation via Symbolic Knowledge Extraction from Opaque Models 

Federico Sabbatini and Catia Grimani

The unprecedented predictive capabilities of machine learning models make them inestimable tools to perform data forecasting and other complex tasks. Benefits of these predictors are even more precious when there is the necessity of surrogating unavailable data due to the lack of dedicated instrumentation on board space missions. For instance, the future ESA space interferometer LISA for low-frequency gravitational wave detection will host, as part of its diagnostics subsystem, particle detectors to measure the galactic cosmic-ray flux and magnetometers to monitor the magnetic field intensity in the region of the interferometer mirrors. No instrumentation dedicated to the interplanetary medium parameter monitoring will be placed on the three spacecraft constituting the LISA constellation. However, important lessons about the correlation between galactic cosmic-ray flux short-term variations and the solar wind speed profile have been learned with the ESA LISA precursor mission, LISA Pathfinder, orbiting around the L1 Lagrange point. In a previous work, we have demonstrated that for LISA Pathfinder it was possible to reconstruct with an uncertainty of 2 nT the interplanetary magnetic field intensity for interplanetary structure transit monitoring. Machine learning models are proposed here to infer the solar wind speed that is not measured on the three LISA spacecraft from galactic cosmic-ray measurements. This work is precious and necessary since LISA, scheduled to launch in 2035, will trail Earth on the ecliptic at 50 million km distance, too far from the orbits of other space missions dedicated to the interplanetary medium monitoring to benefit of their observations.

We built an interpretable machine learning predictor based on galactic cosmic-ray and interplanetary magnetic field observations to obtain a solar wind speed reconstruction within ±65 km s-1 of uncertainty. Interpretability is achieved by applying the CReEPy symbolic knowledge extractor to the outcomes of a k-NN regressor. The extracted knowledge consists of linear equations aimed at describing the solar wind speed in terms of four statistical indices calculated for the input variables.

Details about the model workflow, performance and validation will be presented at the conference, together with the advantages, drawbacks and possible future enhancements, to demonstrate that our model may provide the LISA mission with an effective and human-interpretable tool to carry out reliable solar wind speed estimates and recognise the transit of interplanetary structures nearby the LISA spacecraft, as a support to the data analysis activity for the monitoring of the external forces acting on the spectrometer mirrors.

How to cite: Sabbatini, F. and Grimani, C.: Solar Wind Speed Estimation via Symbolic Knowledge Extraction from Opaque Models, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4471, https://doi.org/10.5194/egusphere-egu24-4471, 2024.

EGU24-6558 | ECS | Orals | ESSI1.5

A New Machine Learning Approach for Predicting Extreme Space Weather 

Andong Hu and Enrico Camporeale

We present an innovative method, ProBoost (Probabilistic Boosting), for forecasting extreme space weather events using ensemble machine learning (ML). Ensembles enhance prediction accuracy, but applying them to ML faces challenges as ML models often lack wellcalibrated uncertainty estimates. Moreover, space weather problems are typically affected by very imbalanced datasets (i.e., extreme and rare events) To overcome these difficulties, we developed a method that incorporates uncertainty quantification (UQ) in neural networks, enabling simultaneous forecasting of prediction uncertainty.
Our study applies ProBoost to the following space weather applications:
• One-to-Six-Hour Lead-Time Model: Predicting Disturbance Storm Time (Dst) values using solar wind data.
• Two-Day Lead-Time Model: Forecasting Dst probability using solar images.
• Geoelectric Field Model: Multi-hour lead time, incorporating solar wind and SuperMag data.
• Ambient Solar Wind Velocity Forecast: Up to 5 days ahead.
ProBoost is model-agnostic, making it adaptable to various forecasting applications beyond space weather.

How to cite: Hu, A. and Camporeale, E.: A New Machine Learning Approach for Predicting Extreme Space Weather, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6558, https://doi.org/10.5194/egusphere-egu24-6558, 2024.

We use the framework of Physics-Informed Neural Network (PINN) to solve the inverse problem associated with the Fokker-Planck equation for radiation belts' electron transport, using 4 years of Van Allen Probes data. Traditionally, reduced models have employed a diffusion equation based on the quasilinear approximation. We show that the dynamics of “killer electrons” is described more accurately by a drift-diffusion equation, and that drift is as important as diffusion for nearly-equatorially trapped ∼1 MeV electrons in the inner part of the belt. Moreover, we present a recipe for gleaning physical insight from solving the ill-posed inverse problem of inferring model coefficients from data using PINNs. Furthermore, we derive a parameterization for the diffusion and drift coefficients as a function of L only, which is both simpler and more accurate than earlier models. Finally, we use the PINN technique to develop an automatic event identification method that allows identifying times at which the radial transport assumption is inadequate to describe all the physics of interest.

How to cite: Camporeale, E.: Data-Driven Discovery of Fokker-Planck Equation for the Earth's Radiation Belts Electrons Using Physics-Informed Neural Networks, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6899, https://doi.org/10.5194/egusphere-egu24-6899, 2024.

The detection of asteroids involves the processing of sequences of astronomical images. The main challenges arise from the huge volume of data that should be processed in a reasonable amount of time. To address this, we developed the NEARBY platform [1], [2] for efficiently automatic detection of asteroids in sequence of astronomical images. This platform encompasses multidimensional data processing capabilities, human-verified visual analysis, and cloud-based adaptability. This paper outlines the enhancements we have made to this automated asteroid detection system by integrating a machine learning-based classifier known as the CERES module. The integration of the CERES module [3] into the NEARBY platform substantially enhances its performance by automatically reducing the number of false positive detections. Consequently, this leads to a more reliable and efficient system for asteroid identification, while also reducing the time and effort required by human experts to validate detected candidates (asteroids). The experiments highlight these improvements and their significance in advancing the field of asteroid tracking. Additionally, we explore the applicability of the asteroid classification model, initially trained using images from a specific telescope, across different telescopes.

Acknowledgment:

  • This work was supported by a grant of the Romanian Ministry of Education and Research, CCCDI - UEFISCDI, project number PN-III-P2-2.1-PED-2019-0796, within PNCDI III. (the development of the dataset and CNN models)
  • This research was partially supported by the project 38 PFE in the frame of the programme PDI-PFE-CDI 2021.

References:

  • Bacu, V., Sabou, A., Stefanut, T., Gorgan, D., Vaduvescu, O., NEARBY platform for detecting asteroids in astronomical images using cloud-based containerized applications, 2018 IEEE 14th International Conference on Intelligent Computer Communication and Processing (ICCP), pp. 371-376
  • Stefanut, T., Bacu, V., Nandra, C., Balasz, D., Gorgan, D., Vaduvescu, O., NEARBY Platform: Algorithm for automated asteroids detection in astronomical images, 2018 IEEE 14th International Conference on Intelligent Computer Communication and Processing (ICCP), pp. 365-369
  • Bacu, V.; Nandra, C.; Sabou, A.; Stefanut, T.; Gorgan, D. Assessment of Asteroid Classification Using Deep Convolutional Neural Networks. Aerospace 2023, 10, 752. https://doi.org/10.3390/aerospace10090752

 

How to cite: Bacu, V.: Enhancement of the NEARBY automated asteroid detection platform with a machine learning-based classifier, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8018, https://doi.org/10.5194/egusphere-egu24-8018, 2024.

EGU24-9174 | ECS | Orals | ESSI1.5

Enhancing Space Mission Return through On-Board Data Reduction using Unsupervised Machine Learning 

Salome Gruchola, Peter Keresztes Schmidt, Marek Tulej, Andreas Riedo, Klaus Mezger, and Peter Wurz

The efficient use of the provided downlink capacity for scientific data is a fundamental aspect of space exploration. The use thereof can be optimised through sophisticated data reduction techniques and automation of processes on board that otherwise require interaction with the operations centres on Earth. Machine learning-based autonomous methods serve both purposes; yet space-based ML applications remain relatively rare compared to the application of ML on Earth to data acquired in space.

In this contribution, we present a potential application of unsupervised machine learning to cluster mass spectrometric data on-board a spacecraft. Data were acquired from a phoscorite rock [1] using a prototype of a laser ablation ionisation mass spectrometer (LIMS) for space research [2]. Two unsupervised dimensionality reduction algorithms, UMAP and densMAP [3,4], were employed to construct low-dimensional representations of the data. Clusters corresponding to different mineral phases within these embeddings were found using HDBSCAN [5]. The impact of data pre-processing and model parameter selection on the classification outcome was investigated through varying levels of pre-processing and extensive grid searches.

Both UMAP and densMAP effectively isolated major mineral phases present within the rock sample, but densMAP additionally found minor inclusions present only in a small number of mass spectra. However, densMAP exhibited higher sensitivity to data pre-processing, yielding lower scores for minimally treated data compared to UMAP. For highly processed data, both UMAP and densMAP exhibited high stability across a broad model parameter space.

Given that the data were recorded using a miniature mass spectrometric instrument designed for space flight, these methods demonstrate effective strategies for substantial reduction of data similarly to what is anticipated on future space missions. Autonomous clustering of data into groups of different chemical composition, followed by the downlink of a representative mass spectrum of each cluster, aids in identifying relevant data. Mission return can therefore be enhanced through the selective downlink of data of interest. As both UMAP and densMAP, coupled with HDBSCAN, are relatively complex algorithms compared to more traditional techniques, such as k-means, it is important to evaluate the benefits and drawbacks of using simpler methods on-board spacecraft.

 

[1] Tulej, M. et al., 2022, https://doi.org/10.3390/universe8080410.

[2] Riedo, A. et al., 2012, https://doi.org/10.1002/jms.3104.

[3] McInnes, L. et al., 2018, https://doi.org/10.48550/arXiv.1802.03426.

[4] Narayan, A., et al., 2021, https://doi.org/10.1038/s41587-020-00801-7.

[5] McInnes, L., et al., 2017, https://doi.org/10.21105/JOSS.00205.

How to cite: Gruchola, S., Keresztes Schmidt, P., Tulej, M., Riedo, A., Mezger, K., and Wurz, P.: Enhancing Space Mission Return through On-Board Data Reduction using Unsupervised Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9174, https://doi.org/10.5194/egusphere-egu24-9174, 2024.

EGU24-10715 | ECS | Posters on site | ESSI1.5

Physics-driven feature combination for an explainable AI approach to flare forecasting 

Margherita Lampani, Sabrina Guastavino, Michele Piana, Federico Benvenuto, and Anna Maria Massone

Typical supervised feature-based machine learning approaches to flare forecasting rely on descriptors extracted from magnetograms, as from Helioseismic and Magnetic Imager (HMI) images, and standardized before being used in the training phase of the machine learning pipeline. However, this artificial intelligence (AI) model does not take into account the physical nature of the features and their role in the plasma physics equations. This talk proposes to generate novel features according to simple physics-driven combinations of the original descriptors, and to show whether this original physically explainable AI model leads to a more predictive solar flare forecasting.

How to cite: Lampani, M., Guastavino, S., Piana, M., Benvenuto, F., and Massone, A. M.: Physics-driven feature combination for an explainable AI approach to flare forecasting, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-10715, https://doi.org/10.5194/egusphere-egu24-10715, 2024.

EGU24-12885 | ECS | Posters on site | ESSI1.5

Finding Hidden Conjunctions in the Solar Wind 

Zoe Faes, Laura Hayes, Daniel Müller, and Andrew Walsh

This study aims to identify sets of in-situ measurements of the solar wind which sample the same volume of plasma at different times and locations as it travels through the heliosphere using ensemble machine learning methods. Multiple observations of a single volume of plasma by different spacecraft - referred to here as conjunctions - are becoming more frequent in the current “golden age of heliophysics research” and are key to characterizing the expansion of the solar wind. Specifically, identifying these related observations will enable us to test the current understanding of solar wind acceleration from the corona to the inner heliosphere with a more comprehensive set of measurements than has been used in previous analyses.

Using in-situ measurements of the background solar wind from Solar Orbiter, Parker Solar Probe, STEREO-A, Wind and BepiColombo, we identify a set of criteria based on features of magnetic field, velocity, density and temperature timeseries of known conjunctions and search for other instances for which the criteria are satisfied, to find previously unknown conjunctions. We use an ensemble of models, including random forests and recurrent neural networks with long short-term memory trained on synthetic observations obtained from magnetohydrodynamic simulations, to identify candidate conjunctions solely from kinetic properties of the solar wind. Initial results show a previously unidentified set of conjunctions between the spacecraft considered in this study. While this analysis has thus far only been performed on observations obtained since 2021 (start of Solar Orbiter science operations), the methods used here can be applied to other datasets to increase the potential for scientific return of existing and future heliophysics missions.

The modular scientific software built over the course of this research includes methods for the retrieval, processing, visualisation, and analysis of observational and synthetic timeseries of solar wind properties. It also includes methods for feature engineering and integration with widely used machine learning libraries. The software is available as an open-source Python package to ensure results can be easily reproduced and to facilitate further investigation of coordinated in-situ data in heliophysics.

How to cite: Faes, Z., Hayes, L., Müller, D., and Walsh, A.: Finding Hidden Conjunctions in the Solar Wind, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12885, https://doi.org/10.5194/egusphere-egu24-12885, 2024.

EGU24-12961 | ECS | Posters on site | ESSI1.5

Physics-informed neural networks for advanced solar magnetic field extrapolations 

Robert Jarolim, Benoit Tremblay, Matthias Rempel, Julia Thalmann, Astrid Veronig, Momchil Molnar, and Tatiana Podladchikova

Physics-informed neural networks (PINNs) provide a novel approach for data-driven numerical simulations, tackling challenges of discretization and enabling seamless integration of noisy data and physical models (e.g., partial differential equations). In this presentation, we discuss the results of our recent studies where we apply PINNs for coronal magnetic field extrapolations of the solar atmosphere, which are essential to understand the genesis and initiation of solar eruptions and to predict the occurrence of high-energy events from our Sun.
We utilize our PINN to estimate the 3D coronal magnetic fields based on photospheric vector magnetograms and the force-free physical model. This approach provides state-of-the-art coronal magnetic field extrapolations in quasi real-time. We simulate the evolution of Active Region NOAA 11158 over 5 continuous days, where the derived time profile of the free magnetic energy unambiguously relates to the observed flare activity.
We extend this approach by utilizing multi-height magnetic field measurements and combine them in a single magnetic field model. Our evaluation shows that the additional chromospheric field information leads to a more realistic approximation of the solar coronal magnetic field. In addition, our method intrinsically provides an estimate of the height corrugation of the observed magnetograms.
We provide an outlook on our ongoing work where we use PINNs for global force-free magnetic field extrapolations. This approach enables a novel understanding of the global magnetic topology with a realistic treatment of current carrying fields.
In summary, PINNs have the potential to greatly advance the field of numerical simulations, accelerate scientific research, and enable advanced space weather monitoring.

How to cite: Jarolim, R., Tremblay, B., Rempel, M., Thalmann, J., Veronig, A., Molnar, M., and Podladchikova, T.: Physics-informed neural networks for advanced solar magnetic field extrapolations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-12961, https://doi.org/10.5194/egusphere-egu24-12961, 2024.

EGU24-14186 | Posters on site | ESSI1.5

Near real-time construction of Solar Coronal Parameters based on MAS simulation by Deep Learning  

Sumiaya Rahman, Hyun-Jin Jeong, Ashraf Siddique, and Yong-Jae Moon

Magnetohydrodynamic (MHD) models provide a quantitative 3D distribution of the solar corona parameters (density, radial velocity, and temperature). However, this process is expensive and time-consuming. For this, we apply deep learning models to reproduce the 3D distribution of solar coronal parameters from 2D synoptic photospheric magnetic fields. We consider synoptic photospheric magnetic fields as an input to obtain 3D solar coronal parameters simulated by the MHD Algorithm outside a Sphere (MAS) from June 2010 to January 2023. Each parameter is individually trained using 150 deep learning models, corresponding to 150 solar radial distances ranging from 1 to 30 solar radii. Our study yields significant findings. Firstly, our model accurately reproduces 3D coronal parameter structures across the 1 to 30 solar radii range, demonstrating an average correlation coefficient value of approximately 0.96. Secondly, the 150 deep-learning models exhibit a remarkably shorter runtime (about 16 seconds for each parameter), with an NVIDIA Titan XP GPU, in comparison to the conventional MAS simulation time. As the MAS simulation is a regularization model, we may significantly reduce the simulation time by using our results as an initial magnetic configuration to obtain an equilibrium condition. In the future, we hope that the generated solar coronal parameters can be used for near real-time forecasting of heliospheric propagation of solar eruptions.

How to cite: Rahman, S., Jeong, H.-J., Siddique, A., and Moon, Y.-J.: Near real-time construction of Solar Coronal Parameters based on MAS simulation by Deep Learning , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14186, https://doi.org/10.5194/egusphere-egu24-14186, 2024.

EGU24-15813 | ECS | Orals | ESSI1.5

Instrument-to-Instrument translation: An AI tool to intercalibrate, enhance and super-resolve solar observations 

Christoph Schirninger, Astrid Veronig, Robert Jarolim, J. Emmanuel Johnson, Anna Jungbluth, Richard Galvez, Lilli Freischem, and Anne Spalding

Various instruments are used to study the Sun, including ground-based observatories and space telescopes. These data products are constantly changing due to technological improvements, different instrumentation, or atmospheric effects. However, for certain applications such as ground-based solar image reconstruction or solar cycle studies, enhanced and combined data products are necessary.

We present a general AI tool called Instrument-to-Instrument (ITI; Jarolim et al. 2023) translation, which is capable of translating datasets between two different image domains. This approach enables instrument intercalibration, image enhancement, mitigation of quality degradations, and super-resolution across multiple wavelength bands. The tool is built on unpaired image-to-image translation, which enables a wide range of applications, where no spatial or temporal overlap is required between the considered datasets.

In this presentation, we highlight ITI as a general tool for Heliospheric applications and demonstrate its capabilities by applying it to data from Solar Orbiter/EUI, PROBA2/SWAP, and the Solar Dynamics Observatory/AIA in order to achieve a homogenous, machine-learning ready dataset that combines three different EUV imagers. 

The direct comparison of aligned observations shows the close relation of ITI-enhanced and real high-quality observations. The evaluation of light-curves demonstrates an improved inter-calibration.

ITI is provided open-source to the community  and can be easily applied to novel datasets and various research applications. 

This research is funded through a NASA 22-MDRAIT22-0018 award (No 80NSSC23K1045) and managed by Trillium Technologies, Inc (trillium.tech)

How to cite: Schirninger, C., Veronig, A., Jarolim, R., Johnson, J. E., Jungbluth, A., Galvez, R., Freischem, L., and Spalding, A.: Instrument-to-Instrument translation: An AI tool to intercalibrate, enhance and super-resolve solar observations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15813, https://doi.org/10.5194/egusphere-egu24-15813, 2024.

EGU24-15981 | ECS | Posters on site | ESSI1.5

Addressing the closure problem using supervised Machine Learning 

Sophia Köhne, Brecht Laperre, Jorge Amaya, Sara Jamal, Simon Lautenbach, Rainer Grauer, Giovanni Lapenta, and Maria Elena Innocenti

When deriving fluid equations from the Vlasov equation for collisionless plasmas, one runs into the so-called closure problem: each equation for the temporal evolution of one particle moment (density, current, pressure, heat flux, …) includes terms depending on the next order moment. Therefore, when choosing to truncate the description at the nth order, one must approximate the terms related to the (n+1)th order moment included in the evolution equation for the nth order moment. The order at which the hierarchy is closed and the assumption behind the approximations used determine how accurately a fluid description can reproduce kinetic processes.

In this work, we aim at reconstructing specific particle moments from kinetic simulations, using as input the electric and magnetic field and the lower moments. We use fully kinetic Particle In Cell simulations, where all physical information is available, as the ground truth. The approach we present here uses supervised machine learning to enable a neural network to learn how to reconstruct higher moments from lower moments and fields.

Starting from the work of Laperre et al., 2022 we built a framework which makes it possible to train feedforward multilayer perceptrons on kinetic simulations to learn to predict the higher moments of the Vlasov equation from the lower moments, which would also be available in fluid simulations. We train on simulations of magnetic reconnection in a double Harris current sheet with varying background guide field obtained with the semi-implicit Particle-in-Cell code iPiC3D (Markidis et al, 2010). We test the influence of data preprocessing techniques, of (hyper-)parameter variations and of different architectures of the neural networks on the quality of the predictions that are produced. Furthermore, we investigate which metrics are most useful to evaluate the quality of the outcome.

How to cite: Köhne, S., Laperre, B., Amaya, J., Jamal, S., Lautenbach, S., Grauer, R., Lapenta, G., and Innocenti, M. E.: Addressing the closure problem using supervised Machine Learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15981, https://doi.org/10.5194/egusphere-egu24-15981, 2024.

EGU24-18534 | ECS | Posters on site | ESSI1.5

Visualizing three years of STIX X-ray flare observations using self-supervised learning 

Mariia Drozdova, Vitaliy Kinakh, Francesco Ramunno, Erica Lastufka, and Slava Voloshynovskiy

Operating continuously for over three years, Solar Orbiter's STIX has observed more than 43 thousand X-ray flares. This study presents a compelling visualization of this publicly available database, using self-supervised learning to organize reconstructed flare images by their visual properties. Networks designed for self-supervised learning, such as Masked Siamese Networks or Autoencoders, are able to learn latent space embeddings which encode core characteristics of the data. We investigate the effectiveness of various pre-trained vision models, fine-tuning strategies, and image preparation. This visual representation offers a valuable starting point for identifying interesting events and grouping flares based on shared morphological characteristics, useful for conducting statistical studies or finding unique flares in this rich set of observations.

How to cite: Drozdova, M., Kinakh, V., Ramunno, F., Lastufka, E., and Voloshynovskiy, S.: Visualizing three years of STIX X-ray flare observations using self-supervised learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18534, https://doi.org/10.5194/egusphere-egu24-18534, 2024.

EGU24-19248 | Posters on site | ESSI1.5

Segmentation and Tracking of Solar Eruptive Phenomena with Convolutional Neural Networks (CNN) 

Oleg Stepanyuk and Kamen Kozarev

Solar eruptive events are complex phenomena, which most often include coronal mass ejections (CME), flares, compressive/shock waves, and filament eruptions. CMEs are large eruptions of magnetized plasma from the Sun’s outer atmosphere or corona, that propagate outward into the interplanetary space. Solar Energetic Particles (SEP) are produced through particle acceleration in flares or CME-driven shocks. Exact mechanisms behind SEP production are yet to be understood, but it is thought that most of their acceleration occurs in shocks starting in the low corona. Over the last several decades a large amount of remote solar eruption observations have become available from ground-based and space-borne instruments. This has required the development of software approaches for automated characterization of eruptive features. Most solar feature detection and tracking algorithms currently in use have restricted applicability and complicated processing chains, while the complexities in engineering machine learning (ML) training sets limit the use of data-driven approaches for tracking or solar eruptive related phenomena. Recently, we introduced a hybrid algorithmic—data driven approach for characterization and tracking of solar eruptive features with the improved wavelet-based, multi-instrument Wavetrack package (Stepanyuk et.al, J. Space Weather Space Clim. (2024)), which was used to produce training datasets for data driven image segmentation with convolutional neural networks (CNN). Its perfomance was shown on a limited set of SDO AIA 193A instrument data perfoming segmentation of EUV and shock waves. Here we extend this approach and present an ensemble of more general CNN models for data-driven segmentation of various eruptive phenomena for the set of ground-based and remote instruments data. We discuss our approach to engineering training sets and data augmentation, CNN topology and training techniques. 

How to cite: Stepanyuk, O. and Kozarev, K.: Segmentation and Tracking of Solar Eruptive Phenomena with Convolutional Neural Networks (CNN), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19248, https://doi.org/10.5194/egusphere-egu24-19248, 2024.

EGU24-19558 | Orals | ESSI1.5

Comparative Analysis of Data Preprocessing Methods for Precise Orbit Determination 

Tom Andert, Benedikt Aigner, Fabian Dallinger, Benjamin Haser, Martin Pätzold, and Matthias Hahn

In Precise Orbit Determination (POD), employing proper methods for pre-processing tracking data is crucial not only to mitigate data noise but also to identify potential unmodeled effects that may elude the prediction model of the POD algorithm. Unaccounted effects can skew parameter estimation, causing certain parameters to assimilate the unmodeled effects and deviate from their true values. Therefore, enhancing the pre-processing of tracking data ultimately contributes to refining the prediction model.

The Rosetta spacecraft, during its two-year mission alongside comet 67P/Churyumov-Gerasimenko, collected a substantial dataset of tracking data. In addition to this data, also tracking data from the Mars Express spacecraft, orbiting Mars since 2004, will serve as a use case to assess and compare diverse data pre-processing methods. Both traditional and AI-based techniques are explored to examine the impact of various strategies on the accuracy of orbit determination. This aims to enhance POD, thereby yielding a more robust scientific outcome.

How to cite: Andert, T., Aigner, B., Dallinger, F., Haser, B., Pätzold, M., and Hahn, M.: Comparative Analysis of Data Preprocessing Methods for Precise Orbit Determination, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19558, https://doi.org/10.5194/egusphere-egu24-19558, 2024.

EGU24-21463 | ECS | Posters on site | ESSI1.5

A machine learning approach to meteor light curve analysis 

Lucas Mandl, Apostolous Christou, and Andreas Windisch

In this work we conduct a thorough examination of utilizing machine learning and computer
vision techniques for classifying meteors based on their characteristics. The focus of the re-
search is the analysis of light curves emitted by meteors as they pass through the Earth’s atmo-
sphere, including aspects such as luminosity, duration, and shape. Through extracting features
from these light curves and comparing them to established meteors orbits, valuable informa-
tion about the meteor’s origin and chemical composition is sought to be obtained. A significant
contribution of the thesis is the development of methods for classifying meteors by extracting
features from the light curve shape through the usage of unsupervised classification algorithms.
This approach allows for the automatic classification of meteors into various groups based on
their properties. Data for the research is collected by a three-camera setup at the Armagh observatory,
comprising one medium-angle camera and
two wide-angle cameras. This setup enables the capturing of detailed images of meteor light
curves, as well as various other observations such as coordinate and angular data. The research
also involves the use of machine learning algorithms for data reduction and classification tasks.
By applying these techniques to the data collected from the camera setup, the identification of
parent objects based on chemical composition and meteor path is facilitated, along with the
acquisition of other valuable information about the meteors.

How to cite: Mandl, L., Christou, A., and Windisch, A.: A machine learning approach to meteor light curve analysis, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21463, https://doi.org/10.5194/egusphere-egu24-21463, 2024.

PS5 – Exoplanets and Origins and evolution of Planetary Systems

EGU24-143 | ECS | Posters on site | PS5.2

Geometric considerations on planetary surface temperatures 

Sabin Roman

We propose a formula for computing the average planetary surface temperatures based solely on the solar irradiance and the bond albedo. The formula is empirically derived from data on Earth, Venus and Titan, and a model is proposed to justify it. We introduce the concept of planetary inner albedo, as a complement to the usual bond albedo. A geometric proof is given for the main finding of the paper, which can be summarized as follows: the ratio of the inner to outer albedo is a constant, related to the universal parabolic constant. Furthermore, we extend the surface temperature formula to gas giants, giving the temperature at which condensates (e.g., of ammonia) start forming within their atmosphere, particularly for Jupiter, Saturn and Uranus. Based on model complexity, applicability and accuracy, the heating mechanism via atmospheric reflectivity (a mirror effect) performs much better than the alternatives.

How to cite: Roman, S.: Geometric considerations on planetary surface temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-143, https://doi.org/10.5194/egusphere-egu24-143, 2024.

EGU24-801 | ECS | Orals | PS5.2

No Venus-like atmosphere on TRAPPIST-1 c: confirmation from 3D climate modelling 

Diogo Quirino, Gabriella Gilli, Martin Turbet, Thomas Fauchez, Thomas Navarro, and Pedro Machado

Recent measurements of the dayside thermal emission of exoplanets TRAPPIST-1b [1] and TRAPPIST-1c [2] were made by the James Webb Space Telescope (JWST) Mid-Infrared Instrument (MIRI) F1500W filter which covers the 15-µm carbon dioxide (CO2) absorption. These photometric secondary-eclipse observations determined the dayside brightness temperature and constrained the magnitude of heat redistribution. For TRAPPIST-1c, which has a Venus-like stellar irradiation, the estimated eclipse depth is 421±94 ppm, corresponding to a dayside brightness temperature of 380±31 K, superior to Venus's equilibrium temperature. Two scenarios stem from the inferred brightness temperature: a moderate heat redistribution or an airless, non-zero bond albedo surface. The observations rendered thick, CO2-enriched atmospheres unlikely for TRAPPIST-1c, excluding a cloudy (sulphuric acid aerosols) and a clear-sky Venus-like atmosphere at a confidence of 2.6σ and 3.0σ, respectively [2].

New JWST observations (Cycle 2 GO Programme 3077) [3] will obtain thermal emission phase curve measurements for most of TRAPPIST-1c’s orbit (P = 58-hours), identifying the day-night temperature contrast. These will be sensitive to test the case of a moderate heat redistribution [4-8], eventually distinguishing it from spectral features from a rocky surface or those from an airless planet [9]. This research is crucial given that CO2–dominated atmospheres were predicted as a likely outcome of atmospheric evolution on rocky planets orbiting cooler and less massive stars (M-dwarf stars) than our Sun [10]. Owing to the CO2 high molecular weight and efficient cooling in the infrared, CO2-rich atmospheres have extremely cold thermospheres and less expanded upper atmospheres; both can improve resilience to atmospheric escape processes, offering partial protection against M-dwarf lifelong stellar activity [10]. Investigating the status of a possible atmosphere on TRAPPIST-1c is critical to understanding atmospheric evolution on M-dwarf planets.

Here, we use a 3D global circulation model of the atmosphere, the Generic-PCM [8,11-13], to simulate a modern Venus-like atmosphere on TRAPPIST-1c: CO2-dominated, 92-bar surface pressure with radiatively-active global cover of sulphuric acid aerosols [13]. We also assumed a tidally-locked planet with zero obliquity and eccentricity. We use these simulations to generate high spectral resolution thermal phase curves for three JWST/MIRI filters: F1280W, F1500W and F1800W. We analyse the relationship between phase curve parameters (hot spot offset and amplitude), temperature and large-scale circulation. We find large eastward offsets and small amplitudes compatible with an efficient day-night heat redistribution driven by a superrotating equatorial jet. In addition, we predict a smaller hot spot offset for F1500W due to upper atmosphere CO2 absorption. These results highlight the possibility of studying at least two different atmospheric levels. The absence of a large hot spot offset on TRAPPIST-1c would rule out a dense, CO2-rich, absorbing atmosphere on the planet. These results can be expanded to the ever-growing population of rocky exoplanets with Venus-like stellar irradiations to be studied in the following decades [14].

References: [1]Greene+2023.Nature.618; [2]Zieba+2023.Nature.620; [3]Gillon+2023.JWST Proposal 3077; [4]Selsis+2011.A&A.532; [5]Demory+2016.Nature.532; [6]Koll+2016.ApJ.825; [7]Kreidberg+2019.Nature.573; [8]Turbet+2016.A&A.596.A112; [9]Whittaker+2022.AJ.164; [10]Turbet+2020.Space Sci. Rev.216; [11]Forget & Leconte, 2014.Phil.Trans R.Soc.A372; [12]Wordsworth+2011.ApJL.733.L48; [13]Quirino+2023.MNRASL.523.L86; [14]Ostberg+2023.AJ.165.

Funding: This work was supported by Fundação para a Ciência e a Tecnologia (FCT) through the research grant 2023.05220.BD.

How to cite: Quirino, D., Gilli, G., Turbet, M., Fauchez, T., Navarro, T., and Machado, P.: No Venus-like atmosphere on TRAPPIST-1 c: confirmation from 3D climate modelling, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-801, https://doi.org/10.5194/egusphere-egu24-801, 2024.

EGU24-1746 | ECS | Orals | PS5.2

Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets. 

Gwenaël Van Looveren, Manuel Güdel, Sudeshna Boro Saikia, and Kristina Kislyakova

JWST is currently at the forefront in the search for exoplanet atmospheres. However, the observation of atmospheres of Earth-like planets pushes the limits of the instruments, often requiring multiple observations to be combined. Their interpretation requires complementary theoretical studies to test plausible atmospheric models. We aim to determine the atmospheric survivability of rocky planets around late M-type dwarfs by modelling the upper atmosphere of the TRAPPIST-1 planets' response to incoming stellar extreme ultraviolet and X-ray (XUV) radiation. This is done using a self-consistent thermo-chemical code to create a grid of models simulating possible atmospheres. Specifically we study the atmospheric mass loss due to Jeans escape induced by XUV radiation. Our models indicate that even Jeans escape is catastrophically large for these N2 or CO2 dominated atmospheres over evolutionary timescales, which has important observational implications.

How to cite: Van Looveren, G., Güdel, M., Boro Saikia, S., and Kislyakova, K.: Airy worlds or barren rocks? On the survivability of secondary atmospheres around the TRAPPIST-1 planets., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1746, https://doi.org/10.5194/egusphere-egu24-1746, 2024.

EGU24-2151 | Orals | PS5.2

Earth-like planets hosting systems: architectures and properties 

Jeanne Davoult and Yann Alibert

The search for Earth-like planets is a subject of great importance in the world of planetology today. Detecting such planets is challenging and requires a great deal of observation time. With future missions such as PLATO or LIFE, one of the main objectives of which is to detect small, moderate-temperature planets like the Earth, it is important to understand in what types of systems these plants form and around which stars we can expect to detect them. We present here a theoretical statistical study of the most favorable conditions for a planetary system to host an ELP (Earth-like planet). Based on three populations of synthetic planetary systems generated using the Bern model around three different types of stars, this study aims to create a profile of a typical system that harbors an ELP. By using an observational bias, we generate new populations that can be compared to observed systems. We initially examine the distribution of ELPs across different categories of theoretical and observed architectures. The changes in architecture resulting from the application of a bias are also investigated, highlighting the relationship between "theoretical" and "biased" architectures. A more detailed analysis is then conducted, linking the “biased” architecture of a system with the physical properties of its innermost observable planet, in order to establish the most favorable conditions for the presence or absence of an ELP in a system. Several quantities, such as the mass, radius, period and water fraction of this planet, emerge as correlated with the presence or the absence of an ELP.

How to cite: Davoult, J. and Alibert, Y.: Earth-like planets hosting systems: architectures and properties, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2151, https://doi.org/10.5194/egusphere-egu24-2151, 2024.

EGU24-2531 | Posters on site | PS5.2

Exploring Trappist-1d with a 3D GCM 

Michael Way

Trappist-1d remains an underexplored planets in the fascinating multi-planet Trappist-1 system.
Some earlier studies have indicated that it may be more of an exo-Venus than an exo-Earth [1,2].
Of course atmospheric composition and density plays a key role and this parameter space
has barely been explored. As well, since these earlier studies the insolation of 1d appears
to be almost 1% lower than earlier estimates [3,4]. A subsequent 1D study using the
lower insolation [5] finds one atmospheric composition places it in the habitable zone,
while the other in the Venus-Zone [6].  We use the ROCKE-3D General Circulation Model [7]
to examine Trappist-1d's possible climate.

[1] Wolf, E.T. (2017) ApJ 839:L1
[2] Turbet et al. (2018) A&A 612, A86
[3] Gillon et al. (2017) Nature 542, 456
[4] Agol et al. (2021) PSJ 2:1
[5] Meadows et al. (2023) PSJ 4:10
[6] Kane, S.R. et al. (2021) AJ 161:53
[7] Way, M.J. et al. (2017) ApJS 213:12

How to cite: Way, M.: Exploring Trappist-1d with a 3D GCM, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2531, https://doi.org/10.5194/egusphere-egu24-2531, 2024.

 

Convective vortices, and their particle-laden counterparts dust devils, are an important feature of the meteorology of both Mars and terrestrial desert areas. In addition to being interesting phenomena in their own right, they can cause occasional damage and even death.  

The last 12 years has seen the generation of statistically-robust catalogs of vortex encounters from long-lived (>1000 Sol) landers and rovers equipped with meteorological instrumentation, namely MSL, InSight and Mars 2020. 

 Although previous landers (Phoenix and Pathfinder, lasting ~100 Sols) yielded catalogs that were enough to indicate useful analytic function descriptions of vortex population functions (e.g. power laws or exponentials of number versus measured pressure drop), the new generation of missions provide much more robust statistics, and also have had more extensive instrumentation, permitting the documentation of wind speed, dust loading and even seismic characteristics of vortex encounters.

In the 2000s, the Mars statistics were in fact rather better than those available for the Earth, but the advent of inexpensive and low-power data logging systems with flash memory permitted the long-duration (months) acquisition of high-cadence (>1/second) pressure and other data required to detect small vortices in unattended field measurement campaigns. Inexpensive timelapse cameras have also permitted optical surveys of dust devils that are comparable with those from Mars landed and orbital missions.

In many respects the populations of vortex events are surprisingly similar on the two worlds, when expressed as a normalized peak pressure drop (pressure drop divided by ambient pressure : this quantity is proportional to the peak wind speed at the wall of the vortex).  The cumulative rate of encounters typically varies as a power law with an exponent of about -2, and Martian rates are a factor of several higher than those on Earth.  Although the convective heating rates of the respective surfaces are somewhat different, a key difference is that the Martian Planetary Boundary Layer, which sets the upper limit on vortex size, is much deeper, and Martian dust devils are typically larger than Earth’s as a result.  

I will review these population functions and their implications for meteorology, dust lifting and safety.

How to cite: Lorenz, R.: Comparing the Dust Devil Vortex Populations on Mars and Earth, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4489, https://doi.org/10.5194/egusphere-egu24-4489, 2024.

EGU24-5832 | Orals | PS5.2

Magma oceanography of the dense, ultrashort-period sub-Earth GJ 367 b 

Gregor J. Golabek, Tim Lichtenberg, Lotte M. Bartels, Paul J. Tackley, Tobias Meier, and Dan Bower

The dawn of high-resolution observations with the James Webb Space Telescope will enable spatially resolved observations of ultrashort-period rocky exoplanets. Some of these planets orbit so closely to their star that they lack an atmosphere [1], which gives direct access to their surfaces and opens a window to infer their geodynamics [2]. The physical parameters of the ultrashort-period sub-Earth GJ 367 b have been observationally constrained to a planetary radius of about 0.72 to 0.75 Earth-radii and a mass between 0.48 and 0.55 Earth-masses, implying a density of 6200 to 8500 kg/m3 [3, 4], which puts this planet in a Mercury-like interior regime with a thin mantle overlying a fractionally large core.

The dayside temperature ranges between 1500 to 1800 K, thus suggesting the presence of a permanent magma ocean or dayside magma pond on the surface, induced by stellar irradiation. The large uncertainty on the age of the stellar system, between 30 Myr [4] and about 8 Gyr [3], however, introduce severe uncertainties related to the compositional and thermal evolution of the planetary mantle. In this study we perform global 2D spherical annulus StagYY simulations [5, 6] of solid-state mantle convection and surface melting with the goal to constrain the geometric and compositional properties of the planet. Constraining the spatial dimensions of thermodynamic properties of partially molten, atmosphere-less planets like GJ 367 b offers unique opportunities to constrain the compositional fractionation during magma ocean epochs and provides avenues to constrain the delivery and loss cycle of atmophile elements on strongly irradiated exoplanets.

References:

[1] L. Kreidberg and 18 co-authors. Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b. Nature, 573:87–90, 2019.

[2] T. G. Meier, D. J. Bower, T. Lichtenberg, P. J. Tackley, and B.-O. Demory. Hemispheric Tectonics on LHS 3844b. Astrophys. J. Lett., 908:L48, 2021.

[3] K.W.F. Lam and 78 co-authors. GJ 367 b: A dense, ultrashort-period sub-earth planet transiting a nearby red dwarf star. Science, 374:1271–1275, 2021.

[4] W. Brandner, P. Calissendorff, N. Frankel, and F. Cantalloube. High-contrast, high-angular resolution view of the GJ367 exoplanet system. Mon. Notices Royal Astron. Soc., 513:661–669, 2022.

[5] J. W. Hernlund and P. J. Tackley. Modeling mantle convection in the spherical annulus. Phys. Earth Planet. Int., 171:48–54, 2008.

[6] P. J. Tackley. Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid. Phys. Earth Planet. Int., 171:7–18, 2008.

How to cite: Golabek, G. J., Lichtenberg, T., Bartels, L. M., Tackley, P. J., Meier, T., and Bower, D.: Magma oceanography of the dense, ultrashort-period sub-Earth GJ 367 b, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5832, https://doi.org/10.5194/egusphere-egu24-5832, 2024.

EGU24-6296 | ECS | Posters virtual | PS5.2

The GAPS Programme at TNG. TOI-5076b: a warm sub-Neptune planet orbiting a thick disk star in a wide binary system. 

Nino Greco and Marco Montalto and the The GAPS Programme at TNG: TOI-5076b.

Aims. We report the confirmation of a new transiting exoplanet orbiting the star TOI-5076.
Methods. We present our vetting procedure and follow-up observations which led to the confirmation of the exoplanet TOI-5076b. In particular, we employed high precision TESS photometry, high-angular resolution imaging from several telescopes and high precision radial velocities from HARPS-N.
Results. From the HARPS-N spectroscopy, we determined the spectroscopic parameters of the host star: Teff=(5070±143) K, log g=(4.6±0.3), [Fe/H]=(+0.20±0.08) and [α/Fe]=0.05±0.06. The transiting planet is a warm sub-Neptune with a mass mp=(16±2) M, a radius rp=(3.2±0.1) R yielding a density ρp=(2.8±0.5) g cm−3. It revolves around its star every ∼23.445 days.
Conclusions. The host star is a metal-rich, K2V dwarf, located at about 82 pc from the Sun with a radius of R=(0.78±0.01) R and a mass of M=(0.80±0.07) M. It forms a common proper motion pair with a M-dwarf companion star located at a projected separation of 2178 au. The chemical analysis of the host-star and the Galactic space velocities indicate that TOI-5076 belongs to the old population of thick disk stars or thin-to-thick transition stars. The density of TOI-5076b suggests the presence of a large fraction by volume of volatiles overlying a massive core. We found that a circular orbit solution is only marginally favoured with respect to an eccentric orbit solution for TOI-5076b. The best-fit eccentricity for the system is e=(0.20±0.09).

How to cite: Greco, N. and Montalto, M. and the The GAPS Programme at TNG: TOI-5076b.: The GAPS Programme at TNG. TOI-5076b: a warm sub-Neptune planet orbiting a thick disk star in a wide binary system., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6296, https://doi.org/10.5194/egusphere-egu24-6296, 2024.

EGU24-6826 | Orals | PS5.2

The CUISINES 2024 menu: Updates and progress on a large exoplanet model intercomparison framework 

Thomas Fauchez, Linda Sohl, Guillaume Chaverot, Duncan Christie, Russell Deitrick, Jacob Haqq-Misra, Sonny Harman, Nicolas Iro, Kostas Tsigaridis, and Geronimo Villanueva

The exoplanet community possesses an incredible variety of models to match the astronomical diversity of exoplanets. Those models are used to either predict or interpret exoplanet data. However, contrary to Earth science, we have no existing ground truth to validate those models. Meanwhile, we would still learn a lot from benchmarking exoplanet models together to increase the robustness in our data prediction and interpretation, to identify bugs and to highlight model features that would require additional developments.

The Climates Using Interactive Suites of Intercomparisons Nested for Exoplanet Studies (CUISINES) Working Group of NASA’s Nexus for Exoplanet Systems Science (NExSS) supports a systematized approach to evaluating the performance of exoplanet models, and provides here a framework for conducting community-organized exoplanet Model Intercomparison Projects (exoMIPs). The CUISINES framework adapts Earth climate community practices specifically for the needs of the exoplanet researchers, encompassing a range of model types, planetary targets, and parameter space studies. 

In this presentation, we will give updates on the various exoMIPs and we will provide insights on our findings to make an exoplanet model intercomparison a success on short and long timescales.

How to cite: Fauchez, T., Sohl, L., Chaverot, G., Christie, D., Deitrick, R., Haqq-Misra, J., Harman, S., Iro, N., Tsigaridis, K., and Villanueva, G.: The CUISINES 2024 menu: Updates and progress on a large exoplanet model intercomparison framework, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6826, https://doi.org/10.5194/egusphere-egu24-6826, 2024.

Hydrogen- and helium-rich primordial atmospheres of small rocky planets, formed as a result of planetary accretion, are subject to subsequent modifications of geochemical outgassing. Two outcomes are possible: a secondary atmosphere forms if the outgassing completely replaces the primordial atmosphere, or a hybrid atmosphere results if the primordial atmosphere undergoes a partial loss with its leftover reacting with the newly outgassed species. We constructed a zero-dimensional thermodynamic model where both scenarios can be consistently simulated. The model assumes chemical equilibrium and admits input parameters of oxidation and sulfidation states of the mantle, melt temperature, atmospheric nitrogen content, surface pressure (for secondary atmosphere models), and hydrogen partial pressure (for hybrid atmosphere models). It computes the chemical compositions of outgassing, namely, the volume mixing ratios of various gaseous species. Non-ideal gas behaviors are accounted for in the model and the calculated secondary and hybrid atmospheres both exhibit a vast chemical diversity. For example, hydrogen-rich atmospheres, conventionally deemed of primordial origin, can also stem from interior outgassing. By Monte Carlo sampling in the possible ranges of the input parameters, we found that outgassed methane-dominated atmospheres, regardless of secondary or hybrid, require rather specific conditions: (1) a reduced rocky mantle; (2) relatively low melt temperatures in comparison to those of basaltic or peridotitic melts; (3) relatively high atmosphere pressures (> c.a. 10 bar) on the rocky surface. Moreover, we found that the abundance ratio of CO2 and CO can serve as a powerful diagnostic of oxygen fugacity of rocky mantles, which could potentially be constrained by future James Webb Space Telescope spectra. The current model does not consider atmospheric escape, chemical kinetics or photochemistry, which awaits to be incorporated in future works.

How to cite: Tian, M. and Heng, K.: Thermodynamic modelling of the outgassing chemistry of Super Earths and sub-Neptunes: applications to secondary and hybrid atmospheres, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7320, https://doi.org/10.5194/egusphere-egu24-7320, 2024.

EGU24-7609 | Posters on site | PS5.2

A favorable sub-Neptune target for JWST and Ariel observations: TOI 1759 b 

Panayotis Lavvas, Athena Coustenis, Therese Encrenaz, Benjamin Charnay, Bruno Bézard, Pierre Drossart, Amélie Gressier, Emilie Panek, Billy Edwards, Marc Ollivier, Karan Molaverdikhani, Olivia Venot, Deborah Bardet, Pierre-Olivier Lagage, and Giovanna Tinetti

Following the extensive exploration of hot and warm exoplanets over the past two decades, recent improvements in instrumental techniques, from ground and space, have allowed the detection of “temperate” exoplanets, with equilibrium temperatures ranging between 300 and 500 K. Opening this new research field will not only enlarge our comprehension of the various physical properties of exoplanets, but also reduce the comprehension gap between these objects and the planets of our solar system, and provide a key step towards the study of habitable exoplanets. Over the past few years, we have started a program [1, 2] for identifying temperate exoplanets, which would be observable with the Ariel mission in the spectroscopic mode (Tier 2 mode). Using the TESS database and analyzing the observability of the candidates with Ariel, we have selected a list of 15 targets (a gas giant, a few big Neptunes and several super-Earths/sub-Neptunes) for which spectroscopic observations with Ariel would allow a characterization of their atmosphere and possibly an identification of the main atmospheric absorbers [3]. Among this list, the sub-Neptune TOI-1759 b appears as a favorable candidate. With a radius of about 3 earth radii and a mass of about 10 earth masses, TOI-1759 b is most likely a hydrogen-rich planet orbiting a M0.0 star located at 40 pc with a revolution period of 19 days. We have calculated the thermal structure, dis-equilibrium composition and size distribution of cloud and haze particles in its atmosphere using a model that couples self-consistently the involved physical and chemical processes [4]. Cloud nucleation rates reach significant values near a pressure level of 0.35 bar, where the condensing gas species (KCl, NaCl and Zn) approach their saturation limit. We have calculated the infrared synthetic spectrum of TOI-1759 b from the visible up to 20 μm for different metallicities and different haze and cloud conditions. Feasibility studies [5] suggest that information could be retrieved about the target’s atmosphere with 16 primary transit observations with Ariel (which could be achieved over a time range of less than a year), or a single primary transit observation with the JWST.

 

[1] Encrenaz, T.  et al., Exp. Astr. 46, 31 (2018) 

[2] Encrenaz, T. et al.,  Exp. Astr. 53, 375 (2022).

[3] Encrenaz, T. et al. Poster presented at the EGU General Assembly, Vienna, April 2023.

[4] Arfaux & Lavvas, MNRAS, 515, 4753 (2022).

[5] Tinetti et al., Exp.Astr. 46, 135 (2018).

How to cite: Lavvas, P., Coustenis, A., Encrenaz, T., Charnay, B., Bézard, B., Drossart, P., Gressier, A., Panek, E., Edwards, B., Ollivier, M., Molaverdikhani, K., Venot, O., Bardet, D., Lagage, P.-O., and Tinetti, G.: A favorable sub-Neptune target for JWST and Ariel observations: TOI 1759 b, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7609, https://doi.org/10.5194/egusphere-egu24-7609, 2024.

EGU24-9116 | Orals | PS5.2 | Highlight

The double phase curve of TRAPPIST-1b and c at 15 microns 

Michael Gillon and the JWST Program 3077 team

Small rocky planets are now known to be very frequent in temperate orbits around low-mass M-dwarfs. The most pressing question regarding these ubiquitous planets concerns their capacity to maintain significant secondary atmospheres despite the adverse environment (high XUV fluxes, winds) and history (long pre-main-sequence) brought by their small host stars. Here, we present the photometric observation by JWST/MIRI of the combined thermal phase curve of the two inner planets of the TRAPPIST-1 system (Cycle 2 program 3077). These observations aimed to determine if the two planets are bare rocks or not by complementing the Cycle 1 measurements of their daysides' thermal emission at 15 microns (for b and c) and 12.8 microns (for b).

How to cite: Gillon, M. and the JWST Program 3077 team: The double phase curve of TRAPPIST-1b and c at 15 microns, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9116, https://doi.org/10.5194/egusphere-egu24-9116, 2024.

EGU24-9521 | ECS | Posters on site | PS5.2

Forming rocky exoplanets around K-dwarf stars 

Petra Hatalova, Ramon Brasser, Elena Mamonova, and Stephanie Werner

How multiple close-in super-Earths form around stars with masses lower than that of the Sun is still an open issue. Several recent modeling studies have focused on planet formation around M-dwarf stars, but so far no studies have focused specifically on K dwarfs, which are of particular interest in the search for extraterrestrial life. We aimed to reproduce the currently known population of close-in super-Earths observed around K-dwarf stars and their system characteristics. Additionally, we investigated whether the planetary systems that we formed allow us to decide which initial conditions are the most favorable. We performed 48 high-resolution N-body simulations of planet formation via planetesimal accretion using the existing GENGA software running on GPUs. In the simulations we varied the initial protoplanetary disk mass and the solid and gas surface density profiles. Each simulation began with 12000 bodies with radii of between 200 and 2000 km around two different stars, with masses of 0.6 and 0.8 MSun. Most simulations ran for 20 Myr, with several simulations extended to 40 or 100 Myr. The mass distributions for the planets with masses between 2 and 12 MEarth show a strong preference for planets with masses Mp < 6 MEarth and a lesser preference for planets with larger masses, whereas the mass distribution for the observed sample increases almost linearly. However, we managed to reproduce the main characteristics and architectures of the known planetary systems and produce mostly long-term angular-momentum-deficit-stable, nonresonant systems, but we required an initial disk mass of 15 MEarth or higher and a gas surface density value at 1 AU of 1500 g cm-2 or higher. Our simulations also produced many low-mass planets with Mp < 2 MEarth, which are not yet found in the observed population, probably due to the observational biases. Earth-mass planets form quickly (usually within a few million years), mostly before the gas disk dispersal. The final systems contain only a small number of planets with masses Mp > 10 MEarth, which could possibly accrete substantial amounts of gas, and these formed after the gas had mostly dissipated.

How to cite: Hatalova, P., Brasser, R., Mamonova, E., and Werner, S.: Forming rocky exoplanets around K-dwarf stars, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9521, https://doi.org/10.5194/egusphere-egu24-9521, 2024.

Many factors influence the long-term evolution of the atmosphere of a rocky planet, including star-planet interactions and late accretion of volatiles. However, for planets where gravity is low enough for a primordial atmosphere to escape (i.e. roughly Earth-size and smaller), the main factor driving the atmospheric evolution will be volcanic outgassing from the interior. 

While for planets in the habitable zone, where liquid water may exist that could allow for an Earth-like carbon-silicate cycle, planets closer to their host star have been suggested to have Venus-like, thick CO2-dominated atmospheres. Our study focusses on the question, how basic planetary parameters such as size, core mass fraction, and surface regime (either stagnant-lid or mobile, such as plate tectonics) may impact the atmosphere, specifically the range of atmospheric pressures as well as their composition, for warm planets where condensation of water as well as an efficient carbon cycle can be excluded. 

We show, that planets with a stagnant lid tend to be hotter in their interior due to the isolating behaviour of the lithosphere, but at the same time tend to have much reduced outgassing efficiencies. At the same time, since volcanic outgassing at the surface of a planet is directly influenced by partial pressures in the atmosphere, compositional variations appear between stagnant-lid or mobile-lid planets, as well as between low-mass and high-mass rocky planets.

Observations with JWST looking at warmer planets (i.e. inside the inner boundary of the habitable zone) might therefore give first-order indications on the outgassing efficiency (coupled with the erosion efficiency of the atmosphere) and surface regime of these rocky planets.

How to cite: Noack, L. and Brachmann, C.: Connecting the interior to the atmosphere: should atmospheres of warm rocky planets differ for stagnant-lid and mobile surface regimes?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9761, https://doi.org/10.5194/egusphere-egu24-9761, 2024.

EGU24-9833 | ECS | Posters on site | PS5.2

The impact of convection on the climate of TRAPPIST-1e in global stretched-mesh simulations 

Denis Sergeev, Ian Boutle, Hugo Lambert, Nathan Mayne, and Thomas Bendall

Convective processes are crucial in shaping exoplanetary atmospheres but are computationally expensive to simulate directly. A novel technique of simulating moist convection, especially on tidally locked exoplanets such as those orbiting TRAPPIST-1, is to use a 3D general circulation model (GCM) with a global stretched mesh. This allows us to locally refine the model resolution to a km-scale and resolve deep convection without relying on parameterization. We explore the impact of explicit vs parameterized convection on the climate of TRAPPIST-1e, a confirmed rocky exoplanet in the habitable zone and a primary candidate for atmospheric characterization. We show allowing for explicit convection in a stretched-mesh simulation results primarily in changes in cloud distribution and precipitation on a planetary scale. Nevertheless, the overall climate state is close to that produced with parameterized convection and a non-stretched mesh. Additionally, these novel simulations shed more light on the bistability of the atmospheric circulation on TRAPPIST-1e. Our methodology opens an exciting and computationally feasible avenue for improving our understanding of fine-scale 3D mixing in exoplanetary atmospheres.

How to cite: Sergeev, D., Boutle, I., Lambert, H., Mayne, N., and Bendall, T.: The impact of convection on the climate of TRAPPIST-1e in global stretched-mesh simulations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9833, https://doi.org/10.5194/egusphere-egu24-9833, 2024.

EGU24-11239 | ECS | Orals | PS5.2

Turbulence statistics of terrestrial Mars-analog and Martian dust devils 

Orkun Temel, Ozgur Karatekin, Víctor Apéstigue Palacio, Toledo Daniel, Ignacio Arruego, Fulvio Franchi, German Martinez, and Cem Berk Senel

Convective instabilities in the lowermost part of the atmosphere, so called the planetary boundary layer, can lead to the formation of convective vortices and form dust devils both on Earth and Mars. We performed mesoscale simulations for a Mars-analog terrestrial site, Makgadikgadi Pan - Botswana [1,2], where a state-of-the art field campaign was conducted to investigate the terrestrial dust devils, and the InSight landing site [3] using WRF/MarsWRF models [4,5]. We then combined our atmospheric modeling with in-situ observations of wind and pressure to perform a comparative boundary-layer meteorology study. We focused on the length and time of scales of turbulence and investigated the turbulent spectrum.

[1] Toledo, D., Apéstigue, V., Arruego, I., Montoro, F., Martinez-Oter, J., Serrano, F., Yela, M., Carrasco-Blázquez, I. and Franchi, F., 2022, September. Investigating dust devils on Mars through the Makadikadi Salt Pans analogue (Botswana). In European Planetary Science Congress (pp. EPSC2022-485).
[2] Toledo, D., Apéstigue, V., Martinez-Oter, J., Franchi, F., Serrano, F., Yela, M., De La Torre Juarez, M., Rodriguez-Manfredi, J.A. and Arruego, I., 2023. Using the Perseverance MEDA-RDS to identify and track dust devils and dust-lifting gust fronts. Frontiers in Astronomy and Space Sciences, 10, p.1221726.
[3] Lorenz, R.D., Spiga, A., Lognonné, P., Plasman, M., Newman, C.E. and Charalambous, C., 2021. The whirlwinds of Elysium: A catalog and meteorological characteristics of “dust devil” vortices observed by InSight on Mars. Icarus, 355, p.114119.
[4] Temel, O., Senel, C.B., Porchetta, S., Muñoz-Esparza, D., Mischna, M.A., Van Hoolst, T., van Beeck, J. and Karatekin, Ö., 2021. Large eddy simulations of the Martian convective boundary layer: towards developing a new planetary boundary layer scheme. Atmospheric Research, 250, p.105381.
[5] Temel, O., Bricteux, L. and van Beeck, J., 2018. Coupled WRF-OpenFOAM study of wind flow over complex terrain. Journal of Wind Engineering and Industrial Aerodynamics, 174, pp.152-169.

How to cite: Temel, O., Karatekin, O., Apéstigue Palacio, V., Daniel, T., Arruego, I., Franchi, F., Martinez, G., and Senel, C. B.: Turbulence statistics of terrestrial Mars-analog and Martian dust devils, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11239, https://doi.org/10.5194/egusphere-egu24-11239, 2024.

EGU24-11513 | Posters on site | PS5.2

Impact of CO2 on water outgassing on rocky planets around TRAPPIST-1 – VPLANET/MagmOcV2.0 

Ludmila Carone, Patrick Barth, Rory Barnes, Christiane Helling, Katy Chubb, and Bertram Bitsch

 

VPLANET MagmOc is a versatile magma ocean model with erosion of water vapour in the open source VPLANET framework. We
present here a major improvement of this model that includes now a) thermal emission calculated with a full radiative transfer code and b) simultaneous outgasing of H2O and CO2 with full feedback on outgassing informed by planet formation models.


We derived evolution tracks of an outgassed mixed H2O/CO2 atmosphere on TRAPPIST-1e, f and g. We find that all planets, in particular TRAPPIST-1 g, run the risk to evolve into Exo-Venuses with thick CO2 atmospheres after the magma ocean stage for an intial water budget of more than 10 terrestrial ocean (TO) of water within tens of million years.

At the inner edge of the habitable zone, on TRAPPIST-1 e, we find that the combination of H2O atmosphere loss and CO2 outgassing reduces the thermal emission on the planet such that the magma ocean stage can be almost doubled from tens of million years to 80 million years for 10 TO intial water.
We thus conclude that careful consideration has to be given to the various geophysical feedback effects as these can have a profound impact on the magma ocean evolution stage and thus on the overall water budget and the secondary atmosphere.

How to cite: Carone, L., Barth, P., Barnes, R., Helling, C., Chubb, K., and Bitsch, B.: Impact of CO2 on water outgassing on rocky planets around TRAPPIST-1 – VPLANET/MagmOcV2.0, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-11513, https://doi.org/10.5194/egusphere-egu24-11513, 2024.

EGU24-13378 | Posters on site | PS5.2

Effect of ocean tidal mixing on exoplanet climates and habitability 

Maria Di Paolo, David Stevens, Manoj Joshi, and Rob Hall

Due to their abundance and their observational advantages, M dwarfs offer the best chance of finding habitable planets through sheer numbers. Therefore, in the race to detect signs of life beyond the Solar System, rocky M-dwarf planets offer exciting prospects.
While the habitable zone serves as a preliminary indicator of the potential habitability of a planet, planetary climate studies are necessary in order to better assess a planet’s ability to host life. Climate is affected by numerous factors that are not considered in the classic habitable zone formulation, but can be included in climate models of varying complexity.
Oceans have a dominant impact on planetary climate, so understanding their effects is a necessary part of modelling terrestrial exoplanets in order to understand future observations.

We have conducted studies with an intermediate complexity coupled atmosphere-ocean general circulation model (FORTE2.0). Using a coupled dynamic ocean enables us to include effects of ocean circulation. Strong tidal interactions are tightly linked to the ocean vertical diffusivity and thus ocean temperature structure (including surface temperature). Taking into account the impact of ocean tides can therefore lead to significant effects on planetary climate.
We investigated the case of non synchronous terrestrial planets in close orbits in the habitable zone of their M host star. In this scenario, we have parameterised the effect of propagating tides, and analysed their impact on ocean circulation and minimum and maximum values of surface temperature. We found that ocean tides are particularly important in setting latitudinal gradients in temperature, with subsequent effects on climate and habitability.
By considering scenarios in which the magnitude of tidal forcings varies over a range of values, we were able to determine that key surface quantities (such as winds, heat flux and water flux) are subjected to change.
The repercussions that ocean vertical diffusion can have on surface quantities is noteworthy from the observational point of view, as observable features - such as cloud patterns – are shaped differently in each scenario.

How to cite: Di Paolo, M., Stevens, D., Joshi, M., and Hall, R.: Effect of ocean tidal mixing on exoplanet climates and habitability, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13378, https://doi.org/10.5194/egusphere-egu24-13378, 2024.

EGU24-15544 * | Posters on site | PS5.2 | Highlight

Large Interferometer for Exoplanets (LIFE): characterizing the mid-infrared thermal emission of terrestrial exoplanets 

Tim Lichtenberg, Sascha Quanz, Lena Noack, Daniel Angerhausen, Sarah Rugheimer, Adrian Glauser, Jens Kammerer, Andrea Fortier, Michael Ireland, Denis Defrère, Hendrik Linz, Nicolas Iro, and Life Collaboration

The atmospheric characterization of a significant number of terrestrial exoplanets is a major goal of 21st century astrophysics. However, none of the currently adopted missions worldwide has the technical capabilities to achieve this goal. Here we present the LIFE mission concept, which addresses this issue by investigating the scientific potential and technological challenges of an ambitious mission employing a formation-flying nulling interferometer in space working at mid-infrared wavelengths. LIFE, in synergy with other planned future missions, will for the first time in human history enable us to understanding global biosignatures and planetary habitability in the context of the diversity of planetary systems. Breakthroughs in our understanding of the exoplanet population and relevant technologies justify the need, but also the feasibility, for future atmosphere characterization and life detection missions to investigate one of the most fundamental questions of humankind: how frequent and diverse are global biospheres in the galaxy?

How to cite: Lichtenberg, T., Quanz, S., Noack, L., Angerhausen, D., Rugheimer, S., Glauser, A., Kammerer, J., Fortier, A., Ireland, M., Defrère, D., Linz, H., Iro, N., and Collaboration, L.: Large Interferometer for Exoplanets (LIFE): characterizing the mid-infrared thermal emission of terrestrial exoplanets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15544, https://doi.org/10.5194/egusphere-egu24-15544, 2024.

EGU24-15714 | ECS | Orals | PS5.2

Cold pool pockets develop at the bottom of Gale crater (Mars) 

María Ruíz-Pérez, Jorge Pla-Garcia, Manuel de la Torre-Juarez, and Scot Rafkin

The Curiosity rover has moved more than 31 km from the landing site at the very bottom of the crater and has climbed more than ∼750 m into the Mnt. Sharp foothills over more than five Martian years. A significant change in temperatures and pressures measured by the REMS monitoring weather station aboard the Curiosity rover has been detected during that traverse.
On Earth deep valleys, like the ones in Alps, and craters on Mars like Gale accumulate masses of cold air at night, a.k.a. cold pools, at the bottom of the craters. These pockets of cold air change aspects of local micrometeorology at the bottom of a deep valley compared to the slopes. Downslope winds originating from both Mnt. Sharp and crater rims converge at the very bottom of the crater floor and may produce a vortex in the very stable and shallow nocturnal air mass [Rafkin et al. 2016]. This flow would prevent the nighttime accumulation of any tracer along the slopes above the cold pool and facilitate the convergence and accumulation of tracers in the bottom of the crater. The exception is during the northern hemisphere winter (around Ls 270 when strong northerly winds tend to scour the crater air mass day and night [Pla-García et al. in 2019].
As Curiosity ascends, we can examine whether these cold air masses exist at the very bottom of the crater and whether the rover moves away from them when reaching a specific height through Mnt. Sharp slopes. One indication is an increase in nighttime temperatures as the rover climbs Mt. Sharp’s slope. Those interannual increments of nighttime temperatures at Gale show a smooth variation within the lower layers before changing scenarios from landing location and tosol’s (Figure). To distinguish this effect from seasonal trends, an analysis of potential temperatures was performed (Figure). Comparing minimum to average temperatures in Figure allows to relate the changes to seasonal or other effects. The figure shows the annual evolution of the Martian air temperature using a Fourier adjustment. Modeling and observations strongly suggest that the rover has ascended to elevations above the cold pool at the bottom of the crater [Ruíz-Pérez et al. 2024 in preparation].

How to cite: Ruíz-Pérez, M., Pla-Garcia, J., de la Torre-Juarez, M., and Rafkin, S.: Cold pool pockets develop at the bottom of Gale crater (Mars), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15714, https://doi.org/10.5194/egusphere-egu24-15714, 2024.

EGU24-16195 | Posters on site | PS5.2

Influence of partially molten layers on the tidal response of rocky exoplanets  

Gabriel Tobie, Mathilde Kervazo, Yann Musseau, Marie Behounkova, Emeline Bolmont, Gael Choblet, Caroline Dumoulin, Alexandre Revol, and Mariana Villamil Sastre

The number of detected Earth-sized exoplanets is now increasing, and most of the detected planets orbit at relatively close distance from their host stars, resulting in strong tidal forcing. As shown for the inner planets of the Trappist-1 system [1] or the newly discovered Earth-sized exoplanet LP 791-18d [2], tidal heating is expected to be a dominant source of heating, potentially exceeding the radiogenic power by one order of magnitude and more. Depending on the orbital eccentricity, tidally-induced thermal runaways may result in strong internal melting and volcanic heat flux comparable to Io [3]. As shown in the case of Io, the presence of silicate melt in the interior of Io has a strong influence on the tidal response of its interior [3,4]. The thickness and melt content of partially molten layer can strongly affect the total dissipated power and its distribution.

In this study, we test the influence of partially molten layers on the tidal response of Earth-sized exoplanets, using Trappist-1 b,c and d and LP 791-18d as examples.  We follow the approach developed to model the solid tides in Io’s partially molten interior [3], taking into account the effect of melt on the viscoelastic properties of the mantle, and test different rheological models (Maxwell, Andrade, Sundberg-Cooper). We use interior structure models consistent with the estimated mass and radius and consider partially molten layers of various thickness,  depth and melt content. Results for various assumptions in interior composition and melt content will be presented and implications for the heat budget of these planets  will be discussed.

[1] Turbet et al. A&A 612, A86;  [2] Peterson et al.  Nature, 617, 701–705 (2023);  [3] Běhounková et al. ApJ, 728(2), 89 (2011) ; [4] Kervazo et al., A&A, 650, A72 (2021) ;  [5] Kervazo et al. Icarus, 373, 114737 (2022).

 

How to cite: Tobie, G., Kervazo, M., Musseau, Y., Behounkova, M., Bolmont, E., Choblet, G., Dumoulin, C., Revol, A., and Villamil Sastre, M.: Influence of partially molten layers on the tidal response of rocky exoplanets , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16195, https://doi.org/10.5194/egusphere-egu24-16195, 2024.

EGU24-16760 | ECS | Posters on site | PS5.2

Linking the interior structure of terrestrial exoplanets to their (tidal) observables 

Michaela Walterová and Marie Běhounková

Tidal effects probe the interior of celestial bodies and are an important source of information on their thermal state and the prevailing deformation mechanisms. In the case of exoplanets, estimation of quantities related to tides might add important constraints on the interior structure of those worlds that would complement the existing measurements of masses and radii [e.g., 1]. In recent years, the fluid Love number hf, which characterises the deformed figure of a rotating celestial body, has been measured for the gaseous exoplanet WASP-103b [2], and the rate of tidal dissipation has also been estimated for several extrasolar gas giants [e.g., 3]. Although not directly detectable today, future measurements might also assess the deformation of Earth-sized exoplanets. Moreover, the measurements of thermal emission light curves, accessible to JWST [4], might shed light on the actual spin states of low-mass exoplanets, which is another parameter affecting the long-term evolution and the habitability prospects of the extrasolar worlds. Detailed analysis of the light curves can also unveil global-scale volcanism that would be indicative of the magnitude of tidal dissipation [5].

Here, we discuss and illustrate the link between various aspects of the planet’s interior structure and a set of potential observables related to tides on close-in rocky exoplanets without atmosphere. Specifically, we focus on the role of different rheological models and their parameters and on the major features of the interior structure, such as liquid layers or low-viscosity zones. We address the stability of various spin-orbit resonances, surface tidal heat flux, the magnitude of the tidal Love numbers h2 and k2, and the present-day effect of tides on the orbital elements. Since the tidal deformation and the rate of energy dissipation in close-in rocky exoplanets also govern the secular orbital evolution, we further discuss the effect of changes in the interior structure, induced by variations in the thermal state, on the long-term orbital dynamics of tidally loaded exoplanets or moons [6].

 

Acknowledgement:

The work presented in this contribution has been supported by the Czech Science Foundation grant nr. 23-06513I.

 

References:

[1] Baumeister & Tosi (2023), doi:10.1051/0004-6361/202346216.

[2] Barros et al. (2022), doi:10.1051/0004-6361/202142196.

[3] Barker et al. (2024), doi:10.1093/mnras/stad3530.

[4] Zieba et al. (2023), doi:10.1038/s41586-023-06232-z.

[5] Selsis et al. (2013), doi: 10.1051/0004-6361/201321661.

[6] Walterová & Běhounková (2020), doi:10.3847/1538-4357/aba8a5.

How to cite: Walterová, M. and Běhounková, M.: Linking the interior structure of terrestrial exoplanets to their (tidal) observables, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16760, https://doi.org/10.5194/egusphere-egu24-16760, 2024.

EGU24-17280 | ECS | Orals | PS5.2

Improving tidal interaction for compact N-body planetary system. 

Alexandre Revol, Emeline Bolmont, Mariana V. Sastre, Anne-Sophie Libert, Gabriel Tobie, and Sergi Blanco-Cuaresma

Recent JWST observations of rocky planets, such as TRAPPIST-1, and the increasing number of rocky planets discovered orbiting close to their host star, strongly motivates the improvement of tidal modeling.
Beside, recent JWST observations of the thermal emission from TRAPPIST-1 b and c have provided constraints on their atmospheres (Greene et al. 2023; Ih et al. 2023; Zieba et al. 2023; Lincowski et al. 2023). 
In this context, It is crucial to use a coherent tidal model that encapsulates the complex response of rocky planets to stress, to understand the evolution of exoplanets and interpret new data.

Our presentation will focus on recent developments on the implementation of the formalism of Kaula (1964) in the N-body code Posidonius (Blanco-Cuaresma & Bolmont 2017; Bolmont et al. 2020).
This formalism consists in using a decomposition of the tidal potential into Fourier harmonic modes, which allows to account for the frequency dependence of the tidal response of rocky bodies.
It makes it general enough to take into account for any type of internal structure, as well as the presence of ice or surface liquid water.
We will present our results on the rotational state of TRAPPIST-1 planets, revisiting the assumption of the perfect synchronization state resulting from tidal evolution. 
Given that the rotational state influences the heat redistribution regime, precise estimation of their rotational state is critical.
Various internal structures were explored with the Burnman code (Cottaar et al. 2014; Myhill et al. 2021)., considering compositions and core sizes compatible with mass and radius estimations from Agol et al. (2021).

Our simulations showed that planet-planet interactions induce rapid variations in the mean motions of the planets. 
These variations occur too quickly for tides to maintain synchronized rotation states with the mean motion. 
This results in sub-stellar point drifts, causing planets to complete full solar days with periods ranging from 42 to 103 years depending on the planet. 
The competition between mean motion variations and tidal damping, and thus sub-stellar drifts, is contingent on the internal structure of the planet under consideration. 
As a result, remnant rotation is expected to facilitate the redistribution of heat on the planet's surface, modifying habitability conditions by mitigating the cold-trap effect on the night side (Turbet et al. 2016) and redistributing cloud formation on the day side (Turbet et al. 2021).
Additionally, we will present preliminary results on the coupling between the spin and the orbital evolution of planets in compact mean motion resonances (MMRs), in particular with the presence of obliquity spin-orbit resonances (SOR), on time transit variations (TTV) and on the mean motion resonances for the TRAPPIST-1 system and the potential observability of such effects.

How to cite: Revol, A., Bolmont, E., Sastre, M. V., Libert, A.-S., Tobie, G., and Blanco-Cuaresma, S.: Improving tidal interaction for compact N-body planetary system., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17280, https://doi.org/10.5194/egusphere-egu24-17280, 2024.

EGU24-17474 | ECS | Orals | PS5.2

Connecting exoplanet mantle mineralogy to surface dynamic regime 

Rob Spaargaren, Maxim Ballmer, Stephen Mojzsis, and Paul Tackley
Based on stellar compositions, we know that rocky exoplanets show a diversity in interior compositions, and therefore mantle mineralogies. The mantle mineralogy controls physical parameters of the mantle, such as viscosity, and therefore strongly affects thermal and dynamical evolution of the interior. However, it is unknown whether mantle mineralogy plays a role in establishing a planets surface dynamic regime (e.g., mobile lid, stagnant lid, episodic lid), which plays a pivotal role in determining a planets’ habitability. Here, we investigate the long-term dynamical evolution of Earth-sized planets with a range of mantle mineralogies based on stellar compositions.

We explore the long-term evolution of an Earth-sized rocky planet, varying mantle mineralogy, by employing a 2D global-scale model of thermochemical mantle convection. We include the effects of composition on planet structure, mantle physical properties, and mantle melting. We investigate how composition affects thermal evolution, and whether it has an effect on the propensity of a planet towards plate tectonics-like behaviour.

We find that density contrast between crustal material and the underlying mantle, governed by mantle Fe content, plays a vital role in determining dynamical behaviour. A very light crust is unable to subduct, locking a planet into a stagnant lid regime. Meanwhile, a very dense crust may settle at the core-mantle boundary, unable to be re-entrained into the overlying mantle. This leaves a depleted, infertile mantle and could potentially lock most of the planets water and heat producing element budget into the lowermost mantle. Mantle viscosity,  governed by Mg/Si ratio, plays a primary role in discerning between an episodically mobile and a fully stagnant lid, but has little effect on the propensity towards a fully mobile lid regime. Therefore, while composition plays a major role in determining planet material properties and dynamics, its effects on habitability are not straightforward.

 

How to cite: Spaargaren, R., Ballmer, M., Mojzsis, S., and Tackley, P.: Connecting exoplanet mantle mineralogy to surface dynamic regime, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17474, https://doi.org/10.5194/egusphere-egu24-17474, 2024.

EGU24-17602 | Posters on site | PS5.2

Diversity of rocky planet atmospheres in the H-C-O-N-S-Cl system with interior dissolution 

Paolo Sossi, Maggie Thompson, Meng Tian, Kaustubh Hakim, and Dan Bower

Given the host of existing and upcoming observations of rocky (exo)planet atmospheres, a quantitative understanding of the key factors that control the nature and composition of atmospheres around these diverse worlds is needed. The speciation of major atmosphere-forming components around molten rocky planets, both within and beyond the solar system, is dictated by their abundances, the equilibrium chemistry between gas species, and their solubilities in the rocky interior. Moreover, as pressure increases at the atmosphere-interior interface, the thermodynamic behaviour of the gas phase diverges from that of the ideal case. Here, we combine these considerations into a new Python package, atmodeller, which is a flexible tool kit for computing the equilibrium conditions at the melt-atmosphere interface. Given a set of planetary parameters (e.g., surface temperature, planetary mass, radius, mantle melt fraction) and an initial volatile budget, atmodeller uses experimentally calibrated solubility laws, together with free energy data for gas species, to determine how volatiles partition between the atmosphere and interior of the planet. This package can be applied widely to rocky planets, from super-Earths to sub-Neptunes with gaseous envelopes. Within the H-C-N-O-S-Cl system, we investigate the diverse range of atmospheric compositions and the impact of volatile dissolution into the interior for a set of known rocky exoplanets (e.g., the TRAPPIST-1 system) based on the current observational constraints from JWST. In addition, we use atmodeller to simulate the effects of volatile solubilities and non-ideal conditions on H2-dominated super-Earth- and sub-Neptune atmospheres (in the H-O-Si system), such as that of the recently observed exoplanet K2-18 b. Atmodeller is a new tool to study rocky (exo)planets, uniquely incorporating equilibrium chemistry, volatile solubilities and gas non-ideality to establish the connection between rocky planet interiors and their atmospheres.

How to cite: Sossi, P., Thompson, M., Tian, M., Hakim, K., and Bower, D.: Diversity of rocky planet atmospheres in the H-C-O-N-S-Cl system with interior dissolution, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17602, https://doi.org/10.5194/egusphere-egu24-17602, 2024.

EGU24-17748 | Orals | PS5.2

Maintenance of atmospheric biosignatures across the inner habitable zone for earthlike planets 

Benjamin Taysum, Iris van Zelst, John Lee Grenfell, Franz Schreier, Juan Cabrera, and Heike Rauer

With ongoing missions such as the James Webb Space Telescope and planned initiatives such as the Large Interferometer For Exoplanets (LIFE), the detection and attribution of biosignatures in exoplanetary atmospheres increasingly becomes a point of focus. However, in order to assess how different biosignatures manifest themselves in the atmospheres of rocky exoplanets in contrast to our temperate Earth, improved insights into the maintenance of earthlike atmospheric biosignatures in different atmospheres are necessary. 

Here, we identify and investigate the main processes and possible couplings between atmospheric climate and photochemistry for earthlike planets across the inner habitable zone. We also study the detectability of the modelled spectral features with the LIFE simulator to assess how the atmospheres of planets with an earthlike biosphere may appear to future missions like the LIFE interferometer. 

We use the global-mean, stationary, coupled climate-chemistry column model, 1D-TERRA, to simulate the climate and chemistry of planetary atmospheres at different distances from the Sun, initially assuming Earth's planetary parameters and evolution. We run six scenarios: we assume rocky exoplanets with Earth’s biomass fluxes forming around the Sun with insolation from 100% to 150% in steps of 10%. From the resulting output of temperature and composition profiles, we calculate theoretical transmission and emission spectra using a radiative transfer model (GARLIC).

The models show moderate ocean evaporation as the planet moves closer to the Sun, which results in water-vapour-rich atmospheres with the partial pressures of steam ranging from about 0.01 bar (modern Earth insolation, S=1) up to 0.6 bar (S=1.5). In the latter model,  the global mean surface temperature increases to 365.4K. This is mainly due to the higher energy input and the enhanced greenhouse effect due to increased amounts of water vapour in the atmosphere. Regarding key atmospheric biosignatures, ozone, surprisingly, mostly survives in the middle atmosphere in all scenarios, mainly because hydrogen oxide abundances, a catalytic sink for ozone, are prevented from strongly increasing due to reactions with nitrogen oxides. Methane is strongly removed for insolations above 20% those of Earth, because rising water abundances strongly increase hydroxyl (OH) (via UV photolysis) the main sink for methane. Nitrous oxide (N2O) generally survives, mainly due to trade-off effects where enhanced photolytic loss on upper layers due to higher insolation is counterbalanced by stronger absorption of photons on the lower layers due to enhanced water from evaporation. Hydrogen escape rates are 0.690 Tg/yr for the highest insolation scenario. Abiotic oxygen production associated with atmospheric escape of atomic hydrogen as well as catalytic in-situ recycling of oxygen atoms present in HOx species, lead to an increase in the O2 vmr to 0.35 mol/mol on increasing solar insolation from S = 1.0-1.3. For all scenarios, the simulated transmission and emission spectra show clearly evident H2O and CH4 features in the near to mid IR, strong CO2 absorption around 15 microns, and O3 absorption at around 9.6 microns.

How to cite: Taysum, B., van Zelst, I., Grenfell, J. L., Schreier, F., Cabrera, J., and Rauer, H.: Maintenance of atmospheric biosignatures across the inner habitable zone for earthlike planets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17748, https://doi.org/10.5194/egusphere-egu24-17748, 2024.

EGU24-18447 | ECS | Orals | PS5.2

Diving into the new dynamical slab ocean of the Generic-PCM: Implications for the climate of TRAPPIST-1e 

Siddharth Bhatnagar, Emeline Bolmont, Maura Brunetti, Jérôme Kasparian, Martin Turbet, Ehouarn Millour, Francis Codron, and Alexandre Revol

Ocean modelling is often sidelined by exoclimate modellers, mostly due to the associated computational expense of spinning up dynamic oceans. However, oceanic heat transport can critically impact the climate and observables for M-planets in the middle of their habitable zones (e.g., [1]) like TRAPPIST-1e. The oceanic description can also affect the number of final stable climatic states of the planet ([2]). Short of using a fully dynamic ocean model, a compromise used in most exoplanet General Circulation Models (GCMs) is a slab ocean model without oceanic heat transport.

Here, we will first present our improved compromise - the new dynamical slab ocean model integrated into the Generic-PCM ([3]), previously known as the LMD Generic GCM (e.g., [4]). Our parallelisable ocean model not only accounts for sea-ice/snow evolution, but also features wind-driven ocean transport (Ekman transport), horizontal eddy diffusion and convective adjustment between oceanic layers. When coupled with the atmosphere, it effectively reproduces critical attributes observed on modern Earth, including the major oceanic heat flows, an annually averaged surface temperature of 13 C, planetary albedo of 0.32 and sea ice coverage spanning 18 million sq. km.

Further, we will delve into the implications of a dynamical slab ocean model for TRAPPIST-1e. Despite recent JWST observations indicating the lack of a (thick) atmosphere for TRAPPIST-1b ([5]) and 1c ([6]), the planets farther away from the star, like 1e, may have retained moderately thick atmospheres. Assuming this, and if 1e formed with a substantial water reservoir ([7]), it could have sustained liquid water oceans ([8]). In general, the presence of oceanic heat transport can give rise to distinct oceanic patterns, as illustrated by the “lobster” pattern observed for Proxima Centauri b by [9], in contrast to the “eyeball” pattern in [4], observed in its absence. Moreover, studies suggest that the climates of Proxima Centauri b and TRAPPIST-1e may share similarities ([4], [8]). In this context, we will present findings from our new dynamical slab ocean within the Generic-PCM for TRAPPIST-1e. These results will then be systematically compared with those of [9], which used ROCKE-3D ([10]) with a dynamic ocean model. We believe that this will help in strengthening our understanding of the climate of TRAPPIST-1e and also offer insights into comparative exoplanetary climate research. Finally, we will discuss our findings in the context of habitability, particularly emphasising the role of a dynamical ocean model in informing our understanding of habitable conditions.

 

References:

[1] Yang et al. (2019b)

[2] Brunetti et al. (2019)

[3] Forget et al. (in prep)

[4] Turbet et al. (2016)

[5] Greene et al. (2023)

[6] Zieba et al. (2023)

[7] Tian & Ida (2015)

[8] Turbet et al. (2018)

[9] Del-Genio et al. (2019)

[10] Way et al. (2017)

How to cite: Bhatnagar, S., Bolmont, E., Brunetti, M., Kasparian, J., Turbet, M., Millour, E., Codron, F., and Revol, A.: Diving into the new dynamical slab ocean of the Generic-PCM: Implications for the climate of TRAPPIST-1e, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18447, https://doi.org/10.5194/egusphere-egu24-18447, 2024.

EGU24-18489 | ECS | Orals | PS5.2 | Highlight

No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c 

Sebastian Zieba, Laura Kreidberg, Elsa Ducrot, Michaël Gillon, Caroline Morley, Laura Schaefer, Patrick Tamburo, Daniel D. B. Koll, Xintong Lyu, Lorena Acuña, Eric Agol, Aishwarya R. Iyer, Renyu Hu, Andrew P. Lincowski, Victoria S. Meadows, Franck Selsis, Emeline Bolmont, Avi M. Mandell, and Gabrielle Suissa

Seven rocky planets orbit the nearby dwarf star TRAPPIST-1, providing a unique opportunity to search for atmospheres on small planets outside the Solar System. Thanks to the recent launch of the James Webb Space Telescope (JWST), possible atmospheric constituents such as carbon dioxide (CO2) are now detectable. Recent JWST observations of the innermost planet TRAPPIST-1 b showed that it is most probably a bare rock without any CO2 in its atmosphere. Here we report the detection of thermal emission from the dayside of TRAPPIST-1 c with the Mid-Infrared Instrument (MIRI) on JWST at 15 µm. We measure a planet-to-star flux ratio of 421 +/- 94 parts per million (ppm), which corresponds to an inferred dayside brightness temperature of 380 +/- 31 K. This high dayside temperature disfavours a thick, CO2-rich atmosphere on the planet. The data rule out cloud-free O2/CO2 mixtures with surface pressures ranging from 10 bar (with 10 ppm CO2) to 0.1 bar (pure CO2). A Venus-analogue atmosphere with sulfuric acid clouds is also disfavoured at 2.6 sigma confidence. Thinner atmospheres or bare-rock surfaces are consistent with our measured planet-to-star flux ratio.

How to cite: Zieba, S., Kreidberg, L., Ducrot, E., Gillon, M., Morley, C., Schaefer, L., Tamburo, P., Koll, D. D. B., Lyu, X., Acuña, L., Agol, E., Iyer, A. R., Hu, R., Lincowski, A. P., Meadows, V. S., Selsis, F., Bolmont, E., Mandell, A. M., and Suissa, G.: No thick carbon dioxide atmosphere on the rocky exoplanet TRAPPIST-1 c, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18489, https://doi.org/10.5194/egusphere-egu24-18489, 2024.

EGU24-18914 | Posters on site | PS5.2

Modelling the Circulation of Hot exoplanet Atmospheres (MOCHA): exhaustive comparison of 3D models for hot Jupiters 

Nicolas Iro, Thomas Fauchez, Thaddeus Komacek, Emily Rauscher, and Lucas Teinturier

With the first exoplanet JWST and Cheops data available, and ARIEL in the near future, we are expecting to get a lot of time-varying measurements of exoplanets (e.g. phase curves and 3D eclipse maps), giving us unprecedented information about their climate. Hot Jupiters will be the best targets for  atmosphere characterisation with these facilities.

 

3D atmospheric circulation models are the main tools to interpret theoretically these upcoming observations, however, it is overwhelming to compare the numerous models developed independently with each various assumptions and setup. Some characteristics of their outputs are then dependent on the model used, impairing physical interpretation. It is therefore necessary to assess the differences, limits and applicability of each models in a controlled manner.

 

We present MOCHA (Modelling the Circulation of Hot exoplanet Atmospheres), the most extensive intercomparision of hot Jupiter 3D circulation models. Our team is built from the experts developing all available codes,  in order to set up a common benchmark methodology.

Our intercomparison project will provide the exoplanet community with protocols and methods to benchmark current and future 3D models. This will lead to better and more robust tools to retrieve physical information from JWST, Cheops, and later ARIEL data.

 

This project is part of CUISINES (Climates Using Interactive Suites of Intercomparisons Nested for Exoplanet Studies), which has already provided Model Intercomparisons Projects (MIPS) such as THAI for the TRAPPIST planets and CAMEMBERT for mini Neptunes.

How to cite: Iro, N., Fauchez, T., Komacek, T., Rauscher, E., and Teinturier, L.: Modelling the Circulation of Hot exoplanet Atmospheres (MOCHA): exhaustive comparison of 3D models for hot Jupiters, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18914, https://doi.org/10.5194/egusphere-egu24-18914, 2024.

EGU24-19056 | ECS | Posters on site | PS5.2

Impact of oxygen fugacity on atmospheric spectra of hot rocky exoplanets 

Fabian Seidler and Paolo Sossi

An essential aspect of understanding how rocky (exo-)planets form and evolve is unravelling their bulk composition. While mass and radius alone do not yield precise estimations of exoplanet compositions due to the degeneracy of interior models that can fit such observations, abundances of refractory elements in their host stars are often used as proxies to constrain terrestrial planet composition. However, oxygen, whose relative abundance governs how iron (and other siderophile elements) partition between the mantle and core, is both a volatile and a refractory element, preventing a straightforward determination from stellar abundances. Therefore, we require independent means to estimate exoplanet oxidation states through observations of their atmospheres and/or surfaces. To do so, observations of ultra-hot rocky exoplanets would be ideal, owing to the fact that their atmospheres are expected to be in thermodynamic equilibrium with their surfaces. To interpret such observations, we investigate the impact of oxygen fugacity (fO2), temperature (T) and composition on the formation of atmospheres on ultra-hot rocky exoplanets. Our approach treats melt vaporisation and atmospheric gas speciation thermodynamically self-consistently, before using radiative transfer simulations to predict atmospheric structure and emission spectra. We find that compositional effects are minor within the range of plausible rocky compositions. However, the emission spectrum is particularly sensitive to fO2, owing to its influence on the partial pressures of gas species in equilibrium with the silicate mantle. This effect is exacerbated when the atmosphere contains a volatile component such as H2O, CO2 or N2. We show that observations made with the James Webb Space Telescope (JWST) hold the potential to distinguish between fO2 scenarios, thereby paving the way for the first independent constraints on the chemistry of rocky exoplanets.

How to cite: Seidler, F. and Sossi, P.: Impact of oxygen fugacity on atmospheric spectra of hot rocky exoplanets, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19056, https://doi.org/10.5194/egusphere-egu24-19056, 2024.

EGU24-19230 | ECS | Orals | PS5.2

Current limitations in chemical abundance measurements for M dwarfs and implications for exoplanet characterisation   

Yutong Shan, Petra Hatalova, Hugo Tabernero, Anina Timmermann, Elena Mamonova, and Stephanie Werner

Planets are assembled from the same material as their parent stars. Therefore, stellar chemical abundance measurements provide important constraints on the formation, composition, and interior structure of exoplanets. M dwarfs are the most prolific hosts of low-mass, rocky, potentially habitable exoplanets. However, owing to the complexity of their atmospheres (which are marred by molecular absorption), elemental abundances of M dwarfs are notoriously difficult to measure. For key rock-forming elements, state-of-the-art abundance precisions attainable from high-resolution spectroscopy of M dwarfs can be up to an order of magnitude poorer than that for sun-like stars. This would mean a comprehensive characterisation of planets around M dwarfs may be more elusive. We explore examples of consequences for uncertainties in exoplanet modelling, such as condensation sequences, bulk compositions, and core-mantle fractions. We discuss what is required from the stellar science community to make progress.  

How to cite: Shan, Y., Hatalova, P., Tabernero, H., Timmermann, A., Mamonova, E., and Werner, S.: Current limitations in chemical abundance measurements for M dwarfs and implications for exoplanet characterisation  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19230, https://doi.org/10.5194/egusphere-egu24-19230, 2024.

EGU24-20183 * | ECS | Orals | PS5.2 | Highlight

Combined analysis of the 12.8 and 15 microns JWST/MIRI eclipse observations of TRAPPIST-1 b 

Elsa Ducrot, Pierre-Olivier Lagage, and Michiel Min and the ExoMIRI Team

The first JWST/MIRI photometric observations of TRAPPIST-1 b allowed for the detection of the thermal emission of the planet at 15 microns, suggesting that the planet could be a bare rock with a zero albedo and no redistribution of heat. Here we present five new occultations of TRAPPIST-1 b observed with MIRI in an additional photometric band at 12.8 microns.  In this presentation we present the results from a joint fit of the 10 eclipses and derive a planet-to-star flux ratio of 452 +/- 86 ppm and 775 +/-90 ppm at 12.8 microns and 15 microns, respectively. 
We show how we tested a large range of models and found that the data can be well fitted by either an airless planet model with an unweathered (fresh) ultramafic surface, that could be indicative of relatively recent geological processes, or, more surprisingly, by a thick pure CO2 atmosphere with photochemical hazes that create a temperature inversion and results in the CO2 feature being seen in emission. 
Our results highlight the challenges in accurately determining a planet's atmospheric or surface nature solely from broadband filter measurements of its emission, but also point towards two very interesting scenarios that will be further investigated with the forthcoming phase curve of TRAPPIST-1 b+c.

How to cite: Ducrot, E., Lagage, P.-O., and Min, M. and the ExoMIRI Team: Combined analysis of the 12.8 and 15 microns JWST/MIRI eclipse observations of TRAPPIST-1 b, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20183, https://doi.org/10.5194/egusphere-egu24-20183, 2024.

EGU24-20933 | Orals | PS5.2

On the feasibility of measuring methane on Mars using 3.3 um lidar from space 

Joel Campbell, Zhaoyan Liu, Bing Lin, Jirong Yu, and Jihong Geng

We investigate the feasibility of measuring methane on Mars using a satellite based lidar at 3.3 um which has the advantage over passive instruments in being able to measure methane at night. Line selection, power requirements, signal to noise, and other details are discussed. Comparisons with other technologies are made. Previous measurements are discussed and the possible advantages of measurements that Lidar can obtain are presented. Subterranean life and other processes are investigated as a possible origin of methane on Mars. Comparisons of similar subterranean life on earth are used as a model for possible subterranean life on Mars and elsewhere.

 

How to cite: Campbell, J., Liu, Z., Lin, B., Yu, J., and Geng, J.: On the feasibility of measuring methane on Mars using 3.3 um lidar from space, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20933, https://doi.org/10.5194/egusphere-egu24-20933, 2024.

We cannot truly understand the general principles that govern planetary processes by studying only one planet or using only one modelling framework. Fortunately, continuing leaps in solar system exploration and recent exoplanetary discoveries, accelerated by the advent of JWST, allow us to start drawing connections between solar system planets and exoplanets — applying the vast knowledge of Earth and its neighbours to more distant worlds, and vice versa. To this end, solar system objects can offer analogues of some of the more exotic exoplanets, e.g. Jupiter's moon Io as an ultra-hot geologically active rocky planet analogue, or Venus as a habitable-zone Earth-like planet with a decidedly non-Earth climate. Within the solar system itself, a lot of atmospheric and geologic phenomena are present on more than one planet: dust devils are observed on both Earth and Mars, Earth's hydrological cycle has its methane counterpart on Titan, to name but a few. On the other hand, expanding our understanding of exoplanets places our own solar system within the broader context of planetary formation, architectures, atmospheres, and habitability.
 
At the same time, a smorgasbord of numerical models, including 3D general circulation models of the atmosphere, are now routinely being applied to different planets, both to test our theory, predict and interpret observations. Drawing from the success stories in the Earth climate community, it is now recognised that benchmarking and comparing the behaviour of numerical models through intercomparison projects is one of the key ways to advance our knowledge. This has a variety of benefits to the planetary science, from better planning for future observations to identifying bugs in the code to feeding back the model improvements to the Earth climate community. Recently, this effort has been re-invigorated under the CUISINES framework, an international effort to systematically contrast and compare models of various complexity for a range of different planets.
 
In this talk, I will first demonstrate how a state-of-the-art 3D climate model can be used to study different planetary atmospheres, from extrasolar hot Jupiters to temperate rocky planets. Using this model as an example, I will discuss some lessons that can be learnt in building planetary climate models. I will then give some highlights of the recent model intercomparisons for exoplanets and solar system planets. I will conclude with a discussion on how model intercomparison projects benefit both planetary and Earth-focused science.

How to cite: Sergeev, D.: Shall I compare thee to a distant world? The importance of inter-planet and inter-model comparative studies., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-22029, https://doi.org/10.5194/egusphere-egu24-22029, 2024.

EGU24-255 | PICO | GD8.1

Iron hydride FeHx in the Earth's inner core and its geophysical implications 

Feiwu Zhang, Hua Yang, and Joshua Muir

The Earth's inner core, formed as a result of cooling and crystallization of the outer core iron alloys, plays a fundamental role in the evolution of our planet. There is still much uncertainty on the phases of iron at high pressures and temperatures. Furthermore, the chemical composition of the Earth's core has attracted growing attention in the last several decades. The presence of small amounts of light alloying elements such as Si, O, S, C, and H in the core has been proposed to explain the seismic and density anomalies in the Earth's core. Among these light elements, hydrogen has the highest abundance in the solar system, and therefore, it is potentially one of the main light elements in the Earth's core.

In order to explore the possibility, structure, mobility, and concentration of H in the Earth's inner core, especially under high temperatures, we have employed evolutionary crystal structure prediction methods and density functional theory (DFT) calculations to examine the structural models of Fe-H binary at core pressure and temperature conditions[1]. The influence of temperature on the stabilities of the Fe-H binary has been simulated within the quasi-harmonic approximation (QHA) framework. Molecular dynamics calculations are also performed to detect the state and mobility of H under core conditions. The ionic conductivity of Fe-H alloy, as well as the H concentration in the Earth's inner core, was determined, and its implications on the composition and evolution of the Earth's core are discussed [2,3].

Our study suggests that the Fe-H binary adopts numerous possible structures under core-like conditions, while the fcc structure is concluded to be a strong candidate for the H-bearing phase in the Earth's inner core. The high mobility of H in the solid Fe lattice at high temperatures indicates that H is transferred to a superionic state, where the H superionic state transfer temperature in Fe fcc lattice is ∼500 K higher than that in the hcp Fe system. H is a key light element for reducing the density and elastic modulus of Fe, but the wave velocities of the Fe-H binary still remain too high to account for the seismological observations of the inner core. Other light elements are, therefore, also required to match all the geophysical models.

References:

[1] Yang H et al (2022) Geochemistry, Geophysics, Geosystems, 23 (12), e2022GC010620

[2] Yang H et al (2023) American Mineralogist, 108 (4), 667-674

[3] ] Yang H et al (2023) Geophysical Research Letters, 50 (22), 2023GL104493

How to cite: Zhang, F., Yang, H., and Muir, J.: Iron hydride FeHx in the Earth's inner core and its geophysical implications, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-255, https://doi.org/10.5194/egusphere-egu24-255, 2024.

EGU24-289 | ECS | PICO | GD8.1

Top-heavy double-diffusive convection with core-mantle boundary heat flux variations 

Souvik Naskar, Jonathan Mound, Christopher Davies, and Andrew Clarke

The geomagnetic field is sustained by thermochemical convection in Earth’s outer core. Crystallization of the solid inner core releases latent heat and light elements, providing both thermal and chemical buoyancy sources. Most geodynamo simulations use the codensity approach, ignoring the vastly different diffusivities and different boundary conditions for the thermal and chemical fields and thus cannot capture double-diffusive effects. In this study, we consider a numerical convection model of a Boussinesq mixture of light elements in a heavy fluid confined within a rotating spherical shell. The governing parameters are the Ekman number (𝐸 = 2 × 10−5), a non-dimensional measure of the rotation rate, the thermal and chemical flux Rayleigh numbers (𝑅𝑎𝑇 = 9 × 106 − 1.2 × 108 and 𝑅𝑎𝜉 = 3 × 106 − 5 × 1010), representing the non-dimensional thermal and chemical forcing, and the thermal and chemical Prandtl numbers (𝑃𝑟𝑇 = 1 and 𝑃𝑟𝜉 = 10), that are fluid properties. We have performed a detailed analysis of the force balance that emerges within these simulations. We find a transition from a thermal wind to a chemical wind balance with increasing chemical forcing in the azimuthally averaged ”mean” forces in the radial direction. The transition is found to occur at buoyancy ratio, Λ = (𝑅𝑎𝑇 /𝑃𝑟𝑇 )/(𝑅𝑎𝜉 /𝑃𝑟𝜉 ) ≃ 1. However, the corresponding ”fluctuating” balance is quasi-geostrophic in all directions. The analysis lets us locate the geophysically relevant ”rapidly rotating” regime in this parameter space.

We proceed by imposing a laterally heterogeneous thermal flux at the core-mantle boundary (CMB) in our rapidly rotating double-diffusive simulations. Recent thermally-driven simulations with lateral variations in CMB heat flux produce local regions with a subadiabatic thermal gradient near the CMB (Mound et al., 2019), termed as regional inversion lenses (RILs). This may reconcile the conflicting inferences about the possibility of a globally stratified layer at the top of the core (Kaneshima 2018; Gastine et al. 2020), by accommodating the possibility of both stable and unstable regions. Our goal is to assess the effect of chemical buoyancy on the RILs. The parameter space now also includes the pattern and amplitude of lateral variation in the CMB heat flux. A standard ’tomographic’ pattern, as suggested by seismic measurements (Masters et al., 1996), has been used in these simulations. The amplitude is characterized as 𝑞 = (𝑞𝑚𝑎𝑥 − 𝑞𝑚𝑖𝑛)/𝑞𝑎𝑣𝑔 where 𝑞𝑚𝑎𝑥, 𝑞𝑚𝑖𝑛, and 𝑞𝑎𝑣𝑔 are the maximum, minimum and horizontally averaged heat flux through the CMB. We study the RILs by varying the lateral heterogeneity with 𝑞∗ = {1, 2.3, 5} and buoyancy ratios with Λ = 400-0.01. These RILs are characterized by their strength, measured by a characteristic Brunt-Väisälä frequency (𝑁). Their thickness (𝐿) is measured as the distance of the point of neutral stability from CMB, and the chemical anomaly (𝛿𝜉 ) represents the difference in chemical composition across the lenses. The scaling dependence of these quantities (Mound & Davies, 2020) on the chemical forcing has been explored to extrapolate their values for Earth-like parameters.

 

How to cite: Naskar, S., Mound, J., Davies, C., and Clarke, A.: Top-heavy double-diffusive convection with core-mantle boundary heat flux variations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-289, https://doi.org/10.5194/egusphere-egu24-289, 2024.

Near the equatorial region of the Earth’s core, secular variation in the geomagnetic field consists of short period fluctuations. Such fluctuations in the magnetic field are believed to be the result of equatorially trapped waves close to the core-mantle boundary. The balance between the magnetic, Coriolis and buoyancy forces can sustain waves if a stably stratified layer exists in the outermost regions of the core. In this study, a shallow water model with additional magnetic field effects has been used to investigate the characteristics of such equatorially trapped waves. A two-layer model is studied analytically to investigate the effects of radially varying background magnetic fields on the equatorially confined MAC waves. Dispersion relations obtained are significantly influenced by the dependency of the second layer pressure gradient on that of the first layer.  Moreover, the reduced gravity effects in the second layer also modifies the second layer dynamics. Additional parameters, formulated in terms of density, magnetic field strength and buoyancy frequency of both layers characterize the system. The modified properties of a two layer model compared to a single layer is investigated for various regimes of such control parameters. It is found that the alteration in the second layer’s buoyancy frequency significantly influences the dynamics of the MAC (Magnetic-Archimedes-Gravity) wave.

How to cite: Sharma, D. K. and Sahoo, S.: Equatorially trapped waves in a stratified region in the Earth’s outer core modeled using 2-layer shallow water equations, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2692, https://doi.org/10.5194/egusphere-egu24-2692, 2024.

EGU24-3475 | ECS | PICO | GD8.1

Back reaction of magnetic field on rotating penetrative convection 

Tirtharaj Barman, Arpan Das, and Swarandeep Sahoo

The origin of the Earth's and planetary magnetic field is thought to arise from the convective flow of conducting liquid metal, particularly iron, in the deep interior of planetary systems through dynamo action. In numerical simulations, the nature of the resulting magnetic field depends on the imposition of buoyancy profiles that drive convection. Additional influence of imposed magnetic field on convective flows have been studied to understand the back reaction of dynamo action on fluid flow. In the present study, onset of  magnetoconvection is investigated to understand the physical effects in polar regions of the Earth's core where buoyancy forces exhibit a substantial component along the rotation axis. A simplified plane layer convection setup has been used to investigate the fundamental physical mechanisms. Various strengths of uniform magnetic fields in both horizontal and vertical directions have been incorporated. The novel aspect of the study is the incorporation of thermally stable layers with weak and strong stratification. Imposition of thermally stable stratification reduces the threshold of convective instability. It also restricts heat transport to unstable regions only. However, rapid rotation favors penetration of axial velocity into the thermally stable region, although critical thermal forcing for initiating convection also increases. The spectral characteristics of the flow is significantly modified due to the imposition of a stable stratified layer with background uniform magnetic field.

How to cite: Barman, T., Das, A., and Sahoo, S.: Back reaction of magnetic field on rotating penetrative convection, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3475, https://doi.org/10.5194/egusphere-egu24-3475, 2024.

EGU24-3539 | PICO | GD8.1

Probing the deep Earth interior by a synergistic use of magnetic and gravity fields, and Earth's rotation   

Mioara Mandea, Veronique Dehant, and Anny Cazenave

In order to understand the processes involved in the deep interior of the Earth and explaining its evolution, in particular the dynamics of the Earth’s fluid iron-rich outer core, only indirect satellite and ground observations are available. They each provide invaluable information about the core flow but are incomplete on their own. This is the case of (1) the magnetic field, which can be used to infer the motions of the fluid at the top of the core on decadal and sub-decadal time scales, (2) the gravity field variations, which reflect changes in the mass distribution within the Earth, and (3) the Earth's rotation changes (or variations in the length of the day). These variations are occurring at multi-annual timescales and largely related to the core fluid motions. Earth's rotation variations are induced through exchange of angular momentum between the core and the mantle at the core-mantle boundary. We are particularly interested by the 6 and 8-year variations. They are presented together with the main activities proposed in the frame of the GRACEFUL ERC project, which aims at combining all information from observation as well as modelling the core flow in a completely coupled core and mantle system.

 

How to cite: Mandea, M., Dehant, V., and Cazenave, A.: Probing the deep Earth interior by a synergistic use of magnetic and gravity fields, and Earth's rotation  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3539, https://doi.org/10.5194/egusphere-egu24-3539, 2024.

EGU24-3649 | ECS | PICO | GD8.1

Estimating core dynamics via the assimilation of magnetic field models into numerical dynamos 

Kyle Gwirtz, Weijia Kuang, and Terence Sabaka

A significant portion of the Earth’s observed magnetic field is sustained by fluid motion in the planet’s outer core (geodynamo) and varies over time. Records of the past magnetic field come from a variety of sources including, paleo- and archaeomagnetic data. In the modern era, satellite-based observations from missions such as SWARM, have led to a new level of spatial and temporal resolution in our knowledge of the magnetic field. Such observations of the field’s secular variation (SV) can provide a unique window into the deep interior of the Earth. However, understanding the origins and implications of observed SV calls for connecting data to models of Earth’s core dynamics.

Over the last 10-15 years, there has been increasing interest in using data assimilation (DA) to connect numerical dynamo simulations with magnetic field observations. DA is a general term for methods by which one can produce a “weighted combination” of numerical models and observations, to estimate a system’s overall state. This approach is widely used in applications such as numerical weather prediction, where DA is used to, for example, determine initial conditions for forecasts.

We present recent work in the development of DA as a tool for understanding the Earth’s deep interior, using NASA’s Geomagnetic Ensemble Modeling System (GEMS). In simple terms, we “nudge” an ensemble of numerical geodynamo model runs toward observed magnetic field variations according to an Ensemble Kalman Filter (EnKF) framework. This process has the potential to recover information about dynamics which cannot be directly observed, such as the fluid flow and magnetic field deep within the interior. We highlight recently improved capabilities of GEMS, investigate its ability to constrain the core state, and discuss the impact of SWARM data on this work.

How to cite: Gwirtz, K., Kuang, W., and Sabaka, T.: Estimating core dynamics via the assimilation of magnetic field models into numerical dynamos, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3649, https://doi.org/10.5194/egusphere-egu24-3649, 2024.

EGU24-4505 | PICO | GD8.1

Non-negligible Oxygen in the Earth's Inner Core: The importance of high temperatures 

Qianxi Chen, Joshua Muir, and Feiwu Zhang

The core of the Earth must have some light elements which are small in concentration but could have dramatic effects on the behavior of the core. Oxygen is one such element. It has long been concluded based on experiments and theoretical calculations (Alfè, Gillan, and Price 2002) that the inner core partitions negligible amounts of O from an enriched outer core and thus its possible effects can be ignored. An oxygen-rich outer and oxygen-poor inner cores has also been proposed as a way to explain various seismic data (Badro, Côté, and Brodholt 2014). The discovery of Fe-O superionic alloys (He et al. 2022) calls these conclusions into questions as the state of O is substantially different at high vs low temperatures which could affect extrapolations of experimental results to high temperatures.

Focusing on the most thermally stable superionic alloys in the inner core, our study systematically investigates the partitioning behaviour of oxygen between solid inner and liquid outer core by an advanced combination of ab initio molecular dynamics (AIMD) simulations and the two-phase thermodynamics (2PT) model (Lin, Blanco, and Goddard 2003). We conclude that while O remains favoured in the liquid state under core conditions non-negligible amounts of O enter the inner core and thus its possible presence cannot be ignored. With realistic concentrations of O in the outer core we produce a density contrast between liquid and solid oxygen that is in the range of that observed at the inner core boundary (ICB) thus showing the importance of obtaining accurate partitioning values and their effect on seismic structure.

This study provides a new and reliable approach to the thermodynamic properties of the superionic state and a new theoretical basis for understanding the internal structure of the Earth's core, contributing to understanding of the complexity of the Earth's interior and providing useful insights into future directions of research in the field of Earth sciences. It also shows the stark difference between high and low temperature structures and how accurate temperatures need to be considered when looking at core structures.

 

Alfè, D., M. J. Gillan, and G. D. Price. 2002. 'Ab initio chemical potentials of solid and liquid solutions and the chemistry of the Earth’s core', The Journal of Chemical Physics, 116: 7127-36.

Badro, James, Alexander S. Côté, and John P. Brodholt. 2014. 'A seismologically consistent compositional model of Earth’s core', Proceedings of the National Academy of Sciences, 111: 7542-45.

He, Yu, Shichuan Sun, Duck Young Kim, Bo Gyu Jang, Heping Li, and Ho-kwang Mao. 2022. 'Superionic iron alloys and their seismic velocities in Earth’s inner core', Nature, 602: 258-62.

Lin, Shiang-Tai, Mario Blanco, and William A. Goddard. 2003. 'The two-phase model for calculating thermodynamic properties of liquids from molecular dynamics: Validation for the phase diagram of Lennard-Jones fluids', The Journal of Chemical Physics, 119: 11792-805.

How to cite: Chen, Q., Muir, J., and Zhang, F.: Non-negligible Oxygen in the Earth's Inner Core: The importance of high temperatures, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4505, https://doi.org/10.5194/egusphere-egu24-4505, 2024.

EGU24-7843 | ECS | PICO | GD8.1

Numerical and experimental investigation on the effect of topography on the hydrodynamics of planetary fluid envelops. 

Vadim Giraud, Jérôme Noir, Fabian Burmann, and David Cébron
The majority of investigations into planetary core and subsurface ocean dynamics have traditionally assumed a perfectly smooth interface. However, geodynamical models and seismic observations on Earth suggest the presence of topography. This study addresses the role of topography in the simplified but fundamental case of differential rotation between the topography and the fluid within a cylinder.
We conducted numerical and experimental analyses, exploring various ranges of Rossby numbers (from 10-1 to 10-4 ) and different wavelengths and heights of topography, always greater than the Ekman boundary layer. Numerical simulations were performed using the spectral elements code Nek5000, while experiments were conducted with water on a rotating table employing particle imagery velocimetry (PIV).
Our observations reveal that the topography emits inertial waves into the fluid, and their patterns are correlated with the derivatives of the topography's height, rather than directly with its height. The controlling parameters influence the frequencies and amplitudes of the inertial waves, leading to the derivation of scaling laws in Rossby number, wavelength, and topography height. From these scaling laws, we propose a model for the dynamics of the fluid, including energy transfers.
 
 

How to cite: Giraud, V., Noir, J., Burmann, F., and Cébron, D.: