Content:

PS – Planetary & Solar System Sciences

PS1.1 – Open Session on Exoplanetary Research

EGU2020-7520 | Displays | PS1.1

Machine-learning inference of the interior structure of low-mass exoplanets

Philipp Baumeister, Sebastiano Padovan, Nicola Tosi, Grégoire Montavon, Nadine Nettelmann, Jasmine MacKenzie, and Mareike Godolt

We explore the application of machine-learning, based on mixture density neural networks (MDNs), to the interior characterization of low-mass exoplanets up to 25 Earth masses constrained by mass, radius, and fluid Love number k2. MDNs are a special subset of neural networks, able to predict the parameters of a Gaussian mixture distribution instead of single output values, which enables them to learn and approximate probability distributions. With a dataset of 900,000 synthetic planets, consisting of an iron-rich core, a silicate mantle, a high-pressure ice shell, and a gaseous H/He envelope, we train an MDN using planetary mass and radius as inputs to the network. We show that the MDN is able to infer the distribution of possible thicknesses of each planetary layer from mass and radius of the planet. This approach obviates the time-consuming task of calculating such distributions with a dedicated set of forward models for each individual planet.

The fluid Love number k2 bears constraints on the mass distribution in the planets' interior and will be measured for an increasing number of exoplanets in the future. Adding k2 as an input to the MDN significantly decreases the degeneracy of possible interior structures.

How to cite: Baumeister, P., Padovan, S., Tosi, N., Montavon, G., Nettelmann, N., MacKenzie, J., and Godolt, M.: Machine-learning inference of the interior structure of low-mass exoplanets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7520, https://doi.org/10.5194/egusphere-egu2020-7520, 2020.

EGU2020-2471 | Displays | PS1.1

Climate bistability of rocky exoplanets

Antonello Provenzale, Giuseppe Murante, Giovanni Vladilo, Laura Silva, Erica Bisesi, Elisa Palazzi, and Jost von Hardenberg

Until about 600 million years ago, our planet experienced temporary snowball conditions, with continental and sea ices covering a large fraction of its surface. This points to a potential bistability of Earth’s climate, that can have at least two different (statistical) equilibrium states for the same external forcing (i.e., solar radiation). Here we explore the probability of finding bistable climates in rocky exoplanets, and consider the properties of planetary climates obtained by varying the semi-major orbital axis (thus, received stellar radiation), eccentricity and obliquity, and atmospheric pressure. To this goal, we use the Earth-like planet surface temperature model (ESTM), an extension of 1D Energy Balance Models developed to provide a numerically efficient climate estimator for parameter sensitivity studies and long climatic simulations. After verifying that the ESTM is able to reproduce Earth climate bistability, we identify the range of parameter space where climate bistability is detected. An intriguing result of the present work is that the planetary conditions that support climate bistability are remarkably similar to those required for the sustainance of complex, multicellular life on the planetary surface. The exploration of potential climate bistability proceeds with the case of a Earth-like planet partially covered by vegetation that generates a positive vegetation-albedo feedback, in the spirit of the Charney conceptual model. In this case, it is shown that the presence of this vegetation feedback can induce relevant changes in climate dynamics and alter the range of habitable conditions for the planet.

How to cite: Provenzale, A., Murante, G., Vladilo, G., Silva, L., Bisesi, E., Palazzi, E., and von Hardenberg, J.: Climate bistability of rocky exoplanets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2471, https://doi.org/10.5194/egusphere-egu2020-2471, 2020.

EGU2020-12792 | Displays | PS1.1

Stellar Proton Events and Exoplanetary Habitability

Dimitra Atri

Superflares of energies up to 1038 ergs have been studied from Kepler and Gaia observations, and estimates of their energy and frequency on different types of stars is improving rapidly. Flares with energies up to 1035 ergs occur about once every 2000-3000 years on slow rotating stars like the Sun, but the occurrence rate is ∼ 100 times higher for younger, faster rotating stars of the same class. More than a dozen potentially habitable planets, like Proxima Centauri b and TRAPPIST-1 e, are in close-in configurations and their proximity to the host star makes them highly sensitive to stellar activity. Episodic events such as flares have the potential to cause severe damage to close-in planets, adversely impacting their habitability. Stellar Energetic Particles (SEPs) emanating from Stellar Proton Events (SPEs) cause atmospheric damage (erosion and photochemical changes), and produce secondary particles, which in turn results in enhanced radiation dosage on planetary surfaces. Taking particle spectra from 70 major solar events (observed between 1956 and 2012) as proxy, we use the GEANT4 Monte Carlo model to simulate SPE interactions with exoplanetary atmospheres. We have demonstrated that radiation dose varies significantly with charged particle spectra and an event of a given fluence can have a drastically different effect depending on the spectrum. Our results show that radiation dose can vary by about five orders of magnitude for a given fluence. In terms of shielding, we found that atmospheric depth is a major factor in determining radiation dose on the planetary surface. Radiation dose is reduced by three orders of magnitude corresponding to an increase in the atmospheric depth by an order of magnitude. We found that the planetary magnetic field is an important but a less significant factor compared to atmospheric depth. The dose is reduced by a factor of about thirty corresponding to an increase in the magnetospheric strength by an order of magnitude.

How to cite: Atri, D.: Stellar Proton Events and Exoplanetary Habitability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12792, https://doi.org/10.5194/egusphere-egu2020-12792, 2020.

In the last two decades, the field of exoplanets has witnessed a tremendous creative surge. Research in exoplanets now encompasses a wide range of fields ranging from astrophysics to heliophysics and climate science. One of the primary objectives of studying exoplanets is to determine the criteria for habitability, and whether certain exoplanets meet these requirements. The classical definition of the Habitable Zone (HZ) is the region around a star where liquid water can exist on the planetary surface given sufficient atmospheric pressure. However, this definition largely ignores the impact of the stellar wind and stellar magnetic activity on the erosion of an exoplanet's atmosphere. Amongst the many factors that determine habitability, understanding the mechanisms of atmospheric loss is of paramount importance.

We will discuss the impact of exoplanetary space weather on the long-term climate evolution and habitability, which offers fresh insights concerning the habitability of exoplanets, especially those orbiting M-dwarfs, such as Proxima b and the TRAPPIST-1 planets. We will focus on a wide range of atmospheric compositions, ranging from exo-Venus candidates to Earth twins, as many factors remain unresolved at this stage. Future missions such as the James Webb Space Telescope (JWST) will play a crucial role in constraining the atmospheres of those exoplanets. For each of these cases, we will demonstrate the importance of the exoplanetary space weather on atmospheric ion loss and habitability.

How to cite: Dong, C.: Atmospheric escape from rocky M-dwarf planets orbiting within the habitable zone, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13528, https://doi.org/10.5194/egusphere-egu2020-13528, 2020.

EGU2020-16746 | Displays | PS1.1

Modeling the Atmospheric Contribution to the Interior Characterization of sub-Neptunes and its Effect on Habitability

Jasmine MacKenzie, Philipp Baumeister, Mareike Godolt, Nicola Tosi, Daria Kubyshkina, and Luca Fossati

As the number of confirmed exoplanets has increased, so too has the diversity in their physical parameters, namely their mass and radius. A common practice is to place these planets on a Mass-Radius diagram with various calculated density curves corresponding to some bulk composition. However, these lines don’t necessarily correspond to the structure of the planet found using interior models, particularly for low mass planets with masses less than 20 M and 4 R, which we call “sub-Neptunes.” Planets in this range can have highly degenerate solutions with no solar system analog, from so-called “ocean worlds” to small dense cores with extended primary composition atmospheres. We have created a model that is able to cover the range of solutions possible for sub-Neptunes, with various levels of complexity for both the interior and atmosphere. This includes both an isothermal and semi-grey atmosphere, along with a high-pressure solar composition envelope when atmospheric pressures exceed approximately 1000 bar. We then apply this model to known sub-Neptunes located in the extended habitable zone of their star using a hydrogen-helium dominated atmosphere. An atmospheric escape model is used to investigate the longevity of the atmosphere and its effect on the overall habitability of the planet.

How to cite: MacKenzie, J., Baumeister, P., Godolt, M., Tosi, N., Kubyshkina, D., and Fossati, L.: Modeling the Atmospheric Contribution to the Interior Characterization of sub-Neptunes and its Effect on Habitability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16746, https://doi.org/10.5194/egusphere-egu2020-16746, 2020.

PS1.2 – Space environments of unmagnetized or weakly magnetized solar system bodies and the effects of space weather on these systems

EGU2020-1508 | Displays | PS1.2

Observations of the Formation of Periodic Plasma Shocks from Fast Mode Waves

Lican Shan, Aimin Du, Bruce Tsurutani, Yasong Ge, Quanming Lu, Christian Mazelle, Can Huang, Karl-Heinz Glassmeier, and Pierre Henri

Collisionless plasma shocks (CPSs), forming when supersonic plasma streams encounter a magnetized obstacle, are invoked to explain the acceleration of ubiquitously energetic cosmic rays. It has long been theorized from magnetohydrodynamics, but not directly observed that the CPSs develop from the growth of small-amplitude, low-frequency plasma waves which excited by reflected ion beams from the obstacle. We present in situ observations of an entire formation sequence of the periodic plasma shocks by the MAVEN spacecraft’s magnetic field and particle instruments. The magnetometer first detected small-amplitude circularly polarized magnetosonic waves that further steepened and eventually evolved into periodic shocks. Moreover, differing from the traditional understanding, characterizations of the fast mode waves show that the free energy of the wave/shock generation is provided by newborn protons, and the increasing sunward proton fluxes provided persistent energy for wave steepening. The unusual evidence presents itself from the combination of two circumstances: radial-aligned (Sun-Mars) magnetic fields and Martian atmospheric atom (hydrogen) photoionization and solar wind pickup. These observations lead to the conclusion that newborn ions play a crucial role in the formation process of some CPSs in the astrophysical and space plasma.

How to cite: Shan, L., Du, A., Tsurutani, B., Ge, Y., Lu, Q., Mazelle, C., Huang, C., Glassmeier, K.-H., and Henri, P.: Observations of the Formation of Periodic Plasma Shocks from Fast Mode Waves, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1508, https://doi.org/10.5194/egusphere-egu2020-1508, 2020.

EGU2020-6871 | Displays | PS1.2

The Spacecraft Potential’s Influence on the FOV of Rosetta-ICA at Low Ion Energies

Sofia Bergman, Gabriella Stenberg Wieser, Martin Wieser, Fredrik Johansson, and Anders Eriksson

Low-energy ions play important roles in many processes in the environments around various bodies in the solar system. At comets, they are, for example, important for the understanding of the interaction of the cometary particles with the solar wind, including the formation of the diamagnetic cavity.

Unfortunately, spacecraft charging makes low-energy ions difficult to measure using in-situ techniques. The charged spacecraft surface will attract or repel the ions prior to detection, affecting both their trajectories and energy. The affected trajectories will change the effective FOV of the instrument. A negatively charged spacecraft will focus incoming positive ions, enlarging and distorting the FOV.

We model the low-energy FOV distortion of the Ion Composition Analyzer (ICA) on board Rosetta. ICA is an ion spectrometer measuring positive ions with an energy range of a few eV to 40 keV. Rosetta was commonly charged to a negative potential throughout the mission, and consequently the positive ions were accelerated towards the spacecraft before detection. This distorted the low-energy part of the data. We use the Spacecraft Plasma Interaction Software (SPIS) to simulate the environment around the spacecraft and backtrace particles from the instrument. We then compare the travel direction of the ions at detection and infinity, and draw conclusions about the resulting FOV distortion. We investigate the distortion for different spacecraft potentials and Debye lengths of the surrounding plasma.

The results show that the effective FOV of ICA is severely distorted at low energies, but the distortion varies between different viewing directions of the instrument. It is furthermore sensitive to changes in the Debye length and we observe a small non-linearity in the relation between FOV distortion, ion energy and spacecraft potential. Generally, the FOV is not significantly affected when the energy of the ions is above twice the spacecraft potential.

How to cite: Bergman, S., Stenberg Wieser, G., Wieser, M., Johansson, F., and Eriksson, A.: The Spacecraft Potential’s Influence on the FOV of Rosetta-ICA at Low Ion Energies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6871, https://doi.org/10.5194/egusphere-egu2020-6871, 2020.

EGU2020-8318 | Displays | PS1.2

Observations of low energy ions around the diamagnetic cavity at comet 67P

Gabriella Stenberg Wieser, Martin Wieser, Sofia Bergman, Elias Odelstad, Fredrik Johansson, and Hans Nilsson

We investigate the variations in low energy cometary ions around comet 67P. Detailed measurements of these ions were made possible by implementing a new instrumental mode of the ion mass spectrometer on the Rosetta spacecraft. The nominal time resolution was increased from 192 s to 4 s at the expense of the energy range and the field-of-view.

In this study we focus on ion observations made outside of, but in the vicinity of, the diamagnetic cavity. The ion dynamics here is clearly linked to variations of the magnetic field strength and properties of the electron velocity distribution, manifested by the spacecraft potential. Preliminary results show that the ion flux correlates with the changes of the spacecraft potential. The maximum ion flux is, however, observed about 20 seconds after a sudden decrease of the potential (corresponding to an increase in electron density if electron temperature is constant). We also find evidence of small ion temperature increases both when the spacecraft potential changes fast and at the time of maximum ion flux.

How to cite: Stenberg Wieser, G., Wieser, M., Bergman, S., Odelstad, E., Johansson, F., and Nilsson, H.: Observations of low energy ions around the diamagnetic cavity at comet 67P, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8318, https://doi.org/10.5194/egusphere-egu2020-8318, 2020.

EGU2020-10596 | Displays | PS1.2

Influence of foreshock electrons impact ionization on the amplitude of pickup protons generated waves at Mars

Christian Mazelle, Karim Meziane, Norberto Romanelli, David L. Mitchell, Suranga Ruhunisiri, Hadi Madanian, Ali Rahmati, Steven J. Schwartz, Jared R. Espley, Jasper S. Halekas, and Emmanuel Penou

Using MAVEN observations, we report variations of the amplitude of electromagnetic waves observed at the local proton cyclotron frequency upstream from the bow shock on short (plasma) time/length-scales: 1) a sharp sudden increase of the amplitude when crossing the electron foreshock boundary and 2) a decrease of this amplitude clearly correlated with the increasing distance from the shock along the magnetic field inside the foreshock without any simple relation to the planetary radial distance. These waves are excited by unstable ring-beam velocity distributions of newborn protons produced by ionization of exospheric hydrogen atoms. The amplitude of these waves is generally expected to depend only on different drivers including the observed large seasonality of the hydrogen exosphere, the EUV solar flux, the solar wind density and velocity or the IMF cone angle at different levels of importance. No noticeable wave amplitude change is expected when crossing the electron foreshock boundary and inside the pure electron foreshock. Surprisingly, we found that that these waves also display the two same aforementioned properties as the foreshock electrons fluxes at Mars though the wave origin is related to the ions only. We investigate the possibility that the extra free energy necessary to increase the wave amplitude could be due to supplementary ionization of hydrogen atoms by electron impact ionization inside the foreshock. Therefore, the electron foreshock also plays a role in the production of pickup protons which contribute to the planetary escape from high altitude.

How to cite: Mazelle, C., Meziane, K., Romanelli, N., Mitchell, D. L., Ruhunisiri, S., Madanian, H., Rahmati, A., Schwartz, S. J., Espley, J. R., Halekas, J. S., and Penou, E.: Influence of foreshock electrons impact ionization on the amplitude of pickup protons generated waves at Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10596, https://doi.org/10.5194/egusphere-egu2020-10596, 2020.

EGU2020-12241 | Displays | PS1.2

MAVEN Observations of Large-amplitude, Quasi-periodic Sawtooth-like Magnetic Field Oscillations Associated with Kelvin-Helmholtz Instability

Gangkai Poh, Jared Espley, Norberto Romanelli, Jacob Gruesbeck, and Gina DiBraccio

In this study, we present a preliminary analysis of large-amplitude sawtooth-like magnetic field oscillations observed by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft at Mars. Initial survey of these quasi-periodic magnetic field oscillations (with periods of ~3 – 4 minutes) shows distinct sawtooth-like magnetic field signatures with steep increase in BY of ~20 – 30 nT, followed by a gentle, but turbulent, return to background magnetic field values. The extrema in the BY component generally coincide with an extrema of opposite polarity in the BX component. Quasi-periodic magnetic field signatures can also be observed in the z-component of the magnetic field vector. Ion and electrons measurements shows corresponding increase in ions and electrons with energies greater than 30eV and 10 eV, respectively, during observations of these sawtooth-like oscillations, indicating some mixing of plasma. We interpret these observations as Kelvin-Helmholtz (KH) waves in the non-linear stages because the plasma and fields signatures are consistent with non-linear KH waves observed at Earth and other planetary environments. KH waves are developed as a result of flow shear-driven KH instability occurring between the boundary separating two moving fluids. In the non-linear stage of the KH instability, rolled-up KH vortex can developed along the boundary, allowing the mixing of plasma between the two plasma regions. Occurrence of KH waves had been observed at Venus’ ionopause and the induced magnetopause, contributing to loss of planetary ions in the form of plasma clouds. Earlier simulations and observational studies have also explored the possibility of non-linear KH instability occurring at Mars. We will discuss the conditions required for the development of KH instability, its growth rate and implications on mass loss at Mars. Comparison with simulations will also be conducted and discussed.

How to cite: Poh, G., Espley, J., Romanelli, N., Gruesbeck, J., and DiBraccio, G.: MAVEN Observations of Large-amplitude, Quasi-periodic Sawtooth-like Magnetic Field Oscillations Associated with Kelvin-Helmholtz Instability , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12241, https://doi.org/10.5194/egusphere-egu2020-12241, 2020.

EGU2020-12363 | Displays | PS1.2

Hemispheric Asymmetry in the Mars Summer Ionosphere at Various Solar Forcing Conditions

Marcin Pilinski, Laila Andersson, and Ed Thiemann

The MAVEN satellite has now made two Martian-years of ionosphere-thermosphere (I-T) observations enabling limited studies of seasonal changes in the upper atmosphere. Before examining the ionospheric dynamics associated with space weather, we wish to understand the climatological conditions of the system.  For example, previous studies have revealed the morning electron temperature overshoot as well as a close dependence between electron temperatures and neutral densities in the equatorial regions. In this presentation, we will examine differences in the northern and southern dayside ionosphere during the summer season of each hemisphere. The differences between these two cases will be contrasted with the seasonal dependence at the equator. Differences between the equatorial and polar regions are expected due to (A) differences in neutral scale heights, (B) differences in the solar zenith angle, and (C) the equilibration of I-T coupling due to differences in solar illumination.

In this work, we present a statistical analysis of MAVEN measurements comparing the north and south summer I-T. We find that when controlling for neutral pressure and latitude, the north and south plasma densities and temperatures are nearly identical below the demagnetization altitude (higher neutral pressures). Above the demagnetization altitude (lower neutral pressures), the southern hemisphere electron densities are higher than those in the northern hemisphere by ~100%. A significantly lower electron temperature is also observed in the south at these lower pressures. Given that the difference in solar EUV (and corresponding neutral heating) is ~20% between the two summer seasons, we postulate that the significantly lower plasma densities (above the demagnetization altitude) in the northern summer are due in part to an increase in ionospheric loss. This loss may be associated with the acceleration of ionospheric particles by the draped magnetic fields at an altitude where ions are not demagnetized. Furthermore, the loss may be diminished in the southern hemisphere where crustal magnetic fields increase the standoff distance to the solar wind magnetic field.

How to cite: Pilinski, M., Andersson, L., and Thiemann, E.: Hemispheric Asymmetry in the Mars Summer Ionosphere at Various Solar Forcing Conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12363, https://doi.org/10.5194/egusphere-egu2020-12363, 2020.

EGU2020-16452 | Displays | PS1.2

Mars’ ionopause: A game of pressures

Beatriz Sanchez-Cano, Clara Narvaez, Mark Lester, Michael Mendillo, Majd Mayyasi, and Mats Holmstrom

The ionopause is a tangential discontinuity in the ionospheric thermal plasma density profile that marks the upper boundary of the ionosphere for unmagnetized planets. This interface is formed by a balance of pressures, as the ionopause is the region where the total pressure of the ionosphere (ionospheric thermal pressure plus magnetic pressure) balances the solar wind ram pressure. Since only Venus and Mars have no global “dipole” magnetic fields, ionopauses are unique to those planets. For Venus, the ionopause formation is well characterized because the thermal pressure of the ionosphere is usually larger than the solar wind dynamic pressure. For Mars, however, the maximum thermal pressure of the ionosphere is usually insufficient to balance the total pressure in the overlying magnetic pileup boundary. Therefore, the Martian ionopause is not always formed, and when it does, it is located at a large range of altitudes, varies rapidly and is highly structured. In this study, we characterise the Martian ionopause formation from the point of view of the thermal, magnetic and dynamic pressure balance. The objective of this paper is to assess under which circumstances the Martian ionopause is formed, both over and far from crustal magnetic fields. We focus on three MAVEN deep dip campaigns that occurred on the dayside of Mars, and we utilize several multi-plasma and magnetic field in-situ observations from the MAVEN mission, as well as solar wind plasma observations from the Mars Express mission.

How to cite: Sanchez-Cano, B., Narvaez, C., Lester, M., Mendillo, M., Mayyasi, M., and Holmstrom, M.: Mars’ ionopause: A game of pressures, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16452, https://doi.org/10.5194/egusphere-egu2020-16452, 2020.

EGU2020-6354 | Displays | PS1.2

ESCAPADE: coordinated multipoint measurements of Mars' near-space plasma environment

Robert Lillis, Shannon Curry, Christopher Russell, Janet Luhmann, Aroh Barjatya, Davin Larson, Ronan Modolo, Roberto Livi, Phyllis Whittlesey, Yuki Harada, Christopher Fowler, Shaosui Xu, David Brain, Paul Withers, and Edward Thiemann

Multi-spacecraft missions after 2000 (Cluster II, THEMIS, Van Allen Probes, and MMS) have revolutionized our understanding of the causes, patterns and variability of a wide array of plasma phenomena in the terrestrial magnetospheric environment. ESCAPADE is a twin-spacecraft Mars mission concept that will similarly revolutionize our understanding of how solar wind momentum and energy flows throughout Mars’ magnetosphere to drive ion and sputtering escape, two processes which have helped shape Mars’ climate evolution over solar system history. 

ESCAPADE will measure magnetic field strength and topology, ion plasma distributions (separated into light and heavy masses), as well as suprathermal electron flows and thermal electron and ion densities, from elliptical, 200 km x 7000 km orbits. ESCAPADE are small spacecraft (<90 kg), traveling to Mars via solar electric propulsion as a rideshare with the Psyche metal-asteroid mission in August 2022, matching Mars’ heliocentric orbit until capture and spiral-down to science orbits. ESCAPADE’s strategically-designed 1-year, 2-part scientific campaign of temporally and spatially-separated multipoint measurements in different parts of Mars’ diverse plasma environment, will allow the cause-and-effect of solar wind control of ion and sputtering escape to be unraveled for the first time. Figure 1 shows ESCAPADE’s orbits within a hybrid simulation of the solar wind interaction with Mars, where the color scale represents ion velocity, blue lines are magnetic field, while white lines are sample proton trajectories and spacecraft orbits.

ESCAPADE has been selected for Phase A and B study by NASA as one of three finalists in the SIMPLEX-II program.  We will report on science goals, engineering and mission design challenges, and provide a status update.

How to cite: Lillis, R., Curry, S., Russell, C., Luhmann, J., Barjatya, A., Larson, D., Modolo, R., Livi, R., Whittlesey, P., Harada, Y., Fowler, C., Xu, S., Brain, D., Withers, P., and Thiemann, E.: ESCAPADE: coordinated multipoint measurements of Mars' near-space plasma environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6354, https://doi.org/10.5194/egusphere-egu2020-6354, 2020.

We study the solar wind interaction with Venus in a 3-dimensional global hybrid model where ions are treated as particles and electrons are a charge-neutralizing fluid. We concentrate on large-scale ultra-low frequency (ULF) waves in the ion foreshock and how they affect the energization and escape of planetary ions. The ion foreshock forms in the upstream region ahead of the quasi-parallel bow shock, where the angle between the shock normal and the magnetic field is smaller than about 45 degrees. The magnetic connection with the bow shock allows backstreaming of the solar wind ions leading to the formation of the ion foreshock. This kind of beam-plasma configuration is a source of free energy for the excitation of plasma waves. The foreshock ULF waves convect downstream with the solar wind flow and encounter the bow shock and transmit in the downstream region. We analyze the coupling of the ULF waves with the planetary ion acceleration and compare Venus and Mars in a global hybrid simulation.

How to cite: Jarvinen, R., Kallio, E., and Pulkkinen, T.: Modulation of the solar wind driven ion escape from unmagnetized planets by ultra-low-frequency foreshock waves in a global hybrid simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6891, https://doi.org/10.5194/egusphere-egu2020-6891, 2020.

EGU2020-7497 | Displays | PS1.2

Statistical occurrence of mirror mode waves at Mars

Cyril Simon Wedlund, Martin Volwerk, Christian Mazelle, Christian Möstl, Diana Rojas-Castillo, Jared Espley, and Jasper Halekas

Ultra low-frequency wave activity such as mirror mode (MM) waves, arising from an ion temperature anisotropy in the plasma, has been ubiquitously detected in the magnetosheaths of Venus and Mars. The MM instability is usually triggered behind a quasi-perpendicular bow shock in a high plasma β. We present here a statistical survey of these waves at Mars using magnetometer and ion data from the NASA/MAVEN mission between 2014 and 2019 (solar cycle 24, receding activity). First, quasi-perpendicular bow shock crossings are identified in the data using simple bow shock models (Edberg et al. 2008, Gruesbeck et al. 2018, Hall et al. 2019). MM waves are then automatically detected for these conditions, first from magnetometer measurements only (in the manner of Volwerk et al., 2016), and second using both magnetometer and ion moments to refine the analysis. Maps of MM wave occurrence for solar cycle 24 are presented and preliminary comparisons with similar and different solar activity conditions with MGS and Mars Express data are discussed.

How to cite: Simon Wedlund, C., Volwerk, M., Mazelle, C., Möstl, C., Rojas-Castillo, D., Espley, J., and Halekas, J.: Statistical occurrence of mirror mode waves at Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7497, https://doi.org/10.5194/egusphere-egu2020-7497, 2020.

EGU2020-7864 | Displays | PS1.2

Crustal magnetic fields at Mars and ion escape

Eduard Dubinin, Markus Fraenz, Marin Pätzold, Joachim Woch, Kai Fan, Yong Wei, Jim McFadden, Olga Tsareva, and Lev Zelenyi

Does an intrinsic field inhibits or enhances ion escape from planetary ionospheres is still an unsolved issue. Mars does not possess a global intrinsic magnetic field but instead has the strong crustal magnetic fields localized mainly in the southern hemisphere. The crustal magnetic field significantly influences the interaction of the solar wind with Mars adding features typical for planets with a global intrinsic magnetic field. Therefore it is interesting to compare ion losses from the ionosphere regions with and without strong crustal fields. Recently such studies were performed and have shown a protective effect of the crustal field on escape of the energized (E > 30 eV) oxygen ions (e.g. Fan et al., Geophysical Review Letters, 2019). However, the main bulk of escaping ions at Mars have energy lower than 30 eV. We will present the results of influence of the crustal magnetic field at Mars on the total losses of O+ and O2+ ions. The global picture of ion escape occurs more complex. Effects of larger ionospheric areas above the crustal field sources exposed by solar wind compensate a shielding effect at lower altitudes. As a result, the ion losses from the southern ionosphere of Mars might be even higher than losses from the northern “unmagnetized” ionosphere.

How to cite: Dubinin, E., Fraenz, M., Pätzold, M., Woch, J., Fan, K., Wei, Y., McFadden, J., Tsareva, O., and Zelenyi, L.: Crustal magnetic fields at Mars and ion escape, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7864, https://doi.org/10.5194/egusphere-egu2020-7864, 2020.

EGU2020-9757 | Displays | PS1.2

Effects of the solar wind dynamic pressure on the accelerated cometary ions in the magnetosphere of comet 67P

Aniko Timar, Zoltan Nemeth, Karoly Szego, Melinda Dósa, and Balazs Nagy

Rosetta observed medium-energy ions around comet 67P/Churyumov-Gerasimenko while orbiting deep inside the coma. These ions are thought to be accelerated towards the anti-sunward direction by some acceleration mechanism in the outer regions of the cometary magnetosphere. They usually reach energies up to 100-1000 eV and undergo deceleration in the dense neutral coma surrounding the nucleus. These ions usually appear in the ion dynamic spectrum as a new population rising from the low energy background, their energy peaking around 1000 eV and then decreasing until the population disappears again. We investigated the properties of these ions, as well as the relationship between the solar wind pressure and the energy of the medium-energy ions to discover the cause of the observed time variation. We show that there is a correlation between the solar wind dynamic pressure around the comet and the energy of the accelerated ions.

How to cite: Timar, A., Nemeth, Z., Szego, K., Dósa, M., and Nagy, B.: Effects of the solar wind dynamic pressure on the accelerated cometary ions in the magnetosphere of comet 67P, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9757, https://doi.org/10.5194/egusphere-egu2020-9757, 2020.

EGU2020-10492 | Displays | PS1.2

Localized heating of the Martian topside ionosphere through the combined effects of magnetic pumping by large scale magnetosonic waves and pitch angle diffusion by whistler waves

Christopher Fowler, Oleksiy Agapitov, Shaosui Xu, David Mitchell, Laila Andersson, Anton Artemyev, Jared Espley, Robert Ergun, and Christian Mazelle

We present Mars Atmosphere and Volatile EvolutioN (MAVEN) observations of periodic (~ 25 s) large scale (100s km) magnetosonic waves propagating into the Martian dayside upper ionosphere. These waves adiabatically modulate the superthermal electron distribution function, and the induced electron temperature anisotropies drive the generation of observed electromagnetic whistler waves. The localized (in altitude) minimum in the ratio fpe / fce provides conditions favorable for the local enhancement of efficient wave-particle interactions, so that the induced whistlers act back on the superthermal electron population to isotropize the plasma through pitch angle scattering. These wave-particle interactions break the adiabaticity of the large scale magnetosonic wave compressions, leading to local heating of the superthermal electrons during compressive wave `troughs'. Further evidence of this heating is observed as the subsequent phase shift between the observed perpendicular-to-parallel superthermal electron temperatures and compressive wave fronts. Such a heating mechanism may be important at other unmagnetized bodies such as Venus and comets.

How to cite: Fowler, C., Agapitov, O., Xu, S., Mitchell, D., Andersson, L., Artemyev, A., Espley, J., Ergun, R., and Mazelle, C.: Localized heating of the Martian topside ionosphere through the combined effects of magnetic pumping by large scale magnetosonic waves and pitch angle diffusion by whistler waves, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10492, https://doi.org/10.5194/egusphere-egu2020-10492, 2020.

We report the preliminary results of a hybrid simulation to differentiate and quantify the energy gain due to different electric field terms in the acceleration of planetary ions escaping from an induced magnetosphere. 

The planetary ions gain energy from the electric field formed in the induced magnetosphere. The electric field is not directly measurable and thus has to be expressed by the generalized Ohm's law with measurable quantities:

E = -Ve×B - ∇Pe/(qene) + j×B/(qene)

Where Ve is the velocity of the electrons that freeze the magnetic field B, Pe is the thermal pressure tensor, and j is the Hall current. The three terms on the right-hand side describe the three different mechanisms of ion acceleration: the motional term, the pressure gradient term, and the Hall term. All these terms contribute to the energization of escaping ions, while they dominate in different positions in an induced magnetosphere, and play different roles in the dynamics of an escaping ion.

We will quantify the energy gain due to each electric field term of escaping ions depending on the birthplaces of the ions. Our tool is AMITIS, a GPU-based 3-D hybrid code (ions as particles and electrons as a fluid) to model the plasma interaction with a planet (Fatemi et al., 2017). For a test, we simulated the solar wind interaction with Mars at nominal space environment conditions until a quasi-steady state. We calculated different electric field terms and compared them with the MAVEN measurements. The simulation results show good agreement with measurements in both magnitude and spatial distribution.

 

We further launched test particles from different positions in the ionosphere and tracked the energy gain/loss due to different electric field terms along their escaping trajectories. The energization history of an ion depends on its trajectory, which further partly depends on the birthplace of the ion. Ions produced outside of the IMB are accelerated or “picked up” totally by the motional electric field. Ions produced in the induced magnetosphere in the dayside may be accelerated by the thermal pressure gradient of the ionosphere, while those produced in the nightside are driven more by the Hall electric field.

How to cite: Wang, X.-D. and Fatemi, S.: Acceleration of Planetary Ions by Different Electric Field Terms in an Induced Magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11419, https://doi.org/10.5194/egusphere-egu2020-11419, 2020.

EGU2020-13746 | Displays | PS1.2

The dependence of deep-nightside Martian ionosphere TEC on crustal magnetic field

Junfeng Qin, Hong Zou, Yuguang Ye, Jinsong Wang, and Erling Nielsen

It has been clear that the main cause of Martian deep-nightside ionosphere is electron precipitation, which is dominated by Martian crustal magnetic field. In this research, the dependence of deep-nightside Martian ionosphere TEC (Total Electron Content) on crustal magnetic field was studied based on Martian ionospheric TEC data from MEX/MARSIS and 400km crustal magnetic field data from MGS. It is found that the strength and inclination of crustal magnetic field have great effects on Martian deep-nightside ionospheric TEC. This kind of effects are worth to be compared with the effects of crustal magnetic field on electron precipitation studied in previous researches (such as Lillis and Brain, 2013, Nightside electron precipitation at Mars: Geographic variability and dependence on solar wind conditions) to find out more about the formation of Martian deep-nightside ionosphere. It is also found that, in a Martian crustal magnetic field cusp region, the observed deep-nightside ionospheric TECs in the center of the cusp are lower than those in the edge of the cusp, a phenomenon not noticed before. It indicates that there may be more precipitated electrons moving along the closed crustal magnetic lines than moving along open crustal magnetic lines, and these precipitated electrons in closed magnetic lines can be related to the energy processes in the nightside of Mars, such as magnetic reconnections.

How to cite: Qin, J., Zou, H., Ye, Y., Wang, J., and Nielsen, E.: The dependence of deep-nightside Martian ionosphere TEC on crustal magnetic field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13746, https://doi.org/10.5194/egusphere-egu2020-13746, 2020.

EGU2020-13754 | Displays | PS1.2

Degenerate induced magnetospheres

Stas Barabash, Andrii Voshchepynets, Mats Holmström, Futaana Yoshifumi, and Robin Ramstad

Induced magnetospheres of non-magnetized atmospheric bodies like Mars and Venus are formed by magnetic fields of ionospheric currents induced by the convective electric field E = - V x B/c of the solar wind. The induced magnetic fields create a magnetic barrier which forms a void of the solar wind plasma, an induced magnetosphere. But what happens when the interplanetary magnetic field is mostly radial and the convective field E ≈ 0? Do a magnetic barrier and solar wind void form? If yes, how such a degenerate induced magnetosphere work? The question is directly related to the problem of the atmospheric escape due to the interaction with the solar and stellar winds. The radial interplanetary magnetic field in the inner solar system is typical for the ancient Sun conditions and exoplanets on near-star orbits. Also, the radial interplanetary field may provide stronger coupling of the near-planet environment with the solar/stellar winds and thus effectively channels the solar/stellar wind energy to the ionospheric ions. We review the current works on the subject, show examples of degenerate induced magnetospheres of Mars and Venus from Mars Express, Venus Express, and MAVEN measurements and hybrid simulations, discuss physics of degenerate induced magnetospheres, and impact of such configurations on the escape processes.

How to cite: Barabash, S., Voshchepynets, A., Holmström, M., Yoshifumi, F., and Ramstad, R.: Degenerate induced magnetospheres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13754, https://doi.org/10.5194/egusphere-egu2020-13754, 2020.

EGU2020-16717 | Displays | PS1.2

A Statistical Analysis of Radar Blackout Events at Mars

Mark Lester, Beatriz Sanchez-Cano, Hannah Biddle, Daniel Potts, Pierre-Louis Blelly, Hermann Opgenoorth, Olivier Witasse, Marco Cartacci, Roberto Orosei, Fabrizio Bernardini, Nathaniel Putzig, Bruce Campbell, Robert Lillis, François Leblanc, Steve Milan, and John M.C. Plane

The loss of signal detection by the sub surface radars currently operational on Mars Express and Mars Reconnaissance Orbiter can be evidence of enhanced ionisation at lower altitudes in the Martian atmosphere as a result of solar energetic particles penetrating to these altitudes.  The MARSIS instrument on Mars Express and SHARAD on MRO operate at different frequencies, with MARSIS up to 5 MHz and SHARAD between 10 and 20 MHZ.  In addition MARSIS can operate in an additional mode as an Active Ionospheric Sounder, although here we focus only on the sub surface mode.  We present an analysis of the data during the lifetimes of both instruments, extending from 2005 to 2018.  Here we identify the radar blackouts as either total or partial and investigate their occurrence as a function of solar cycle.  We find a clear solar cycle dependence with more events occurring during the solar maximum years, as expected.  However, we also note the duration of events is often much longer than expected, in excess of several days, sometimes reaching 10 – 14 days.  Investigation of other data sets, notably from the MAVEN SEP instrument complements the analysis.  We finally compare our observations at Mars with similar observations at Earth.

How to cite: Lester, M., Sanchez-Cano, B., Biddle, H., Potts, D., Blelly, P.-L., Opgenoorth, H., Witasse, O., Cartacci, M., Orosei, R., Bernardini, F., Putzig, N., Campbell, B., Lillis, R., Leblanc, F., Milan, S., and Plane, J. M. C.: A Statistical Analysis of Radar Blackout Events at Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16717, https://doi.org/10.5194/egusphere-egu2020-16717, 2020.

EGU2020-17083 | Displays | PS1.2

Dusty plasma effects in the nighttime ionosphere of mars

Yulia Izvekova, Sergey Popel, and Alina Besedina

A self-consistent consideration of the motion of dust particles in plasma systems in the atmosphere of Mars can lead to the detection of oscillations and waves, which, in particular, can be detected from the surface of the planet. The presence of local magnetic fields leads to significant inhomogeneities in the ionosphere of Mars, especially noticeable on the night side. On the night side of the ionosphere, there are areas of sharp increase in electron concentrations in areas where the lines of force of the magnetic field are perpendicular to the surface of the planet. In the areas where the magnetic field is parallel to the surface, the electrons of the solar wind do not penetrate the atmosphere and there is no ionization. Horizontal gradients of electron density on the night side can exceed 10 ^ 4 cm ^ -3 for several tens of kilometers. Such high plasma density gradients lead to local plasma transfer perpendicular to the external magnetic field, horizontal currents and electric fields are generated. Interaction of the plasma of the solar wind with a plasma containing dust particles can lead to the generation of high-frequency waves.

The work is supported by the Russian Science Foundation (project No 18-72-00119).

How to cite: Izvekova, Y., Popel, S., and Besedina, A.: Dusty plasma effects in the nighttime ionosphere of mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17083, https://doi.org/10.5194/egusphere-egu2020-17083, 2020.

EGU2020-18500 | Displays | PS1.2

Sounder Accelerated Particles at Mars: Observations, Mechanisms, and Applications

Andrii Voshchepynets, Stas Barabash, Mats Holmstrom, Rudy Frahm, and Andrew Kopf

We report the first observations of sounder accelerated particles (SAP) in the ionosphere of a planet which does not possess a strong magnetic field (Mars). These observations were conducted onboard the Mars Express spacecraft by the ion and electron sensors of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) experiment and the powerful topside sounder: Mars Advanced Radar for Subsurface and Ionosphere Sounding (MARSIS). Accelerated ions (O2+ , O+, and lighter ions) are observed in an energy range up to 800 eV when MARSIS transmits at a frequency close to the plasma frequency. Individual observations consist of almost monoenergetic ion beams either aligned with the MARSIS antenna or lying in the perpendicular plane. The observed ion beams are often accompanied by a decrease in the electron flux. Accelerated electrons are observed at energies up to 400 eV when MARSIS transmits at a frequency between the local plasma frequency and its harmonics (up to four times the plasma frequency). The majority of the sounder accelerated electrons are recorded close to the regions of intense crustal magnetic fields. The voltage applied to the MARSIS antenna causes spacecraft charging to 100’s of volts by electrons from the ambient plasma. Positively charged ions are accelerated when the spacecraft discharges. Accelerated photoelectrons are released by the highly charged spacecraft and after one gyration in the strong magnetic field, return to the spacecraft which has already discharged. The acceleration effect influences which ions can be observed by increasing the energy of the thermal ion species making it possible to detect them whereas they would be indistinguishable under normal circumstances. We present the relevant data and discuss how these effects can be used for diagnostic of the local plasma.

How to cite: Voshchepynets, A., Barabash, S., Holmstrom, M., Frahm, R., and Kopf, A.: Sounder Accelerated Particles at Mars: Observations, Mechanisms, and Applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18500, https://doi.org/10.5194/egusphere-egu2020-18500, 2020.

EGU2020-19305 | Displays | PS1.2

A study of kinematic relaxation at the Venus bow shock

Simon A. Pope and Michael A. Balikhin

A new type of very-low Mach number shock in which the primary method of energy re-distribution is the kinematic relaxation of a non-gyrotropic ion population, was discovered at Venus early in the Venus Express mission. This led to the development of an associated theory and numerical analysis. The recent discovery of such a shock at the Earth using THEMIS data experimentally verified this theory using simultaneous magnetic field and plasma data. It also showed that the most favourable conditions for the formation of such a shock is the magnetic cloud phase of an ICME. Venus Express provides an excellent opportunity to study such shocks further. Here we present results from the duration of the mission, which identifies over thirty shock crossings showing evidence of kinematic relaxation. These shock crossings are investigated to understand how the upstream conditions and heavy ions (including pick-up ions) affect their formation.

How to cite: Pope, S. A. and Balikhin, M. A.: A study of kinematic relaxation at the Venus bow shock, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19305, https://doi.org/10.5194/egusphere-egu2020-19305, 2020.

EGU2020-20178 | Displays | PS1.2

Rosetta electric field observations in the plasma environment of comet 67P/Churyumov-Gerasimenko

Elias Odelstad, Tomas Karlsson, and Anders Eriksson
The plasma environments of active comets are dominated by the interaction of the solar wind with newly born cometary heavy ions, predominantly water group ions produced by ionization of cometary neutral volatiles over large distances in the extensive and diffuse cometary coma. The resulting vast comet-solar wind interaction region hosts a plethora of plasma instabilities, waves and turbulence phenomena, and thus constitutes a formidable natural laboratory for studying such processes.
 
Waves are also important in determining many of the plasma properties of this environment. They can, e.g., heat or cool plasma populations, create supra-thermal electrons responsible for X-ray emissions, reduce plasma anisotropies and gradients, couple different plasma species, and provide anomalous resistivity.
 
Electric field measurements in the cometary plasma environment have until recently been rare, and have only been performed during short fly-by missions, at relatively large distances from the comet nucleus. The electric field measurements by the LAP instrument onboard the Rosetta spacecraft, collected during more than two years in the vicinity of comet 67P/Churyumov-Gerasimenko therefore represent a truly unique data set.
 
We use the database of 60 Hz electric field measurements of waves in the lower-hybrid frequency range, and correlate the comet-related parameters, (relative spacecraft position, solar distance, plasma and neutral gas density, etc.) with wave related parameters, such as amplitude/spectral density and frequency. We also compare statistically the properties of the waves with theoretical predictions of lower-hybrid wave generation, regarding e.g. amplitude dependence on plasma density gradients, with the aim of clarifying the importance of the plasma waves in different regions of the cometary plasma environment.
 
Electric field measurements allow investigating both electrostatic wave modes and electromagnetic ones. We investigate frequencies and amplitudes of the electric field oscillations and use background magnetic field values and plasma properties to determine relevant expected frequencies, as well as magnetic field oscillations (for low and medium frequencies) to determine if the plasma waves are electrostatic or electromagnetic. Lower hybrid waves are almost electrostatic, but have a small magnetic field signature from second order effects. Determination of the most common wave modes gives an indication of the role of plasma waves in the cometary plasma environment probed by Rosetta.
 
Lower hybrid waves are common in the inner coma of 67P. Such waves are predicted to energize electrons parallel to the ambient magnetic field, and ions in the perpendicular direction. With the help of ion and electron data, we test this prediction, which may explain the presence of a hot electron population reported on, but of hitherto unknown origin. These results give clues to the role of the waves in the formation of the cometary plasma environment.

How to cite: Odelstad, E., Karlsson, T., and Eriksson, A.: Rosetta electric field observations in the plasma environment of comet 67P/Churyumov-Gerasimenko, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20178, https://doi.org/10.5194/egusphere-egu2020-20178, 2020.

EGU2020-20751 | Displays | PS1.2

MHD Predictions of Plasma Conditions Above Insight Landing Site based on MAVEN observations

Yingjuan Ma, Chris Russell, Yanan Yu, Andrew Nagy, Gabor Toth, and Bruce Jakosky2

The Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) mission was launched on 5 May 2018 and successfully landed at Elysium Planitia (4.5oN, 135.9oE)on Mars on 26 November 2018. The InSight Lander carries a magnetometer to measure disturbances from the Martian ionosphere. In order to understand the daily variations in the magnet field measurements on Martian surface, in this study, we use the time-dependent MHD model to study how plasma conditions vary with local time above insight landing site using solar wind condition from MAVEN observation. Significant diurnal variations can be seen in all plasma quantities due to solar wind interactions and planetary rotation. The induced magnetic field is mainly in the same direction as the upstream IMF. However, it seems that the variations seen by the Insight magnetometer cannot be only due to the interaction of the solar wind. We also add a neutral wind effect in our simulations to further investigate possible causes of surface field changes.

How to cite: Ma, Y., Russell, C., Yu, Y., Nagy, A., Toth, G., and Jakosky2, B.: MHD Predictions of Plasma Conditions Above Insight Landing Site based on MAVEN observations , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20751, https://doi.org/10.5194/egusphere-egu2020-20751, 2020.

EGU2020-20922 | Displays | PS1.2

Modeling Ionospheric Densities and Flows in Crustal and Draped Magnetic Fields at Mars

Antonio Renzaglia, Thomas Cravens, Christopher Fowler, Ali Rahmati, Shotaro Sakai, Jack Connerney, Mehdi Benna, and Laila Andersson

NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) explorer has been in orbit around Mars for over 5 years now, collecting valuable data about the planet. Specifically, the Langmuir Probe and Waves (LPW), the Neutral Gas and Ion Mass Spectrometer (NGIMS), and the Suprathermal and Thermal Ion Composition (STATIC) instruments measure important ionospheric properties. The instruments measure electron densities and temperature (LPW), neutral gas and ion composition (NGIMS), and the properties of escaping ions (STATIC). Electron and ion density and flux measurements are presented. The data indicates significant differences in ion properties between open crustal, closed crustal, and draped magnetic fields. Similar differences are noted for electrons as well. An ionospheric model has been developed that produces a profile of the ionosphere. The model then explores the evolution of the ionosphere, via chemistry and transport. At low altitudes (z<300 km), chemistry dominates, while transport dominates at higher altitudes. Results show significant differences in the ionosphere between the types of fields. The model utilizes data from the Magnetometer (MAG) instrument to provide properties of magnetic fields at Mars. The model may also help explain some of the atmospheric loss occurring at Mars. This is compared to data from STATIC. Analytic arguments for subsonic vs supersonic flow speeds (in the open field case) are also presented.

How to cite: Renzaglia, A., Cravens, T., Fowler, C., Rahmati, A., Sakai, S., Connerney, J., Benna, M., and Andersson, L.: Modeling Ionospheric Densities and Flows in Crustal and Draped Magnetic Fields at Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20922, https://doi.org/10.5194/egusphere-egu2020-20922, 2020.

PS1.3 – Planetary, Solar and Heliospheric Radio Emissions

EGU2020-1025 | Displays | PS1.3

On the fine structures in interplanetary radio emissions

Immanuel Christopher Jebaraj, Jasmina Magdalenic, and Stefaan Poedts

Solar radio emission is studied for many decades and a large number of studies have been dedicated to metric radio emission originating from the low corona. It is generally accepted that solar radio emission  observed at wavelengths below the metric range is produced by the coherent plasma emission mechanism. Fine structures seem to be an intrinsic part of solar radio emission and they are very important for understanding plasma processes in the solar medium. Extensive reporting and number of studies of the metric range fine structures were performed, but studies of fine structures in the interplanetary domain are quite rare. New and advanced ground-based radio imaging spectroscopic techniques (e.g. LOFAR, MWA, etc.,) and space-based observations (Wind/WAVES, STEREO/WAVES A & B, PSP, and SolO in the future) provide a unique opportunity to study radio fine structures observed  all the way from metric to kilometric range.

Radio signatures of solar eruptive events, such as flares and CMEs, observed in the interplanetary space are mostly confined to type II (radio signatures of magneto-hydrodynamic shock waves), and type III  bursts(electron beams propagating along open and quasi-open magnetic field lines). In this study, we have identified, and analyzed three types of fine structures present within the interplanetary radio bursts. Namely, the striae-like fine structures within type III bursts, continuum-like emission patches, and very slow drifting narrowband structures within type II radio bursts. Since space-based radio observations are limited to dynamic spectra, we use the novel radio triangulation technique employing direction finding measurements from stereoscopic spacecraft (Wind/WAVES, STEREO/WAVES A & B) to obtain the 3D position of the radio emission. The novelty of the technique is that it is not dependent on a density model and in turn can probe the plasma density in the triangulated radio source positions (Magdalenic et al. 2014). Results of the study show that locating the radio source helps not only to understand the generation mechanism of the fine structures but also the ambient plasma conditions such as e.g. electron density. We found that fine structures are associated with complex CME/shock wave structures which interact with the ambient magnetic field structures. We also discuss the possible relationship between the fine structures, the broadband emission they are part of, and the solar eruptive events they are associated with.

How to cite: Jebaraj, I. C., Magdalenic, J., and Poedts, S.: On the fine structures in interplanetary radio emissions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1025, https://doi.org/10.5194/egusphere-egu2020-1025, 2020.

EGU2020-1252 | Displays | PS1.3

Spectral Analysis of Solar Radio Type III Bursts from 10 kHz to 80 MHz

Kantepalli Sasikumar Raja, Milan Maksimovic, Xavier Bonnin, Philippe Zarka, Laurent Lamy, Eduard P. Kontar, Alain Lecacheux, Vratislav Krupar, Baptiste Cecconi, Nora Lahmiti, and Laurent Denis

Solar radio type III bursts are produced by electron beams that are propagating along the open magnetic field lines in the corona and interplanetary medium (IPM). They are the intense, fast drifting, and frequently observed bursts. Recently, it was reported that observations of type III bursts show a maximum spectral response at around 1 MHz. But this behavior of type III bursts is not sufficiently discussed in the literature. In order to understand this behavior we have revisited this problem and studied 2279 isolated type III bursts that are observed with Wind/Waves instrument (from space during 1995-2009) in the frequency range 10 kHz-14 MHz and found that all of them show a maximum spectral response at around 1 MHz. Since type III bursts are somewhat directive, we have studied separately, another 115 type III bursts that are simultaneously observed (in 2013-2014) using Wind/Waves and ground-based facility Nancay Decameter Array (10-80 MHz) and compared the spectral profiles. In this presentation, we will discuss the observations, applied calibration techniques and the possible theoretical explanation of why type III bursts show such behavior. 

How to cite: Sasikumar Raja, K., Maksimovic, M., Bonnin, X., Zarka, P., Lamy, L., Kontar, E. P., Lecacheux, A., Krupar, V., Cecconi, B., Lahmiti, N., and Denis, L.: Spectral Analysis of Solar Radio Type III Bursts from 10 kHz to 80 MHz, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1252, https://doi.org/10.5194/egusphere-egu2020-1252, 2020.

EGU2020-14784 | Displays | PS1.3

Strongly structured radio emission observed by LOFAR on August 25, 2014

Jasmina Magdalenic, Christophe Marque, Richard Fallows, Gottfried Mann, Christian Vocks, and Pietro Zucca

On August 25, 2014, NOAA AR 2146 produced the M2.0 class flare (peaked at 15:11 UT). The flare was associated with a halo CME and a radio event observed by LOFAR (the LOw-Frequency Array). The radio event consisted of a type II, type III and type IV radio emissions. In this study, we present LOFAR observations of the type II (radio signatures of shock waves) and type III bursts (radio signatures of fast electron beams propagating along open or quasi open field lines).  Both, the type II burst and type III bursts show strong fragmentation of the radio emission. Although fine structures of type II bursts were already reported, the richness of the fine structures observed in the studied event is unprecedented. We found type II fine structures morphologically very similar to the ones sometimes seen superposed on type IV continuum emission, and similar to simple narrowband super short structures (Magdalenic et al., 2006). The group of type III bursts was as usually, observed during the impulsive phase of the flare. The high frequency/time resolution LOFAR observations reveal that only few of the observed type III bursts have a smooth emission profile, and the majority of bursts is strongly fragmented. Surprisingly, fine structures of some type III bursts show similarities to the fine structures observed in the type II burst, but on a smaller frequency scale. Some of the type III bursts show a non-organized patchy structure which gives an indication on the possibly related turbulence processes. We show that these LOFAR observations bring completely new insight and pose a new challenge for the physics of the acceleration of electron beams and associated emission processes.

How to cite: Magdalenic, J., Marque, C., Fallows, R., Mann, G., Vocks, C., and Zucca, P.: Strongly structured radio emission observed by LOFAR on August 25, 2014, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14784, https://doi.org/10.5194/egusphere-egu2020-14784, 2020.

EGU2020-21394 | Displays | PS1.3

Analysis of solar radio imaging-spectroscopic observations

Yihua Yan, Minghui Zhang, Zhichao Zhou, Xingyao Chen, Chengming Tan, Baolin Tan, Wei Wang, Linjie Chen, Fei Liu, Lihong Geng, Zhijun Chen, Yin Zhang, and Muser Team

Solar radio fine structures observed in wide frequency ranges are manifestations of the physical processes related to the energy release, particle accelerations and propagations, etc. The locations of these fine structures are mostly not clear so it is important to have imaging spectroscopic observations to address these problems.

Mingantu Spectral Radioheliograph (MUSER) is an aperture-synthesis imaging telescope, dedicated to observe the Sun, operating on multiple frequencies in dm to cm range. The ability of MUSER allows one to diagnose coronal magnetic field and the plasma parameters such as electron beam velocity, density, spectral index, etc.

During 2014 to 2019, MUSER has registered a number of solar radio bursts corresponding to 2 X-class, 15 M-class, 38 C-class, 19 B-class, 4 A-class and 5 below A-class flares as well as quiet Sun observations. Here we demonstrate some interesting events from MUSER imaging-spectroscopic observations.

How to cite: Yan, Y., Zhang, M., Zhou, Z., Chen, X., Tan, C., Tan, B., Wang, W., Chen, L., Liu, F., Geng, L., Chen, Z., Zhang, Y., and Team, M.: Analysis of solar radio imaging-spectroscopic observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21394, https://doi.org/10.5194/egusphere-egu2020-21394, 2020.

EGU2020-7876 | Displays | PS1.3

Solar Type III radio bursts at Saturn’s orbit: Case study of stereoscopic observations by Cassini/RPWS and Wind/WAVES experiments

Ahmed Abou el-Fadl, Mohammed Boudjada, Patrick H.M. Galopeau, Muhamed Hammoud, and Helmut Lammer

Type III radio bursts are produced by electron beams accelerated in active regions and following open magnetic field lines. Type III observed frequency is found to be nearly equal to the plasma frequency directly linked to the local electron density. The source regions of such solar bursts are the solar corona and the interplanetary medium where, respectively, higher and lower frequencies are generated. In this work, we consider specific Type III solar bursts simultaneously observed by Cassini/RPWS and Wind/WAVES experiments. Despite the distance of Cassini spacecraft to the Sun such Type III bursts have been detected at Saturn’s orbit, i.e. at about 10AU. Those considered bursts are covering a frequency bandwidth from about 10 MHz down to 100 kHz. We attempt in this study to characterize the spectral pattern, i.e. the flux density versus the observation time and the frequency range, and the visibility of the source regions to the observer (i.e. Wind and Cassini spacecraft). In this context, we analyze the evolution of the Type III bursts from the solar corona and up to Saturn’s orbit taking into consideration the Archimedean spiral which is the geometrical configuration of the solar magnetic field extension in the interplanetary medium. We principally discuss the physical parameters, i.e. solar wind speed and the electron density, which lead to constraint the location of the source region and its visibility to both spacecraft.

How to cite: Abou el-Fadl, A., Boudjada, M., Galopeau, P. H. M., Hammoud, M., and Lammer, H.: Solar Type III radio bursts at Saturn’s orbit: Case study of stereoscopic observations by Cassini/RPWS and Wind/WAVES experiments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7876, https://doi.org/10.5194/egusphere-egu2020-7876, 2020.

We use five different Jupiter’s magnetic field models (O6, VIP4, VIT4, VIPAL and JRM09) to investigate the angular distribution of the Jovian decameter radiation occurrence probability, relatively to the local magnetic field B and its gradient B in the source region. The most recent model JRM09, proposed by Connerney et al. [Geophys. Res. Lett., 45, 2590-2596, 2018], was derived from Juno’s first nine orbits observations. The JRM09 model confirms the results obtained several years ago using older models (O6, VIP4, VIT4 and VIPAL): the radio emission is beamed in a hollow cone presenting a flattening in a specific direction. The same assumptions were made as in the previous studies: the Jovian decameter radiation is supposed to be produced by the cyclotron maser instability (CMI) in a plasma where B and B are not parallel. As a consequence, the emission cone does not have any axial symmetry and then presents a flattening in a privileged direction. This flattening appears to be more important for the northern emission (34.8%) than for the southern emission (12.5%) probably due to the fact that the angle between the directions of B and B is greater in the North (~10°) than in the South (~4°).

How to cite: Galopeau, P. and Boudjada, M.: Relevance of the magnetic field model for studying the beaming cone of the Jovian decameter emission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10781, https://doi.org/10.5194/egusphere-egu2020-10781, 2020.

EGU2020-19055 | Displays | PS1.3

New remote radio observations of Jupiter by Parker Solar Probe

Alain Lecacheux, Stuart D. Bale, Milan Maksimovic, and Marc Pulupa

The FIELDS/RFS experiment aboard the Parker Solar Probe spacecraft, in orbit around the Sun, is able to detect and remotely study low frequency radio emissions from Jupiter. Accurate measurements of the intensity and polarisation of those emissions (mainly the HOM/DAM components) were obtained throughout years 2018 and 2019. They are compared to similar ones, obtained 20 years ago, during Cassini’s remote flyby of Jupiter. A particular emphasis is brought on the so-called “attenuation bands” phenomenon, - a well-defined intensity extinction/enhancement feature modulating the HOM dynamic spectrum -, which likely results from the radiation propagating to the observer through some permanent or long lived plasma structure (not firmly identified so far) lying in the rotating Jovian inner magnetosphere.

How to cite: Lecacheux, A., Bale, S. D., Maksimovic, M., and Pulupa, M.: New remote radio observations of Jupiter by Parker Solar Probe, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19055, https://doi.org/10.5194/egusphere-egu2020-19055, 2020.

EGU2020-2906 | Displays | PS1.3

Saturn lightning activity from a cyclone at 50°North latitude

Georg Fischer and Jacob Gunnarson

During the Cassini mission (2004-2017) the Radio and Plasma Wave Science (RPWS) experiment has recorded the lightning radio emissions from multiple thunderstorms in Saturn's atmosphere. Most of the storms were located in the storm alley at a planetocentric latitude of 35°South, and there was one extra-large storm at 35°North called "Great White Spot" (GWS), which emitted millions of SEDs. This is short for "Saturn Electrostatic Discharges", a widely-used synonym for the radio emission from Saturn lightning. Most lightning storms have also been observed by the Cassini cameras or by ground-based amateur astronomers as bright white spots with diameters around 2000 km ("smaller" storms in the storm alley) or as large as 10,000 km (GWS at 35°North).

In this presentation we focus on a cyclone at 50°North planetocentric latitude, which was observed by the Cassini cameras from 2007 until the end of 2013. Its average diameter was around 3000 km, and it also exhibited some weak SED activity. The first SED outbreak was in December 2010, at the same time when the GWS was raging further south. Due to the differences in longitude and SED rate of the 50°N cyclone compared to the GWS, it is partly possible to separate the SEDs emitted from the cyclone to those emitted from the GWS. The SED rate of the cyclone is rather low, typically a few SEDs per minute, whereas the GWS showed SED rates up to 10 SEDs per second. The SED activity of the 50°North cyclone was very intermittent, it usually lasted for a few weeks before disappearing again for several months. After the first outbreak in December 2010, there was some more activity in early 2011, autumn 2011, December 2011, spring 2012, July 2012, summer 2013, and finally autumn 2013. By comparing SED data from RPWS with images from the Cassini camera we will show that almost all SEDs taking place after the GWS had their origin in the 50°N cyclone, since the SED sub-spacecraft longitude range is consistent with the longitude of the cyclone. The last SED activity from this cyclone took place in November 2013, and it was also the last SED activity recorded by RPWS during the whole Cassini mission. No more SEDs were found from November 2013 until Cassini burned up in Saturn's upper atmosphere in September 2017.

 

How to cite: Fischer, G. and Gunnarson, J.: Saturn lightning activity from a cyclone at 50°North latitude, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2906, https://doi.org/10.5194/egusphere-egu2020-2906, 2020.

Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges, even larger than those in dust storms on Earth.  There are three key elements in the characterization of Martian electrostatic discharges: dependence on Martian environmental conditions, event rate, and the strength of the generated electric fields.  The detection and characterization of electric activity in Martian dust storms has important implications for habitability, and preparations for human exploration of the red planet. Furthermore, electrostatic discharges may be linked to local chemistry and plays an important role in the predicted global electrical circuit.

 

Because of the continuous Mars telecommunication needs of NASA’s Mars-based assets, the Deep Space Network (DSN) is the only facility in the world that combines long term, high cadence, observing opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and characterizing electrostatic activity from large scale convective dust storms at Mars. We will describe a program at NASA’s Madrid Deep Space Communication Complex that has been carrying out a long-term monitoring campaign to search for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of spacecraft at Mars on an entirely non-interfering basis. The ground-based detections will also have important implications for the design of a future instrument that could make similar in-situ measurements from orbit or from the surface of Mars, with far greater sensitivity and duty cycle, opening up a new window in our understanding of the Martian environment.

How to cite: Majid, W.: Radio Emissions from Electrical Activity in Martian Dust Storms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19929, https://doi.org/10.5194/egusphere-egu2020-19929, 2020.

PS1.4 – Planetary Space Weather

EGU2020-7422 | Displays | PS1.4 | Arne Richter Award for Outstanding ECS Lecture

Space Weather effects on Mars’ ionosphere: From our current knowledge to the way forward

Beatriz Sánchez-Cano

Planetary Space Weather is an emerging topic of increasing interest. Forecast this planetary space weather, however, is currently very challenging mainly due to the lack of continuous solar wind observations for each planet. In the particular case of Mars, understanding the ionospheric behaviour following Space Weather activity is essential in order to assess the response of the Martian plasma environment to the dissipation of energy from solar storms. Moreover, it gives information on the effects on the current technology deployed on the red planet. Despite the recent considerable exploration, however, there is still no continuous upstream solar wind observations at Mars. This fact makes the analysis of the different Martian plasma datasets challenging, relying on solar wind models and upstream solar wind observations at 1 AU (e.g. at Earth’s L1 point, STEREO, etc.) when Mars and those satellites are in apparent opposition or perfectly aligned in the Parker spiral.

This lecture will focus on our current knowledge of the Martian ionosphere, which is the layer that links the neutral atmosphere with space, and acts as the main obstacle to the solar wind. In particular, I will focus on our recent advances in the understanding of the Martian ionospheric reaction to different Space Weather events during the solar cycle, both from the data analysis and ionospheric modelling perspectives. Some important aspects to consider are the bow shock, magnetic pileup boundary, and ionopause characterization, as well as the behaviour of the topside and bottomside of the ionosphere taking into account the planet’s orbital eccentricity. Moreover, I will show the effect of electron precipitation from large Space Weather events in the very low Martian ionosphere, a region that it is non-accessible to in-situ spacecraft observations. Finally, I will conclude the presentation by giving my perspective on some of the key outstanding questions that remain unknown, and I consider they constitute the next generation of Mars’ ionospheric and Space Weather science and exploration.

How to cite: Sánchez-Cano, B.: Space Weather effects on Mars’ ionosphere: From our current knowledge to the way forward, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7422, https://doi.org/10.5194/egusphere-egu2020-7422, 2020.

EGU2020-13186 | Displays | PS1.4

Global Ten-Moment Multifluid Simulations of the Solar Wind Interaction with Mercury: From the Planetary Conducting Core to the Dynamic Magnetosphere

Chuanfei Dong, Liang Wang, Ammar Hakim, Amitava Bhattacharjee, James Slavin, Gina DiBraccio, and Kai Germaschewski

For the first time, we explore the tightly coupled interior‐magnetosphere system of Mercury by employing a three‐dimensional ten‐moment multifluid model. This novel fluid model incorporates the nonideal effects including the Hall effect, electron inertia, and tensorial pressures that are critical for collisionless magnetic reconnection; therefore, it is particularly well suited for investigating collisionless magnetic reconnection in Mercury's magnetotail and at the planet's magnetopause. The model is able to reproduce the observed magnetic field vectors, field‐aligned currents, and cross‐tail current sheet asymmetry (beyond magnetohydrodynamic approach), and the simulation results are in good agreement with spacecraft observations. We also study the magnetospheric response of Mercury to an extreme event with an enhanced solar wind dynamic pressure, which demonstrates the significance of induction effects resulting from the electromagnetically coupled interior. More interestingly, plasmoids (or flux ropes) are formed in Mercury's magnetotail during the event, indicating the highly dynamic nature of Mercury's magnetosphere. This novel ten‐moment multifluid model represents a crucial step toward establishing a revolutionary approach that enables the investigation of Mercury's tightly coupled interior‐magnetosphere system beyond the traditional fluid model and has the potential to enhance the science returns of both the MESSENGER mission and the BepiColombo mission.

How to cite: Dong, C., Wang, L., Hakim, A., Bhattacharjee, A., Slavin, J., DiBraccio, G., and Germaschewski, K.: Global Ten-Moment Multifluid Simulations of the Solar Wind Interaction with Mercury: From the Planetary Conducting Core to the Dynamic Magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13186, https://doi.org/10.5194/egusphere-egu2020-13186, 2020.

EGU2020-18327 | Displays | PS1.4

Can we forecast the arrival of ICMEs for the whole Solar Systems?

Dario Del Moro, Gianluca Napoletano, Francesco Berrilli, Luca Giovannelli, Ermanno Pietropaolo, and Raffaello Foldes

Solar wind transients, i.e. interplanetary coronal mass ejections (ICMEs) drive Space Weather throughout the heliosphere and the prediction of their impact on different solar system bodies is one of the primary goals of the Planetary Space Weather forecasting. We realized a procedure based on the Drag-Based Model (Vrsnak et al., 2013, Napoletano et al. 2018) which uses probability distributions for the input parameters, and allows the evaluation of the uncertainty on the forecast. This approach has been tested against a set of ICMEs whose transit times are known, obtaining extremely promising results.

We apply this model to propagate a sample of ICMEs from their sources on the solar surface into the heliosphere. We made use of the seminal works by Prise et al. (2015), Winslow et al. (2015) and Witasse et al. (2017) who tracked the ICMEs through their journeys using data from several spacecraft.

Considering the extremely short computation time needed by the model to propagate ICMEs, this approach is a promising candidate to forecast ICME arrival to planetary bodies and spacecraft in the whole heliosphere, with relevant application to space-mission short-term planning.

How to cite: Del Moro, D., Napoletano, G., Berrilli, F., Giovannelli, L., Pietropaolo, E., and Foldes, R.: Can we forecast the arrival of ICMEs for the whole Solar Systems?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18327, https://doi.org/10.5194/egusphere-egu2020-18327, 2020.

EGU2020-20905 | Displays | PS1.4

Revisiting the Strongest Martian X-Ray Halo Observed by XMM-Newton on 2003 November 19–21

Limei Yan, Jiawei Gao, Lihui Chai, Lingling Zhao, Zhaojin Rong, and Yong Wei

On 2003 November 20–21, when the most intense geomagnetic storm during solar cycle 23 was observed at Earth, XMM-Newton recorded the strongest Martian X-ray halo hitherto. The strongest Martian X-ray halo has been suggested to be caused by the unusual solar wind, but no direct evidence has been given in previous studies. Here, based on the Mars Global Surveyor (MGS) observations, unambiguous evidence of unusual solar wind impact during that XMM-Newton observation was found: the whole induced magnetosphere of Mars was highly compressed. The comparison between the solar wind dynamic pressure estimated at Mars from MGS observation and that predicted by different solar wind propagation models suggests that the unusal solar wind is probably related to the interplanetary coronal mass ejection observed at Earth on 2003 November 20.

How to cite: Yan, L., Gao, J., Chai, L., Zhao, L., Rong, Z., and Wei, Y.: Revisiting the Strongest Martian X-Ray Halo Observed by XMM-Newton on 2003 November 19–21, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20905, https://doi.org/10.5194/egusphere-egu2020-20905, 2020.

EGU2020-3489 | Displays | PS1.4

Interplanetary effects on planetary environments: Earth, Venus, and Mercury

Monica Laurenza, Anna Milillo, Tommaso Alberti, Valeria Mangano, Stefano Massetti, Christina Plainaki, Alessandro Mura, Elisabetta De Angelis, Rosanna Rispoli, Stavro Ivanovski, and Stefano Orsini

The interplanetary and planetary environments are characterized by several intrinsic and induced properties as magnetic fields, waves and instabilites, boundaries, and ionizing radiation components. These features usually evolve on timescales ranging from seconds up to years, mainly controlled by the solar activity.

BepiColombo and Solar Orbiter flybys will offer an interesting opportunity to investigate the dynamical features of both magnetic fields and particle populations when passing from the interplanetary to the planetary environments, thus allowing us to properly characterize different regions of the interplanetary and planetary space.

This contribution discusses some outstanding features of planetary environments (Earth, Venus, and Mercury) when they interact with the interplanetary medium by considering data coming from in-flight space missions as ACE, MESSENGER, and Venus Express. Moreover, a special attention will be devoted to BepiColombo flybys which will be helpful for deeper investigations.

How to cite: Laurenza, M., Milillo, A., Alberti, T., Mangano, V., Massetti, S., Plainaki, C., Mura, A., De Angelis, E., Rispoli, R., Ivanovski, S., and Orsini, S.: Interplanetary effects on planetary environments: Earth, Venus, and Mercury, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3489, https://doi.org/10.5194/egusphere-egu2020-3489, 2020.

EGU2020-9895 | Displays | PS1.4

A detailed look on the interaction of solar wind helium with Mercury’s surface in the laboratory

Herbert Biber, Paul S. Szabo, Noah Jäggi, Martin Wallner, Reinhard Stadlmayr, Anna Niggas, Marcos V. Moro, Daniel Primetzhofer, Andreas Nenning, Andreas Mutzke, Markus Sauer, Jürgen Fleig, Annette Foelske-Schmitz, Klaus Mezger, Helmut Lammer, André Galli, Peter Wurz, and Friedrich Aumayr

EGU2020-4118 | Displays | PS1.4

Transpolar Arc Observed by the Wide-Field Auroral Imager Onboard Fengyun Satellite

Fei He, Xiao-Xin Zhang, Zhonghua Yao, Yong Wei, and Weixing Wan

Transpolar arcs that occur primarily under northward interplanetary magnetic field (IMF) are a class of auroral features in the polar cap region. Many mechanisms have been proposed to interpret the generation of the arcs, including reconnection and sudden change in the IMF. It is now generally accepted that IMF BYcomponent plays a key role in the generation and evolution of the arcs. Here we report an interesting long-lasting and moving transpolar arc observed during a geomagnetically quiet period (Dst<10 nT and AE<50 nT) by the wide-field auroral imager (WAI) onboard the Chinese Fengyun satellite. The WAI is a recently launched imager operated in far ultraviolet wavelength (LBH band in 140-180 nm) in a sun-synchronous orbit with a height of ~840 km. It is shown that the arc was initiated at the poleward auroral boundary on dawnside after the IMF turned to be northward and persisted for more than 5 hours. The arc moved toward the noon-midnight line as the IMF BYcomponent changed its direction and then moved back toward dawnside. An interesting phenomenon was that the arc was accompanied with strong energetic proton (30-80 keV) precipitations with geomagnetic latitude greater than 70° but no significant electron precipitations. However, the origin of these energetic protons is unknown and is worthy study in future.

How to cite: He, F., Zhang, X.-X., Yao, Z., Wei, Y., and Wan, W.: Transpolar Arc Observed by the Wide-Field Auroral Imager Onboard Fengyun Satellite, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4118, https://doi.org/10.5194/egusphere-egu2020-4118, 2020.

Earth’s present dipolar magnetic field extends into the interplanetary space and interacts with the solar wind, forming a magnetosphere filled up with charged particles mostly originating from the Earth’s atmosphere. In the elongated tail of the magnetosphere, the particles were observed to move either Earthward or tailward with different speeds at different locations, even outside the Moon’s orbit. We hypothesize that the lunar soil, on both the nearside and farside, should have been impacted by these particles during the geological history, and the impact was controlled by the size and morphology of the magnetosphere. We predict that the farside soil could also have the features similar to those in the nearside soil, e.g., 15N-enrichment. Furthermore, we may infer the evolution of the magnetosphere and atmosphere by examining the implanted particles in the lunar soil from both sides. This hypothesis could provide an alternative way to study the evolution of Earth’s dynamo and atmosphere.

How to cite: Wei, Y., Zhong, J., He, F., and zhang, H.: Implantation of Earth’s atmospheric ions into the nearside and farside lunar soil: implications to geodynamo evolution, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7762, https://doi.org/10.5194/egusphere-egu2020-7762, 2020.

EGU2020-12469 | Displays | PS1.4

The magnetic flux transport along the -Esw direction in the magnetotails on Mars and Venus

Lihui Chai, James Slavin, Yong Wei, Weixing Wan, Charlie F. Bowers, Gina DiBraccio, Eduard Dubinin, Markus Fraenz, Willi Exner, Moritz Feyerabend, Uwe Motschmann, Kun Li, Jun Cui, and Tielong Zhang

The induced magnetotails on Mars and Venus are considered to arise through the interplanetary magnetic field (IMF) draping around the planet and the solar wind deceleration due to the mass loading effect. They have very similar structures as that on Earth, two magnetic lobes of opposite radial magnetic fields and a plasma sheet in between. However, the orientation and geometry of the induced magnetotails are controlled by the IMF, not the planetary intrinsic magnetic field. In this study, we present another characteristic of the induced magnetotails on Mars and Venus with the observations of MAVEN and Venus Express. It is found that the magnetic flux in the induced magnetotails on Mars and Venus are inhomogeneous. There is more magnetic flux in the +E hemisphere than -E hemisphere. The magnetic flux is observed to transport gradually from the +E hemisphere to the -E hemisphere along the magnetotail. The magnetotail magnetic flux transport seems to be faster on Mars than that at Venus. Based on these observations, we suggest that the finite gyro-radius effect of the planetary ions that are picked up by the solar wind is responsible to the magnetic flux inhomogeneity and transport in the induced magnetotails. The role of the magnetic pressure gradient in the magnetotail will be discussed.

How to cite: Chai, L., Slavin, J., Wei, Y., Wan, W., Bowers, C. F., DiBraccio, G., Dubinin, E., Fraenz, M., Exner, W., Feyerabend, M., Motschmann, U., Li, K., Cui, J., and Zhang, T.: The magnetic flux transport along the -Esw direction in the magnetotails on Mars and Venus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12469, https://doi.org/10.5194/egusphere-egu2020-12469, 2020.

EGU2020-19700 | Displays | PS1.4

MoMo’s prediction of Mars’ ionosphere contribution to InSight RISE Doppler data

sebastien Le Maistre, Nicolas Bergeot, Olivier Witasse, Pierre-Louis Blelly, Wlodek Kofman, Kerstin Peter, Veronique Dehant, Jean-Marie Chevalier, and Ozgur Karatekin

The NASA InSight mission is operating from the surface of Mars for more than a year. RISE (for Rotation and Interior Structure Experiment) is one of the scientific payloads of InSight. This radio-science experiment consisting in an X-band transponder and two horn-antennas enabling two-way coherent radio-link between Mars and the Earth [Folkner et al., 2018]. The main goal of RISE is to measure the slight modulations of the nutational motion of the spin axis of Mars induced by the liquid core of the planet in order to constrain its interior structure and core properties. To increase our chance to achieve this challenging goal, we must calibrate the RISE Doppler data by accounting to 2nd order effects like the Mars atmospheric noise.

This study shows the predicted contribution of the Martian ionosphere to the RISE data collected so far. To do so, we use a new empirical model of the Mars’ ionosphere called MoMo [Bergeot et al. 2019]. This model is based on the large database of Total Electron Content (TEC) derived from the subsurface mode of the Mars Express MARSIS radar. The model provides the vertical TEC as a function of solar zenith angle, solar activity, solar longitude and the location. Using MoMo, we produce vTEC maps for Mars that are then used to estimate the slant TEC in the Earth line of sight, enabling to infer the phase delay and Doppler shift affecting the RISE X-band measurements. These computed effects are shown to be of the order of 10-3mm.s-1 in Doppler observables, with a larger effect around sunrise and sunset. This is about one order of magnitude below the typical measurement noise of RISE, but it is comparable to the contribution of the liquid core in the Doppler (~10-3-10-2mm.s-1).

The MoMo model is suitable for any Mars radio-science data calibration, and in particular the forthcoming ExoMars 2020 LaRa measurements [Dehant et al. 2019]. The predictions made with MoMo will be of great use either for the data corrections or to define the timing of observations in order to avoid operating when the TEC rapidly varies (i.e. close to sunrise and sunset). The model output is further discussed here in terms of climatologic behavior of the Mars’ ionosphere. For comparison, we also investigate the contribution of the Earth ionosphere using Global Ionospheric Maps (GIMs) based on GNSS data.

How to cite: Le Maistre, S., Bergeot, N., Witasse, O., Blelly, P.-L., Kofman, W., Peter, K., Dehant, V., Chevalier, J.-M., and Karatekin, O.: MoMo’s prediction of Mars’ ionosphere contribution to InSight RISE Doppler data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19700, https://doi.org/10.5194/egusphere-egu2020-19700, 2020.

EGU2020-6400 | Displays | PS1.4

Energetic ion dynamics near the cusp region of Mercury

Eunjin Jang, Jiutong zhao, Chao Yue, Qiugang Zong, Ying Liu, and Zhiyang Liu

Energetic ions in Mercury’s magnetosphere are very dynamic, just like in the magnetosphere of Earth. In this study, we have shown two energetic proton observations by MESSENGER near the cusp region of Mercury. For one case, we have observed large flux of energetic protons while the other case has almost no flux, indicating that the near cusp region may trap energetic particles under particular conditions. In order to understand that under what conditions the near cusp region of Mercury could trap energetic particles, we have traced the trajectories of single particle with different energies by using a modeled magnetic field, called KT17. Under different magnetic field geometry, the motions of single particle with various energies are different. The test particles can be trapped around the cusp region when the disturbance activity is strong, generating the magnetic field local minimum near the cusp region while the particles can’t be trapped and escape along the magnetic field through the dawn side cusp when there is little solar activity.

How to cite: Jang, E., zhao, J., Yue, C., Zong, Q., Liu, Y., and Liu, Z.: Energetic ion dynamics near the cusp region of Mercury, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6400, https://doi.org/10.5194/egusphere-egu2020-6400, 2020.

EGU2020-7086 | Displays | PS1.4

Reconstruction of the magnetic connection from Mercury to the solar corona

Alessandro Ippolito, Christina Plainaki, Gaetano Zimbardo, Stefano Massetti, and Anna Milillo

The magnetic foot point of Mercury on the solar disk has been reconstructed for selected case studies, in order to better understand the interaction between the solar corona and the planet. The transport of the magnetic field lines in the heliosphere is here evaluated with a Monte Carlo code that gives a random displacement at each step of the integration along the Parker magnetic field model. Such displacement is proportional to a “local” diffusion coefficient, which is a function of the fluctuation level and magnetic field correlation lengths. The simulation is tailored to specific events by using the observed values of solar wind velocity and magnetic fluctuation levels. Magnetic data from MAG/MESSENGER have been considered to compute the magnetic fluctuation level, while, concerning proton fluxes, FIPS/MESSENGER data has been taken into account. A number of SEP events observed on Mercury during 2011 and 2012 have been analysed, studying, for each event, the magnetic connection from Mercury to the solar corona, and the position of the active region possibly source of the accelerated particles observed.

How to cite: Ippolito, A., Plainaki, C., Zimbardo, G., Massetti, S., and Milillo, A.: Reconstruction of the magnetic connection from Mercury to the solar corona, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7086, https://doi.org/10.5194/egusphere-egu2020-7086, 2020.

EGU2020-7143 | Displays | PS1.4

Space weather at Mercury as observed by the THEMIS telescope from Earth

Melinda Dósa, Valeria Mangano, Anna Milillo, Stefano Massetti, Zsofia Bebesi, and Anikó Timár

The dynamic changes of Mercury’s Na exosphere are investigated here, in relation to space weather conditions. Sodium plays a special role in Mercury’s exosphere: due to its strong resonance D lines at 5890-95Å it has been observed and monitored by Earth-based telescopes for decades. Different and highly variable patterns of Na-emission have been identified. In addition to the release processes already studied extensively in the past, we aim here to investigate the following factors more in detail: the distance to the Sun, position in relation to the ecliptic plane and solar wind magnetic field strength and direction. In order to better investigate the relationship of these factors, we have studied the intensity of Na-emission as a function of solar wind dynamic pressure and TAA of Mercury by means of the extended dataset images collected from 2009 to 2013 by Earth-based observations performed at the THEMIS solar telescope. Solar wind velocity and density values are propagated with the magnetic lasso method to the position of Mercury from nearby space probes and compared with Na emission intensity. Data of either ACE or one of the two STEREO spacecraft were used, depending on which spacecraft had a smaller angular distance to Mercury. Single cases are studied qualitatively, and a longer-term quantitative comparison is shown, including further parameters (solar wind magnetic field strength and direction, TAA).

How to cite: Dósa, M., Mangano, V., Milillo, A., Massetti, S., Bebesi, Z., and Timár, A.: Space weather at Mercury as observed by the THEMIS telescope from Earth, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7143, https://doi.org/10.5194/egusphere-egu2020-7143, 2020.

EGU2020-1974 | Displays | PS1.4

Recent advances on magnetic reconnection and dipolarization at Saturn

Zhonghua Yao and Ruilong Guo

Magnetic reconnection and dipolarization are crucial processes in driving magnetospheric dynamics, including particle energization, mass circulation, auroral processes etc. Recent studies revealed that these processes at Saturn are fundamentally different to the ones at Earth. The reconnection and dipolarization processes are far more important than previously expected at Saturn’s dayside magnetodisc. Dayside magnetodisc reconnection was directly identified using Cassini measurements (Guo et al. 2018), and was found to be drizzle-like and rotating in Saturn’s magnetosphere (Yao et al. 2017 and Guo et al. 2019). Moreover, magnetic dipolarization could also exist at Saturn’s dayside, which is fundamentally different to the terrestrial situation (Yao et al. 2018). We here review these recent advances and their potential implications to future investigations, for example the application to Jupiter’s magnetosphere.

How to cite: Yao, Z. and Guo, R.: Recent advances on magnetic reconnection and dipolarization at Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1974, https://doi.org/10.5194/egusphere-egu2020-1974, 2020.

EGU2020-2395 | Displays | PS1.4

Interplanetary shocks at 5 AU and their effects on Jupiter's decametric radio emissions

Ezequiel Echer

EGU2020-19022 | Displays | PS1.4

Exospheric Na distributions along the Mercury orbit with the THEMIS telescope

Anna Milillo, Valeria Mangano, Stefano Massetti, alessandro Mura, christina Plainaki, Tommaso Alberti, Stavro Ivanovski, Elisabetta De Angelis, and Rosanna Rispoli

The variability of Na exosphere of Mercury shows time scales from less than one hour to seasonal variations. While the faster variations, accounting of about 10-20% of fluctuations are probably linked to the planet response to solar wind and IMF variability, the seasonal variations (up to about 80%) should be explained by a complex mechanisms involving different surface release processes, loss, source and migrations of the exospheric Na atoms. Eventually, a Na annual cycle can be identified. In the past, integrated disk emission from ground-based observations and equatorial density from MESSENGER have been analysed. In this study, for a better investigation of the exospheric Na features, we have studied the local time and latitudinal distributions of the exospheric Na column density as a function of the True Anomaly Angle (TAA) of Mercury by means of the extended dataset of images, collected from 2009 to 2013, by the THEMIS solar telescope. In particular, THEMIS images, in agreement with previous results, registered a strong general increase at aphelion and a dawn ward emission predominance with respect to dusk ward and subsolar region between 90° and 150° TAA. We find a predominance of subsolar column density along the rest of the Mercury orbit. Also an unexpected relation between Northward or Southward peak emission and both TAA and local time is evidenced by our analysis requiring further investigations. Possible relationship with distance from the dust disk or IMF polarity is being considering.

How to cite: Milillo, A., Mangano, V., Massetti, S., Mura, A., Plainaki, C., Alberti, T., Ivanovski, S., De Angelis, E., and Rispoli, R.: Exospheric Na distributions along the Mercury orbit with the THEMIS telescope , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19022, https://doi.org/10.5194/egusphere-egu2020-19022, 2020.

EGU2020-9386 | Displays | PS1.4

Combining Experiments and Modelling to Understand the Role of Potential Sputtering by Solar Wind Ions

Paul Stefan Szabo, Herbert Biber, Noah Jäggi, Matthias Brenner, David Weichselbaum, Markus Wappl, Marcos V. Moro, Anna Niggas, Reinhard Stadlmayr, Daniel Primetzhofer, Andreas Nenning, Andreas Mutzke, Markus Sauer, Jürgen Fleig, Annette Foelske-Schmitz, Klaus Mezger, Helmut Lammer, André Galli, Peter Wurz, and Friedrich Aumayr

In the absence of a protecting atmosphere, the surfaces of rocky bodies in the solar system are affected by significant space weathering due to the exposure to the solar wind [1]. Fundamental knowledge of space weathering effects, such as optical changes of surfaces as well as the formation of an exosphere is essential for gaining insights into the history of planetary bodies in the solar system [2]. Primarily the exospheres of Mercury and Moon are presently of great interest and the interpretation of their formation processes relies on the understanding of all space weathering effects on mineral surfaces.

Sputtering of refractory elements by solar wind ions is one of the most important release processes. We investigate solar wind sputtering by measuring and modelling the sputtering of pyroxene samples as analogues for the surfaces of Mercury and Moon [3, 4]. These measurements with thin film samples on Quartz Crystal Microbalance (QCM) substrates allow recording of sputtering yields in-situ and in real time [5]. For the simulation of kinetic sputtering from the ion-induced collision cascade we use the software SDTrimSP with adapted input parameters that consistently reproduce measured kinetic sputtering yields [4, 6].

This study focuses on investigating the potential sputtering of insulating samples by multiply charged ions [7]. Changes of these sputtering yields with fluence are compared to calculations with a model based on inputs from SDTrimSP simulations. This leads to a very good agreement with steady-state sputtering yields under the assumption that only O atoms are sputtered by the potential energy of the ions. The observed decreasing sputtering yields can be explained by a partial O depletion on the surface [4]. Based on these findings expected surface composition changes and sputtering yields under realistic solar wind conditions can be calculated. Our results are in line with previous investigations (see e.g. [8, 9]), creating a consistent view on solar wind sputtering effects from experiments to established modelling efforts.

 

References:

[1]          B. Hapke, J. Geophys. Res.: Planets, 106, 10039 (2001).

[2]          P. Wurz, et al., Icarus, 191, 486 (2007).

[3]          P.S. Szabo, et al., Icarus, 314, 98 (2018).

[4]          P.S. Szabo, et al., submitted to Astrophys. J. (2020).

[5]          G. Hayderer, et al., Rev. Sci. Instrum., 70, 3696 (1999).

[6]          A. Mutzke, et al., “SDTrimSP Version 6.00“, IPP Report, (2019).

[7]          F. Aumayr, H. Winter, Philos. Trans. R. Soc. A, 362, 77 (2004).

[8]          H. Hijazi, et al., J. Geophys. Res.: Planets, 122, 1597 (2017).

[9]          S.T. Alnussirat, et al., Nucl. Instrum. Methods Phys. Res. B, 420, 33 (2018).

How to cite: Szabo, P. S., Biber, H., Jäggi, N., Brenner, M., Weichselbaum, D., Wappl, M., Moro, M. V., Niggas, A., Stadlmayr, R., Primetzhofer, D., Nenning, A., Mutzke, A., Sauer, M., Fleig, J., Foelske-Schmitz, A., Mezger, K., Lammer, H., Galli, A., Wurz, P., and Aumayr, F.: Combining Experiments and Modelling to Understand the Role of Potential Sputtering by Solar Wind Ions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9386, https://doi.org/10.5194/egusphere-egu2020-9386, 2020.

Low frequency quasiperiodic (QP) magnetic field fluctuations are commonly observed in terrestrial and planetary magnetosphere.  At Earth,  these magnetohydrodynamic (MHD) waves are often observed in ultralow frequency (ULF) band (~1 mHz to 1 Hz), which could be generated by solar wind buffeting, Kelvin-Helmholtz instability and/or wave-particle interactions inside the Earth's magnetosphere. At giant planets (Saturn or Jupiter), their enormous magnetospheres often produce QP fluctuations with frequencies lower than the terrestrial ULF waves. In this study, we use Cassini spacecraft observations to analysis waves at period of 10 min to 60 min in Saturnian magnetosphere. We compare wave activities during different solar activities.

How to cite: Pan, D. and Yao, Z.: Wave activities during different phase of solar cycle : Cassini observations on Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3994, https://doi.org/10.5194/egusphere-egu2020-3994, 2020.

EGU2020-2537 | Displays | PS1.4

A wedgelet current system on Saturn

Ruilong Guo, Zhonghua Yao, Benjamin Palmaerts, William Dunn, Nick Sergis, Denis Grodent, Shengyi Ye, Zuyin Pu, Japheth Yates, Sarah Badman, and Yong Wei

Magnetic energy and mass release processes are key issues to understand the magnetospheric dynamics and aurorae processes on planets. Recent studies reveal that rotationally driven processes at dayside on giant planets are much more important than we ever expected. The discovery on the dayside magnetodisc reconnection demonstrates that the rotation effect can overcome the solar wind compression to sufficiently stretch magnetic field lines at dayside (Guo et al., 2018, doi: 10.1038/s41550-018-0461-9). A long-standing small-scale reconnection process was also shown at all local times (Guo et al., 2019, doi: 10.3847/2041-8213/ab4429). Using Cassini in situ multiple instruments data, we here proposed a wedgelet current system governing the entire magnetosphere of Saturn, which can explain the observational phenomena of quasi-periodical electron energization recurrence and beads-like structure in the main aurora region. Localized active regions with finite azimuthal lengths in the magnetosphere were discretely and azimuthally distributed along the magnetodisc and rotated with the magnetosphere. The electron energizations recurred at the spacecraft are related to each active region that passed by. These studies reveal that the dynamics in magnetodisc are global effects on giant planets, which are not always restrained at nightside.

How to cite: Guo, R., Yao, Z., Palmaerts, B., Dunn, W., Sergis, N., Grodent, D., Ye, S., Pu, Z., Yates, J., Badman, S., and Wei, Y.: A wedgelet current system on Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2537, https://doi.org/10.5194/egusphere-egu2020-2537, 2020.

EGU2020-5405 | Displays | PS1.4

Kinetic simulations of the Jovian ion circulation around Ganymede and space weather implications

Christina Plainaki, Stefano Massetti, Xianzhe Jia, Alessandro Mura, Milillo Anna, Davide Grassi, Giuseppe Sindoni, and Emiliano D'Aversa

The exosphere of Jupiter’s moon Ganymede is the interface region linking the moon’s icy surface to Jupiter’s magnetospheric environment. Space weather phenomena driven by the variability of the radiation environment within the Jupiter system can have a direct impact on the sputtering-induced exosphere of Ganymede.

In this work we simulate the Jovian ion precipitation to Ganymede’s surface for different moon orbital phases around Jupiter. In particular, we consider three different configurations between Ganymede’s magnetic field and Jupiter plasma sheet, similar to those encountered during the Galileo G2, G8, and G28 flyby (i.e., the moon above, inside, below the Jupiter plasma sheet). We discuss the differences between the various ion precipitation patterns and the implications in the density distribution of the sputtered-water exosphere of this moon. We also comment the possible relation of these ion precipitation patterns with the surface brightness asymmetries both between Ganymede’s polar cap and equatorial regions and between the leading and trailing hemispheres. The results of this preliminary analysis are relevant to the JUICE mission and in particular to the preparation of the future observation strategies for the environment of Ganymede.

How to cite: Plainaki, C., Massetti, S., Jia, X., Mura, A., Anna, M., Grassi, D., Sindoni, G., and D'Aversa, E.: Kinetic simulations of the Jovian ion circulation around Ganymede and space weather implications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5405, https://doi.org/10.5194/egusphere-egu2020-5405, 2020.

PS2.1 – Small Bodies Open (Asteroids, Comets, Meteoroids, and Dust)

EGU2020-3685 | Displays | PS2.1

The partitioning of the inner and outer solar system by a structured protoplanetary disk

Ramon Brasser and Stephen Mojzsis

Mass-independent isotopic anomalies in planets and meteorites define two cosmochemically distinct regions: the carbonaceous and non-carbonaceous meteorites, implying that the non-carbonaceous (terrestrial) and carbonaceous (jovian) reservoirs were kept separate during and after planet formation. The iron meteorites show a similar dichotomy.

The formation of Jupiter is widely invoked to explain this compositional dichotomy by acting as an effective barrier between the two reservoirs. Jupiter’s solid kernel possibly grew to ~20 Mearth in ~1 Myr from the accretion of sub meter-sized objects (termed “pebbles”), followed by slower accretion via planetesimals. Subsequent gas envelope contraction is thought to have led to Jupiter’s formation as a gas giant.

We show using dynamical simulations that the growth of Jupiter from pebble accretion is not fast enough to be responsible for the inferred separation of the terrestrial and jovian reservoirs. We propose instead that the dichotomy was caused by a pressure maximum in the disk near Jupiter’s location, which created a ringed structure such as those detected by the Atacama Large Millimeter/submillimeter Array(ALMA). One or multiple such long-lived pressure maxima almost completely prevented pebbles from the jovian region reaching the terrestrial zone, maintaining a compositional partition between the two regions. We thus suggest that our young solar system’s protoplanetary disk developed at least one and likely multiple rings, which potentially triggered the formation of the giant planets [1].


[1] Brasser, R. and Mojzsis, S.J. (2020) Nature Astronomy doi: 10.1038/s41550-019-0978-6

How to cite: Brasser, R. and Mojzsis, S.: The partitioning of the inner and outer solar system by a structured protoplanetary disk, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3685, https://doi.org/10.5194/egusphere-egu2020-3685, 2020.

EGU2020-9973 | Displays | PS2.1

Statistics of Saturn Ring occultations

Larry W. Esposito, Miodrag Sremcevic, Joshua E Colwell, and Stephanie Eckert

We give calculations for the excess variance, excess skewness and excess kurtosis with formulas that combine the effects of cylindrical shadows, along with gaps, ghosts and clumps (all calculated for the granola bar model for rectangular clumps and gaps). Wherever the rings have significant gaps or clumps, those will dominate the statistics over the individual ring particles contribution. We have refined an overlap correction for multiple shadows, which is important for larger optical depth. This correction results from summing a geometric series, and is similar to the empirical formula, eq. (22) in Colwell et al (2018). The comparison to Monte Carlo calculations is improved for large particle size by including the edge effects when large particles cross the edges of the viewing area A in Cassini UVIS occultations. As a check, we can explain the upward curvature of the dependence of normalized excess variance for Saturn’s background C ring by the observation of Jerousek etal (2018) that the increased optical depth is directly correlated with effective particle size. Assuming a linear dependence Reff = 12 * (tau – 0.08) + 1.8m, we match both the curvature of excess variance E and the skewness Gamma in the region between 78,000 and 84,600km from Saturn. This explanation requires no gaps or ghosts (Baillie etal 2013) in this region of Saturn’s C ring.

How to cite: Esposito, L. W., Sremcevic, M., Colwell, J. E., and Eckert, S.: Statistics of Saturn Ring occultations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9973, https://doi.org/10.5194/egusphere-egu2020-9973, 2020.

EGU2020-6899 | Displays | PS2.1

Carbon-rich composition of the icy moons of Jupiter and Saturn, and asteroid 1-Ceres

Bruno Reynard, Adrien Neri, François Guyot, and Christophe Sotin

The inner structure of icy moons comprises ices, liquid water, a silicate rocky core and sometimes an inner metallic core depending on thermal evolution and differentiation. Mineralogy and density models for the silicate part of the icy satellites cores were assessed assuming a carbonaceous chondritic (CI) bulk composition and using a free-energy minimization code and experiments [1]. Densities of other components, solid and liquid sulfides, carbonaceous matter, were evaluated from available equations of state. Model densities for silicates are larger than assessed from magnesian terrestrial minerals, by 200 to 600 kg/m3 for the hydrated silicates, and 300 to 500 kg/m3 for the dry silicates, due to the lower iron bulk concentration in terrestrial silicates as a lot of iron is segregated in the core.

We find that CI density models of icy satellite cores taking into account only the silicate and metal/sulfide fraction cannot account for the observed densities and reduced moment of inertia of Titan and Ganymede without adding a lower density component. We propose that this low-density component is carbonaceous matter derived from insoluble organic matter, in proportion of ~30-40% in volume and 15-20% in mass. This proportion is compatible with contributions from CI and comets, making these primitive bodies including their carbonaceous matter component likely precursors of icy moons, and potentially of most of the objects formed behind the snow line of the solar system. Similar conclusions are reached for 1-Ceres when applying this compositional model, with even higher carbon content of the order of 25±5wt% in line with independent estimates [2]. It suggests that the building materials are similar for asteroid 1-Ceres and the icy moons of giant planets.

 

[1]Neri et al., Earth Planet Sci Letters, 530 (2020) 115920

[2]Zolotov, Icarus, 335 (2020) 113404

How to cite: Reynard, B., Neri, A., Guyot, F., and Sotin, C.: Carbon-rich composition of the icy moons of Jupiter and Saturn, and asteroid 1-Ceres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6899, https://doi.org/10.5194/egusphere-egu2020-6899, 2020.

EGU2020-4679 | Displays | PS2.1

Thermal and porosity properties of meteorites: A compilation of published data and new measurements

Assi-Johanna Soini, Ilmo Kukkonen, Tomas Kohout, and Arto Luttinen

We report direct measurements of thermal diffusivity and conductivity at room temperature for 38 meteorite samples of 36 different meteorites including mostly chondrites, and thus almost triple the number of meteorites for which thermal conductivity is directly measured. Additionally, we measured porosity for 34 of these samples. Thermal properties were measured using optical infrared scanning method on samples of cm-sizes with a flat, sawn surface.

    A database compiled from our measurements and literature data suggests that thermal diffusivities and conductivities at room temperature vary largely among samples even of the same petrologic and chemical type and overlap among e.g. different ordinary chondrite classes. Measured conductivities of ordinary chondrites vary from 0.4 to 5.1 W/m/K. On average, enstatite chondrites show much higher values (2.33 – 5.51 W/m/K) and carbonaceous chondrites lower values (0.5 – 2.55 W/m/K).

    Mineral composition (silicates vs. iron-nickel) and porosity control conductivity. Porosity shows (linear) negative correlation with conductivity. Variable conductivity is attributed to heterogeneity in mineral composition and porosity by intragranular and intergranular voids and cracks, which are important in the scale of typical meteorite samples. The effect of porosity may be even more significant for thermal properties than that of the metal content in chondrites.

 

Reference

Soini A.-J., Kukkonen I. T., Kohout T., and Luttinen A. (accepted for publication). Thermal and porosity properties of meteorites: A compilation of published data and new measurements. Meteoritics & Planetary Science.

How to cite: Soini, A.-J., Kukkonen, I., Kohout, T., and Luttinen, A.: Thermal and porosity properties of meteorites: A compilation of published data and new measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4679, https://doi.org/10.5194/egusphere-egu2020-4679, 2020.

EGU2020-15089 | Displays | PS2.1 | Highlight

The Latest (Dusty) Pieces in the Rosetta Story

Stavro Lambrov Ivanovski

The ESA’s Rosetta spacecraft had the unique opportunity to follow comet 67P/Churyumov-Gerasimenko (hereafter 67P) for about 2.5 years – from January 2014 to September 2016 – observing how the comet evolved while approaching the Sun, passing through perihelion and then moving back into the outer solar system. Remote sensing and in-situ instruments onboard Rosetta acquired data to study the comet’s dust environment during the entire duration of the mission, while telescopes followed the large-scale coma and tails from Earth. Here we report the latest advances of the ongoing multi-instrument approach that the Rosetta dust working group has been following in the recent years. Individual instrument data analyses have been carried on providing a first characterization of 67P dust environment. Timely, multi-instruments data analyses are now progressing a step forward in understanding how comet works and are providing critical results for a more comprehensive and unified knowledge of cometary dust environments. We will illustrate the progress we have made and the results we have reached following this constructive and collaborative approach.

We also discuss the latest achievements on the cometary dust modelling using the multi-instrument Rosetta data. In particular, what additional information these calibrated dust models provide and what we are still missing in cometary dust characterization.

How to cite: Ivanovski, S. L.: The Latest (Dusty) Pieces in the Rosetta Story, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15089, https://doi.org/10.5194/egusphere-egu2020-15089, 2020.

EGU2020-8393 | Displays | PS2.1

The spatial distribution of dust in the inner comae of comets: Evidence for and modelling of nightside emission

Nicolas Thomas, Selina-Barbara Gerig, Olga Pinzon, Raphael Marschall, Jong-Shinn Wu, and Clemence Herny

Spacecraft imaging of the inner comae of 1P/Halley (Giotto/HMC) and 19P/Borrelly (DS1/MICAS) indicated unexpectedly low ratios for the dust brightness above the dayside hemisphere to that above the nightside. Neither ratio was consistent with dust emission being directly proportional to sublimation loss of H2O using purely insolation-driven models. The near-terminator observations of 67P/Churyumov-Gerasimenko from Rosetta allow very precise separation of the dayside and nightside hemispheres and confirm low dayside to nightside dust brightness ratios. In the case of 67P values of ~3.3:1 were observed and an interesting trend towards increased ratios with decreasing heliocentric distance. Detailed modelling using insolation-driven models do not fit the data by factors of several. Dust from the dayside may contribute to the brightness on the nightside if particles are not escaping and therefore gravitationally bound. However, the radial distribution of brightness on the nightside is inconsistent with this interpretation as can be demonstrated with a simple model. The source is also not in the form of single nightside (e.g. “sunset”) jets. Furthermore, shadowing of emitted dust by the nucleus itself indicates that much of the observed brightness on the nightside is very close to the nucleus and distributed roughly uniformly around in the nightside hemisphere (Gerig et al., submitted).

Gas emission from the nightside has been a consistent element of source distributions (e.g. Bieler et al., 2015) required to model ROSINA/COPS data. However, the composition is frequently not specified. We have been investigating self-consistent, physically generated, numerical models of combined H2O and CO2 emission (see also Herny et al., submitted). Dust emission has been incorporated into the model chain allowing modelling of the observation of the gas composition, the gas density, and the dust brightness distribution in the vicinity of the nucleus for specific times. The results of investigation will be presented.

How to cite: Thomas, N., Gerig, S.-B., Pinzon, O., Marschall, R., Wu, J.-S., and Herny, C.: The spatial distribution of dust in the inner comae of comets: Evidence for and modelling of nightside emission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8393, https://doi.org/10.5194/egusphere-egu2020-8393, 2020.

EGU2020-2617 | Displays | PS2.1

The ROSINA Perspective on the CN/HCN Ratio at Comet 67P/Churyumov-Gerasimenko

Nora Hänni, Kathrin Altwegg, and Martin Rubin

The origin of cyano (CN) radicals in comets presents a long-standing riddle to the science community. Remote observations, e.g. reviewed by Fray et al. [1], show that for some comets the scale lengths, production rates, and spatial distributions of hydrogen cyanide (HCN) and CN using a Haser-based model are not consistent. Consequently, a process additional to photolysis of HCN seems to be required to explain the observed CN densities. Possible scenarios include (1) degradation of CN-producing refractories (e.g. HCN-polymers, tholins, or ammonium salts [2-3]) and (2) photolysis of other gaseous CN-bearing parent species (e.g. HC3N or C2N2).

The CN/HCN ratio observed in the inner coma of comet 67P/Churyumov-Gerasimenko with the Double Focusing Mass Spectrometer DFMS, part of the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) sensor package [4] onboard ESA’s Rosetta spacecraft, is not compatible with fragmentation of HCN under electron impact ionization. Even though from fragmentation a constant CN/HCN ratio of about 0.15 [5-7] is expected, the observed values range from almost 0.4 at the beginning of the mission (August 2014) to about 0.15 shortly after perihelion passage (August 2015). Towards the end of the mission (September 2016), CN/HCN ratios increase again. This presentation will discuss the data from ROSINA/DFMS in detail and present laboratory-based indications that direct production of CN from sublimating ammonium cyanide (NH4CN) occurs, leading to increased CN/HCN ratios. Could this be the process generating a surplus of CN radicals with respect to photolysis of HCN in certain comets?

 

 

[1] N. Fray et al. The origin oft he CN radical in comets: A review from observations and models Planetary and Space Science 53 (2005) 1243-1262.

[2] N. Hänni et al. Ammonium Salts as a Source of Small Molecules Observed with High-Resolution Electron-Impact Ionization Mass Spectrometry. J. Phys. Chem. A 123 (2019) 27, 5805-5814.

[3] K. Altwegg et al. Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae. Nat. Astron. (2019) in print.

[4] H. Balsiger et al. Rosina - Rosetta Orbiter Spectrometer for Ion and Neutral Analysis. Space Science Reviews 128 (2007) 745-801.

[5] S.E. Steins in NIST Chemistry WebBook, NIST Standard Reference Database Number 69, Eds. P.J. Linstrom and W.G. Mallard, National Institute of Standards and Technology, (2018).

[6] P. Kusch et al. The Dissociation of HCN, C2H2, C2N2, and C2H4 by Electron Impact. Phys. Rev. 52 (1937) 843-854.

[7] D. P. Stevenson. Ionization and Dissociation by Electron Impact: Cyanogen, Hydrogen Cyanide, and Cyanogen Chloride and the Dissociation Energy of Cyanogen. J. Chem. Phys. 18 (1950) 1347-1351.

How to cite: Hänni, N., Altwegg, K., and Rubin, M.: The ROSINA Perspective on the CN/HCN Ratio at Comet 67P/Churyumov-Gerasimenko, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2617, https://doi.org/10.5194/egusphere-egu2020-2617, 2020.

EGU2020-20089 | Displays | PS2.1

What does really happen in a dust impact?

Sascha Kempf, William Goode, Ralf Srama, and Frank Postberg

Our current understanding of the solar system’s micrometeoroid environment relies to a substantial extent on in-situ data acquired by impact ionization dust detectors such as Ulysses’ and Galileo’s DDS or Cassini’s CDA. Such detectors derive the mass and speed of striking dust particles from the properties and evolution of the plasma created upon impact. In particular, empirical evidence suggests that the impact speed is a function of the duration of impact charge delivery onto the target - the so-called plasma rise time. Often, this dependence has been attributed to secondary impacts of target and projectile ejecta. 

During recent years the capabilities of laboratory impact detectors have been significantly improved. In particular we now have ample evidence that secondary ejecta impacts are not responsible for the rise-time dependence. In fact the plasma rise-time is rather related to the ionization of target contaminants in the vicinity of the impact site. 

In this talk we present new experimental data obtained with state-of-the-art impact ionization mass spectrometers, which shed new light on what is really going on during a hypervelocity dust impact. We further discuss the implications for the interpretation of dust data obtained with previous generations of impact ionization detectors.

How to cite: Kempf, S., Goode, W., Srama, R., and Postberg, F.: What does really happen in a dust impact?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20089, https://doi.org/10.5194/egusphere-egu2020-20089, 2020.

EGU2020-1805 | Displays | PS2.1

Dust detection by antenna instruments

Zoltan Sternovsky, Ming-Hsueh Shen, Michael DeLuca, Åshild Fredriksen, Mihály Horányi, Sean Hsu, Samuel Kočiščák, David Malaspina, Libor Nouzák, and Shengyi Ye

Antenna instruments on space missions have been used to detect dust particles and characterize dust populations. The antennas register the transient electric signal generated by the expansion of the impact plasma from the dust impact on the spacecraft body or the antenna. Given the large effective sensitive area, antenna instruments offer an advantage over dedicated dust detectors for dust populations with low fluxes. The dust accelerator facility operated at the University of Colorado has been employed to investigate the physical mechanisms of antenna signal generation. The dominant mechanism is related to the charging of the spacecraft (or antenna) by collecting some fraction of electrons and ions from the impact plasma. We have carried out a number of experimental campaigns in order to characterize the dust impact charge yields from relevant materials, the effective temperatures of dust impact plasmas, and variations of the antenna signals with spacecraft potential, or magnetic field. Here we report on a physical model that provides a good qualitative and quantitative description of the antenna waveforms recorded in laboratory conditions. The model is based on the separation of the electrons from the ions in the impact plasma and their different timescales of expansion. The escaping and collected fractions of charges are driven by the spacecraft potential. Fitting the model to the laboratory data revealed that the electrons in the impact plasma have an isotropic distribution, while ions are dominantly moving away from the dust impact location. Identifying the fine details in the antenna signals requires a relatively high sampling rate and thus not commonly resolved for past instruments. The high-rate mode of the FIELDS instrument on the Parker Solar Probe, however, can be used to verify the proposed model.

How to cite: Sternovsky, Z., Shen, M.-H., DeLuca, M., Fredriksen, Å., Horányi, M., Hsu, S., Kočiščák, S., Malaspina, D., Nouzák, L., and Ye, S.: Dust detection by antenna instruments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1805, https://doi.org/10.5194/egusphere-egu2020-1805, 2020.

EGU2020-4160 | Displays | PS2.1

The Effects of Hyperbolic Meteoroids from Parker Solar Probe to the Moon

Jamey Szalay, Petr Pokorny, Mihaly Horanyi, Stuart Bale, Eric Christian, Keith Goetz, Katherine Goodrich, Matthew Hill, Marc Kuchner, Rhiannon Larsen, David Malaspina, David McComas, Donald Mitchell, Brent Page, and Nathan Schwadron

The zodiacal cloud in the inner solar system undergoes continual evolution, as its dust grains are collisionally ground and sublimated into smaller and smaller sizes. Sufficiently small (~<500 nm) grains known as beta-meteoroids are ejected from the inner solar system on hyperbolic orbits under the influence of solar radiation pressure. These small grains can reach significantly larger speeds than those in the nominal zodiacal cloud and impact the surfaces of airless bodies. Since the discovery of the Moon's asymmetric ejecta cloud, the origin of its sunward-canted density enhancement has not been well understood. We propose impact ejecta from beta-meteoroids that hit the Moon's sunward side could explain this unresolved asymmetry. The proposed hypothesis rests on the fact that beta-meteoroids are one of the few truly asymmetric meteoroid sources in the solar system, as unbound grains always travel away from the Sun and lack a symmetric inbound counterpart. This finding suggests beta-meteoroids may also contribute to the evolution of other airless surfaces in the inner solar system as well as within other exo-zodiacal disks. We will also highlight recent observations from the Parker Solar Probe (PSP) spacecraft, which suggest it is being bombarded by the very same beta-meteoroids. We discuss how observations by PSP, which lacks a dedicated dust detector, can be used to inform the structure and variability of beta-meteoroids in the inner solar system closer to the Sun than ever before.

How to cite: Szalay, J., Pokorny, P., Horanyi, M., Bale, S., Christian, E., Goetz, K., Goodrich, K., Hill, M., Kuchner, M., Larsen, R., Malaspina, D., McComas, D., Mitchell, D., Page, B., and Schwadron, N.: The Effects of Hyperbolic Meteoroids from Parker Solar Probe to the Moon, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4160, https://doi.org/10.5194/egusphere-egu2020-4160, 2020.

EGU2020-20056 | Displays | PS2.1

Parker Solar Probe Observations of a Dust Trail in the Orbit of 3200 Phaethon

Karl Battams, Guillermo Stenborg, Russell Howard, Brendan Gallagher, Matthew Knight, and Michael Kelley

We present details on the first white-light detection of a dust trail following the orbit of asteroid 3200 Phaethon, seen in images recorded by the Wide-field Imager for Parker Solar Probe (WISPR) instrument on the NASA Parker Solar Probe (PSP) mission. In this talk we will present a brief introduction to the PSP mission and the WISPR instrument. We will then show observations returned by WISPR in multiple perihelion 'encounters' that clearly show a diffuse dust trail perfectly aligned with the perihelion portion of the orbit of 3200 Phaethon, recorded while the asteroid itself was near aphelion. We will discuss the physical parameters that we have derived for the dust trail, including its visual magnitude, surface brightness and mass. We also speculate on the relationship of this trail to the Geminid meteor shower, of which Phaethon is assumed to be the parent, and demonstrate why the trail has not been detected visually until now, despite a number of dedicated observing campaigns. We also hope to present initial analyses of the most recent set of WISPR observations (January 2020), where we anticipate the trail should again be visible in the WISPR observations.

How to cite: Battams, K., Stenborg, G., Howard, R., Gallagher, B., Knight, M., and Kelley, M.: Parker Solar Probe Observations of a Dust Trail in the Orbit of 3200 Phaethon, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20056, https://doi.org/10.5194/egusphere-egu2020-20056, 2020.

EGU2020-20135 | Displays | PS2.1 | Highlight

White-light observations of features in the Zodiacal dust cloud from within the solar corona

Russell Howard, Guillermo Stenborg, Phil Hess, Brendan Gallagher, and Karl Battams

The Parker Solar Probe (PSP) mission has completed four solar encounters, observing the solar corona from distances significantly closer to the Sun than from previous missions (to 36 solar radii during the first three perihelia and to 28 solar radii during the fourth). During these encounters, the Wide-field Imager for Solar Probe (WISPR) onboard PSP has been observing the F-corona/Zodiacal light - probing the dust environment in the solar corona as PSP moves through the corona. This allowed WISPR to find 1) a gradual decrease of the expected brightness of the F-corona for distances shorter than about 0.1 AU, 2) dust trails of short-period asteroid/cometary objects (e.g., 3200 Pheathon and 2P/Encke) and 3) a changing rate of dust impacts on the S/C throughout the encounter period. In this presentation, we will present these findings, discuss their nature, and elaborate on the novelty of these results. The authors acknowledge support from the NASA Parker Solar Probe program.

How to cite: Howard, R., Stenborg, G., Hess, P., Gallagher, B., and Battams, K.: White-light observations of features in the Zodiacal dust cloud from within the solar corona, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20135, https://doi.org/10.5194/egusphere-egu2020-20135, 2020.

EGU2020-12800 | Displays | PS2.1

Didymos Gravity Science through Ground-based and Satellite-to-Satellite Doppler Tracking

Paolo Tortora, Igor Gai, Marco Lombardo, Marco Zannoni, Ian Carnelli, Michael Kueppers, Paolo Martino, and Patrick Michel

Hera is ESA’s contribution to an international effort supported by ESA and NASA named Asteroid Impact and Deflection Assessment (AIDA). NASA’s DART mission will first perform a kinetic impact on Didymos secondary, nicknamed Didymoon, then Hera will follow-up with a detailed post-impact survey, to fully characterize this planetary defense technique. Two CubeSats will be deployed by the Hera spacecraft once the Early Characterization Phase has completed.

The Hera spacecraft communicates with the ground station on the Earth by means of a standard two-way X-band system. The microwave signal is sent to the S/C from a ground antenna and coherently retransmitted back to Earth, where Doppler (the key observable for gravity science) and range measurements are obtained. In addition, Hera will track the two CubeSats by means of a space-to-space inter-satellite link (ISL). This represents a very nice add-on to the gravity investigation carried out by means of Hera tracking observables as the Doppler effect that affects the inter-satellite link contains the information on the dynamics of the system, i.e. masses and gravity field of Didymos primary and secondary.

We describe here the mission scenario for the gravity science experiments to be jointly carried out by the three mission elements, i.e. Hera, CubeSat#1 (named Juventas) and CubeSat#2, via Ground-based and Satellite-to-Satellite Doppler Tracking. Also, our results and achievable accuracy for the estimation of the mass and gravity field of Didymos primary and secondary are presented.

How to cite: Tortora, P., Gai, I., Lombardo, M., Zannoni, M., Carnelli, I., Kueppers, M., Martino, P., and Michel, P.: Didymos Gravity Science through Ground-based and Satellite-to-Satellite Doppler Tracking, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12800, https://doi.org/10.5194/egusphere-egu2020-12800, 2020.

EGU2020-22173 | Displays | PS2.1

A Summary and Update on NASA’s Planetary Defense Program.

Doris Daou and Lindley Johnson

NASA and its partners maintain a watch for near-Earth objects (NEOs), asteroids and comets that pass within Earth’s vicinity, as part of an ongoing effort to discover, catalog, and characterize these bodies and to determine if any pose an impact threat. NASA’s Planetary Defense Coordination Office (PDCO) is responsible for:

  • Ensuring the early detection of potentially hazardous objects (PHOs) – asteroids and comets whose orbits are predicted to bring them within 0.05 astronomical units of Earth's orbit; and of a size large enough to reach Earth’s surface – that is, greater than perhaps 30 to 50 meters;
  • Tracking and characterizing PHOs and issuing warnings about potential impacts;
  • Providing timely and accurate communications about PHOs; and
  • Performing as a lead coordination node in U.S. Government planning for response to an actual impact threat.

 

NASA’s current congressionally-mandated objective is to detect, track, and catalogue at least 90 percent of NEOs equal to or greater than 140 meters in size by 2020, and characterize the physical properties of a subset representative of the entire population. This mandate will likely not be met given current resources dedicated to the task; however significant progress is being made.

In this paper, we will report on the status of our program and the missions working to support our planetary defense coordination office. In addition, we will provide the latest detections and characterizations results. Our office continues to work diligently with our international partners to achieve our goals and continue to safeguard Earth with the latest technologies available.

How to cite: Daou, D. and Johnson, L.: A Summary and Update on NASA’s Planetary Defense Program., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22173, https://doi.org/10.5194/egusphere-egu2020-22173, 2020.

EGU2020-20885 | Displays | PS2.1

Thermal modeling of the binary asteroid Didymos

Özgür Karatekin, Gregoire Henry, Elodie Gloesener, and Bart van Hove

The target of the ESA’s HERA mission is asteroid 65803 Didymos (1996 GT), an Apollo-type near-Earth object (NEO). Didymos is a binary asteroid; the primary body has a diameter of around 775 m and a rotation period of 2.26 hours, whereas the secondary body (informally called Didymoon) has a diameter of around 165 m and rotates around the primary at a distance of around 1.2 km in around 12 hours.

Thermophysical properties of the uppermost surface govern the exchange of radiative energy between the asteroid and its environment, hence determine surface and subsurface temperatures.  These thermophysical properties are characterized by grain size, porosity, or packing of the surface materials.  Diurnal change in surface temperature show large variations in fine soils like sand and highly porous rock with low thermal inertia, and much smaller variations in in dense rock with high thermal inertia. Here we present a thermophysical model of Didymoon based on known, assumed and derived range of physical properties.  A parameter study has been carried out for surface temperatures assuming possible thermal inertia ranges.  

Results from this study are used to investigate performance for Thermal Infrared instrument TIRA onboard HERA spacecraft. Hera is the European contribution to an international double-spacecraft collaboration. Due to launch in 2024, Hera would travel to the binary asteroid system. TIRA onboard HERA will be operating in the 8-14 µm wavelength range. It will be used for scientific analysis and to demonstrate the feasibility of using a TIR camera for GNC (Guidance, navigation and control). The main scientific output for TIRA is to determine the thermal inertia and thus the properties of the surface material.

How to cite: Karatekin, Ö., Henry, G., Gloesener, E., and van Hove, B.: Thermal modeling of the binary asteroid Didymos, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20885, https://doi.org/10.5194/egusphere-egu2020-20885, 2020.

EGU2020-19957 | Displays | PS2.1

Low Frequency Radar (LFR) on the JUVENTAS CubeSat for HERA / ESA mission

Alain Herique, Dirk Plettemeier, Wlodek Kofman, Yves Rogez, and Hannah Goldberg

The Low Frequency Radar (LFR) on the JUVENTAS CubeSat for HERA / ESA mission to Didymos Binary Asteroid is a unique opportunity to perform direct measurements of its internal structure and regolith. LFR has been developed to fathom asteroid from a small platform. This instrument is inherited from CONSERT/Rosetta and has been redesigned in the frame of the AIDA and HERA ESA mission.

Onboard JUVENTAS, LFR is operating in monostatic mode to probe down to the first hundreds of meters into the subsurface and to achieve a full tomography of the Didymos' moonlet. Direct observations of the internal structure of asteroids can solve still open basic questions like: Is the body a monolithic piece of rock or a rubble-pile? How high is the porosity? What is the typical size of the constituent blocks? Are these blocks homogeneous or heterogeneous? How is the regolith covering its surface constituted?

The low frequency aboard the Juventas CubeSat will contribute to the solution of these open and for planetary defense crucial questions.
- The first LRF objective is the characterization of the moonlet interior, to identify internal structure and to analyze the size distribution and heterogeneity of constitutive blocks from sub metric to global
- The second objective is the estimation of average permittivity and mapping of its spatial variation especially in the crater area.
- The same characterization applied to the main of the binary system is among secondary objectives.
- Supporting shape modeling and determination of the dynamical state by radar ranging is a further secondary objective.

This paper will present the instrument concept and measurement strategy, its performances and the expected science return.

How to cite: Herique, A., Plettemeier, D., Kofman, W., Rogez, Y., and Goldberg, H.: Low Frequency Radar (LFR) on the JUVENTAS CubeSat for HERA / ESA mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19957, https://doi.org/10.5194/egusphere-egu2020-19957, 2020.

EGU2020-18758 | Displays | PS2.1

Deciphering compositional processes in inner airless bodies of our Solar System

Francesca Zambon, Federico Tosi, Sébastien Besse, Rosario Brunetto, Cristian Carli, Jean-Philippe Combe, Olivier Forni, Rachel Klima, Katrin Krohn, David Rothery, Katrin Stephan, Kerri Donaldson-Hanna, Oceane Barraud, and Jacopo Nava

Over the last decades, the exploration of our Solar System carried out by automatic probes allowed a huge leap in our understanding of the planets, their main satellites and minor bodies such as asteroids and comets. However, despite the large number of diverse datasets available nowadays, comparative studies of different bodies are still poorly addressed in several cases, in particular for airless bodies.

The primary goal of our two-year project, selected in the framework of the “ISSI/ISSI-BJ Joint Call for Proposals 2019 for International Teams in Space and Earth Sciences”, is to quantify similarities and differences in the surface mineralogy of Vesta, Mercury and the Moon, substantially enhancing the scientific return of individual instrumental datasets and/or individual space missions. Here, we give an overview of our project, we clarify what is the status after the first team meeting held in March 2020.

Our project focuses on two specific questions:

Our overall approach is to apply various techniques of analysis on hyper- and multispectral data sets that are publicly available, such as those on acquired by the Dawn mission at Vesta, MESSENGER datasets obtained at Mercury and Chandrayaan-1 data for the Moon.

This work is supported by the International Space Science Institute (ISSI) and by INAF-IAPS.

How to cite: Zambon, F., Tosi, F., Besse, S., Brunetto, R., Carli, C., Combe, J.-P., Forni, O., Klima, R., Krohn, K., Rothery, D., Stephan, K., Donaldson-Hanna, K., Barraud, O., and Nava, J.: Deciphering compositional processes in inner airless bodies of our Solar System, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18758, https://doi.org/10.5194/egusphere-egu2020-18758, 2020.

EGU2020-8598 | Displays | PS2.1

The Santa Rosa Meteorite from Colombia: An example of critical raw materials in a meteorite

Franziska D.H. Wilke, Barbara Bsdok, Uwe Altenberger, and Ana E. Concha

Meteorites, especially the undifferentiated ones like primitive chondrites, provide information about the origin and initial conditions of the solar system since they contain presolar and solar nebula materials (Scott, 2007). Differentiated meteorites like iron meteorites play a distinct role in constraining the early phases of planetary accretion (Yang et al. 2007). They also provide the possibility to receive information about core properties and planetary bodies. In addition to the gain in such fundamental scientific knowledge both types are of interest for the exploration of critical and precious elements (CRMs).

In the future, the tremendous increase of the consumption of these elements from terrestrial deposits and the subsequent shortage could lead to an exploitation of extra-terrestrial deposits. Therefore, “space-mining” of near Earth objects could be used as alternative source of raw materials (Ross, 2001).

While improving the characterization and classification of the Santa Rosa de Viterbo Iron Meteorite, we found notable concentrations of Au and Ge alongside major elements such as Fe, Ni and Co in the bulk composition of that meteorite. Major and rock-forming minerals such as kamacite and taenite incorporate hundreds of ppm of Ge whereas schreibersite, itself a minor component in that particular meteorite, is a source for Au. In kamacite and taenite also Ir and Ga were found in minor amounts.

 

Scott, E. R. (2007). Chondrites and the protoplanetary disk. Annu. Rev. Earth Planet. Sci., 35, 577-620.

Ross, S. D. (2001). Near-earth asteroid mining. Space, 1-24.

Yang, J., Goldstein, J. I., & Scott, E. R. (2007). Iron meteorite evidence for early formation and catastrophic disruption of protoplanets. Nature, 446(7138), 888.

 

How to cite: Wilke, F. D. H., Bsdok, B., Altenberger, U., and Concha, A. E.: The Santa Rosa Meteorite from Colombia: An example of critical raw materials in a meteorite, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8598, https://doi.org/10.5194/egusphere-egu2020-8598, 2020.

EGU2020-5144 | Displays | PS2.1

Modification of cometesimal interiors by early thermal evolution and collisions

Martin Jutzi and Gregor Golabek

In the early solar system radiogenic heating by 26Al and collisions are the two prominent ways expected to modify the internal composition of cometesimals, building blocks of comets, by removing highly volatile compounds like CO, COand NH3. However, observations indicate that even large comets like Hale-Bopp (R ≈ 70 km) can be rich in these highly volatile compounds [1].

Here we constrain under which conditions cometesimals experiencing both internal heating and collisions can retain pristine interiors. For this purpose, we employ both the state-of-the-art finite-difference marker-in-cell code I2ELVIS [2] to model the thermal evolution in 2D infinite cylinder geometry and a 3D SPH code [3] to study the interior heating caused by collisions among cometesimals. For simplicity we assume circular porous cometesimals with a low density ( ≈ 470 kg/m3) based on measurements for comet 67P/Churyumov-Gerasimenko [4].

For the parameter study of the thermal history we vary (i) cometesimal radii, (ii) formation time and the (iii) the silicate/ice ratio. For the latter we keep the mean density fixed and change the porosity of the cometesimal. For the impact models we use porous, low-strength objects and vary (i) target and (ii) projectile radii, (iii) impact velocity as well as (iv) impact angle. Potential losses of volatile compounds from their interiors are calculated based on their critical temperatures taken from literature [5]. Our combined results indicate that only small or late-formed cometesimals remain mostly pristine, while early formed objects can even reach temperatures high enough to melt the water ice.

 

REFERENCES

[1] Biver et al., Nature 380, 137-139 (1996).

[2] Gerya & Yuen, Phys. Earth Planet. Int. 163, 83-105 (2007).

[3] Jutzi, Planet. Space Sci. 107, 3–9 (2015).

[4] Sierks et al. Science 347, 1044 (2015).

[5] Davidsson et al. Astronomy & Astrophysics 592, A63 (2016).

How to cite: Jutzi, M. and Golabek, G.: Modification of cometesimal interiors by early thermal evolution and collisions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5144, https://doi.org/10.5194/egusphere-egu2020-5144, 2020.

EGU2020-5711 | Displays | PS2.1

The Rosetta Science Archive: Closing Out the Science Content

David Heather, Diego Fraga, Laurence O'Rourke, and Matt Taylor

On 30 September 2016, Rosetta completed its mission by landing on comet 67P/Churyumov-Gerasimenko. Although this marked an end to the spacecraft’s operations, intensive work has continued for several years, with the instrument teams updating their data in response to scientific reviews and delivering them to ESA’s Planetary Science Archive (PSA). ESA has also been working with the instrument teams to produce new and enhanced data, and to improve documentation, aiming to provide the best long-term archive possible for the Rosetta mission.

All teams have now completed their nominal science data deliveries from the comet phase, and samples of final data from the enhanced archiving activities went through a last science review in September 2019. The aim is to to complete any updates requested and deliver final products in the first half of 2020.

As soon as Rosetta’s operational mission ended, ESA established a number of activities with the Rosetta instrument teams to allow them to continue working on enhancing their archive content. The updates were focused on key aspects of an instrument’s calibration or the production of higher level data / information, and were therefore specific to each instrument. Most activities are now complete, but a few are still in the process of being closed in early 2020.

Almost all instrument teams have now provided a Science User Guide for their data, which have been highly appreciated by the scientists in the recent reviews. Many teams have also updated their calibrations to deliver higher level and/or derived products. For example, OSIRIS have delivered data with improved calibrations, as well as straylight corrected, I/F corrected, and three-dimensional georeferenced products. These are all already available in the archive. They now also provide their data additionally in FITS format, and have added quicklook (browse) versions of their products to allow an end-user to more easily identify the images they may be interested in. Internal straylight data and boresight corrected / full frame data are currently in preparation and will be added to the archive early this year.

Similarly, the VIRTIS team will update both their spectral and geometrical calibrations, and deliver mapping products to the final archive. The Rosetta Plasma Consortium instruments completed several cross-calibrations and a number of activities individual to each instrument, as well as producing illumination maps of the comet. The MIDAS team have produced a dust particle catalog from the comet coma. GIADA have produced dust environment maps with omni-directional products. COSIMA has delivered laboratory data to help understand their inflight measurements. An activity is also ongoing to produce data set(s) containing supporting ground-based observations of the comet.

The Rosetta ESA archiving team are also producing calibrated data for the NAVCAM instrument, and will include the latest shape models from the comet in the final Rosetta archive. Work is also underway to incorporate the radiation monitor (SREM) and spacecraft housekeeping (MUST) data into the archive.

This presentation will outline the current status of the Rosetta archive, and highlight the work being done this year to close out the archive and prepare it for legacy use.

How to cite: Heather, D., Fraga, D., O'Rourke, L., and Taylor, M.: The Rosetta Science Archive: Closing Out the Science Content, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5711, https://doi.org/10.5194/egusphere-egu2020-5711, 2020.

EGU2020-9308 | Displays | PS2.1

An Analysis of Regional H2O and CH3OH Production rates of Comet 67P from the MIRO Measurements

Hsuan-Ting Lai, Wing-Huen Ip, Wei-Ling Tseng, Ian-Lin Lai, and David Marshall

EGU2020-3347 | Displays | PS2.1

Determining the ion velocity in the inner magnetosphere of comet 67P/Churyumov–Gerasimenko using Rosetta IES measurements

Zoltan Nemeth, Karoly Szego, Aniko Timar, Lajos Foldy, Jim Burch, and Raymond Goldstein

Determining the ion bulk velocity is essential to understand the physics of the inner magnetosphere of comets. This velocity controls the strength of the ion-neutral drag force, which plays a very important role in the energy and momentum transfer processes of that region. Unfortunately there are no direct measurements of this quantity available. The energy thresholds of the ion instruments on board the Rosetta orbiter would prevent the direct detection of the bulk ion content of the plasma as long as the plasma is relatively slow and cold. The picture is further complicated by the spacecraft potential, which accelerates the thermal ions to energies higher than the measurement threshold, but effectively screens the magnitude and direction of their original velocity. That distortion effect is not arbitrary however; it is possible to recover the original ion velocity distribution from IES measurements by simulating the effects of the spacecraft potential on the ion motion. We performed these simulations for several bulk and thermal velocity as well as spacecraft potential values, and compared the results with IES measurements. From this we could determine the most probable values of the bulk and thermal speeds of the plasma ions in the inner magnetosphere of comet 67P/ Churyumov–Gerasimenko.

How to cite: Nemeth, Z., Szego, K., Timar, A., Foldy, L., Burch, J., and Goldstein, R.: Determining the ion velocity in the inner magnetosphere of comet 67P/Churyumov–Gerasimenko using Rosetta IES measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3347, https://doi.org/10.5194/egusphere-egu2020-3347, 2020.

EGU2020-13051 | Displays | PS2.1

Halogen-containing species at Comet 67P/Churyumov-Gerasimenko: Full mission results

Frederik Dhooghe, Johan De Keyser, Kathrin Altwegg, Nora Hänni, Martin Rubin, Jean-Jacques Berthelier, Gaël Cessateur, Michael Combi, Stephen Fuselier, Romain Maggiolo, and Peter Wurz

Dhooghe et al. (2017) studied halogen-bearing compounds in the coma of 67P/C-G with the Double Focusing Mass Spectrometer (DFMS) of Rosetta’s ROSINA instrument during a few time periods from first encounter up to perihelion (August 2014-August 2015). The main halogen-bearing compounds identified in the comet atmosphere were the hydrogen halides HF (hydrogen fluoride), HCl (hydrogen chloride) and HBr (hydrogen bromide). The halogen to oxygen ratios were found to vary between ~10-4 (Cl/O and F/O) to ~10-6 (Br/O), which shows these compounds have a very low abundance. In a follow-up article, De Keyser et al. (2017) observed an increase in the halogen-to-oxygen ratio as a function of distance, which suggests a distributed source for HF and HCl, probably through progressive release of these compounds from grains. Fayolle et al. 2017 and recent work by Altwegg et al. 2020 show that also CH3Cl and NH4Cl, respectively are present in the coma.

 

To further our knowledge on halogen containing species, we have applied recent improvements in DFMS data analysis techniques (De Keyser et al. 2019) to obtain a high quality time series for the complete mission duration. These data analysis techniques improve the retrieval of the abundances for overlapping mass peaks (18OH+ for F+, H218O+ for HF+, H34S+ for 35Cl+, and 36Ar+ and H234S+ for H35Cl+). The contribution of CS2++ to the signal of H37Cl+ has been determined from data for CS2+.

 

Based on the full mission data, and focusing on chlorine, we determine the 37Cl/35Cl isotopic ratio. An interesting finding is that the 35Cl+/H35Cl+ and 37Cl+/H37Cl+ ratios in the DFMS mass spectrometer do not match the NIST ones for the H35Cl and H37Cl parents. This indicates that at least one additional chlorine source must be present. The variability of halogen-containing species as a function of time is discussed, as well as the possible role of distributed sources.

 

Altwegg, K. et al. (2020): Evidence of ammonium salts in comet 67P as explanation for the nitrogen depletion in cometary comae. Nature Astronomy, in press

Dhooghe, F. et al (2017): Halogens as tracers of protosolar nebula material in comet 67P/Churyumov-Gerasimenko, MNRAS, 472, Issue 2, 1336, doi 10.1093/mnras/stx1911.

De Keyser, J. et al (2017): Evidence for distributed gas sources of hydrogen halides in the coma of comet 67P/Churyumov–Gerasimenko, MNRAS, 469, Issue Suppl_2, S695, doi 10.1093/mnras/stx2725.

De Keyser, J. et al. (2019): Position-dependent microchannel plate gain correction in Rosetta's ROSINA/DFMS mass spectrometer. IJMS, 446, 116232, doi 10.1016/j.ijms.2019.116232.

Fayolle et al. (2017): Protostellar and cometary detections of organohalogens. Nature Astronomy 1, 703, doi.org/10.1038/s41550-017-0237-7

How to cite: Dhooghe, F., De Keyser, J., Altwegg, K., Hänni, N., Rubin, M., Berthelier, J.-J., Cessateur, G., Combi, M., Fuselier, S., Maggiolo, R., and Wurz, P.: Halogen-containing species at Comet 67P/Churyumov-Gerasimenko: Full mission results, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13051, https://doi.org/10.5194/egusphere-egu2020-13051, 2020.

EGU2020-19173 | Displays | PS2.1

Accurate reconstruction of comet 67P orbit through re-analysis of Rosetta ranging data acquired during proximity operations

Riccardo Lasagni Manghi, Marco Zannoni, Paolo Tortora, Michael Küppers, Laurence O'Rourke, Patrick Martin, Stefano Mottola, Uwe Keller, Frank Budnik, Matt Taylor, Laurent Jorda, Olivier Groussin, and Nicolas Thomas

Following its arrival at comet 67P/Churyumov-Gerasimenko in August 2014, the Rosetta spacecraft successfully navigated in its proximity for two years, using a combination of Earth-based astrometric and radiometric tracking data as well as space-based optical navigation data. 

Depending on the mission phase, the orbital navigation system was tasked with the simultaneous estimation of both spacecraft and comet state, in addition to several other physical parameters including amongst others the comet rotational state, its gravitational field and the body-fixed coordinates of surface landmarks.

Estimating the heliocentric trajectory of 67P has proven to be challenging, due to the lack of reliable models to take into account the non-gravitational accelerations acting on the comet (particularly close to perihelion) and to occasional degradations of the ranging observables caused by geometrical constraints (solar conjunctions).

The accuracy of the resulting comet heliocentric trajectories, which show discontinuities in the order of tens of kilometers between consecutive short-arc solutions, was sufficient for spacecraft proximity operations, where navigators are mostly concerned by the relative comet/spacecraft position. However, a continuous and more accurate orbital solution is strictly coupled with the development of analytical models for non-gravitational accelerations and comet outgassing for which the Rosetta mission represents an ideal test case.

The work presented here represents a joint effort between academic institutions and ESA’s Flight Dynamics team to improve the accuracy of 67P’s orbit, by re-analyzing the radiometric data over long time scales for the whole duration of Rosetta proximity operations at comet 67P.

Details on the orbit determination process and filter implementation will be presented, together with a discussion on the achieved formal uncertainties and on the observables’ residuals.

How to cite: Lasagni Manghi, R., Zannoni, M., Tortora, P., Küppers, M., O'Rourke, L., Martin, P., Mottola, S., Keller, U., Budnik, F., Taylor, M., Jorda, L., Groussin, O., and Thomas, N.: Accurate reconstruction of comet 67P orbit through re-analysis of Rosetta ranging data acquired during proximity operations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19173, https://doi.org/10.5194/egusphere-egu2020-19173, 2020.

EGU2020-2476 | Displays | PS2.1

Nanoscale Dust Production at 1 Au; Identification and Tracking with 12 Spacecraft

Hairong Lai, Yingdong Jia, Martin Connors, and Christopher Russell

Interplanetary Field Enhancements are phenomena in the interplanetary magnetic field, first discovered near Venus, during an extremely long duration (12 hours) and large size (about 0.1 AU) passage across the Pioneer Venus spacecraft. Three and a half hours later and 21 x 106 km farther from the Sun, this structure, somewhat weaker and off to the side of the expected radial path of any solar initiated disturbance, was seen by first Venera 13 and then Venera 14, trailing behind V13. Since this discovery, many smaller such disturbances have been observed and attributed to collisions of small rocks in space at speeds of about 20 km/s at 1 AU and faster, closer to the Sun. All sightings with magnetometers and other space plasma instruments give very precise measurements of the radial structure (of usually the magnetic field), but the scale transverse to the solar radius is poorly defined, as is the temporal evolution of the structure from single spacecraft data.

On January 16, 2018, near Earth, 12 spacecraft equipped with plasma spectrometers and magnetometers observed the passage of a single Interplanetary Field Enhancement. The magnetic field profiles at the four 1 AU spacecraft were very similar. The profiles were obtained at different times appropriate to their locations. The 4 Cluster spacecraft were closer to the Earth and in a region in which the solar wind had slowed down because of the Earth’s bow wave (shock) in the solar wind. The disturbance in the shocked solar wind occurred at the time expected if the IFE structure had not been slowed by the plasma, but rather had proceeded with the momentum it had prior to the shock crossing. If the disturbance causing particles are small bits of rock (not protons), then they should have kept most of their momentum in crossing the bow shock. We view this as a complete test of the dust producing collisional origin of these Interplanetary Field Enhancements, and a clear demonstration of how the solar wind clears out the dust in the inner solar system produced by the continuing destructive collisional process.

How to cite: Lai, H., Jia, Y., Connors, M., and Russell, C.: Nanoscale Dust Production at 1 Au; Identification and Tracking with 12 Spacecraft, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2476, https://doi.org/10.5194/egusphere-egu2020-2476, 2020.

EGU2020-9599 | Displays | PS2.1

What can we learn from observations of small dust grains in the interstellar space?

Andrzej Czechowski and Ingrid Mann

A fraction of the dust that is contained in the local interstellar medium around the Sun can enter the heliosphere and be observed in the solar system. The exception is the small size component of the interstellar dust spectrum, which can be directly observed only beyond the heliopause. 

The charge-to-mass ratio of the interstellar dust grains of nanometer size can be high enough to make their dynamics highly sensitive to the magnetic field and plasma flow. Based on numerical simulations and analytical models, we show how the small interstellar grains entering the transition region between the undisturbed interstellar medium and the outer boundary of the heliosphere respond to plasma and magnetic field structures (in particular the heliospheric bow shock and the heliopause) expected in this region. We also point out which dust impact measurements from a spacecraft in the interstellar space would be most desirable for imaging the structure of the transition region by means of interstellar dust.

How to cite: Czechowski, A. and Mann, I.: What can we learn from observations of small dust grains in the interstellar space?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9599, https://doi.org/10.5194/egusphere-egu2020-9599, 2020.

EGU2020-7486 | Displays | PS2.1

Model Calculations of the F-Corona and inner Zodiacal Light

Saliha Eren and Ingrid Mann

The white-light Fraunhofer corona (F-corona) and inner Zodiacal light are generated by interplanetary (Zodiacal) dust particles that are located between Sun and observer. At visible wavelength the brightness comes from sunlight scattered at the dust particles. F-corona and inner Zodiacal light were recently observed from STEREO (Stenborg et al. 2018) and Parker Solar Probe (Howard et al. 2019) spacecraft which motivates our model calculations. We investigate the brightness by integration of scattered light along the line of sight of observations. We include a three-dimensional distribution of the Zodiacal dust that describes well the brightness of the Zodiacal light at larger elongations, a dust size distribution derived from observations at 1AU and assume Mie scattering at silicate particles to describe the scattered light over a large size distribution from 1 nm to 100 µm. From our simulations, we calculate the flattening index of the F-corona, which is the ratio of the minor axis to the major axis found for isophotes at different distances from the Sun, respectively elongations of the line of sight. Our results agree well with results from STEREO/SECCHI observational data where the flattening index varies from 0.45° and 0.65° at elongations between 5° and 24°. To compare with Parker Solar Probe observations, we investigate how the brightness changes when the observer moves closer to the Sun. This brightness change is influenced by the dust number density along the line of sight and by the changing scattering geometry.

-Stenborg G., Howard R. A., and Stauffer J. R., 2018: Characterization of the White-light Brightness of the F-corona between 5° and 24° Elongation, Astrophys. J. 862: 168 (21pp).

-Howard, R.A. and 25 co-authors, 2019: Near-Sun observations of an F-corona decrease and K-corona fine structure, Nature 576, 232–236.

How to cite: Eren, S. and Mann, I.: Model Calculations of the F-Corona and inner Zodiacal Light , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7486, https://doi.org/10.5194/egusphere-egu2020-7486, 2020.

EGU2020-18932 | Displays | PS2.1

A fragmentation model approach for low velocity impact charging

Tarjei Antonsen, Ingrid Mann, Jakub Vaverka, and Libor Nouzak

This work addresses the generation of charge during impacts of nano- to microscale projectiles on metal surfaces at speeds from 0.1 to 10 km/s. These speeds are well above the range of elastic deformation and well below speeds where volume ionization occures. Earlier models have utilized impurity diffusion through molten grains together with a Saha-equation to model impact ionization at these speeds. In this work we employ a model of capacitive contact charging in which we allow for projectile fragmentation upon impact. We show that this model well describes laboratory measurements of metal projectiles impacting metal targets. It also can describe in-situ measurements of dust in the Earth’s atmosphere made from rockets. We also address limitations of the currently most used model for impact ionization.

How to cite: Antonsen, T., Mann, I., Vaverka, J., and Nouzak, L.: A fragmentation model approach for low velocity impact charging, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18932, https://doi.org/10.5194/egusphere-egu2020-18932, 2020.

EGU2020-5268 | Displays | PS2.1

Gas flow through porous cometary media

Maria Schweighart, Günter Kargl, Patrick Tiefenbacher, and CoPhyLab Team

Over the last few decades, our picture of comets has been continuously changing and growing due to several successful space missions, as well as cometary simulation projects in the laboratory (e.g. KOSI 1987-1992, CoPhyLab 2018 - 2021). This work aims for a better understanding of the gas transport through a porous cometary surface layer. Therefore, gas flow measurements have been performed in our laboratory to investigate the permeability of several analogue materials, which have been chosen to mimic cometary surface properties.

For the first measurements, which we are reporting here, only dry materials, free of volatiles have been selected, to isolate the gas transport from gas production inside the materials. They include glass beads made of soda lime glass, which are sieved into separate fractions to obtain distinct grain size ranges from 45 µm up to 4.3 mm. The Mars simulant JSC-Mars 1 is used in the experiments, as well as JSC-1 as a lunar soil simulant. Furthermore, an Asteroid analogue material named UCF/DSI-CI-2 from the Exolith Lab in Florida is also used. A quartz sand called UK4 mined at a local quarry in Graz is investigated as well. In a further step, a sample is created by mixing different grain size fractions of the glass beads replicating the grain size distribution of the Asteroid simulant.

The materials are also treated on a shaking table in order to obtain the packing properties of the samples. For the gas flow experiments a cylindrical sample container, with 4 cm diameter, is filled with the sample (30 mm in height) and placed inside of the vacuum chamber at the interface of two separate volumes. Four pressure sensors covering different pressure ranges monitor the gas pressure in the two volumes. A vacuum pump in the lower volume removes the gas from the chamber and through a gas inlet a defined flow of the test gas (compressed air) is inserted into the upper volume. Due to this set-up, the gas flow can only pass through the sample material. To avoid particle fluidisation and thus a texture change in the sample the gas flow is intentionally directed downwards through the sample. The gas flow is controlled by regulators from 0.15 mg/s up to 19.2 mg/s. Via the measured pressure difference between the upper and lower volume, in equilibrium flow, the gas permeability and the Knudsen diffusion coefficient of the sample material are obtained. The gas flow experiments show that the grain size distribution and the packing density of the sample play a major role for the permeability of the sample. From the analysis of the permeability measurements it is clearly visible that the larger the grains the bigger the permeability. The measured permeability values range from 10-13 to 10-8 m². This work is part of the CoPhyLab project funded by the D-A-CH programme (DFG GU1620/3-1 and BL 298/26-1 / SNF 200021E 177964 / FWF I 3730-N36).

How to cite: Schweighart, M., Kargl, G., Tiefenbacher, P., and Team, C.: Gas flow through porous cometary media, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5268, https://doi.org/10.5194/egusphere-egu2020-5268, 2020.

EGU2020-12541 | Displays | PS2.1

Single-Crystal Structure Refinement of Presolar Silicon Carbide

Warren McKenzie and Przemyslaw Dera

Presolar silicon carbide, identified by anomalous 12C/13C, have long been the only direct physical sampling of asymptotic giant branch stars and Type-II supernovae (SNII) ejecta. The bulk of non-novae grains form in the dust clouds of 1-3M carbon stars in the thermally pulsing asymptotic giant branch (AGB) phase of their life. While these grains have been extensively studied for their unique isotopic signature characteristic of their exotic origin and trace gasses carrying the s-process and r-process nucleosynthetic signature, to date studies on their structures of presolar grains have been limited to electron diffraction surveys using transmission electron microscopy. We present high-resolution single-crystal structural refinement of presolar silicon carbides determined using data synchrotron x-ray diffraction data collected at Advanced Photon Source. Preservation and resolvability of the circumstellar pressure/temperature regime was determined with an examination of nanostrain states in several grains of presolar silicon carbide. By accounting for the environment present at (1) circumstellar formation, (2) interstellar transport, and (3) asteroidal and meteoritic storage and shock environments we hope to open a new opportunity to directly study the limits of our theoretical understanding of stellar structures.

How to cite: McKenzie, W. and Dera, P.: Single-Crystal Structure Refinement of Presolar Silicon Carbide, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12541, https://doi.org/10.5194/egusphere-egu2020-12541, 2020.

EGU2020-3698 | Displays | PS2.1

Dust impact signals detected by Cassini RPWS instrument at Saturn

Libor Nouzak, Jiří Pavlů, Jakub Vaverka, Jana Šafránková, Zdeněk Němeček, David Píša, Mitchell Shen, Zoltan Sternovsky, and Shengyi Ye

Cassini spacecraft spent at Saturn almost half of the Saturn year. During these 13 years in the Saturn magnetosphere, the RPWS (Radio Plasma Wave Science) instrument recorded more than half a million of waveforms with signatures that can be interpreted as dust impact signals. The RPWS antennas in both dipole and monopole configurations operated with 10 kHz or 80 kHz sampling rates during the mission.
We qualitatively and quantitatively analyze the registered waveforms taking into account the spacecraft potential, density of the ambient plasma, magnitude of the Saturn’s magnetic field and its orientation with respect to the spacecraft. The magnetic field orientation is also used for distinguishing between signals resulting from dust impacts and signals produced by solitary waves, which can exhibit similar shapes. The results of analysis are compared with a prediction of the dust impact model that was recently developed on a base of laboratory simulations. The simulations used the reduced model of Cassini that was bombarded with submicron-sized iron grains in the velocity range of 1–40 km/s at the 3 MV dust accelerator operated at the LASP facility of University of Colorado. The model predicts generation of impact signals due to different fractions of collected and escaped electron and ion charges from the impact plasma plume and different timescales of their expansion. The core of the paper is devoted to a discussion of differences between model predictions and observations.

How to cite: Nouzak, L., Pavlů, J., Vaverka, J., Šafránková, J., Němeček, Z., Píša, D., Shen, M., Sternovsky, Z., and Ye, S.: Dust impact signals detected by Cassini RPWS instrument at Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3698, https://doi.org/10.5194/egusphere-egu2020-3698, 2020.

EGU2020-3095 | Displays | PS2.1

Components of Impact Plasma: Velocity and Temperature

Samuel Kočiščák, Åshild Fredriksen, Michael DeLuca, Jiří Pavlů, and Zoltan Sternovsky

Impact ionization is a process of plasma generation upon hypervelocity impact of a small body (e.g., interplanetary dust grain) onto a solid surface.  Such process may play an important role in astrochemistry. Understanding the plasma generation, we can clarify the interpretation of proclaimed dust impact detections onto antenna-equipped space experiments, which have become widely popular in the recent years.

We present the data gained in charge generation and collection experiments conducted at the University of Colorado IMPACT hypervelocity dust accelerator facility. The impacts are of sub-micrometer cosmic dust simulants onto a metal target in the range of velocities between 1 and 50 km/s. We discuss measured charge collection on a microsecond scale as well as aggregated results of electron and ion drift velocities and temperatures and specifically their dependence on the velocity of the impactor.

How to cite: Kočiščák, S., Fredriksen, Å., DeLuca, M., Pavlů, J., and Sternovsky, Z.: Components of Impact Plasma: Velocity and Temperature, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3095, https://doi.org/10.5194/egusphere-egu2020-3095, 2020.

EGU2020-3085 | Displays | PS2.1

Dust Interaction with Energetic Particles — A Laboratory Simulation

Jiří Pavlů, Libor Nouzák, Jan Wild, Jakub Vaverka, Ivana Richterova, Jana Šafránková, and Zdeněk Němeček

Dust grains in space frequently face energetic particles, e.g., ions, electrons, X-ray, positrons, etc. Such a broad variety of particle–dust interactions plays a significant role in dust charging and surface modification. The combination of high energy of particles together with a limited size of objects (dust) comprises interesting mesoscopic structure with non-obvious behavior. While in situ experiments are difficult and rare, we observed particular interactions experimentally in an electrodynamic trap. It allows us to study of a single dust grain temporal evolution under well defined conditions, i.e., to somewhat separate aforementioned processes and to investigate them individually. We present a summary of laboratory simulations and their
comparison with simple theoretical models. We discuss dust charging by different elementary particles and its importance for various space regions.

How to cite: Pavlů, J., Nouzák, L., Wild, J., Vaverka, J., Richterova, I., Šafránková, J., and Němeček, Z.: Dust Interaction with Energetic Particles — A Laboratory Simulation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3085, https://doi.org/10.5194/egusphere-egu2020-3085, 2020.

EGU2020-3082 | Displays | PS2.1

Dust impact detections by a set of Faraday cups in the lunar environments

Oleksii Kononov, Jiří Pavlů, Libor Nouzák, Jana Šafránková, Zdeněk Němeček, and Lubomír Přech

The Bright Monitor of the Solar Wind (BMSW) for the Luna-Resurs-1 mission is an instrument designed for high-time (30 ms) resolution measurements of moments of the ion energy distribution by Faraday cups in the solar wind and in a plasma environment at altitudes between 65 and 150 km above the lunar surface. Previous studies performed by a similar instrument located on-board the Spektr-R spacecraft demonstrated a possibility to detect hypervelocity impacts of dust grains by such instruments Our analysis shows that the main problem of the reliable detection of dust impacts using such types of instruments is their sampling rate. In the paper, we present a novel design of a set of FCs that improves the ability of the dust detection using a simple identification algorithm that can store data with a higher sampling rate around the impact pulse. Moreover, we discuss a calibration of the detectors and their front-end electronics using the dust accelerator in order to find a relation between impact parameters and pulse heights.

How to cite: Kononov, O., Pavlů, J., Nouzák, L., Šafránková, J., Němeček, Z., and Přech, L.: Dust impact detections by a set of Faraday cups in the lunar environments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3082, https://doi.org/10.5194/egusphere-egu2020-3082, 2020.

EGU2020-2743 | Displays | PS2.1

Ion cloud expansion after hypervelocity dust impacts detected by the MMS spacecraft

Jakub Vaverka, Jiří Pavlů, Libor Nouzák, Samuel Kočiščák, Jana Šafránková, and Zdeněk Němeček

Dust grains impacting with high velocities the spacecraft body can be partly or totally evaporated and create clouds of charged particles. Presence of electrons and ions generated by such hypervelocity impacts can consequently influence the spacecraft potential and/or measurements of on-board scientific instruments. Electric field instruments are able to register signals generated by dust impacts as short pulses in the measured electric field. These signals can be used for detection of dust grains by the spacecraft without dedicated dust detectors. This dust detection method has been successfully used for data collected by many spacecraft as Voyager, Cassini, Wind, STEREO, MAVEN, and MMS. On the other hand, our understanding of this complex process comprising from dust grain evaporation, generation of charged particles, to impact cloud expansion and signal detection is still not complete.

We present a study of events related to dust impacts on the spacecraft body detected by electric field probes operating simultaneously in the monopole (probe-to-spacecraft potential measurement) and dipole (probe-to-probe potential measurement) configurations by the Earth-orbiting MMS spacecraft. The presented study is focused on events when expanding ions affect not only the potential of the spacecraft body but also one or more electric probes on the end of antenna booms. Expanding ions can influence electric probes located far from the spacecraft body only when the spacecraft is located in tenuous ambient plasma as inside of the Earth’s magnetosphere. This analysis can confirm if these events are really connected to dust impacts and gives us some information about ion expansion velocity, and improve our knowledge of dust impact process.

How to cite: Vaverka, J., Pavlů, J., Nouzák, L., Kočiščák, S., Šafránková, J., and Němeček, Z.: Ion cloud expansion after hypervelocity dust impacts detected by the MMS spacecraft , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2743, https://doi.org/10.5194/egusphere-egu2020-2743, 2020.

EGU2020-2438 | Displays | PS2.1

Identification and preliminary analysis of dust impacts on the MAVEN spacecraft

Klára Ševčíková, František Němec, Libor Nouzák, Jakub Vaverka, and Laila Andersson

Electric field data obtained by the Langmuir Probe and Waves (LPW) instrument on board the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft are used to identify signals related to dust impacts on the spacecraft body and/or on the instrument probes. The analyzed waveforms snapshots are 62.5 ms long (4,096 points sampled at 65,536 Hz). An automatic procedure to identify short electric field pulses with signatures corresponding to those expected for the dust impacts has been developed and applied to available data in years 2014–2018, resulting in about 40,000 of events. Each of the identified pulses is characterized by several quantitative parameters (polarity, magnitude, relaxation time, magnitude of a possible pre-spike). The event occurrence and respective quantitative parameters of detected pulses are then analyzed as a function of local plasma conditions in the Martian ionosphere (electron density and temperature), the spacecraft location, and the spacecraft potential. The obtained results are compared with a simple scheme of the signal formation upon a dust impact.

How to cite: Ševčíková, K., Němec, F., Nouzák, L., Vaverka, J., and Andersson, L.: Identification and preliminary analysis of dust impacts on the MAVEN spacecraft, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2438, https://doi.org/10.5194/egusphere-egu2020-2438, 2020.

EGU2020-8793 | Displays | PS2.1

In situ dust measurements in the solar wind from S/WAVES TDS instrument on STEREO mission

Kristina Rackovic Babic, Karine Issautier, and Arnaud Zaslavsky

Dust particles represent an important fraction of the matter composing the interplanetary medium. At 1 A.U. dust mass density is comparable to the one of the solar wind. The large number and broad diversity of dust particles detected by the radio instrument on the STEREO satellites recommend this mission for a closer dust investigation. In situ dust measurements are based on the detection of the charges generated by dust impacts, recorded by the S/WAVES instrument near 1 A.U. since the beginning of the STEREO mission. We study the electric signals produced by these impacts, using the waveform sampler data produced by the TDS subsystem of the radio instrument, connected to three monopole antennas. For this study, we concentrate on macroscopic dust particles (~0.1 microns) whose impact generated nearly simultaneous pulses on the antennas. In particular, we present statistics of typical shapes and features of these signals based on the TDS electric potential time-series and compare the data to a theoretical model of how pulses are generated by charge collection.
These results will have implications on dust detection from Parker Solar Probe and Solar Orbiter missions.

How to cite: Rackovic Babic, K., Issautier, K., and Zaslavsky, A.: In situ dust measurements in the solar wind from S/WAVES TDS instrument on STEREO mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8793, https://doi.org/10.5194/egusphere-egu2020-8793, 2020.

EGU2020-19159 | Displays | PS2.1

LICIACube observation capabilities of dust plume evolution after DART impact

Vincenzo Corte, Elena Mazzotta Epifani, Elisabetta Dotto, Marilena Amoroso, Simone Pirrotta, and Andy Cheng and the LICIAcube TEAM

The NASA Double Asteroid Redirection Test (DART) mission will be the first test to check an asteroid deflection by a kinetic impactor. The target of DART mission is the secondary element of the (65803) Didymos binary asteroid system and the impact is expected in late September – early October, 2022. The DART S/C will carry a 6U cubesat called LICIACube (Light Italian Cubesat for Imaging of Asteroid), provided by the Italian Space Agency, with the aim to collect pictures of the impact’s effects. The impact of the 610 kg DART spacecraft at 6.58 km/s on the 163 m Didymos B will result in a change of the binary orbital period of about 10 minutes assuming momentum transfer efficiency β = 1. Values of β > 1 are expected because the produced ejecta carries momentum, primarily in the direction opposite the DART speed direction. The LICIACube mission profile consists in a flyby of Didymos system with closest approach about 3 minutes after the DART impact. LICIACube will be able to acquire the structure and evolution of the DART impact ejecta plume and will obtain high-resolution images and also in 3 colour of the surfaces of both bodies. The nominal mission foresees also imaging of the Dydymos B non-impact hemisphere. The contributions of LICIACube observations to the DART investigations are important for determination of the momentum transfer efficiency β, that is a crucial result of the planetary defence test. Moreover, captured images can enable scientific investigations about the main features of the asteroid system. 

In order to check the imaging capability and to optimize the fast scientific phase of LICIAcube, the LICIA team performed several simulations of pictures’ acquisition. In these simulations, considering the specifications of the 2 optical payloads and the foreseen mission design, we reconstructed synthetic images mainly of the plume. As the plume evolution remains the most important uncertainty, since it depends on a very high number of impacting phase parameters, we simulated imaging of different expected evolution behaviours, to obtain instrument operative parameters and to prepare the data analysis.  

How to cite: Corte, V., Mazzotta Epifani, E., Dotto, E., Amoroso, M., Pirrotta, S., and Cheng, A. and the LICIAcube TEAM: LICIACube observation capabilities of dust plume evolution after DART impact, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19159, https://doi.org/10.5194/egusphere-egu2020-19159, 2020.

The risk of asteroids impacting the earth is a common space security issue facing human beings. Since the ground-based monitoring network cannot cover the space area comprehensively, there are cases of celestial body out of monitoring. In response to this problem, this report studies the space-based platform's monitoring system, and calculates its performance for orbit determination and monitoring of small celestial bodies. For small celestial bodies that are not in the catalog, the initial orbit determination needs to be performed before the orbit improvement. In addition, this paper proposes a method based on Fibonacci search method to quickly predict the impact location of asteroids.

How to cite: yezhi, S.: Space-based platform asteroid orbit determination and collision warning, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12597, https://doi.org/10.5194/egusphere-egu2020-12597, 2020.

EGU2020-12729 | Displays | PS2.1

Accurate Near-Earth-Object Astrometry using Synthetic Tracking and Applications

Chengxing Zhai, Michael Shao, Navtej Saini, Russell Trahan, Philip Choi, Kutay Nazli, Nez Evans, and William Owen

Synthetic tracking technique uses multiple short exposure images to observe moving objects to prevent the objects from streaking in an individual frame. It integrates frames in post-processing, where the tracking of telescope at any desired rate can be simulated by shifting frames accordingly. Such an approach avoids trailing loss, thus improves detection sensitivity, especially for fast moving objects. It also yields accurate astrometry for moving objects independent of rate of motion with precision comparable to stellar astrometry. Using the Gaia DR2 catalog, we are able to demonstrate 10 mas level near-Earth-object (NEO) astrometry with the synthetic tracking technique. Accurate NEO astrometry allows us to determine NEO orbit more precisely. We discuss applications such as cataloging newly discovered NEOs with less measurements and/or from observation time windows covering shorter orbit arcs, better predicting the chance for a potentially hazardous asteroid to impact the Earth, measuring non-gravitational acceleration to infer physical properties of minor planets, and optical navigation for future spacecraft carrying optical communication lasers.

How to cite: Zhai, C., Shao, M., Saini, N., Trahan, R., Choi, P., Nazli, K., Evans, N., and Owen, W.: Accurate Near-Earth-Object Astrometry using Synthetic Tracking and Applications, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12729, https://doi.org/10.5194/egusphere-egu2020-12729, 2020.

PS2.2 – Particle and plasma interactions in the ionospheres, exospheres and at surfaces of solar system bodies

EGU2020-9587 | Displays | PS2.2

Specular meteor observations and full wave scattering modelling: observing faint meteors

Gunter Stober, Peter Brown, Carsten Schult, Rob Weryk, Margaret Campbell-Brown, and Petr Pokorny

There is a continuous flux of meteoroids entering the Earth's atmosphere, which are decelerated and heated by collisions with atmospheric molecules, and, depending on the meteoroid kinetic energy, they vaporize and form an ambipolar diffusing plasma trail, which is easily detectable using radar remote sensing. Specular meteor observations are a widely used radar technique to measure winds at the Mesosphere and Lower Thermosphere (MLT). The altitude dependent lifetime (decay time) of the meteor plasma columns provides valuable information about the mean temperature of the atmosphere.  Part of the success of these systems is based on the efficient scattering process compared to meteor head echoes.

Here we present observations with the Middle Atmosphere Alomar Radar System to detect the faintest observable meteors using the specular geometry, but a focused beam with a beamwidth of 3.6° and the full power of 866kW of the system. We compare our observations to an orbital dynamics model of JFC comets and derive a meteor velocity distribution for the observed population.

Further, we performed extensive modeling using a full-wave scattering model based on the model presented in Poulter and Baggaley, 1977. We conducted extensive simulations with the full-wave scattering model to investigate how different plasma distributions would affect the detectability of the meteoric plasma cylinders considering the initial trail radius, diffusion, and electron line density. The obtained reflection coefficients are validated with the triple frequency CMOR (Canadian Meteor Orbit Radar) measurements convolving them with the Fresnel integrals. Our results indicate that the plasma distribution can significantly alter the detectability. Further, the model shows that the observed decay time depends on the polarization of the transmitted wave relative to the meteor trajectory, which also revealed resonance effects for certain critical plasma frequencies. 

How to cite: Stober, G., Brown, P., Schult, C., Weryk, R., Campbell-Brown, M., and Pokorny, P.: Specular meteor observations and full wave scattering modelling: observing faint meteors , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9587, https://doi.org/10.5194/egusphere-egu2020-9587, 2020.

EGU2020-4775 | Displays | PS2.2

Impact of the Wintertime Meteor Showers on the Sporadic E Layer Activity at Midlatitudes

Veronika Barta, Zbysek Mosna, Daniel Kouba, Antal Igaz, and Krisztián Sárneczky

The impact of meteor showers and individual meteors on the ionosphere has been investigated during wintertime meteor showers using synchronised measurements of two DPS-4D Digisondes installed at Pruhonice (50°, 14.5°) and at Sopron (47.63°, 16.72°). Rather short distance between Pruhonice and Sopron allow us to perform special joint campaigns of vertical and oblique sounding under the high sampling rate to detect fine structures within ionospheric plasma.

 

High cadence campaigns have been performed to observe behavior of sporadic E layer (Es) during the Leonids, Geminids and Quadrantids meteor showers in 2018 and 2019. The time resolution of the ionograms have been set to approximately 0.5 - 2 ionograms per minute. We used vertical and oblique reflections to investigate the fine structure and the movement of Es layer. Based on the first results the oblique sounding is a good technique to detect the Es activity between two stations, however there were periods (typically 10 to 40 minutes of duration) when the Es was observed using oblique trace but there was no observation of Es layer in vertical ionograms. Furthermore, double Es structures have been detected more times for tens of minutes during the observation nights.

 

Beside the regular behavior of Es we concentrated on observation of intervals of increased plasma frequency in the Es region presumably directly induced by the meteors. In the framework of GINOP-2.3.2-15-2016-00003 (“Kozmikus hatások és kockázatok") an optical camera has been installed at the MTA Széchenyi István Geophysical Observatory (Sopron) in September 2019 with the cooperation of the Konkoly Observatory to monitor the meteors. Therefore, we were able to compare the ionograms measured during meteor showers with the optical data to determine the plasma trails of individual meteors. In the 20-25% of the observed meteors a faint Es layers were detected on the ionograms during and after (< 1 min) the optical record. The direction of the detected plasma traces determined by the SAO Explorer was in good agreement with the direction of the optically observed meteors in most of the cases. Consequently, the plasma trace of individual meteors could be detected on the high time resolution ionograms.

How to cite: Barta, V., Mosna, Z., Kouba, D., Igaz, A., and Sárneczky, K.: Impact of the Wintertime Meteor Showers on the Sporadic E Layer Activity at Midlatitudes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4775, https://doi.org/10.5194/egusphere-egu2020-4775, 2020.

EGU2020-1168 | Displays | PS2.2

A technique for reconstructing the spatial characteristics of a long-lived meteor trails on all-sky cameras

Tatiana Syrenova, Roman Vasilyev, Alexander Beletsky, Alexander Mikhalev, and Eselevich Maxim

Over the years, reports of meteor trails lasting up to one hour have periodically appeared in the literature. These observations are usually associated with particularly strong meteor showers, such as Leonids. In [Kelley et al. 2000] some interesting observations of such trails related to the 1998 Leonid meteor shower event are presented [2]. In publications devoted to the study of this phenomenon in the optical range, the main attention is paid to processes that cause a prolonged luminescence of meteor showers [Kelley et al., 2000]. Meanwhile, this phenomenon is of great interest for diagnosing the Earth upper atmosphere state and the ionosphere. The bulk of the work in this direction is based on radar observations of ionization traces, the duration of which in some cases reaches several minutes [Kashcheev et al., 1967].

This paper reports on long-lived meteor trails (LMT), which was recorded simultaneously using two optical instruments recording night sky emissions. The first all-sky camera is located at the Geophysical Observatory of the ISTP SB RAS, near the Tory (51.80 N, 103.10 E) and is designed to record the spatial picture of the 630 nm emission intensity [http: // atmos. iszf.irk.ru/ru/data/keo]. The second all-sky camera is located in the Sayan Solar Observatory of the ISTP SB RAS, near the Mondy (51.60 N, 100.90 E). A meteor trail lasting 35-40 minutes was recorded on November 18, 2017 after a meteoroid explosion on 22.23.19 UT with two cameras from different directions. Further, an algorithm was developed with the Python programming language the geographical coordinates of this event were calculated, as well as the height of the highlight

. The meteoroid explosion height and the ellipsoidal trail was being 65-70 km. Then the meteor track bow spread horizontally in a southward for 30-40 minutes at an average velocity of 58 m/s. This technique can be used to determine the main characteristics of various phenomena in the atmosphere, such as waves, SAR-arcs, meteor tracks and others.

This work was supported by a grant from the Russian Foundation for Basic Research N19-35-90093.

How to cite: Syrenova, T., Vasilyev, R., Beletsky, A., Mikhalev, A., and Maxim, E.: A technique for reconstructing the spatial characteristics of a long-lived meteor trails on all-sky cameras, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1168, https://doi.org/10.5194/egusphere-egu2020-1168, 2020.

EGU2020-2448 | Displays | PS2.2

Derivation of metallic plasma layers in Earth's ionosphere (Sporadic E layer) from FORMOSAT-3/COSMIC satellites at a global scale

Bingkun Yu, Christopher Scott, Xianghui Xue, Xinan Yue, and Xiankang Dou

In the past decades, the scintillations of Global Navigation Satellite System (GNSS) radio occultation (RO) measurements have been widely employed to study the occurrence of sporadic E (Es) layers. Recent results indicated that amplitude scintillation index (S4max) observations can be used to study the intensity of global Es layers. In this study, we show a statistical assessment of the hourly ionospheric Es layer measurements between 90 and 130 km from FORMOSAT-3/COSMIC satellites. The Es observations from FORMOSAT-3/COSMIC satellites are in agreement with those from ground-based ionosonde stations at different latitudes. With the successful launch of FORMOSAT-7/COSMIC-2, an accurate, high-resolution (< 5° ×5°×1 hour) map of Es layers on a global scale is available in the hopeful future.

How to cite: Yu, B., Scott, C., Xue, X., Yue, X., and Dou, X.: Derivation of metallic plasma layers in Earth's ionosphere (Sporadic E layer) from FORMOSAT-3/COSMIC satellites at a global scale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2448, https://doi.org/10.5194/egusphere-egu2020-2448, 2020.

EGU2020-1543 | Displays | PS2.2

Occurrence and altitude of the non-specular long-lived meteor trails during meteor showers at high latitudes

Alexander Kozlovsky, Renata Lukianova, and Mark Lester

Meteoroids entering the Earth’s atmosphere produce ionized trails, which are detectable by radio sounding. Majority of such radar detections are the echoes from cylindrical ionized trails, which occur if the radar beam is perpendicular to the trail, i.e., the reflection is specular. Typically such echoes detected by VHF radars last less than one second. However, sometimes meteor radars (MR) observe unusually long-lived meteor echoes and these echoes are non-specular (LLNS echoes). The LLNS echoes last up to several tens of seconds and show highly variable amplitude of the radar return. The LLNS echoes are received from the non-field-aligned irregularities of ionization generated along trails of bright meteors and it is believed that key role in their generation belongs to the aerosol particles arising due to fragmentation and burning of large meteoroids. The occurrence and height distributions of LLNS are studied using MR observations at Sodankylä Geophysical Observatory (SGO, 67° 22' N, 26° 38' E, Finland) during 2008-2019. Two parameters are analyzed: the percentage and height distribution of LLNS echoes. These LLNS echoes constitute about 2% of all MR detections. However during certain meteor showers (Geminids, Perseids, Quadrantids, Arietids or/and Daytime ζ-Perseids, and Lyrids) the percentage of LLNS echoes is noticeably higher (about 6, 5, 4, 4, and 3%, respectively). Typically, the LLNSs occur ~2 km higher than other echoes (in June-July the height difference is reduced to ~1 km). Due to this elevation, a larger percentage of LLNSs is manifested as an upward shift of the height distribution of meteor trails during meteor showers. Moreover, during Lyrids, η-Aquariids, Perseids, Orionids, and Leonids the LLNS echoes occur noticeably, up to 3-6 km, higher than the echoes from other types of trails. Thus, enhanced heights of meteor detections during major meteor showers (Quadrantids, Lyrids, η-Aquariids, Arietids or/and Daytime ζ-Perseids, Perseids, Orionids, Leonids, and Geminids) are predominantly due to long-lived non-specular echoes from the non-field-aligned irregularities associated with large meteoroids.

How to cite: Kozlovsky, A., Lukianova, R., and Lester, M.: Occurrence and altitude of the non-specular long-lived meteor trails during meteor showers at high latitudes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1543, https://doi.org/10.5194/egusphere-egu2020-1543, 2020.

EGU2020-8999 | Displays | PS2.2

Formation of complex organosulfur compounds by sulfur implantation in astrophysical ice analogs – implications for the chemical evolution of the surface of icy objects

Alexis Bouquet, Alexander Ruf, Philippe Boduch, Philippe Schmitt-Kopplin, Vassilissa Vinogradoff, Fabrice Duvernay, Riccardo Giovanni Urso, Rosario Brunetto, Louis Le Sergeant d'Hendecourt, Olivier Mousis, and Grégoire Danger

Irradiation of ices is a ubiquitous cause of chemical evolution of the surface of icy bodies of the solar system, due to solar UVs, solar wind particles, and magnetospheric particles. Sulfur is present in the solar wind and, in large quantities, in the jovian magnetosphere; in addition of acting as a projectile and inducing radiation chemistry, it is reactive and may be incorporated into the compounds produced. This may be a factor in increasing the chemical complexity of the surface of KBOs, TNOs, and jovian moons.

We have performed implantation of 105 keV sulfur ions into a water-methanol-ammonia ice at the Grand Accélérateur National d’Ions Lourds (GANIL) in Caen, France. Similar samples were also irradiated with argon (non-reactive projectiles). The samples were monitored in the infrared during the implantation process. The organic residues left after heating and sublimating the volatiles were then analyzed with Very High Resolution Mass Spectrometry (VHRMS). The infrared spectra of the argon-irradiated and sulfur-irradiated samples are qualitatively the same, but VHRMS shows the residue of the sulfur-irradiated sample contains more than a thousand of CHNOS formulas that are not present in the argon-irradiated sample. This indicates an active and rich sulfur chemistry induced by the implantation. The compounds formed are mostly aliphatic and can reach masses up to 700 amus. We discuss the implications for icy objects of the solar system and other ongoing experiments to explore the chemistry induced by sulfur implantation on the surface of the jovian moons.

How to cite: Bouquet, A., Ruf, A., Boduch, P., Schmitt-Kopplin, P., Vinogradoff, V., Duvernay, F., Giovanni Urso, R., Brunetto, R., Le Sergeant d'Hendecourt, L., Mousis, O., and Danger, G.: Formation of complex organosulfur compounds by sulfur implantation in astrophysical ice analogs – implications for the chemical evolution of the surface of icy objects, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8999, https://doi.org/10.5194/egusphere-egu2020-8999, 2020.

EGU2020-7593 | Displays | PS2.2

A direct measurement of water vapor at Europa and implications for the magnetospheric environment

Lorenz Roth, Lucas Paganini, Geronimo Villanueva, Avi Mandell, Terry Hurford, Michael Mumma, Kurt Retherford, and Aljona Blöcker

Previous investigations suggested local anomalies in Europa’s atmosphere, advancing the idea of possible water plumes. Now a global survey with the Keck observatory provided a direct detection (3.1 sigma) of line emission from H2O at infrared wavelengths on one out of 17 observing dates in 2016 and 2017. The non-detections on the 16 other dates resulted in sensitive upper limits for H2O abundance at various longitudes, providing reference to the rate and location of occurrence.

When active, outgassing at plumes locally increases the neutral density in Europa’s bound atmosphere. Such atmosphere anomalies in turn might lead to small scale (compared to Europa’s diameter) features in the electromagnetic interaction signals such as in magnetic field perturbations, or to an increased mass loss from Europa. The strength and detectability of plume-related magnetospheric signals depend on the relative abundance of plume gas (when active) compared to the sputtered atmosphere.

The new results from the infrared survey suggest that outgassing occurs at lower levels than previously estimated, with only rare localized events of somewhat stronger plume activity. In this presentation, we put these observations in context and discuss if and how plume activity might affect the magnetospheric environment.

How to cite: Roth, L., Paganini, L., Villanueva, G., Mandell, A., Hurford, T., Mumma, M., Retherford, K., and Blöcker, A.: A direct measurement of water vapor at Europa and implications for the magnetospheric environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7593, https://doi.org/10.5194/egusphere-egu2020-7593, 2020.

EGU2020-3149 | Displays | PS2.2

Monte Carlo test-particle model of Mercury's ionized exosphere: Global structure and dynamics

Anita Linnéa Elisabeth Werner, François Leblanc, Jean-Yves Chaufray, and Ronan Modolo
The Mercury plasma environment is enriched in heavy ions (mass-per-charge ratio m/q > 4) from photo-ionization of the tenuous exosphere. The MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) time-of-flight spectrometer Fast Imaging Plasma Spectrometer (FIPS) has detected many planetary ion species of which He+, the Na+-group (including Na+, Mg+ and Si+) and the O+-group (including O+ and several water group ions) are the most abundant. The Mercury Atmospheric and Surface Composition Spectrometer (MASCS) UltraViolet and Visible Spectrometer (UVVS) has also detected Ca+ ions in the nightside plasma sheet. Models of the planetary ion distribution inside Mercury's magnetosphere have mostly concentrated on the abundant Na+ and H+ ion populations. Comparison with FIPS data has been limited to the first two MESSENGER flybys and no comparison has been made with MASCS/UVVS observations.
 
We have developed a Monte Carlo test-particle model which describes the ion density distribution produced from photo-ionization of several neutral species in Mercury's exosphere. The global ion density and energy distribution of Ca+, Mg+, Na+, O+ and He+ will be presented here. We will review the influence of the interplanetary magnetic field (IMF) Bx and By components on the global structure of the ion density distribution, the composition of the nightside plasma sheet and the evolution of the Na+ ion density along the Mercury year.

How to cite: Werner, A. L. E., Leblanc, F., Chaufray, J.-Y., and Modolo, R.: Monte Carlo test-particle model of Mercury's ionized exosphere: Global structure and dynamics, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3149, https://doi.org/10.5194/egusphere-egu2020-3149, 2020.

EGU2020-2746 | Displays | PS2.2

Assessments of Magnetic Reconnection and Kelvin-Helmholtz Instability at Ganymede's Upstream Magnetopause

Nawapat Kaweeyanun, Adam Masters, and Xianzhe Jia

Ganymede is the largest moon of Jupiter and the only Solar System moon known to generate a permanent magnetic field. Motions of Jupiter’s magnetospheric plasma around Ganymede create an upstream magnetopause, where energy flows are thought to be driven by magnetic reconnection and/or Kelvin-Helmholtz Instability (KHI). Previous numerical simulations of Ganymede indicate evidence for transient reconnection events and KHI wave structures, but the natures of both processes remain poorly understood. Here we present an analytical model of steady-state conditions at Ganymede’s magnetopause, from which we conduct first assessments of reconnection and KHI onset criteria at the boundary. We find that reconnection may occur wherever Ganymede’s closed magnetic field encounters Jupiter’s ambient magnetic field, regardless of variations in magnetopause conditions. Unrestricted reconnection onset highlights possibilities for multiple X-lines or widespread transient reconnection at Ganymede. The reconnection rate is controlled by the ambient Jovian field orientation and hence driven by Jupiter’s rotation. We also determine Ganymede’s magnetopause conditions to be favorable for KHI wave growths in two confined regions each along a magnetopause flank, both of which grow in area whenever Ganymede moves toward Jupiter’s magnetospheric current sheet. KHI growth rates are calculated with the Finite Larmor Radius (FLR) effects incorporated and found to be asymmetric favoring the magnetopause flank closest to Jupiter. The significance of KHI wave growth on energy flows at Ganymede’s magnetopause remains to be investigated. Future progress on both topics is highly relevant for the upcoming JUpiter ICy moon Explorer (JUICE) mission.

How to cite: Kaweeyanun, N., Masters, A., and Jia, X.: Assessments of Magnetic Reconnection and Kelvin-Helmholtz Instability at Ganymede's Upstream Magnetopause, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2746, https://doi.org/10.5194/egusphere-egu2020-2746, 2020.

Phobos is the closest of the two moons of Mars and its surface is not only exposed to ions coming from the solar wind (mainly protons H+ and alpha particles He++), but is also bombarded by ions coming from Mars itself (mainly atomic and molecular oxygen ions O+ and O2+). Space weathering at Phobos would be intimately linked to the planetary atmospheric escape if Martian ions significantly alter the properties of the moon’s surface.
In this presentation, the long-term averaged ion environment seen by the surface of Phobos (omnidirectional and directional fluxes, and composition) is constructed from 4 years of ion measurements gathered in-situ by the NASA MAVEN mission. The MAVEN spacecraft repeatedly crossed the orbit of Phobos from January 2015 to February 2019 and was uniquely suited to unprecedently observe ions there with its three ion instruments: SWIA, STATIC, and SEP. These three experiments together constrain the entire range of ion kinetic energies that impact Phobos, from cold ions of a few eV to solar energetic ions of several MeV. In addition, the STATIC instrument (1 eV to 30 keV) is able to discriminate the mass of the observed ions by measuring their time-of-flight. This capability is important to understand the weathering of the surface of Phobos, as for instance the effect on the surface of a precipitating heavy molecular oxygen ion is significantly different from the one of a proton.
The relative importance of Martian and solar wind ions is in turn assessed from the observed ion omnidirectional fluxes for two space weathering effects: (1) surface sputtering, which is computed by using ion specie and energy-dependent sputtering yields available in the literature and (2) the production of vacancies inside the regolith grains, which is estimated with the SRIM software. (1) We find that Martian ions dominate solar wind ions in sputtering the surface of Phobos when the moon crosses the Martian magnetotail. We also reveal that molecular oxygen O2+ ions sputter as much as or more from the surface of Phobos than atomic O+ ions. (2) Martian heavy ions significantly contribute to the production of vacancies in the uppermost nanometer of Phobos regolith grains. Finally, MAVEN directional flux measurements are used to study the anisotropy of the bombarding ion fluxes at Phobos, which we find implies an asymmetric weathering of the surface: the near side (always facing Mars) is primarily weathered by Martian ions, whereas the far side is primarily altered by solar wind ions. 

How to cite: Nenon, Q. and Poppe, A.: Ion weathering of the surface of the Martian moon Phobos as inferred from MAVEN ion observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2455, https://doi.org/10.5194/egusphere-egu2020-2455, 2020.

EGU2020-3061 | Displays | PS2.2

Energy and momentum flux around comet 67P throughout the Rosetta mission

Hans Nilsson, Hayley Williamson, Gabriella Stenberg Wieser, Ingo Richter, and Charlotte Götz

We calculate the momentum and energy flux of ions measured by the Ion Composition Analyzer (ICA) on the Rosetta mission at comet 67P/Churyumov-Gerasimenko. We find that the total ion energy and momentum flux stay roughly constant over the mission, but the relative contribution of solar wind ions and cometary ions changes drastically depending on the spacecraft position in the ionosphere and distance from the comet to the sun. We also see that the magnetic pressure, calculated from the magnetic field measured by the Rosetta magnetometer, is on the order of the total ion momentum flux and roughly corresponds with the cometary ion momentum flux. Near both the beginning and end of the mission, solar wind momentum and energy flux are roughly two orders of magnitude larger than the corresponding heavy cometary ion fluxes. When the spacecraft enters the solar wind ion cavity near the comet’s periapsis, the solar wind energy and momentum flux drop drastically, mainly due to reduced density. Meanwhile, the cometary energy flux increases to be roughly equal to the solar wind flux earlier in the mission and the cometary momentum flux as measured by ICA becomes roughly an order of magnitude higher than previous and later solar wind fluxes. We also examine the changes in flux on two excursions, one on the dayside and one on the nightside of the comet, and see that during the nightside excursion, the cometary ion fluxes drop off roughly with the square of the distance from the comet. During the dayside excursion the flux was approximately constant, indicating that the excursion distance was small compared to the region where the observed ions were produced. ICA does not measure the lowest energy ions, so we also discuss the energy and momentum of the full ion population based on density estimates from the LAP and MIP instruments.

How to cite: Nilsson, H., Williamson, H., Stenberg Wieser, G., Richter, I., and Götz, C.: Energy and momentum flux around comet 67P throughout the Rosetta mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3061, https://doi.org/10.5194/egusphere-egu2020-3061, 2020.

EGU2020-5971 | Displays | PS2.2

Interaction of Interplanetary Shocks with the Moon

Xiaoyan Zhou and Nojan Omidi

In this presentation, we use data from THEMIS-ARTEMIS spacecraft and electromagnetic hybrid (kinetic ions, fluid electrons) simulations to describe the nature of the interaction between interplanetary shocks and the Moon. In the absence of a global magnetic field and an ionosphere at the Moon, solar wind interaction is controlled by (1) absorption of the core solar wind protons on the dayside; (2) access of supra-thermal and energetic ions in the solar wind to the lunar tail; (3) penetration and passage of the IMF through the lunar body. This results in a lunar tail populated by energetic ions and enhanced magnetic field in the central tail region. In general, ARTEMIS observations show a clear jump in the magnetic field strength associated with the passage of the interplanetary shock regardless of the position in the tail. Compared to the shock front observed in the solar wind, the magnetic field strength in the tail is stronger both upstream and downstream of the shock which is consistent with the expectations of larger field strengths in the tail. In addition, the transition from upstream to downstream magnetic field strength takes longer time as compared to the solar wind, indicating the broadening in space of the shock transition region. In contrast, plasma observations show that depending on the position of the spacecraft in the tail, a density enhancement in association with the shock front may or may not be observed. Using the observed solar wind conditions, we have used hybrid simulations to examine the interaction of interplanetary shocks with the Moon. The results indicate that by virtue of IMF passage through the lunar body, the magnetic field shock front also passes through the Moon and as such a jump in the magnetic field strength is observed throughout the lunar tail in association with the passage of the shock. As expected, the field strength in the upstream and downstream regions in the tail are larger than the corresponding values in the solar wind. In addition, the passage of the shock through the lunar tail is associated with the broadening of the shock front. The absorption of the core solar wind protons on the dayside introduces a density hole in the shock front as it passes through the Moon and the lunar tail and, as such, the shock front as a whole is disrupted. This hole is gradually filled with the ambient plasma while it travels further down the tail until eventually the shock front is fully restored a few lunar radii away from the Moon. The simulation results are found to be consistent with ARTEMIS observations. Here we also discuss the impacts of shock Mach number on the interaction. These results depict the lunar environment under transient solar wind conditions, which provide helpful information for the NASA’s plan to return humans to the Moon.

How to cite: Zhou, X. and Omidi, N.: Interaction of Interplanetary Shocks with the Moon, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5971, https://doi.org/10.5194/egusphere-egu2020-5971, 2020.

EGU2020-18137 | Displays | PS2.2

Numerical simulation of ion reflection by lunar crustal magnetic fields

Andrey Divin, Jan Deca, Charles Lue, and Roman Beliaev

We investigate the dynamics of solar wind - Moon interaction by means of large-scale Particle-in-Cell (PIC) simulations in this study. Implicit moment PIC method and open boundaries are implemented in the code (iPIC3D) allowing to use large-scale domains in three dimensions. Even though the Moon has no global dipolar magnetic field, satellite magnetic field measurements at low-altitude (8-80 km) orbits discovered the presence of patches of intense remanent magnetization of the lunar crust. In order to simulate the scattering effect of the lunar remanent magnetic field we implemented an empirical proton reflection model based on low-attitude survey by the Chandrayaan-1 spacecraft [Lue, 2011]. In this study we focus on the day side effects only and thus do not resolve wake and limb effects. Reflected ions are found to create an energized population of particles in the solar wind and are responsible for sub-ion scale instabilities over the strongest anomalies with non-Maxwellian ion distribution functions.

How to cite: Divin, A., Deca, J., Lue, C., and Beliaev, R.: Numerical simulation of ion reflection by lunar crustal magnetic fields, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18137, https://doi.org/10.5194/egusphere-egu2020-18137, 2020.

A fraction of up to 20% of the solar wind impinging onto the lunar surface is reflected as energetic neutral atoms back to space, as established by remote sensing, e.g. by the SARA instrument on Chandrayaan-1 or by IBEX. Mapping of these reflected energetic neutral atoms to the surface opened a new way to remotely study the solar wind precipitation onto the surface. However, the high reflection rate remained an enigma given the high porosity of the lunar regolith, but no measurements directly on the surface were available.

With the Advanced Small Analyzer for Neutrals (ASAN) mounted on the Yuyu-2 the rover of Chang'E-4, for the first time measurements of the energetic neutral atom flux originating from the lunar surface were preformed directly on the lunar surface itself. ASAN measures with a single angular pixel the energy spectrum of energetic neutral atoms reflected or sputtered form the surface with coarse mass resolution. ASAN uses the mobility of the rover to cover different solar wind illumination angles and scattering angles from the surface.

Since the landing of Chang'E-4 in the Von Kármán crater on the lunar far side in January 2019, ASAN has spent more than one year on the lunar surface and performed typically two measurement sessions per lunar day with nominal performance.

We review the ASAN instrument status and operations; present energy and mass spectra of energetic neutral atoms backscattered and sputtered from the surface, and discuss sputtering yields observed during different observation sessions. We put these observations into context of earlier remote sensing data by the SARA instrument on Chandrayaan-1.

How to cite: Wieser, M., Barabash, S., Wang, X.-D., Zhang, A., Wang, C., and Wang, W.: Solar wind interaction with the lunar surface: Observation of energetic neutral atoms on the lunar surface by the Advanced Small Analyzer for Neutrals (ASAN) instrument on the Yutu-2 rover of Chang'E-4. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9199, https://doi.org/10.5194/egusphere-egu2020-9199, 2020.

EGU2020-6186 | Displays | PS2.2

Simulating the Reiner Gamma Swirl and Magnetic Anomaly: The Impact of the Solar Wind Alpha Population

Jan Deca, Douglas J. Hemingway, Andrey Divin, Charles Lue, Andrew R. Poppe, Ian Garrick-Bethell, Bertrand Lembège, and Mihály Horányi

The Reiner Gamma swirl is one of the most prominent albedo features on the lunar surface. Its modest spatial scales and structure allows fully kinetic modelling. The region therefore presents a prime location to investigate the lunar albedo patterns and their co-location with magnetic anomalies. The precise relationship between the impinging plasma and the swirl, and in particular, how these interactions vary over the course of a lunar day, remains an open issue.

Here we use the fully kinetic particle-in-cell code,  iPIC3D, coupled with a magnetic field model based on Kaguya and Lunar Prospector observations, and simulate the interaction with the Reiner Gamma anomaly for all plasma regimes the region is exposed to along a typical orbit, including different solar wind incidence angles and the Moon's crossing through the terrestrial magnetosphere. We focus on the impact of the solar wind alpha population and construct energy and velocity distributions in key locations surrounding the interaction region of the anomaly.

The energy flux profile provides a better match to the albedo pattern only when integrating over the full lunar orbit. Including He2+ as a self-consistent plasma species improves the brightness ratios between the inner and outer bright lobes, the dark lanes, and the mare background. However, substantial differences between the observed albedo pattern and the predicted flux remain.  For example, the bright outer lobes are substantially brighter than predicted and the central portion of the anomaly is darker than predicted. This is likely due to an incomplete model of the near-surface field structure.

Solar wind standoff can explain the large-scale correlation between the Reiner Gamma swirl and the co-located magnetic anomaly. In particular, the outer bright lobes emerge in the simulated weathering pattern only when integrating over the entire lunar orbit, although they are much weaker than observed. Both the proton and helium energy flux to the surface need to be taken into account to best reproduce the swirl pattern. A complete understanding of the solar wind interaction with lunar magnetic anomalies and swirl formation could be vastly improved by low altitude measurements of the magnetic field and solar wind.

How to cite: Deca, J., Hemingway, D. J., Divin, A., Lue, C., Poppe, A. R., Garrick-Bethell, I., Lembège, B., and Horányi, M.: Simulating the Reiner Gamma Swirl and Magnetic Anomaly: The Impact of the Solar Wind Alpha Population, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6186, https://doi.org/10.5194/egusphere-egu2020-6186, 2020.

EGU2020-9656 | Displays | PS2.2

A Double-Disturbed Lunar Plasma Wake

Anthony Rasca, Shahab Fatemi, William Farrell, Andrew Poppe, and Yihua Zheng

Under nominal solar wind conditions, a low density wake region forms downstream of the nightside lunar surface.  However, the lunar plasma environment undergoes a transformation as the Moon passes through the Earth’s magnetotail, with the warm plasma typically not having a strong flow, and thus the wake structure disappears.  However, while in the tail, there can be a sudden intense change due to solar-driven events such as coronal mass ejections.  With a new planned human presence on the Moon, it is important to understand the near-surface plasma environment’s response to these extreme conditions.  We investigate the response of the lunar wake to a passing coronal mass ejection on 2012 March 8 while crossing the Earth’s magnetotail using both a large-scale MHD model of the Earth’s global magnetosphere and smaller-scale 3-D hybrid-PIC simulations.

The CME plasma shock was detected by the Wind spacecraft around 10:30 UT and in the Earth’s magnetotail around 11:20 UT by the ARTEMIS spacecraft in lunar orbit.  Wind observations are used as time-dependent up-stream conditions for a 24-hour global magnetosphere MHD simulation run through NASA’s Community Coordinated Modeling Center using the OpenGGCM model.  Extracted plasma parameters from the ARTEMIS spacecraft following the plasma shock are used as upstream static boundary conditions for hybrid-PIC simulations using the AMITIS code.

Results for the hybrid-PIC lunar wake simulations performed during a momentary jump in magnetotail plasma velocity and density show a short misaligned plasma void relative to nominal SW conditions.  MHD results indicate that changes near the Moon appear as a result of a warped magnetopause boundary moving inward after 11:00 UT, causing the Moon to enter the magnetosheath.  These results also show a number of plasmoids developing and propagating down the tail, including one seen at 11:20 UT that corresponds temporarily with plasmoid-like features in the ARTEMIS magnetic field profiles.

How to cite: Rasca, A., Fatemi, S., Farrell, W., Poppe, A., and Zheng, Y.: A Double-Disturbed Lunar Plasma Wake, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9656, https://doi.org/10.5194/egusphere-egu2020-9656, 2020.

EGU2020-13261 | Displays | PS2.2

On the Space Weather Effect and CME-Driven Exospheres of the Moon and Ceres

Hua-Shan Shi, Zheng-Xian Chen, and Wing-Huen Ip

A number of moon-sized objects in the solar system are characterized by the formation of a surface-bound exosphere. These include the Moon, Ceres, Jupiter’s icy moons, namely, Europa, Ganymede and Callisto, and several of the Saturnian icy moons including Rhea, Dione, and Tethys. There are several major source mechanisms ranging from micrometeoroid bombardment, photo-stimulated desorption, and energetic ion sputtering - in addition to the surface (or subsurface) thermal sublimation in the case of Ceres and the icy Moon. It is interesting that Ceres and the Moon could experience extreme space weather effects when they encounter large solar flare events or coronal mass ejection events. An important consequence is the production of a transient exosphere due to the sudden increase of ion sputtering rates. We have developed time-dependent Monte Carlo models that can be applied to the Moon and Ceres. Some simulation results will be described in this presentation with a view to construct the CME-driven H2O and O2 exosphere of Ceres and the flare-up of the lunar sodium corona and tail emission.

How to cite: Shi, H.-S., Chen, Z.-X., and Ip, W.-H.: On the Space Weather Effect and CME-Driven Exospheres of the Moon and Ceres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13261, https://doi.org/10.5194/egusphere-egu2020-13261, 2020.

EGU2020-19415 | Displays | PS2.2

Imaging of Ganymede through Energetic Neutral Atoms sputtered/backscattered from the surface

Angèle Pontoni, Manabu Shimoyama, Shahab Fatemi, Andrew Poppe, Yoshifumi Futaana, and Stas Barabash

Brightness asymmetries on the surface of Ganymede are thought to be caused by ion impact from Jovian co-rotating plasma. The Jovian Neutrals Analyzer instrument onboard the JUICE spacecraft will help investigate this theory by yielding a map of ion precipitation at the surface of Ganymede through the observation of low-energy Energetic Neutral Atoms (ENAs) (10 eV to 3300 eV) sputtered or backscattered by the Jovian plasma.


In order to optimize JNA operations planning at Ganymede, we
estimate the expected energy distribution of ENAs caused by the impacting Jovian plasma. As an input, we use results from a three dimensional hybrid plasma simulation, which gives us the energy distribution of precipitating H+, O++ and S+++ at the surface of Ganymede. We then calculate the ENA yield using respectively Famà’s model (Famà, 2008) for the sputtering yield of water ice and Thompson-Sigmund’s model (Sigmund, 1969) for electronic sputtering to get the energy distribution of the ENAs.

How to cite: Pontoni, A., Shimoyama, M., Fatemi, S., Poppe, A., Futaana, Y., and Barabash, S.: Imaging of Ganymede through Energetic Neutral Atoms sputtered/backscattered from the surface, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19415, https://doi.org/10.5194/egusphere-egu2020-19415, 2020.

EGU2020-21771 | Displays | PS2.2

A new MHD model for Io's and Europa's plasma interaction

Aljona Blöcker, Lorenz Roth, Nickolay Ivchenko, Emmanuel Chané, and Ronny Keppens

Io and Europa are embedded in Jupiter’s magnetosphere and the moons’ surfaces and atmospheres interact with the surrounding moving magnetized plasma forming a complex plasma interaction. The interaction scenarios for both moons are characterized by inhomogeneities in the atmospheres from local outgassing. These inhomogeneities affect the electromagnetic environment but can also lead to localized features in the moons' auroral emissions. The moons’ aurora in turn is sensitive to the energy or temperature of the exciting electrons in the plasma. To simulate the interaction scenarios including atmospheric inhomogeneities and aurora generation, we expand the magnetohydrodynamic code MPI-AMRVAC by implementing a self-consistent description of the electron temperature and the electron density where the cooling by inelastic collisions between the magnetospheric electrons and the atmosphere, and the electron heat flux from the magnetospheric plasma to the moons’ ionosphere are included. Furthermore, the numerical schemes of MPI-AMRVAC are able to handle discontinuities that arise from the atmospheric inhomogeneities. Here, we demonstrate the implementation of the physical effects and first modeling results of Io’s and Europa’s plasma interaction with the advanced MHD code.

How to cite: Blöcker, A., Roth, L., Ivchenko, N., Chané, E., and Keppens, R.: A new MHD model for Io's and Europa's plasma interaction, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21771, https://doi.org/10.5194/egusphere-egu2020-21771, 2020.

EGU2020-4881 | Displays | PS2.2

Energetic ion depletions near Europa and Io: the effect of plumes and atmospheric charge exchange

Hans Huybrighs, Christiaan van Buchem, Aljona Blöcker, Elias Roussos, Norbert Krupp, Vincent Dols, Futaana Yoshifumi, Stas Barabash, Olivier Witasse, and Mika Holmberg

Introduction

The flux of energetic ions (protons, oxygen and sulfur) near the Galilean moons were measured by the Energetic Particle Detector (EPD) on the Galileo mission (1995 - 2003). Near Galilean moons (such as Io and Europa) depletions of the energetic ion flux, of several orders of magnitude, were identified.

Such energetic ion depletions can be caused by the absorption of these particles onto the moon’s surfaces or by the loss due to charge exchange with neutral molecules in the atmospheres or potential plumes. To interpret the depletion features in the EPD data, a Monte Carlo particle tracing simulation has been conducted. The expected fluxes of the energetic ions are simulated under different scenarios including those with and without an atmosphere or plume. By comparing the simulated flux [YF1] to the EPD data, we investigate the cause of the depletion features with particular focuses on Europa and Io flybys.

Results

For Europa we report the following findings:

  • For flyby E12 we find that a global atmosphere should produce a depletion region along the trajectory that is symmetrical to the closest approach, for energetic protons in the energy range of 80-220 keV. No such feature is visible in the data. Upper limits of the atmosphere are consistent with surface densities (⩽ 108 cm-3) and scale heights (50-350 km) of previous studies. We find that a depletion of energetic protons (80-220 keV) occurring before closest approach is consistent with the field perturbations associated with a plume. This plume features coincides in time with the plume reported by Jia et al., 2018.
  • For flyby E26 we find that the depletions of energetic protons (80-220 keV) are consistent with a simulation that takes into account the perturbations of the fields as calculated by an MHD simulation and atmospheric charge exchange. Furthermore, a depletion feature occurring shortly after closest approach is consistent with the field perturbations associated with a plume, located near the plume reported by Arnold et al., 2019.
  • From these investigations, we confirm, independently from previous reports, that the Galileo spacecraft could have passed near plumes.

For Io we report the following results:

  • We identify regions of proton (80-220 keV) depletions during Io flybys I24, I27 and I31 extending beyond one Io radius. The depletions features are not consistent with Io as an inert body. We investigate atmospheric charge exchange as a cause for the depletions.

How to cite: Huybrighs, H., van Buchem, C., Blöcker, A., Roussos, E., Krupp, N., Dols, V., Yoshifumi, F., Barabash, S., Witasse, O., and Holmberg, M.: Energetic ion depletions near Europa and Io: the effect of plumes and atmospheric charge exchange, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4881, https://doi.org/10.5194/egusphere-egu2020-4881, 2020.

EGU2020-19091 | Displays | PS2.2

Io’s auroral footprints: MHD simulations of the interaction between Io and Jupiter

Stephan Schlegel and Joachim Saur

The electromagnetic interaction between Jupiter and its innermost Galilean moon Io is a prime example for moon-planet and star-planet interaction. A very striking feature is the Io Foot Print (IFP) in Jupiter’s upper atmosphere. With the Juno spacecraft orbiting Jupiter, new insights about the complex structure of the IFP have been achieved which can not be fully explained by existing models. A deeper understanding is necessary to explain these Juno observations [Mura et al. 2018, Szalay et al. 2018]. For that purpose a simulation of the system with the single fluid MHD-Code Pluto is set up to study the Alfvén wing generated by Io in detail. In our study, we use a model similar to Jacobsen et al. 2007 with a constant magnetic field and spatially varying density. Then we increase the complexity of this model by including a more realistic wave generator, i.e. Io, and a more complex model of the Jovian inner magnetosphere.

How to cite: Schlegel, S. and Saur, J.: Io’s auroral footprints: MHD simulations of the interaction between Io and Jupiter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19091, https://doi.org/10.5194/egusphere-egu2020-19091, 2020.

EGU2020-3420 | Displays | PS2.2

Electron irradiation of water ice samples in the laboratory - Implications for icy moons and comets

André Galli, Romain Cerubini, Antoine Pommerol, Peter Wurz, Audrey Vorburger, Martin Rubin, Apurva Oza, Marek Tulej, Nicolas Thomas, and Niels F.W. Ligterink

The surfaces of icy bodies in the solar system are continuously irradiated by charged particles from planetary magnetospheres or from the solar wind. This irradiation induces chemical reactions in the surface ice and also acts as an atmospheric release process. Remote observations, theoretical modelling, and laboratory experiments must be combined to understand this plasma-ice interaction. In this presentation, we concentrate on laboratory experiments with electron irradiation (energy range of 0.1 to 10 keV) of water ice. The samples include thin ice films on a microbalance as well as thick layers of porous ice, resembling regolith. The physical and optical properties of the latter make them realistic analogues for the surfaces of icy moons.

We measure the sputtering yield and monitor the irradiation-induced alterations in the ice samples with a dedicated new time-of-flight mass spectrometer.
Previous results obtained with an earlier quadrupole mass spectrometer (Galli et al. 2018, Planetary and Space Sciences) indicated that most water escaping the ice sample upon electron irradiation does so in the form of the radiolysis products H2 and O2. The freshly produced H2 appeared to leave the porous water ice sample immediately whereas the O2 escape slowly increased until reaching a steady-state ratio of 1:2 of O2 to H2. With the new mass spectrometer, we investigate the release and storage of radiolysis products at a higher temporal resolution and sensitivity for a variety of ice sample porosities and thicknesses. We pay special attention to less abundant radiolysis products such as H2O2 and to the O2/H2O ratio in the irradiated water ice layer.

How to cite: Galli, A., Cerubini, R., Pommerol, A., Wurz, P., Vorburger, A., Rubin, M., Oza, A., Tulej, M., Thomas, N., and Ligterink, N. F. W.: Electron irradiation of water ice samples in the laboratory - Implications for icy moons and comets , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3420, https://doi.org/10.5194/egusphere-egu2020-3420, 2020.

EGU2020-5731 | Displays | PS2.2

Ionization profile of meteors from simultaneous video and radio forward scatter observations

Hervé Lamy, Michel Anciaux, Sylvain Ranvier, Antoine Calegaro, and Carl Johannink

In this study, optical video observations of meteors with the CAMS (Camera for All-sky Meteor Surveillance)-BeNeLux network and radio forward scatter observations with the BRAMS (Belgian RAdio Meteor Stations) network obtained on 4-5 October 2018  are combined in order to obtain an ionization profile along a meteor path.

The trajectory, initial speed and deceleration parameters of a given meteor are provided by the CAMS-BeNeLux data. For a given trajectory, the positions of the specular reflection points for radio waves are computed for each combination of a given BRAMS receiving station and the BRAMS transmitter. For each receiving station which recorded a meteor echo (depending on the geometry and the SNR ratio), the power profile is computed and the peak power values of the underdense meteor profiles are used to determine the ionization (electron line density) at the various specular reflection points along the meteor path. This is done using the McKinley (1961) formula which is strictly valid for underdense meteor echoes.  We discuss how we compute the gains of the antennas, the polarization factor, and how the peak power values are transformed from arbitrary units into watts using the signal recorded from a device called the BRAMS calibrator. We also discuss how to extend this study to overdense meteor echoes or those with intermediate electron line densities.

Finally, these results are combined with a simple ablation meteor model in order to obtain an estimate of the initial mass of the meteoroid.

Mc Kinley D.W.R., Meteor science and engineering, Mc Graw-Hill eds, 1961

How to cite: Lamy, H., Anciaux, M., Ranvier, S., Calegaro, A., and Johannink, C.: Ionization profile of meteors from simultaneous video and radio forward scatter observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5731, https://doi.org/10.5194/egusphere-egu2020-5731, 2020.

EGU2020-5097 | Displays | PS2.2

Pomeranian Bolide

Helena Ciechowska, Aleksandra Fronczak, Maciej Karasewicz, Klaudia Mocek, Mikołaj Zawadzki, and Marek Grad

October 31st of 2015 the bolide lightened up the sky above Northern Poland. The main purpose of the project  was to define the place and time of its explosion in Earth’s atmosphere. To calculate these values and define the velocity of acoustic wave in the air, MATLAB model has been created. The model was based on seismic records of the event from GKP permanent seismological station and few stations of temporary array 13 BB star, arrival time of the wave to each station was read from seismograms. Using this data it was possible to indicate the narrowed area on plane where the explosion could take place. Next step was to model elevated point of explosion, time of the explosion, and the velocity of sonic wave in Earth’s atmosphere for spherical Earth 3D model, needed for the wave to travel from the point of explosion to seismological station.

How to cite: Ciechowska, H., Fronczak, A., Karasewicz, M., Mocek, K., Zawadzki, M., and Grad, M.: Pomeranian Bolide, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5097, https://doi.org/10.5194/egusphere-egu2020-5097, 2020.

EGU2020-3931 | Displays | PS2.2

Concerning the impact of deorbiting spacecraft to the upper atmosphere

Leonard Schulz and Karl-Heinz Glassmeier

The increasing activities in space due to more and more countries with space programs, advancing commercialization, and large satellite constellation projects lead to a rising number of human-made objects in space. While many of those stay in orbit at high altitudes, objects in low Earth orbit reenter the atmosphere mostly disintegrating and injecting material into the atmosphere. The growing concern about space debris has led to policies encouraging deorbiting of satellites at the end of their lifetime. All that will increase the annual mass influx into the atmosphere by human-made (anthropogenic) objects in the future. We compare the influx of those objects to the natural mass influx of entering meteoroids of asteroidal, cometary, and planetary origin into Earth's atmosphere. We look at the mass and the elemental composition of the entering bodies also incorporating different ablation of those objects. This way, a quantitative assessment of the annual injection of aerosols and atomic remnants into the atmosphere is possible. Today, anthropogenic material makes up way less than 1 % of the overall injected mass. However, future large spacecraft constellations could increase the anthropogenic influx significantly, then contributing 4 % or more of the whole injection. As spacecraft have a high abundance of metal elements, the metal mass portion of the injection can reach up to 15 %. For some elements, the anthropogenic injection may even prevail the natural injection. This implies for future large satellite constellations that the anthropogenic injection can become significant with unknown effects on the upper atmosphere and the terrestrial habitat.

How to cite: Schulz, L. and Glassmeier, K.-H.: Concerning the impact of deorbiting spacecraft to the upper atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3931, https://doi.org/10.5194/egusphere-egu2020-3931, 2020.

EGU2020-14165 | Displays | PS2.2

Model Calculations on the Influence of Charged Mesospheric dust on the Incoherent Radar Spectrum

Tinna Gunnarsdottir, Ingrid Mann, and Wojciech Miloch

Detection of charged dust in the spectrum of incoherent radars has previously been proposed and examined to some degree. These dust particles are of nanometer size and reside at mesospheric altitudes due to incoming ablating meteors. They are difficult to detect and thus their influence on atmospheric processes is hard to determine. Theoretical studies suggest that charged nanometer sized dust in the mesosphere can be successfully detected in the radar spectrum. However, current radar systems like EISCAT are not capable to distinguish adequately the dust signal from the main signal because the influence is small. We expect however, that the upcoming new EISCAT_3D radar will improve the observation conditions. We here present model calculations to examine the influence of the charged dust component on the radar signal, a so-called dusty plasma effect. Instead of the previously assumed one size dust component, we simulate the incoherent scatter spectrum including a large set of dust size bins. We show that different sizes, number density and charge of dust influence the signal in different ways, either causing a narrowing or broadening of the spectrum. Here the results are presented in a systematic way and specific conditions identified that provide the largest chance of dust detection in the signal. A simple charging model is used to model the most probable charge and altitude dependence to simulate realistic dust distributions that are then used as input to the radar spectrum model. These results can then be used to compare with actual radar measurements. Off which the new EISCAT_3D radar system, ready in 2022, might provide the adequate resolution for these requirements.

How to cite: Gunnarsdottir, T., Mann, I., and Miloch, W.: Model Calculations on the Influence of Charged Mesospheric dust on the Incoherent Radar Spectrum, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14165, https://doi.org/10.5194/egusphere-egu2020-14165, 2020.

EGU2020-19548 | Displays | PS2.2

Does organic carbon hold micrometeoroids together?

David L. Bones, Juan Diego Carrillo-Sánchez, Alexander D. James, Simon D. Connell, John M. C. Plane, and Graham W. Mann

The cosmic dust input into the Earth’s atmosphere has been estimated at 28 tonnes per day. However, the models behind this estimate do not include fragmentation. If the particles fragment significantly, the input rate of dust would be considerably higher. Millimetre sized meteoroids have been observed to fragment. If this is true for the majority of the cosmic dust particles that enter the Earth’s atmosphere (size range 10 micron to 1 mm), it would make a difference to the rates of ablation of these particles and our understanding of the meteoric inputs into the Earth’s mesosphere. Fragmentation would result in a broader size distribution and a greater number of 0.2 – 1.0 micron-sized particles sedimenting into the stratosphere.

The Meteoric Ablation Simulator (MASI) is a chamber for investigating the ablation of volatile species from meteoroid proxies. Here, we run it at relatively low temperatures to investigate the pyrolysis of hydrocarbon compounds. It has been proposed that organic carbon compounds act as a glue to hold the grains within micrometeoroids together. The carbon compounds are thought to be tarry, refractory kerogen compounds similar to those found in terrestrial oil shale. At moderate temperatures, these compounds pyrolyse into species such as butane and pentane.

The MASI employs a heated surface, the temperature of which can be varied from 300 to 1200 K. Once the surface is up to temperature, particles are dropped onto it. The ablating carbon-containing compounds are detected by mass spectrometry. The majority of the ablated carbon combusts to CO2. Measuring the rate of CO2 production as the particles are exposed to specific temperatures enables the temperature-dependent rate of pyrolysis of the carbon compounds to be measured.

To measure the effect of the removal of the carbon compounds on the strength of the particle, particles are subjected to yield stress tests in an atomic force microscope (AFM). Particles that have been flash heated, breaking bonds in the hydrocarbon glue, are expected to be more fragile.

Powdered meteorite samples (2% organic carbon) lose carbon over a broader range of temperatures than powdered oil shale (15% organic carbon). The effective activation energies measured for this pyrolysis are low – about 90 and 60 kJ mol-1 for the oil shale and CM2 meteorite, respectively. This is likely a combination of 1) particles not reaching the surface temperature due to evaporative cooling and 2) the complexity of the reactions occurring in the carbonaceous particles as they heat. Analysis of TGA traces for oil shale samples give a higher effective activation energy of 191 kJ mol-1. This value agrees with other TGA analyses of oil shale. In both cases, the biggest loss of carbon happens at around 700 – 800 K. AFM yield stress tests show evidence of fracturing, but so far only at pressures too high to be relevant for fragmentation in the atmosphere.

How to cite: Bones, D. L., Carrillo-Sánchez, J. D., James, A. D., Connell, S. D., Plane, J. M. C., and Mann, G. W.: Does organic carbon hold micrometeoroids together?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19548, https://doi.org/10.5194/egusphere-egu2020-19548, 2020.

EGU2020-6717 | Displays | PS2.2

The influence of surface charge on dust agglomeration growth in the mesosphere

Ingrid Mann, Joshua Baptiste, John Fox, Anthony J. Stace, and Elena Besley

The growth of particles is an important consideration toward a better understanding of the role of dust, ice and refractory particles in the upper mesosphere and lower thermosphere: in short, the MLT region (60 to 130 km). We investigate the conditions of dust growth via mutual collisions. It is assumed that meteoric smoke particles (MSP) are the main dust component in the mesosphere. MSP are small condensates that form in the diffusing meteor and are transported in the atmosphere where they grow by condensation. A second dust component are ice particles that form during summer months at mid and high latitude. These Polar Mesospheric Cloud (PMC) particles are composed of water ice and possibly include a fraction of the smaller MSP.

In this work, we investigate the effect of surface charge on the aggregation and growth of particles in the MLT region. The specific materials of the particles considered are similar to those typically found or expected in this region such as silica, metal oxides and ice, with particle sizes of 0.5 nm and larger. To consider the influence of the surface charges, we apply a model of the electrostatic interaction between particles of dielectric materials that, given the right conditions, includes the possibility for an attractive interaction between like-charged particles (Bichoutskaia et al. 2010). This like-charge attraction occurs due to the mutual polarisation of surface charge densities leading to regions of negative and positive surface densities close to the point of contact between the particles (Stace et al. 2011). This general model allows to investigate the interactions between particles of different size, charge and compositions. We simulate the interactions for particles of same charge and pairs of neutral and charged particles under different collision conditions in the MLT.

Bichoutskaia, E., (E. Besley), et al. J. Chem. Phys., 133(2), 024105 (2010).

Stace, A. J., et al. J. Colloid Interface Sci. 354(1), 417-420 (2011).

 

How to cite: Mann, I., Baptiste, J., Fox, J., Stace, A. J., and Besley, E.: The influence of surface charge on dust agglomeration growth in the mesosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6717, https://doi.org/10.5194/egusphere-egu2020-6717, 2020.

PS3.6 – Atmospheres and exospheres of terrestrial planets, satellites, and exoplanets

EGU2020-1032 | Displays | PS3.6

The dependence of global and local metrics of super-rotation on planetary rotation rate

Neil Lewis, Greg Colyer, and Peter Read
Super-rotation is a phenomenon in atmospheric dynamics where the axial angular momentum of an atmosphere in some way exceeds that of the underlying planet. In this presentation, we will discuss the dependency of both globally-integrated, and local metrics of super-rotation on planetary rotation rate, revealed through analysis of idealised General Circulation Model experiments. The model used here is based on the Held-Suarez benchmark for a dry, 'Earth-like' atmosphere, and results from both axisymmetric and three-dimensional experiments will be presented. Previous work has shown that the three-dimensional configuration used here will transition to a state of equatorial super-rotation if the rotation rate is reduced sufficiently from the Earth's. This motivates the question: How does super-rotation strength depend on rotation rate?

We will use the term 'global super-rotation' to refer to an atmosphere with excess of globally-integrated axial angular momentum relative to that achieved by solid body co-rotation with the underlying planet, and 'local super-rotation' to refer to the existence of some region within the atmosphere where axial angular momentum exceeds that of the underlying planet at the equator. In an inviscid, axisymmetric atmosphere, the axial component of specific angular momentum is materially conserved. Consequently, in such a system local super-rotation is forbidden, although global super-rotation may still be achieved if a meridional circulation is able to transport fluid equilibrated with the equatorial surface poleward. If the restriction of axisymmetry is lifted, then local super-rotation may exist if non-axisymmetric disturbances that act to transport angular momentum up-gradient are present. The atmospheres of Venus, the Earth, Mars, and Titan may be considered to be globally super-rotating, however only Venus and Titan exhibit permanent local super-rotation at the equator.

The results from axisymmetric experiments reveal that at high rotation rate (e.g., greater than 1/4 of the Earth's), the degree of global super-rotation scales inversely with the square of the rotation rate. In the low rotation rate limit, the degree of global super-rotation saturates, and becomes independent of rotation rate. We will show that the high, and low rotation rate dependencies can be predicted by a single analytic scaling for global super-rotation. Our three-dimensional experiments exhibit the same scaling behaviour for global super-rotation as observed in the axisymmetric experiments. The degree of global super-rotation achieved by the three-dimensional experiments is less than that of the axisymmetric experiments at high rotation rates, and greater at lower rotation rates, but in both limits the deviation from the axisymmetric 'base circulation' is small. In the low-rotation rate limit, local super-rotation is accelerated at the equator, which is consistent with the three-dimensional experiments obtaining a higher degree of global super-rotation than their axisymmetric counterparts. Estimates for global super-rotation strength on the Earth and Mars agree closely with the results of our three-dimensional numerical experiments, but Venus and Titan achieve substantially stronger global, and local super-rotation than found here. It appears that low rotation rate alone cannot induce substantial excess global super-rotation, relative to the axisymmetric base circulation we identify.

How to cite: Lewis, N., Colyer, G., and Read, P.: The dependence of global and local metrics of super-rotation on planetary rotation rate, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1032, https://doi.org/10.5194/egusphere-egu2020-1032, 2020.

EGU2020-3000 | Displays | PS3.6

Galactic cosmic ray induced ionisation on Venus and its effect on cloud droplet stability

Martin Airey, Giles Harrison, Karen Aplin, and Christian Pfrang

Galactic cosmic rays are ubiquitous in solar system atmospheres. On Venus, the altitude of peak ion production due to cosmic rays (the Pfotzer-Regener maximum) occurs at ~63 km, within the optically thick region of the upper clouds. This indicates the possibility of electrical effects on droplets within Venusian clouds. Motivated by this, our VENI (Venusian Electricity, Nephology, and Ionisation) project explores effects of galactic cosmic ray (GCR) induced ionisation on cloud droplets in circumstances with relevance to Venus’ atmosphere. Charge is known to lower the critical supersaturation required for cloud droplets to form; slightly larger droplets are stable at lower saturation ratios if sufficiently charged. Condensation of gas directly onto ions is also potentially possible on Venus if the atmosphere is sufficiently supersaturated. GCRs and the secondary charged particles they produce are therefore anticipated to affect cloud droplet behaviour on Venus.

Experiments have been conducted using electrically isolated droplets, through levitation in a standing acoustic wave. The droplets are monitored with a high-magnification CCD camera to determine their evaporation rate and charge. The charge is measured both by the deflection in an electric field and by passing the droplet through a custom-built induction ring. A relationship between the evaporation rate and charge of the droplets is found to be consistent with theory, allowing droplet lifetime to be predicted for a given charge. Further experiments using sulphuric acid droplets in a carbon dioxide environment offer more direct relevance to the Venusian environment and cosmic ray enhancement due to solar energetic particles (SEPs) in space weather events will be simulated using a corona source.

How to cite: Airey, M., Harrison, G., Aplin, K., and Pfrang, C.: Galactic cosmic ray induced ionisation on Venus and its effect on cloud droplet stability, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3000, https://doi.org/10.5194/egusphere-egu2020-3000, 2020.

EGU2020-16220 | Displays | PS3.6

Possibility of lightning in the Venusian clouds due to Super-rotation

Adhithiyan Neduncheran and Sruthi Uppalapati

Lightning in Venus is still a matter of debate due to lack of evidence in optical and simultaneous radio emissions. Several evidence of electromagnetic emissions were previously measured by various landers and orbiters studying Venus atmosphere such as the Venera 13 and 14 landers, Venus Express and the Pioneer Venus Orbiter. This theoretical work proposes the mechanism of lightning is possibly due to the super-rotation of the clouds. Excessive amount of atmospheric turbulence and the formation of plumes in the clouds of Venus should possibly lead to the formation of charges in the clouds and thereby trigger lightning. As per Lorenz 2018, it is expected that there might exist charged aerosols in the lower atmosphere. This imposes another possibility of triboelectric charging mechanism which lead to lightning in the lower and middle cloud region. Lightning induced electromagnetic emissions that takes place in the clouds might be a result of momentum transfer and charge dispersion in the clouds of Venus. Venus can be considered to be an optically active planet with phenomenon like reflection and refraction ruling to some extent which possibly imposes a difficulty in lightning detection as the photons emitted during this process are scattered away. In the end, the possible lightning mechanism and difficulties related to its detection shall be discussed

How to cite: Neduncheran, A. and Uppalapati, S.: Possibility of lightning in the Venusian clouds due to Super-rotation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16220, https://doi.org/10.5194/egusphere-egu2020-16220, 2020.

EGU2020-17962 | Displays | PS3.6

The distribution and saturation of water vapor as inferred from ACS during the first Martian year of TGO Science observations

Anna Fedorova, Franck Montmessin, Oleg Korablev, Mikhail Luginin, Alexander Trokhimovskiy, Denis Belyaev, Juan Alday, Nikolay Ignatiev, Franck Lefevre, Kevin Olsen, Ehouarn Millour, Jean-Loup Bertaux, Alexey Shakun, Alexey Grigoriev, Andrey Patrakeev, Svyatoslav Korsa, Colin Wilson, Francois Forget, and Anna Maattanen

The water vapour vertical distribution is an eloquent gauge of the relative roles of the various sources, sinks and processes that control the Martian water cycle. However, its behaviour is still poorly studied while it is instrument for our understanding of the loss of water from Mars to space, which results from the transport of water to the upper atmosphere where it is disassociated to hydrogen atoms that later escape. We use the Atmospheric Chemistry Suite on the ExoMars Trace Gas Orbiter to characterize the water distribution with altitude. Here we present results of the Atmospheric Chemistry Suite (ACS) instrument NIR channel for the first year of TGO observations covering the almost full year from Ls 160° of the Martian year 34 (April 2018) to Ls 130° of the Martian year 35 (January 2020). Simultaneous measurements of the water vapour mixing ratio, temperature and dust vertical distribution and formation of water ice clouds allow us to constrain the complex water behaviour and estimate the saturation state of H2O. Water profiles during the 2018-2019 southern spring and summer stormy seasons show that high altitude water is preferentially supplied close to perihelion and that large supersaturation occurs even when clouds are present. Here we attempt to complete the story by studying water vapor during the northern spring and summer to explore whether saturation impacts water transport between hemispheres in this season. The data analysis of MY35 was supported by RSF (project No. 20-42-09035).

How to cite: Fedorova, A., Montmessin, F., Korablev, O., Luginin, M., Trokhimovskiy, A., Belyaev, D., Alday, J., Ignatiev, N., Lefevre, F., Olsen, K., Millour, E., Bertaux, J.-L., Shakun, A., Grigoriev, A., Patrakeev, A., Korsa, S., Wilson, C., Forget, F., and Maattanen, A.: The distribution and saturation of water vapor as inferred from ACS during the first Martian year of TGO Science observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17962, https://doi.org/10.5194/egusphere-egu2020-17962, 2020.

EGU2020-2183 | Displays | PS3.6

Large amplitude exospheric waves seen in MAVEN NGIMS data

Hayley Williamson, Robert Johnson, Ludivine Leclercq, and Meredith Elrod

We examine high altitude gravity waves in the upper atmosphere of Mars using the data from the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, orbiting Mars since late 2014. Since the Martian atmosphere is very thin it is also highly perturbed and the effects of these perturbations are debated. Therefore, on 252 trajectories through the Martian atmosphere large amplitude, high altitude perturbations seen in the NGIMS database are examined. When the perturbations are organized by column density rather than altitude, the perturbations both peak and dissipate at similar column densities. These perturbations also increase the O/CO2 ratio above that measured for orbits without a significant perturbation. To understand this effect, the perturbations are subsequently categorized by location and found to be roughly consistent with wave activity seen lower in the atmosphere. Because the NGIMS data for each perturbation cannot measure the temperature or long term behavior, we simulate wave propagation using a Direct Simulation Monte Carlo (DSMC) model. The results from such simulations suggest that these perturbations are most likely large amplitude acoustic gravity waves, whose high frequency and fast phase speed allow them to propagate into the Martian exosphere, affecting the diffusive separation of species and depositing heat.

How to cite: Williamson, H., Johnson, R., Leclercq, L., and Elrod, M.: Large amplitude exospheric waves seen in MAVEN NGIMS data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2183, https://doi.org/10.5194/egusphere-egu2020-2183, 2020.

EGU2020-433 | Displays | PS3.6

Dynamics of the extremely elongated cloud on Mars Arsia Mons volcano

Jorge Hernandez Bernal, Agustín Sánchez-Lavega, Teresa del Río-Gaztelurrutia, Ricardo Hueso, Iñaki Ordóñez-Etxeberria, Alejandro Cardesín-Moinelo, Eleni Ravanis, Simon Wood, Dmitrij Titov, Kyle Connour, Nick Schneider, Daniela Tirsch, Ralf Jaumann, Ernst Hauber, and Brigitte Gondet

Starting in September 2018, a daily repeating extremely elongated cloud was observed extending from the Mars Arsia Mons volcano. We study this Arsia Mons Elongated Cloud (AMEC) using images from VMC, HRSC, and OMEGA on board Mars Express, IUVS on MAVEN, and MARCI on MRO. We study the daily cycle of this cloud, showing how the morphology and other parameters of the cloud evolved with local time. The cloud expands every morning from the western slope of the volcano, at a westward velocity of around 150m/s, and an altitude of around 30-40km over the local surface. Starting around 2.5 hours after sunrise (8.2 Local True Solar Time, LTST), the formation of the cloud resumes, and the existing cloud keeps moving westward, so it detaches from the volcano, until it evaporates in the following hours. At this time, the cloud has expanded to a length of around 1500km. Short time later, a new local cloud appears on the western slope of the volcano, starting around 9.5 LTST, and grows during the morning.

This daily cycle repeated regularly for at least 90 sols in 2018, around Southern Solstice (Ls 240-300) in Martian Year (MY) 34. According with these and previous  MEx/VMC observations, this elongated cloud is a seasonal phenomenon occurring around Southern Solstice every Martian Year. We study the interannual variability of this cloud, the influence of the Global Dust Storms in 2018 on the cloud’s properties (Sánchez-Lavega et al., Geophys. Res. Lett. 46, 2019), and its validity as a proxy for the global state of the Martian atmosphere (Sánchez-Lavega et al., J. Geophys. Res., 123, 3020, 2018). We discuss the physical mechanisms behind the formation of this peculiar cloud in Mars.

How to cite: Hernandez Bernal, J., Sánchez-Lavega, A., del Río-Gaztelurrutia, T., Hueso, R., Ordóñez-Etxeberria, I., Cardesín-Moinelo, A., Ravanis, E., Wood, S., Titov, D., Connour, K., Schneider, N., Tirsch, D., Jaumann, R., Hauber, E., and Gondet, B.: Dynamics of the extremely elongated cloud on Mars Arsia Mons volcano, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-433, https://doi.org/10.5194/egusphere-egu2020-433, 2020.

EGU2020-22650 | Displays | PS3.6

Mercury's Na exosphere as seen with very high spectral resolution from the ground, and from space with MESSENGER

Nelly Mouawad, Judy Chebly, François Leblanc, Jonathan Fraine, and Kahil Fatima

The MErcury Surface, Space ENvironment, GEochemistry, and Ranging NASA’s spacecraft, known as MESSENGER, flew by Mercury on September 29, 2009. It was the spacecraft’s third and final flyby, before it went into orbit around the planet. The flyby presented a unique trajectory approach and perspective on the planet’s exosphere, not available when in orbit. We present very high spectral resolution ground-based data obtained at the University of Texas McDonald 2.7-m telescope. These data were acquired within hours of the data taken with the Ultraviolet and Visible Spectrometer (UVVS) onboard MESSENGER. Both datasets targeted similar spatial regions, in the polar altitudes of Mercury. We compare the sodium emissions from both measurements in the exosphere. We find that close to the surface, both intensity measurements match, but the intensities fall off differently with altitude, with the MESSENGER data showing an exponential drop off, sharper than that of the ground-based data; an effect that we attribute to atmospheric seeing. In addition, our ground-based data provided Full Width Half Maximum (fwhm) speeds and Doppler shift speeds; our results suggest energetic processes took place in the polar regions on the dusk side of the planet, but arguably on the dawn side as well. We confirm previous conclusions of Leblanc et al. (2008, 2009) where signatures of energetic processes seem to be coupled with high fwhm speeds and intensity peaks. We compare our Doppler shift velocities with previous works, and find agreement within the uncertainties with Potter et al., (2013) on their transit velocity measurements. Although our peak emissions along the terminator vary in structure and in brightness, they do not exhibit distinctive signatures in the intensity profiles at altitudes above the poles, when compared with convolved MESSENGER space data.

How to cite: Mouawad, N., Chebly, J., Leblanc, F., Fraine, J., and Fatima, K.: Mercury's Na exosphere as seen with very high spectral resolution from the ground, and from space with MESSENGER, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22650, https://doi.org/10.5194/egusphere-egu2020-22650, 2020.

EGU2020-21185 | Displays | PS3.6

An uppermost haze layer above 100 km found over Venus by the SOIR instrument onboard Venus Express

Seiko Takagi, Arnaud Mahieux, Valérie Wilquet, Séverine Robert, Ann Carine Vandaele, and Naomoto Iwagami

The Venus cloud consists of a main cloud deck at 47 – 70 km, with thinner hazes above and below.The upper haze on Venus lies above the main cloud surrounding the planet, ranging from the top of the cloud (70 km) up to as high as 90 km.

The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express was designed to measure the Venusian atmospheric transmission at high altitudes (65 – 220 km) in the infrared range (2.2 – 4.3 µm) with a high spectral resolution. We investigate the optical properties of Venus’s haze layer above 90 km using SOIR solar occultation observations. Vertical and latitudinal profiles of the extinction coefficient, optical thickness, and mixing ratio of aerosols are retrieved. One of the most remarkable results is that the aerosol mixing ratio tends to increase with altitude above 90 km at both high and low latitude. We speculate how aerosols could be produced at such high altitudes.

How to cite: Takagi, S., Mahieux, A., Wilquet, V., Robert, S., Vandaele, A. C., and Iwagami, N.: An uppermost haze layer above 100 km found over Venus by the SOIR instrument onboard Venus Express, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21185, https://doi.org/10.5194/egusphere-egu2020-21185, 2020.

EGU2020-18583 | Displays | PS3.6

Exploring the variability of the venusian atmosphere above the clouds with the IPSL Venus GCM

Sebastien Lebonnois, Gabriella Gilli, Diogo Quirino, Vasco Silva, Thomas Navarro, Franck Lefevre, and Anni Määttänen

To investigate the amount of data recently acquired by the Venus Express (VEx) and Akatsuki missions as well as from ground-based telescopes, Venus Global Climate Models (GCM) are powerful tools. Our understanding of the Venusian climate has increased with recent progresses with these models.
The IPSL Venus GCM has been used recently to investigate all regions of the Venusian atmosphere, as it covers the surface up to the thermosphere (150 km). It involves a photochemical module with a simplified cloud scheme that enables the study of the composition and the coupling with the upper atmosphere, where composition plays a crucial role on the non-LTE and EUV heating processes. Other relevant physical processes in the thermosphere (e.g. molecular diffusion and thermal conduction) are taken into account. Below 100 km, the infrared energy budget is computed based on a Net Exchange Rate formalism. The cold collar structure has been modeled when taking into account the latitudinal distribution of the cloud structure. Globally averaged profiles (e.g spatially and temporally) extracted from the state-of-the-art IPSL Venus GCM provide realistic templates of the atmosphere of Venus. 
VEx observations revealed a more variable atmosphere than expected, in particular the “transition” region (~70-120 km) between the retrograde superrotating zonal flow and the day-to-night circulation showed latitude and day-to-day variations of temperature up to 80 K above 100 km at the terminator, and apparent zonal wind velocities measured around 96 km on the Venus nightime highly changing in space and time. Those variations are not fully explained by current 3D models and specific processes (e.g. gravity wave propagation, thermal tides, large scale planetary waves) responsible for driving them are still under investigation. The role of convectively-generated gravity waves and their impact on zonal wind and temperature in the region of aerobraking can be explored with the IPSL-VGCM, thanks to the inclusion of a stochastic non-orographic gravity waves parameterization, based on the Earth GCM. Data-model comparison of distribution of dynamical tracers above the clouds  (e.g O2(1Δ) nightglow, CO and O density) will be crucial to shed a light on a region where no direct wind measurements are available.
Akatsuki’s LIR camera revealed the presence of  planetary-scale mountain waves at the cloud top in the afternoon. Simulations of the upper atmosphere suggest that mountain waves can easily reach the upper atmosphere, to polar latitudes and the nightside, thus affecting atmospheric dynamics as high as 130 km.

How to cite: Lebonnois, S., Gilli, G., Quirino, D., Silva, V., Navarro, T., Lefevre, F., and Määttänen, A.: Exploring the variability of the venusian atmosphere above the clouds with the IPSL Venus GCM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18583, https://doi.org/10.5194/egusphere-egu2020-18583, 2020.

EGU2020-11323 | Displays | PS3.6

Mesospheric water vapor and D/H ratio at the Venus terminator from SOIR/VEx

Arnaud Mahieux, Ann Carine Vandaele, Sarah Chamberlain, Valérie Wilquet, Séverine Robert, Arianna Piccialli, Ian Thomas, and Loic Trompet

The Solar Occultation in the InfraRed (SOIR) instrument onboard Venus Express sounded the Venus mesosphere and lower thermosphere at the terminator using solar occultation technique between April 2006 and December 2014.

We report on the water vapor vertical distribution above the clouds and geo-temporal variations, observed during the full Venus Express mission. Water vapor profiles are sampled between 80 and 120 km, and calculations of the water vapor volume mixing ratio agrees with those from previous studies. Short term variations over several Earth days dominate the data set, with densities varying by up to a factor 19 over a 24 hr period. Similarly to what was found for other trace gases detected with the SOIR instrument, such as HCl, HF and SO2, no significant spatial or long term trends are observed.

287 water vapor vertical profiles obtained at the Venus terminator between 80 km and 120 km from August 2006 and September 2014 were analyzed for temporal and spatial abundance variations. Standard deviations are significantly smaller than the full range of volume mixing ratio values at all altitudes indicating that the variations are real.

The decrease in volume mixing ratio abundance below 100 km appears to be a common feature of most water vapor volume mixing ratio profiles and agrees with the decrease in water vapor reported in previous studies. Based on a very limited number of spectra, the variability of the water vapor VMR was found to be higher in the lower than in the upper mesosphere of Venus; this is in agreement with our observations as the standard deviation of the SOIR mean profile is the smallest at 100 km and increases with decreasing altitude.

No significant spatial variations or long term temporal variations are observed in the present data set in which short term variability masks all other possible trends. Our observations agree that short term (between 1 and 10 Earth days) variability is dominant.

We also report on simultaneous observations of the water first isotopologue HDO made by SOIR, which occurred 194 times during the whole VEx mission. Similarly to water vapor, we observe a large variation of HDO with time and space, without any clear time of spatial dependency.

We report on the ratio of the simultaneously measured HDO and H2O profiles, that show a constant ratio of 0.1 ± 0.1 below 100 km, and increase exponentially at higher altitude to reach a value of 1 ± 0.4 at 120 km of altitude. The results are in agreement with previous works below 100 km.

How to cite: Mahieux, A., Vandaele, A. C., Chamberlain, S., Wilquet, V., Robert, S., Piccialli, A., Thomas, I., and Trompet, L.: Mesospheric water vapor and D/H ratio at the Venus terminator from SOIR/VEx, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11323, https://doi.org/10.5194/egusphere-egu2020-11323, 2020.

EGU2020-18609 | Displays | PS3.6

Characterization of the atmospheric gravity waves on Mars at altitudes 10-180 km as measured by the ACS/TGO solar occultations

Ekaterina Starichenko, Denis Belyaev, Alexander Medvedev, Anna Fedorova, Oleg Korablev, Franck Montmessin, and Alexander Trokhimovskiy

Atmospheric gravity waves (GW) are periodic oscillations of air masses that manifest themselves as fluctuations of density, temperature, pressure and other quantities. Studying vertical distributions of density and temperature helps to characterize vertical propagation of GWs and evaluate their influence on the coupling between atmospheric layers.

We report on the first results of GWs retrievals in the Martian atmosphere from the solar occultation experiment performed by the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter TGO [1]. This is the first time when GWs were measured simultaneously in almost the entire atmosphere. The ACS is a set of infrared spectrometers operating on the orbit of Mars since April 2018. The mid-infrared channel (ACS-MIR) is a cross-dispersion spectrometer covering the 2.3–4.2 µm spectral range with the resolving power reaching ~30 000. In the solar occultation mode the spectrometer can observe thin layers of the Martian thermosphere and lower atmosphere in strong (e.g. 2.7 and 4.3 μm) and weak (about 3 μm) CO2 absorption bands with vertical resolution ~1 km. The near-infrared channel (ACS-NIR) is another echelle spectrometer working in the 0.73–1.6 µm spectral range with the resolving power ~25000 [2]. Due to the high resolution, these instruments (operating simultaneously) allow for deriving the temperature, pressure and density fluctuations at the unprecedented altitude range from 10 to 180 km. The dataset we present consists of more than 100 vertical profiles derived at seasons from the second half of MY34 to the beginning of MY35 in the both Martian hemispheres. The data analysis in IKI is supported by the RSF grant #20-42-09035.

 

REFERENCES

[1] Korablev O. et al., 2018. The Atmospheric Chemistry Suite (ACS) of three spectrometers for the ExoMars 2016 Trace Gas Orbiter. Space Sci. Rev., 214:7. DOI 10.1007/s11214-017-0437-6.

[2] Fedorova A. et al., 2020. Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season. Science, eaay9522. DOI: 10.1126/science.aay9522.

How to cite: Starichenko, E., Belyaev, D., Medvedev, A., Fedorova, A., Korablev, O., Montmessin, F., and Trokhimovskiy, A.: Characterization of the atmospheric gravity waves on Mars at altitudes 10-180 km as measured by the ACS/TGO solar occultations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18609, https://doi.org/10.5194/egusphere-egu2020-18609, 2020.

EGU2020-18371 | Displays | PS3.6

Temperature and CO2 density distribution in Mars upper atmosphere from the ACS-MIR / TGO solar occultations at 2.7 μm absorption band

Denis Belyaev, Anna Fedorova, Alexander Trokhimovskiy, Oleg Korablev, Franck Montmessin, Juan Alday, Kevin S. Olsen, and Miguel Lopez-Valverde

The mid-infrared channel of the Atmospheric Chemistry Suite (ACS-MIR) is a cross-dispersion echelle spectrometer dedicated to solar occultation measurements in the 2.3–4.3 μm wavelength range [1]. The instrumental resolving power λ/Δλ reaches ~30 000, while the altitude resolution is ~1 km. ACS-MIR began regular science operations in April 2018 on board the ExoMars Trace Gas Orbiter (TGO). Each occultation session covers a spectral interval with one or a few CO2 absorption bands appropriate for the atmospheric density and temperature retrievals.

In this paper, we present results from data analysis in the 2.65-2.7 μm spectral range hosting strong CO2 absorption bands detectable up to 180 km. It provides us with unprecedented capability to profile CO2 from 20 to 180 km, covering the troposphere, the mesosphere and the thermosphere of Mars. The homopause is found around ~130 km and CO2 mixing ratio decreases from 96% to 20-40% at 180 km due to photolysis and molecular diffusion. A multiple iteration scheme was applied to retrieve CO2 density and temperature from the rotational absorption lines, while pressure was estimated assuming hydrostatic equilibrium. The vertical profiles coincide well with the simultaneous occultations performed below 100 km by the near-infrared channel ACS-NIR [2]. At the moment, our MIR channel dataset is made of >100 profiles encompassing the second half of MY34 and the beginning of MY35 in both martian hemispheres. The retrievals of density/temperature profiles in IKI are funded by the RSF grant #20-42-09035.

REFERENCES

[1] Korablev O. et al., 2018. The Atmospheric Chemistry Suite (ACS) of three spectrometers for the ExoMars 2016 Trace Gas Orbiter. Space Sci. Rev., 214:7. DOI 10.1007/s11214-017-0437-6.

[2] Fedorova A. et al., 2020. Stormy water on Mars: The distribution and saturation of atmospheric water during the dusty season. Science, eaay9522. DOI: 10.1126/science.aay9522.

How to cite: Belyaev, D., Fedorova, A., Trokhimovskiy, A., Korablev, O., Montmessin, F., Alday, J., Olsen, K. S., and Lopez-Valverde, M.: Temperature and CO2 density distribution in Mars upper atmosphere from the ACS-MIR / TGO solar occultations at 2.7 μm absorption band, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18371, https://doi.org/10.5194/egusphere-egu2020-18371, 2020.

EGU2020-17433 | Displays | PS3.6

First observation of the magnetic dipole CO2 main isotopologue absorption band at 3.3 µm in the atmosphere of Mars by ACS ExoMars

Alexander Trokhimovskiy, Valery Perevalov, Oleg Korablev, Anna Fedorova, Kevin S. Olsen, Jean-Loup Bertaux, Franck Montmessin, Franck Lefèvre, Andrey Patrakeev, and Alexey Shakun

The CO2-dominated atmosphere of Mars is an ideal natural laboratory to study the spectroscopy of this gas. The Atmospheric Chemistry Suite (ACS) package onboard the ExoMars 2016 Trace Gas Orbiter (TGO) sounds the atmosphere in solar occultation, allowing, in case of a very clear atmosphere, reaching an optical path of 300-400 km at an effective pressure of a few millibars. During the first year of ACS observations, the focus of attention was kept on the spectral range covering the fundamental methane absorption band, 2900-3300 cm–1. No methane was detected, while a further improvement of the data processing led to the identification of weak periodic absorption lines, missing from spectroscopic databases. The observed frequencies of the lines match theoretically computed positions of the Q, P and R branches of the magnetic dipole 01111-00001 absorption band of the main CO2 isotopologue, never measured or computed before. We will report the first observational evidence of a magnetic dipole CO2 absorption. The data analysis was supported by RSF (project No. 20-42-09035).

How to cite: Trokhimovskiy, A., Perevalov, V., Korablev, O., Fedorova, A., Olsen, K. S., Bertaux, J.-L., Montmessin, F., Lefèvre, F., Patrakeev, A., and Shakun, A.: First observation of the magnetic dipole CO2 main isotopologue absorption band at 3.3 µm in the atmosphere of Mars by ACS ExoMars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17433, https://doi.org/10.5194/egusphere-egu2020-17433, 2020.

EGU2020-13984 | Displays | PS3.6

Estimate of the D/H ratio in the Martian upper atmosphere from the low spectral resolution mode of MAVEN/IUVS

Jean-Yves Chaufray, Majd Mayyasi, Michael Chaffin, Justin Deighan, Dolon Bhattacharyya, John Clarke, Sonal Jain, Nick Schneider, and Bruce Jakosky

The recent observations performed with the high-resolution “echelle mode” by the Imaging Ultraviolet Spectrograph (IUVS) aboard the Mars Atmosphere and Volatile EvolutioN (MAVEN) mission indicated large deuterium brightness near Ls=270°. The deuterium brightness observed at the beginning of the mission, when Mars was close to its perihelion show brightness ~ 1 kR much larger than the first deuterium detection from Earth ~ 20-50R in 20-21 January 1997 (Ls = 67°). This low brightness of the deuterium emission is consistent with the lack of deuterium observation with the echelle mode of IUVS at solar longitudes around aphelion (Ls = 71°). During southern summer (Ls = 270°), especially near the terminator, the Lyman-α emission observed at 121.6 nm with the “low resolution mode” presents some vertical profiles that were not reproducible with models including only the emission from the thermal hydrogen population. In this study, we investigate the possibility to derive quantitative information on the D/H ratio at Mars from the vertical Lyman-α profiles observed with the “low resolution mode”, and the main limits of the method.

How to cite: Chaufray, J.-Y., Mayyasi, M., Chaffin, M., Deighan, J., Bhattacharyya, D., Clarke, J., Jain, S., Schneider, N., and Jakosky, B.: Estimate of the D/H ratio in the Martian upper atmosphere from the low spectral resolution mode of MAVEN/IUVS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13984, https://doi.org/10.5194/egusphere-egu2020-13984, 2020.

EGU2020-20354 | Displays | PS3.6

Investigating the relationship between ozone and water-ice in the martian atmosphere

Megan Brown, Manish Patel, Stephen Lewis, and Amel Bennaceur

This project maps ozone and ice-water clouds detected in the martian atmosphere to assess the atmospheric chemistry between ozone, water-ice and hydroxyl radicals. Hydroxyl photochemistry may be indicated by a non-negative or fluctuating correlation between ozone and water-ice. This will contribute to understanding the stability of carbon dioxide and atmospheric chemistry of Mars.

Ozone (O3) can be used for tracking general circulation of the martian atmosphere and other trace chemicals, as well as acting as a proxy for water vapour. The photochemical break down of water vapour produces hydroxyl radicals known to participate in the destruction of ozone. The relationship between water vapour and ozone is therefore negatively correlated. Atmospheric water-ice concentrations may also follow this theory. The photochemical reactions between ozone, water-ice clouds and hydroxyl radicals are poorly understood in the martian atmosphere due to the short half-life and rapid reaction rates of hydroxyl radicals. These reactions destroy ozone, as well as indirectly contributing to the water cycle and stability of carbon dioxide (measured by the CO2–CO ratio). However, the detection of ozone in the presence of water-ice clouds suggests the relationship between them is not always anti-correlated. Global climate models (GCMs) struggle to describe the chemical processes occurring within water-ice clouds. For example, the heterogeneous photochemistry described in the LMD (Laboratoire de Météorologie Dynamique) GCM did not significantly improve the model. This leads to the following questions: what is the relationship between water-ice clouds and ozone, and can the chemical reactions of hydroxyl radicals occurring within water-ice clouds be determined through this relationship?

This project aims to address these questions using nadir and occultation retrievals of ozone and water-ice clouds, potentially using retrievals from the UVIS instrument aboard NOMAD (Nadir and Occultation for Mars Discovery), ExoMars Trace Gas Orbiter. Analysis will include temporal and spatial binning of data to help identify any patterns present. Correlation tests will be conducted to determine the significance of any relationship at short term and seasonal scales along a range of zonally averaged latitude photochemical model from the LMD-UK GCM will be used to further explore the chemical processes.

Interactions between hydroxyl radicals and the surface of water-ice clouds are poorly understood. Ozone abundance is greatest in the winter at the polar regions, which also coincides with the appearance of the polar hood clouds. The use of nadir observations will enable the comparison between total column of ozone abundance at high latitudes (>60°S) in a range of varying water-ice cloud opacities, as well as the equatorial region (30°S – 30°N) during aphelion. Water-ice clouds may remove hydroxyl radicals responsible for the destruction of ozone and thus the previously assumed anticorrelation between ozone and water-ice will not hold. The project will therefore assess the hypothesis that: water-ice clouds may act as a sink for hydroxyl radicals.

How to cite: Brown, M., Patel, M., Lewis, S., and Bennaceur, A.: Investigating the relationship between ozone and water-ice in the martian atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20354, https://doi.org/10.5194/egusphere-egu2020-20354, 2020.

EGU2020-10361 | Displays | PS3.6

Mars' Annular Polar Vortex

Emily Ball, Dann Mitchell, William Seviour, Geoffrey Vallis, and Stephen Thomson

The Martian winter polar vortex has recently been shown to be annular in nature, with a local minimum in potential vorticity near the pole. This suggests barotropic instability, yet the vortex is remarkably persistent. It has been shown that its annular nature may be due to the release of latent heat from CO2 condensation, CO2 clouds, changes in dust distributions, and the strength of the Hadley circulation circulation, with many of these being interlinked. In this poster, we present results using the the Mars Analysis Correction Data Assimilation (MACDA) reanalysis dataset, which demonstrates clearly the annular vortex. Additionally, we perform simulations of the Martian atmosphere and its response to varying topography and radiation scheme in the flexible Isca framework, a climate model capable of simulating the Martian basic state at varying levels of complexity. It is noted that the strength of the Martian polar vortex is significantly lower in Isca simulations than in the MACDA dataset. Through further simulations with Isca, we aim to investigate the effect of CO2 condensation on the strength and shape of the Martian polar vortex.

How to cite: Ball, E., Mitchell, D., Seviour, W., Vallis, G., and Thomson, S.: Mars' Annular Polar Vortex, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10361, https://doi.org/10.5194/egusphere-egu2020-10361, 2020.

Dust devils play a major role on Mars, providing a significant proportion of the total dust removal from the surface and its injection into the atmosphere, thus largely determining the overall radiative regime and the climatic state of the Martian atmosphere. The amount of dust lifted to the atmosphere by a population of dust devils is determined by the number density of dust devils (their number per unit area) and by their size-frequency and intensity-frequency distributions. Using the Abel transform, a two-step methodology has been developed to determine the marginal statistical distributions of convective vortices, including dust devils, on their intensity (pressure drop in the vortex center) and size (diameter), based on statistics of transient pressure drops recorded when the vortices pass near a pressure sensor placed on the surface of the planet. In a first step, if the pressure profile within the vortex is realistically modeled then the intensity-frequency distribution in the population of vortices can be inferred from the statistics of peak pressure drops recorded alone. If the observed statistics can be approximated with a truncated power-law distribution and in the absence of an apparent correlation between the vortex diameter and the maximum pressure drop at its center, then the measurements provide an unbiased power-law estimate of the actual intensity-frequency distribution. In a second step and in a practically important case when the distribution of vortices on their intensity follows the power law, the problem of determining the vortex size-frequency distribution is solved from data obtained in pressure time-series surveys. This two-step technique has been applied with success to Mars Science Laboratory (MSL) convective vortices.

This work was supported by the Presidium of the Russian Academy of Sciences, project no. 19-270. The method of inferring the vortex size-frequency distribution was developed with the support from the Russian Science Foundation (grant no. 18-77-10076).

References:

Kurgansky M.V. On the statistical distribution of pressure drops in convective vortices: Applications to Martian dust devils // Icarus. Volume 317, 1 January 2019, Pages 209-214. https://doi.org/10.1016/j.icarus.2018.08.004.

Kurgansky M.V. On determination of the size-frequency distribution of convective vortices in pressure time-series surveys on Mars // Icarus. Volume 335, 1 January 2020, 113389. https://doi.org/10.1016/j.icarus.2019.113389.

How to cite: Kurgansky, M.: On Determination of the Intensity and Size Frequency Distribution of Convective Vortices: Applications to Martian Dust Devils, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1738, https://doi.org/10.5194/egusphere-egu2020-1738, 2020.

EGU2020-17846 | Displays | PS3.6

Re-analysis of limb anomaly detections in three HST/STIS transit images of Europa: No evidence for plumes

Lorenz Roth, Gabriel Giono, Nickolay Ivchenko, Joachim Saur, Kurt Retherford, Darrell Strobel, Stephan Schlegel, and Marcus Ackland

After evidence for present-day geological activity on Jupiter’s moon Europa remained elusive for decades, several recent studies derived the existence of plumes on various locations. We have re-analyzed the three HST/STIS transit images in which Sparks et al. (2016) identified limb anomalies as evidence for Europa’s plume activity. After reproducing the results of Sparks et al. (2016), we find that positive outliers are similarly present in the images as the negative outliers that were attributed to plume absorption. A physical explanation for the positive outliers is missing. We identify two factors that affect the significance of the measured outliers in the region above Europa’s limb: The exact location of Europa on the detector and the description of the statistical fluctuations in the images. When accounting for these factors, the statistical significance of the plume candidate features is about 3 sigma or lower in the three images. The resulting positive and negative outliers are consistent with random statistical occurrence in a sample size given by the number of pixels in Europa's limb region.

How to cite: Roth, L., Giono, G., Ivchenko, N., Saur, J., Retherford, K., Strobel, D., Schlegel, S., and Ackland, M.: Re-analysis of limb anomaly detections in three HST/STIS transit images of Europa: No evidence for plumes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17846, https://doi.org/10.5194/egusphere-egu2020-17846, 2020.

EGU2020-8892 | Displays | PS3.6

3D climate simulations of Earth-like planets with a range of atmospheric composition, radiative transfer, ocean, and resolution configurations, using the new version of ROCKE-3D

Kostas Tsigaridis, Anthony D. Del Genio, Igor Aleinov, Eric T. Wolf, Maxwell Kelley, Michael J. Way, Linda E. Sohl, and Reto A. Ruedy

Understanding the climate of terrestrial planetary atmospheres has been increasingly the focus of research worldwide, in light of the increasing amount of rocky planet discoveries orbiting other stars in or near their habitable zone. Here we present simulations with the new version of the 3D climate model ROCKE-3D, whose version 2.0 will soon become publicly available. A wide range of configurations will be supported, compared to a handful ones in its predecessor, version 1.0 (Way et al., 2017). These include two model resolutions (4x5 and 2x2.5), two radiation schemes (GISS and SOCRATES), three atmospheric configurations (Earth-like, Earth-like without O3 and aerosols, and N2-dominated), and three ocean setups (prescribed sea-surface temperatures and ice cover, q-flux, and dynamic). Simulations of all different configuration combinations have been performed and will become available for use by the community. Key results will be presented across those configurations, together of the role of the structural uncertainty in model setup in the resulting climate calculated by the model.

How to cite: Tsigaridis, K., Del Genio, A. D., Aleinov, I., Wolf, E. T., Kelley, M., Way, M. J., Sohl, L. E., and Ruedy, R. A.: 3D climate simulations of Earth-like planets with a range of atmospheric composition, radiative transfer, ocean, and resolution configurations, using the new version of ROCKE-3D, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8892, https://doi.org/10.5194/egusphere-egu2020-8892, 2020.

EGU2020-11502 | Displays | PS3.6

Enceladus geyser study using Markov Chain Monte Carlo fits of DSMC simulations

David Goldstein, Arnaud Mahieux, Philip Varghese, and Laurence Trafton

The two-phase water plumes arising from the Enceladus South pole and extending hundreds of km from the moon are a key signature of what lies below the surface. Multiple Cassini instruments measured the gas-particle plume over the warm Tiger Stripe region during several close flybys. A lot of work has been put into constraining the vent and flow characteristics, such the vent positions and orientations, the mass flows, speeds and temperatures.
The most likely source for these extensive geysers is a subsurface liquid reservoir of somewhat saline water and oth-er volatiles boiling off through crevasse-like conduits into the vacuum of space. The plumes thus provide a window for understanding Enceladus’ subsurface composition and geysering.
We used a DSMC code to simulate the plume, as it exits a vent, under axisymmetric conditions, in a vertical domain extending up to 10 km, where the flows become collisionless. We performed a DSMC parametric study of the flow parameters considering the following eight parameters: vent diameter, outgassed flow density, water vapor/ice mass ratio, gas and ice speed, ice grain diameter, temperature and vent exit angle.
We constructed parametric expressions for the plume characteristics – number density, temperature, velocity compo-nents – using simple analytic expressions to depict the constrained surfaces of these parameter values, at the 10 km upper boundary.
We use these parametrizations to propagate the plumes to higher altitudes – up to thousands of km – assuming free-molecular conditions. The density field at higher altitude is determined from the parametrizations described above, and explicit analytical expressions for the various force fields that the plumes are experiencing: Enceladus and Saturn gravity fields, Coriolis and centripetal accelerations due to Enceladus rotation.
This split domain approach enables rapid numerical computations – ~10 minutes – and tabulations of the density and velocity fields in space.
We then performed a formal Monte Carlo sensitivity analysis of twelve vent parameters – the ones cited above plus vent latitude, longitude, azimuth and zenith angles of the venting direction – conditioned on the number density field measured by the INMS instrument, considering the 98-vent geometry reported in Porco et al. (2014). The sensitivity analysis is used to determine which vent parameters should be considered for a subsequent fit of the INMS observa-tion. We present an advanced way to constrain the vent parameters by performing a Markov Chain Monte Carlo search that returns probability values for the preselected vent parameters, considering a few INMS observations. This ap-proach allows us to constrain many vent parameters (up to a few hundreds), and, uniquely, return probability distri-bution for each of them.

How to cite: Goldstein, D., Mahieux, A., Varghese, P., and Trafton, L.: Enceladus geyser study using Markov Chain Monte Carlo fits of DSMC simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11502, https://doi.org/10.5194/egusphere-egu2020-11502, 2020.

EGU2020-10457 | Displays | PS3.6

Meteor Ablated Phosphorus as a Source of Bioavailable P to the Terrestrial Planets

Kevin Douglas, Thomas Mangan, Jaun Diego Carrillo-Sanchez, David Bones, Wuhu Feng, Mark Blitz, and John Plane

             Phosphorus, P, is a key biological element with major roles in replication, information transfer, and metabolism. Interplanetary dust particles (IDPs) contain ~0.8 % P by elemental abundance, and meteoric ablation in a planetary atmosphere is a significant source of atomic P. Orthophosphate (oxidation state +5) is the dominant form of inorganic P at the Earth’s surface, however, due to their low water solubility and reactivity, such P(V) salts have a poor bio-availability. Less oxidised forms of P (oxidation state ≤ +3) are however far more bio-available. Previous studies have focused on the direct delivery of P to the surface in meteorites. In contrast, the atmospheric chemistry of P has so far been ignored.

            The vaporized P atoms entering the upper atmospheres of the terrestrial planets will undergo chemical processing to form a variety of compounds in which P may exist in different oxidation states due to the presence of both oxidizing and reducing agents. Initial oxidation of P will proceed to produce PO2. From PO2, an exothermic route to phosphoric acid (H3PO4) exists via the formation of HOPO2; however, the bio-available compound phosphonic acid (H3PO3) should also form via HPO2.

            Using a combination of both experiment and theory, rate coefficients for the reactions of meteor ablated P have been determined. Using a pulsed laser photolysis-laser induced fluorescence (LIF) technique, the reactions of P, PO, and PO2 with atmospherically relevant species have been studied as a function of temperature for the first time. Rate coefficients for the subsequent reactions of PO2 leading onto to phosphoric and phosphonic acid were calculated from high-level electronic structure calculations.

            In addition to understanding the reaction kinetics, the delivery of P to the upper atmospheres of Earth, Mars, and Venus via the ablation of IDPs has also been investigated. Using a meteor ablation simulator, micron-size particles were flash heated, and the ablation of PO and Ca recorded simultaneously by LIF. These ablation profiles were used to validate the output of a Chemical Ablation Model (CABMOD), a thermodynamic model that predicts the ablation rates of different elements from IDPs. By combining CABMOD with an astronomical model of dust sources, the global injection rates of P into the atmospheres of Earth, Mars, and Venus has been estimated to be 0.017, 1.15×10-3, and 0.024 t d-1 (tonnes per Earth day) respectively.

            The results from the kinetics experiments, together with the P injection rates from CABMOD, have been input into a global chemistry-climate model of the Earth’s atmosphere (WACCM). Using WACCM, the relative amounts of phosphoric and phosphonic acid produced from meteor ablated P in the Earth’s atmosphere can be assessed. Preliminary results indicated that both H3PO4, and the bio-available H3PO3 are formed, with around a third of the ablated P ending up as H3PO3. Further work is also underway to determine where on the Earth’s surface H3PO3 will be deposited, to understand how accretion rates would have differed on the early Earth, and to input the P chemical scheme into a Mars atmospheric model.

How to cite: Douglas, K., Mangan, T., Carrillo-Sanchez, J. D., Bones, D., Feng, W., Blitz, M., and Plane, J.: Meteor Ablated Phosphorus as a Source of Bioavailable P to the Terrestrial Planets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10457, https://doi.org/10.5194/egusphere-egu2020-10457, 2020.

PS4.1 – InSight into Mars after 18 months

EGU2020-22031 * | Displays | PS4.1 | Highlight

Results From the Insight Mission After a Year and a Half on Mars

William T. Pike, William Banerdt, Suzanne Smrekar, Philippe Lognonné, Domenico Giardini, Don Banfield, Véronique Dehant, William Folkner, Matthew Golombek, Catherine Johnson, Christopher Russell, Aymeric Spiga, and Tilman Spohn

The InSight mission landed on Mars in November of 2018 and completed installation of a seismometer (SEIS) on the surface about two months later. In addition to SEIS, InSight carries a diverse geophysical observatory including a heat flow and sub-surface physical properties experiment (HP3), a geodesy (planetary rotation dynamics) experiment (RISE), and a suite of environmental sensors measuring the magnetic field and atmospheric temperature, pressure and wind (APSS). For more than a year, SEIS has been providing near-continuous seismic monitoring of Mars, with background noise levels orders of magnitude lower than that achievable on the Earth. Since installation was completed, the SEIS team has identified more than 400 events that we have not attributed to the local environment or spacecraft activity, and dozens that appear to be marsquakes of tectonic origin. We present an overview of observations by the SEIS instrument as well as a summary of other geophysical observations made by InSight during the past year and a half.

How to cite: Pike, W. T., Banerdt, W., Smrekar, S., Lognonné, P., Giardini, D., Banfield, D., Dehant, V., Folkner, W., Golombek, M., Johnson, C., Russell, C., Spiga, A., and Spohn, T.: Results From the Insight Mission After a Year and a Half on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22031, https://doi.org/10.5194/egusphere-egu2020-22031, 2020.

EGU2020-20437 * | Displays | PS4.1 | Highlight

Seismicity of Mars

Domenico Giardini, Philippe Lognonne, Bruce Banerdt, Maren Boese, Savas Ceylan, John Clinton, Martin van Driel, Raphael Garcia, Taichi Kawamura, Amir Khan, Martin Knapmeyer, Mark Panning, Clement Perrin, Tom Pike, and Simon Stähler

NASA’s InSight mission deployed the Seismic Experiment for Interior Structure (SEIS) instrument on Mars, with the goal of detecting, discriminating, characterizing and locating the seismicity of Mars and study its internal structure, composition and dynamics. 44 years since the first attempt by the Viking missions, SEIS has revealed that Mars is seismically active. So far, the Marsquake Service (MQS) has identified 365 events that cannot be explained by local atmospheric or lander-induced vibrations, and are interpreted as marsquakes. We identify two families of marsquakes: (i) 35 events of magnitude MW=3-4, dominantly long period in nature, located below the crust and with waves traveling inside the mantle, and (ii) 330 high-frequency events of smaller magnitude and of closer distance, with waves trapped in the crust, exciting an ambient resonance at 2.4Hz. Two long period events with larger SNR and excellent P and S waves occurred on Sol 173 and 235, visible both on the VBB and the SP channels; the location of these events has been determined at distances of 26°-30° towards the East, close to the Cerberus Fossae tectonic system. Over ten additional long period events show consistent body-wave phases interpreted as P and S phases and can be aligned with distance using models of P and S propagation. Marsquakes have spectral characteristics similar to seismicity observed on the Earth and Moon. From the spectral characteristics of the recorded seismicity and the event distance, we constrain attenuation in the crust and mantle, and find indications of a potential low S-wave-velocity layer in the upper mantle. In contrast, the high-frequency events provide important constraints on the elastic and anelastic properties of the crust. The first seismic observations on Mars deliver key new knowledge on the internal structure, composition and dynamics of the red planet, opening a new era for planetary seismology. Here we review the seismicity detected so far on Mars, including location, distance, magnitude, magnitude-frequency distribution, tectonic context and possible seismic sources.

How to cite: Giardini, D., Lognonne, P., Banerdt, B., Boese, M., Ceylan, S., Clinton, J., van Driel, M., Garcia, R., Kawamura, T., Khan, A., Knapmeyer, M., Panning, M., Perrin, C., Pike, T., and Stähler, S.: Seismicity of Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20437, https://doi.org/10.5194/egusphere-egu2020-20437, 2020.

EGU2020-18429 | Displays | PS4.1

Is there a Seasonality of the Martian Seismic Event Rate?

Martin Knapmeyer, Simon C. Stähler, Martin van Driel, John F. Clinton, W. Bruce Banerdt, Maren Böse, Savas Ceylan, Constantinos Charalambous, Raphael F. Garcia, Anna Horleston, Taichi Kawamura, Amir Khan, Philippe Lognonne, Mark Panning, Domenico Giardini, William T. Pike, John-Robert Scholz, and Renee C. Weber

We analyze the sequence of seismic events of different types as recorded by the SEIS instrument of the InSight mission. After several weeks without any detection, event counts started to increase at the end of May 2019. The majority of recorded events belongs to the class of 2.4 Hz events, which prominently excite a continuously observed natural resonance frequency.

After a sudden onset of seismic detections by the end of May 2019 (about sol 180, LS≈32°), especially the combined event rate of the High Frequency, Very High Frequency, and 2.4 Hz family of events increased from 3.6 events/sol in June 2019 to more than 9 events/sol until late August 2019, i.e. increased by a factor of about 3.

Estimating event rates as if events are the result of a constant-rate Poisson process leads to contradictions with the statistical properties of those, either in the cumulative event count or in the lag time distribution. These contradictions can be overcome by assuming a step-wise increase of the event rate.

Any deviation from a purely random occurrence of quakes, in both time and space, requires a mechanism to suppress or support the source process. The seismic activity of the Moon is mainly controlled by tidal deformation, at least in terms of source time. What controls the event rate of Martian high frequency events is currently elusive.

How to cite: Knapmeyer, M., Stähler, S. C., van Driel, M., Clinton, J. F., Banerdt, W. B., Böse, M., Ceylan, S., Charalambous, C., Garcia, R. F., Horleston, A., Kawamura, T., Khan, A., Lognonne, P., Panning, M., Giardini, D., Pike, W. T., Scholz, J.-R., and Weber, R. C.: Is there a Seasonality of the Martian Seismic Event Rate?, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18429, https://doi.org/10.5194/egusphere-egu2020-18429, 2020.

EGU2020-18020 | Displays | PS4.1

Source mechanism solutions of low frequency Martian events based on body wave coda from a single seismic station

Nienke Brinkman, Alice Jacob, Simon Stähler, Cédric Schmelzbach, Nobuaki Fuji, Clément Perrin, Alex Batov, Maren Böse, John Clinton, Martin van Driel, Mélanie Drilleau, Domenico Giardini, Tamara Gudkova, Johan Olof Anders Robertsson, and William Bruce Banerdt and the MQS frontline and review team

On the 26th of November 2018, NASA’s InSight lander successfully touched down on the Martian ground in Elysium Planitia. The lander transported among other instruments a single three-component broadband seismometer to measure seismic events and subsequently determine the seismic activity level and eventually the internal structure of Mars. In this study we focus on characterizing the source mechanisms of the highest-quality marsquakes detected so far: The events with highest SNR occurred on sols 173 (S0173a, May 23rd 2019) and 235 (S0235b, July 27th 2019) with Mw > 3.5, showing clearly polarized P and S waves. The InSight MarsQuake Service has estimated their distances to be around 27 degrees, nearby the Cerberus Fossae Graben system. Two more events, S0183a and S0325b have less clear body wave phases and locations, but are also interpreted to be related to it.

We have developed a grid-search based method to fit synthetic waveforms to the observed first arriving P and S wave trains. The four source parameters we invert for in this study are the three unique orientation angles of the source mechanism, strike (φ), dip (δ) and rake (λ), and the depth of the event. Synthetic seismograms are generated by computing Green’s functions based on the epicentral distance determined by the InSight MarsQuake Service (MQS) and radially symmetric velocity models. These Green’s function are then convolved with a source time function including an estimated global body wave attenuation to obtain realistic seismograms. 

The two high-quality event recordings originating from the Cerberus Fossae (CF) fault system were analyzed. Multiple velocity models, frequency bands and window lengths around the arriving phases were used to explore the non-uniqueness in the inverse problem of the inherently ambiguous single-station data. We found that using plausible structural models based on geophysical modeling, the first 10-15 seconds of the waveforms can be fit, constraining the source mechanism and depth, but that the estimation of the uncertainty remains challenging.

How to cite: Brinkman, N., Jacob, A., Stähler, S., Schmelzbach, C., Fuji, N., Perrin, C., Batov, A., Böse, M., Clinton, J., van Driel, M., Drilleau, M., Giardini, D., Gudkova, T., Robertsson, J. O. A., and Banerdt, W. B. and the MQS frontline and review team: Source mechanism solutions of low frequency Martian events based on body wave coda from a single seismic station, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18020, https://doi.org/10.5194/egusphere-egu2020-18020, 2020.

EGU2020-9163 | Displays | PS4.1

Mars Regolith Properties as Constrained from HP3 Mole Operations and Thermal Measurements

Tilman Spohn, Matthias Grott, Nils Müller, Jörg Knollenberg, Christian Krause, Troy Hudson, Robert Deen, Eloise Marteau, Matthew Golombek, Kenneth Hurst, Sylvain Piqueux, Susanne Smrekar, Ann Louise Thomas, Cinzia Fantinati, Roy Lichtenheldt, and Torben Wippermann

The Heat Flow and Physical Properties Package HP3 onboard the Nasa InSight mission has been on the surface of Mars for more than one Earth year. The instrument's primary goal is to measure Mars' surface heat flow through measuring the geothermal gradient and the thermal condunctivity at depths between 3 and 5m. To get to depth, the package includes a penetrator nicknamed the "Mole"  equipped with sensors to precisely measure the thermal conductivity. The Mole tows a tether with printed temperature sensors;  a device to measure the length of the tether towed and a tiltmeter will help to track the path of the Mole and the tether. Progress of the Mole has been stymied by difficulties of digging into the regolith. The Mole functions as a mechanical diode with an internal hammer mechanism that drives it forward. Recoil is balanced mostly by internal masses but a remaining 3 to 5N has to be absorbed by hull friction. The Mole was designed to work in cohesionless sand but at the InSight landing a cohesive duricrust of at least 7cm thickness but possibly 20cm thick was found. Upon initial penetration to 35cm depth, the Mole punched a hole about 6cm wide and 7cm deep into the duricrust, leaving more than a fourth of its length without hull friction.  It is widely agreed that the lack of friction is the reason for the failure to penetrate further. The HP3 team has since used the robotic arm with its scoop to pin the Mole to the wall of the hole and helped it penetrate further to almost 40cm. The initial penetration rate of the Mole has been used to estimate a penetration resistance of 300kPa. Attempts to crush the duricrust a few cm away from the pit have been unsuccessful from which a lower bound to the compressive strength of 350kPa is estimated.  Analysis of the slope of the steep walls of the hole gave a lower bound to cohesion of 10kPa. As for thermal properties, a measurement of the thermal conductivity of the regolith with the Mole thermal sensors resulted in 0.045 Wm-1K-1.  The value is considerably uncertain because part of the Mole having contact to air.  The HP³ radiometer has been monitoring the surface temperature next to the lander and a thermal model fitted to the data give a regolith thermal inertia of  189 ± 10 J m-2 K-1 s-1/2. With best estimates of heat capacity and density, this corresponds to a thermal conductivity of 0.045 Wm-1K-1, consistent with the above measurement using the Mole. The data can be fitted well with a homogeneous soil model, but observations of Phobos eclipses in March 2019 indicate that there possibly is a thin top layer of lower thermal conductivity. A model with a top 5 mm layer of 0.02 Wm-1K-1 above a half-space of 0.05 Wm-1K-1 matches the amplitudes of both the diurnal and eclipse temperature curves. Another set of eclipses will occur in April 2020.

 

How to cite: Spohn, T., Grott, M., Müller, N., Knollenberg, J., Krause, C., Hudson, T., Deen, R., Marteau, E., Golombek, M., Hurst, K., Piqueux, S., Smrekar, S., Thomas, A. L., Fantinati, C., Lichtenheldt, R., and Wippermann, T.: Mars Regolith Properties as Constrained from HP3 Mole Operations and Thermal Measurements , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9163, https://doi.org/10.5194/egusphere-egu2020-9163, 2020.

EGU2020-20295 | Displays | PS4.1

The winds of Mars: Why InSight wind data are so valuable and what they tell us

Claire Newman and the TWINS and InSight Teams

Measurements of near-surface winds on Mars are vital to understand momentum, heat, and gas exchange (e.g. water vapor, methane) at the surface; to interpret surface aeolian features, from wind streaks to dunes; to understand the conditions required for raising dust from the surface; to combine with other observations of atmospheric phenomena such as baroclinic waves, convective vortices, and clouds; to test and improve atmospheric models, which may then be used with greater confidence for other locations and epochs; to provide ground truth for Entry-Descent-Landing, the Mars2020 helicopter, and Ascent Vehicles; and finally, to help quantify the conditions that will be faced by future human explorers of Mars.

Despite this, however, good wind datasets are very rare for Mars. The Viking Landers provided valuable information on seasonal and diurnal variations in wind speed and direction, including the impact of dust storms, but recorded high frequency winds only a small portion of the time. Mars Pathfinder lasted only a few months on the surface and recorded wind directions but could not produce calibrated wind speeds. Phoenix similarly had a short lifetime and only measured intermittently at low temporal resolution and accuracy, although provided both wind speed and direction. Spirit and Opportunity carried no wind sensors at all. The ongoing Mars Science Laboratory mission’s Curiosity Rover carried the first wind sensor to operate in a region of strong topography (Gale Crater); however, electronic noise and damage upon landing resulted in many data gaps and biases in the wind dataset, and the wind sensor was permanently lost after fewer than three Mars years due to further damage.

InSight carries the TWINS wind sensor, consisting of two booms facing in opposite directions. The wind speed and direction at any time is obtained by selecting the boom with the least interference by lander components or heating. By the time of this presentation, InSight should have measured wind continuously at ~1.2m above the surface for over 500 Mars sols (nearly three-quarters of a Mars year), with the majority of this dataset available at a frequency of 1Hz.

We will present the InSight wind dataset and describe how it has already helped Mars scientists to make progress in a range of fields. These include understanding the origins of aeolian features and inferring thresholds for sand motion or dust lifting, as well as quantifying the impact of topography and dust loading on modifying the regional circulation. Comparison with the winds predicted by atmospheric models has shown areas of disagreement, pointing to places where a different model setup or boundary condition (e.g. resolution, roughness map) may be needed, or where the model’s parameterizations of sub-grid scale physical processes (e.g. vertical mixing) need to be improved. Finally, given InSight’s proximity to the Curiosity Rover, we will show how winds in some seasons provide information on the regional flow before it reaches Gale Crater, and hence aid in interpreting Curiosity’s more complex wind dataset.

How to cite: Newman, C. and the TWINS and InSight Teams: The winds of Mars: Why InSight wind data are so valuable and what they tell us, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20295, https://doi.org/10.5194/egusphere-egu2020-20295, 2020.

EGU2020-11771 | Displays | PS4.1

Magnetic Pulsations and Transients on Martian Surface

Peter Chi, Christopher Russell, Steve Joy, Yanan Yu, Don Banfield, Matthew Fillingim, Yingjuan Ma, Suzanne Smrekar, and William Banerdt

InSight is the first Mars surface mission that includes a magnetometer, and one of the first discoveries made by the InSight FluxGate (IFG) magnetometer is the ultra-low-frequency (ULF) waves, or magnetic pulsations, on the Martian surface. By studying magnetic pulsations and transient signatures in more than six months of IFG data, we find that the morphologies of these two types of perturbations have considerable variations from their counterparts on the Earth, reflecting the fundamental differences between the magnetospheres with and without a global magnetic field. The most noticeable ULF waves are the continuous pulsations (Pc) occurring at around midnight and with wave periods of the order of 100 sec, or in the Pc 4 frequency band when the terminology of terrestrial magnetic pulsations is used. Broadband pulsations at Pc 5 frequencies (i.e., a few mHz) have also been observed. Comparisons with lander activities and InSight’s Temperature and Wind for InSight Subsystem (TWINS) data confirm that the observed magnetic pulsations are not caused by tremors of the lander. Simultaneous observations by MAVEN in the solar wind and InSight on Mars indicate that the upstream waves in front of Mars bow shock can hardly reach the dayside surface, leading to a dearth of magnetic pulsations in the daytime. In addition, solar wind discontinuities or transient events can induce noticeable surface magnetic responses only in the nightside, suggesting that the magnetic pileup region and ionosphere can effectively shield external magnetic disturbances. MAVEN observations also help identify sources of magnetic pulsations seen on the Martian surface. While the low-frequency, broad-band Pc 5 pulsations may be excited by the oscillations on the flanks of the induced magnetosphere associated with solar wind variations or the Kelvin-Helmholtz instability, there is a strong indication that the nightside Pc 4 pulsations on the surface originate from the compressional oscillations in the magnetotail. Different from the flow-generated fast mode waves in the terrestrial magnetotail, the fast mode in the Martian magnetotail could travel toward the planet without substantial coupling to the Alfvén mode. The Mars-propagating fast mode experiences little reflection from the ionosphere and can produce surface magnetic pulsations at low latitudes on the nightside. These first findings of magnetic pulsations and transients on the Martian surface not only reveal the origins and propagation of magnetic signals from the outer space but also help determine the source model for the magnetic sounding of Mars' interior.

How to cite: Chi, P., Russell, C., Joy, S., Yu, Y., Banfield, D., Fillingim, M., Ma, Y., Smrekar, S., and Banerdt, W.: Magnetic Pulsations and Transients on Martian Surface, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11771, https://doi.org/10.5194/egusphere-egu2020-11771, 2020.

EGU2020-6826 | Displays | PS4.1

Engaging Schools with InSight Data

Jean Luc Berenguer, Tammy Bravo, Anne Sauron-Sornette, and John Stevenson

After a 6-month flight to Mars and a successful landing, InSight has deployed SEIS … its seismometer designed to sit on the Martian surface. The goal of this mission is to investigate the dynamics of Martian seismic activity and understand the processes that shaped the Red Planet.

SEIS InSight has engaged a generation of school kids, teens and students which, like scientists, follow the mission live. The data from InSight offers a chance to leverage existing Seismometers in Schools networks to allow a large and growing number of students to interact with seismic data recorded on Mars as soon as it is available on Earth.  Students in these international networks have experience with seismic data and software and are primed to engage with this NASA Discovery mission.

Seismic data in the classroom has provided both a hook for inquiry with real data as well as a common language for international collaboration.

These resources input innovative educational strategies acculturating pupils in the acquisition, processing, display and exploration of seismic and weather data.

A very large school network (middle and high schools) share resources and activities using InSight data. Networks are preparing lessons, software, web tools, data viewers, and other resources to allow students to explore and interrogate shaking on Mars to better understand the heart of the planet.

In this presentation, we will show all the practical activities and all the different tools created for the kids, teens and students. This work has been developed by teachers, educators, and scientists in international cooperation, and can be found on dedicated websites.

How to cite: Berenguer, J. L., Bravo, T., Sauron-Sornette, A., and Stevenson, J.: Engaging Schools with InSight Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6826, https://doi.org/10.5194/egusphere-egu2020-6826, 2020.

EGU2020-13034 | Displays | PS4.1

Updated Magnitude Scales for Mars

Maren Böse, Simon Stähler, Domenico Giardini, Savas Ceylan, John Clinton, Martin van Driel, Martin Knapmeyer, Philippe Lognonné, and Bruce Banerdt

About one year after the successful deployment of the InSight (Interior exploration using Seismic Investigations, Geodesy and Heat Transport) very-broadband seismometer on the Martian surface and the identification of several hundreds of seismic events in the current InSight catalogue, we revise the pre-launch magnitude relations in Böse et al. (2018) to account for the seismic and noise characteristics observed on Mars. The data collected so far indicate that (1) marsquakes are characterized by energy between ~0.1-10Hz; (2) neither surface-wave nor secondary phase arrivals have yet been identified; and (3) a class of high-frequency events exists that are visible mainly as an increased excitation of the 2.4Hz mode. In view of these observations, we up-date scaling relations for the spectral and body-wave magnitudes, and introduce a new magnitude scale for high-frequency events. We use these relations to determine that the magnitudes of events in the current InSight catalogue range between 1.0 and 4.0.

How to cite: Böse, M., Stähler, S., Giardini, D., Ceylan, S., Clinton, J., van Driel, M., Knapmeyer, M., Lognonné, P., and Banerdt, B.: Updated Magnitude Scales for Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13034, https://doi.org/10.5194/egusphere-egu2020-13034, 2020.

EGU2020-13482 | Displays | PS4.1

Seismic activity rate of Mars, based on 420 Sols of InSight data

Simon C. Stähler, Martin Knapmeyer, Domenico Giardini, John Clinton, Tom Pike, Philippe Lognonné, Mark Panning, Maren Böse, Savas Ceylan, Constantinos Charalambous, Martin van Driel, Anna Horleston, Taichi Kawamura, Sharon Kedar, Amir Khan, John-Robert Scholz, and Bruce Banerdt

We present an updated estimate of the seismic activity rate of Mars after seven months of high-quality recording of the InSight SEIS instrument. The instrument has been deployed fully on Sol 60 (February 2, 2019) and has been recording with excellent performance since then. The first distant marsquake was observed on Sol 105 (March 14), the first local event on Sol 128 (April 7). From then until early January 2020 (Sol 400), 23 likely events and another 13 candidate events have been observed. Due to a strong diurnal variation in background noise and the generally low magnitude of the activity (compared to Earth), events have been observed only in few low-noise periods of the day. The change of seasons varied the duration of these low-noise periods over the mission, with a magnitude and time-dependent effect on detectability of events and the quantitative estimation of event rates and moment release.

We present a statistical analysis of the global seismic activity level based on a preliminary seismic magnitude model, weighted by the temporal evolution of the ambient noise over half a Martian year. The resulting number of events smaller magnitude 3 is roughly consistent with the pre-mission estimate of Golombek (1992) and the medium model of Knapmeyer et al. (2006), however, as of now, there is a statistically significant lack of events above magnitude 3.5. This hints at a distribution that is skewed towards smaller events, compared to terrestrial global averages.

How to cite: Stähler, S. C., Knapmeyer, M., Giardini, D., Clinton, J., Pike, T., Lognonné, P., Panning, M., Böse, M., Ceylan, S., Charalambous, C., van Driel, M., Horleston, A., Kawamura, T., Kedar, S., Khan, A., Scholz, J.-R., and Banerdt, B.: Seismic activity rate of Mars, based on 420 Sols of InSight data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13482, https://doi.org/10.5194/egusphere-egu2020-13482, 2020.

EGU2020-11577 | Displays | PS4.1

Monitoring Seismicity on Mars - the Marsquake Service for InSight

John Clinton, Domenico Giardini, Savas Ceylan, Martin van Driel, Simon Stähler, Bruce Banerdt, Maren Böse, Constantinos Charalambous, Fabian Euchner, Anna Horleston, Taichi Kawamura, Raphael Garcia, Sharon Kedar, Amir Khan, Philippe Lognonnne, Guenole Mainsant, Mark Panning, Tom Pike, John-Robert Scholz, and Sue Smrekar and the ERP Gurus

InSight landed on Mars in late November 2018, and the SEIS seismometer package was fully deployed by February 2019. By January 2020, SEIS continues to exceed performance expectations in terms of observed minimum noise. The Marsquake Service (MQS) has been setup to create and curate a seismicity catalogue for Mars over the lifetime of the InSight mission. Seismic waveforms are downloaded daily from the station and are analysed and processed by the MarsQuake Service, with the goal of detecting seismic vibrations not due to local ambient sources. To this end, every precaution is applied to eliminate possible non-seismic sources, such as noise induced by atmospheric phenomena, lander vibrations and orbiter activity. At the date of submission, we have detected 365 events, of different quality and SNR levels. Signal amplitudes remain small and signal can generally only be detected at night. Some events show only low-frequency waves in the 1-10 sec band, others have a high-frequency content up to several Hz, and others have a more broad-band character. A special class of events involves the excitation of a very prominent ambient vibration at 2.4Hz. Despite the scattered nature of the energy, in many cases, distinct phases can be inferred in the waveforms. Body wave character, and back-azimuth, can only be confirmed for 3 broadband events so far.  The MQS approach for determining distances from broadband events identifies phases as mantle P and S-phases and uses an a priori set of several thousand martian models, derived from geophysical, mineralogical and orbital constraints. High frequency events are currently located assuming phases are trapped crustal Pg and Sg and using a simple crustal layer. The MQS works in conjunction with the Mars Structural Service (MSS) on building and adopting updated models. The MQS consists of an international team of seismologists that screen incoming data to identify and characterise any seismicity. In this presentation, we present the MQS, demonstrate how we detect and characterise marsquakes, and describe the challenges we face dealing with the Martian dataset.

How to cite: Clinton, J., Giardini, D., Ceylan, S., van Driel, M., Stähler, S., Banerdt, B., Böse, M., Charalambous, C., Euchner, F., Horleston, A., Kawamura, T., Garcia, R., Kedar, S., Khan, A., Lognonnne, P., Mainsant, G., Panning, M., Pike, T., Scholz, J.-R., and Smrekar, S. and the ERP Gurus: Monitoring Seismicity on Mars - the Marsquake Service for InSight, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11577, https://doi.org/10.5194/egusphere-egu2020-11577, 2020.

EGU2020-19482 | Displays | PS4.1

Overview of observed seismic signals on Mars

Savas Ceylan, John F. Clinton, Domenico Giardini, Maren Böse, Martin van Driel, Fabian Euchner, Anna Horleston, Taichi Kawamura, Amir Khan, Guénolé Orhand-Mainsant, John-Robert Scholz, Simon Stähler, Constantinos Charalambous, W. Bruce Banerdt, Raphaël F. Garcia, Sharon Kedar, Philippe Lognonné, Mark Panning, Tom Pike, and Suzanne E. Smrekar

InSight landed on Mars in late November 2018, and the SEIS package, which consists of one short period and one very broadband sensor, was deployed on the surface shortly after. The data returned by the InSight is monitored in a timely manner by the Marsquake Service (MQS), a ground segment support group of InSight that has been set up to establish and maintain the seismicity catalogue. The MQS has at least one member on duty who routinely checks the data for any type of seismic signals. All suspicious signals are then communicated to the InSight team after evaluation.

To date, MQS has identified more than 365 events which are classified into two general families as high and low frequency, with each family having unique features in terms of their energy content. The most distinct quakes detected so far belong to the low frequency family that occurred on Sol 173 and 235, and have clear P and S-wave arrivals that reveal a distance around 30 degrees east of the lander, pointing the region in the vicinity of Cerberus Fossae. In addition to the signals of seismic origin, the SEIS data contain features that originate from other sources such as atmospheric effects or electronics. Part of these non-seismic observations may resemble quakes which may lead to wrong interpretations, and therefore require careful analysis.

Here, we show examples of signals of both seismic and non-seismic origins. We describe the characteristics of these observations in time and frequency domains in order to give an overview of martian data content.

How to cite: Ceylan, S., Clinton, J. F., Giardini, D., Böse, M., van Driel, M., Euchner, F., Horleston, A., Kawamura, T., Khan, A., Orhand-Mainsant, G., Scholz, J.-R., Stähler, S., Charalambous, C., Banerdt, W. B., Garcia, R. F., Kedar, S., Lognonné, P., Panning, M., Pike, T., and Smrekar, S. E.: Overview of observed seismic signals on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19482, https://doi.org/10.5194/egusphere-egu2020-19482, 2020.

EGU2020-22525 | Displays | PS4.1

First seismic constraints on the Martian crust – receiver functions for InSight

Brigitte Knapmeyer-Endrun, Felix Bissig, Nicolas Compaire, Raphael Garcia, Rakshit Joshi, Amir Khan, Doyeon Kim, Vedran Lekic, Ludovic Margerin, Mark Panning, Martin Schimmel, Nicolas Schmerr, Eleonore Stutzmann, Benoit Tauzin, Saikiran Tharimena, Simon Stähler, Paul Davis, Baptiste Pinot, and John-Robert Scholz and the InSight crustal structure team

NASA’s InSight mission arrived on Mars in November 2018 and deployed the first very broad-band seismometer, SEIS, on the planet’s surface. SEIS has been collecting data continuously since early February 2019, by now recording more than 400 events of different types. InSight aims at enhancing our understanding of the internal structure and dynamics of Mars, including better constraints on its crustal thickness. Various models based on topography and gravity observed from the orbit currently vary in average crustal thickness from 30 km to more than 100 km, with important implications for Mars’ thermal evolution, and the partitioning of silicates and heat-producing elements between different layers of Mars.

We present P-to-S and S-to-P receiver functions, which are available for 4 and 3 marsquakes, respectively, up to now. Out of all of the marsquakes recorded to date, these are the only ones with clear enough P- or S-arrivals not dominated by scattering to make them suitable for the analysis. All of the quakes are located at comparatively small epicentral distances, between 25° and 40°. We observe three consistent phases within the first 10 seconds of the P-to-S receiver functions. The S-to-P receiver functions also show a consistent first phase. Later arrivals are harder to pinpoint, which could be due to the comparatively shallow incidence of the S-waves at the considered distances, which prevents the generation of converted waves. Identification of later multiple phases in the P-to-S receiver functions likewise remains inconclusive. To obtain better constraints on velocity, we also calculated apparent velocity curves from the P-to-S receiver functions, but these provide meaningful results for only one event so far, implying a large uncertainty. Due to difficulties in clearly identifying multiples, the receiver functions can currently be explained by either two crustal layers and a thin (25-30 km) crust or three crustal layers and a thicker (40-45 km) crust at the landing site. This model range already improves the present constraints by providing a new maximum value of less than 70 km for the average crustal thickness. Information from noise autocorrelations as a complementary method, identification of P-reverberations and S-precursors in the event recordings, and more extensive modeling, ultimately including 3D-effects, are considered to further our understanding of the waveforms and tighten the constraints on the crust.

How to cite: Knapmeyer-Endrun, B., Bissig, F., Compaire, N., Garcia, R., Joshi, R., Khan, A., Kim, D., Lekic, V., Margerin, L., Panning, M., Schimmel, M., Schmerr, N., Stutzmann, E., Tauzin, B., Tharimena, S., Stähler, S., Davis, P., Pinot, B., and Scholz, J.-R. and the InSight crustal structure team: First seismic constraints on the Martian crust – receiver functions for InSight, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22525, https://doi.org/10.5194/egusphere-egu2020-22525, 2020.

For Earth and Moon, the seismic observation data is the most direct and effective means to detect their internal structure. However, due to the long distance between Mars and Earth and the harsh observation conditions on Mars, the exploration of Martian velocity structure model is a very challenging task. The InSight lander deployed the first seismic observation instrument SEIS (Seismic Experiment for Internal Structure) on the Mars’ surface after its successful landing on Mars on November 26, 2018. In this study, we performed horizontal-to-vertical spectral ratio (HVSR) and polarization analysis of three component VBB seismic waveforms recorded by the SEIS station released on the IRIS website. We are trying to constrain the thickness of the Martian regolith at the landing site of InSight from the SEIS data. The VBB ambient noise data we used are in HHV/HHU/HHW channels of ELYSE station in 30 Martian days. These data are predominantly ambient noise data caused by wind effects and do not contain any known marsquake data. We found that the HVSR curves from nearly all released data show two distinct peaks at 11.9 Hz and 24.5 Hz, respectively. Furthermore, we conducted particle motion and polarization analysis on these data in various frequency bands, which indicate that the ground motion at the highest peak show linearly polarized and vertically incident motion with a fixed azimuth. This could be explained by the S-wave resonance of the Martian regolith at the InSight landing site caused by the wave motion source from the wind induced motion of the lander. Using the possible S-wave velocity of the Martian regolith proposed by previous studies and the peak frequencies of the HVSR results in this study, thickness of the Martian regolith at the InSight landing site was obtained that is smaller than the pre-evaluated thickness (3~5 m) for the InSight mission.

How to cite: Xiao, W. and Wang, Y.: Study on the Structural Characteristics of Martian Regolith by Ambient Noise Data from SEIS Observation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20940, https://doi.org/10.5194/egusphere-egu2020-20940, 2020.

Investigating the interior structure of Mars is important to study not only its past and present state and future evolution, but also the formation and evolution of the Earth and solar system. Seismological methods played import roles in the study of the Earth and Moon’s interior. The first mission about Martian seismology began in 1976, but no seismic events were convincingly detected during the observation. The InSight Spacecraft landed on Mars on November 26, 2018 in Elysium Planitia and installed the first seismometer on Mars. It will provide the in situ observation of interior structure and seismic activity of Mars for the first time. In this study, we perform numerical modelling of seismic wave propagation in whole-mars models by solving the seismic wave equations using a hybrid pseudospectral and finite difference method on staggered grid. Firstly, based on the Martian internal models derived from geochemical analysis (Sohl and Spohn, 1997), we present numerical simulations of seismic wave propagation in the whole Mars models. The generation and propagation of various seismic phases in the whole Mars models are shown by synthetic seismograms and wavefield snapshots. We analyze the effects of crustal thickness and depth of core mantle boundary on seismic wave propagation. Then based on the present model of Martian crustal thickness (Wieczorek and Zuber, 2004), we simulate seismic wave propagation in laterally heterogeneous Martian crust and analyze the influence of lateral heterogeneity on global seismic wave propagation. Multiple reflections and conversions of seismic waves and their constructive interference occurred inside the low-velocity Martian crust form reverberating wave trains. Thickness of Martian crust has strong effect on the propagation of multiple surface reflections and surface waves. Seismic reflections from core-mantle boundary can be clearly identified from the calculated transverse component seismogram.

How to cite: Wang, Y., Xiao, W., and Deng, D.: Numerical Modeling of Global Seismic Wave Propagation in the Whole Mars Models and Effect of Lateral Crustal Variation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20959, https://doi.org/10.5194/egusphere-egu2020-20959, 2020.

EGU2020-16469 | Displays | PS4.1

Investigation of Mars Seismic Attenuation Using InSight SEIS Data.

Taichi Kawamura, Ludovic Margerin, Mélanie Drilleau, Sabrina Ménina, Philippe Lognonné, Nicholas C. Schmerr, Simon Stäehler, Martin van Driel, and Bruce Banerdt

 NASA InSight (the Interior Exploration using Geodesy and Heat Transport) has placed the first broadband seismometer (SEIS) on the Martian surface and now continuously monitoring Martian seismic activity. Since the first detection of a marsquake in March 2019, SEIS detected more than 200 marsquakes and Mars has been revealed to be a seismically active planet. The dataset can now be used to perform the seismic investigation of the Mars interior and interpret this in a comparative manner by referring to the examples from the Earth and the Moon.

In this study, we investigate the seismic attenuation on Mars and compare this with the Earth and the Moon. Attenuation can be described as a combination of inelastic absorption and elastic diffusion of energy. Such properties will give important constraints on the composition of the Mars interior and also its thermal state. Another interesting aspect will be to discuss the water content with respect to the attenuation. Given the large variety of water content for the Earth, the Moon and Mars, the attenuation feature will be likely to differ significantly between these planets and satellite. Here we use the seismic dataset obtained by InSight SEIS and construct a 1D structure of seismic attenuation on Mars. Then we refer to the values obtained for the Earth and the Moon to discuss the possible implication on their differences and similarities.

 The presentation aims to summarize the results from different approaches taken by the authors. The approach includes; 1) spectral analyses of seismic signals and spectral decay fitting, 2) seismic coda analyses with coda rise time and decay, 3) numerical coda simulation with diffusion theory on seismic energy. With these approaches we will be constraining seismic quality factor Q and diffusivity D for different depth range. Different approaches have sensitivities to different depth and prarameters and we aim to provide our view on the martian attenuation and diffusion to date by summarizing the obtained results.

How to cite: Kawamura, T., Margerin, L., Drilleau, M., Ménina, S., Lognonné, P., Schmerr, N. C., Stäehler, S., Driel, M. V., and Banerdt, B.: Investigation of Mars Seismic Attenuation Using InSight SEIS Data. , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16469, https://doi.org/10.5194/egusphere-egu2020-16469, 2020.

EGU2020-20748 | Displays | PS4.1

Pressure effects on SEIS-INSIGHT instrument, improvement of seismic records and characterization of gravity waves from ground displacements

Raphael François Garcia, Balthasar Kenda, Melanie Drilleau, Aymeric Spiga, Taichi Kawamura, Philippe Henri Lognonné, Naomi Murdoch, Nicolas Compaire, Donald Banfield, Rudolf Widmer-Schnidrig, Guenole Orhand-Mainsant, and Williams Bruce Banerdt

Mars atmospheric pressure variations induce ground displacements through elastic deformations. The various sensors of INSIGHT mission were designed in order to be able to understand and correct these ground deformations induced by atmospheric effects. Particular efforts were done on one side to avoid direct pressure and wind effects on the seismometer, and on the other side to have a high performance pressure sensor operating in the same frequency range than the seismometer.
As a consequence of the high performances of both instruments, their very efficient protection systems against direct atmospheric disturbances, and the low Mars background seismic noise, INSIGHT mission is opening a new science domain for which the ground displacements can be used to perform atmospheric science.
This study presents an analysis of pressure and seismic signals and their relations. After a short description of the pressure and seismic sensors deployed by INSIGHT, we present an analysis of these signals as a function of local time at INSIGHT location.
Then, the background and event like coherent signals between Pressure and seismometer sensors are interpreted in terms of various atmospheric excitations and induced  ground deformation processes. Different methods to remove the pressure effects recorded by SEIS sensors are presented, and their efficiency is estimated. Finally, we demonstrate that the pressure and ground deformations measurements can be used to decipher between various atmospheric excitation types (meteorological pressure variations, acoustic and gravity waves)  and characterize these. Effects of the local sub-surface structure are also suggested by the data analysis.

How to cite: Garcia, R. F., Kenda, B., Drilleau, M., Spiga, A., Kawamura, T., Lognonné, P. H., Murdoch, N., Compaire, N., Banfield, D., Widmer-Schnidrig, R., Orhand-Mainsant, G., and Banerdt, W. B.: Pressure effects on SEIS-INSIGHT instrument, improvement of seismic records and characterization of gravity waves from ground displacements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20748, https://doi.org/10.5194/egusphere-egu2020-20748, 2020.

EGU2020-12178 | Displays | PS4.1

Aeolian Changes at the Insight Landing Site on Mars: Multi-instrument Observations

Constantinos Charalambous, Mariah Baker, Matthew Golombek, John McClean, Tom Pike, Aymeric Spiga, Alexander Stott, Veronique Ansan, Catherine Weitz, John Grant, Nicholas Warner, Sebastien Rodriguez, Ralph Lorenz, Anna Mittelholz, Catherine Johnson, Justin Maki, Mark Lemmon, Maria Banks, Naomi Murdoch, and Ingrid Daubar and the Co-authors

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed in western Elysium Planitia on November 26, 2018. Because of its stationary position and a multi-instrument package, InSight offers the unique opportunity of detecting changes induced by aeolian activity and constraining the atmospheric conditions responsible for particle motion.

In this work, we present the most significant changes from aeolian activity as detected by the InSight lander during its first 400 Martian days of operations. We will show that particle entrainment by wind activity around InSight is a subtle process and report simultaneous measurements observed across multiple instruments. The changes observed are episodic and are seen correlated with excursions in both seismic and magnetic signals, which will be discussed further. Our observations show that all aeolian movements are consistent with the passage of deep convective vortices between noon to 3 pm local time. These vortices may be the primary initiators for aeolian transportation at InSight, inducing episodic particulate motion of grains up to 3 mm in diameter.

How to cite: Charalambous, C., Baker, M., Golombek, M., McClean, J., Pike, T., Spiga, A., Stott, A., Ansan, V., Weitz, C., Grant, J., Warner, N., Rodriguez, S., Lorenz, R., Mittelholz, A., Johnson, C., Maki, J., Lemmon, M., Banks, M., Murdoch, N., and Daubar, I. and the Co-authors: Aeolian Changes at the Insight Landing Site on Mars: Multi-instrument Observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12178, https://doi.org/10.5194/egusphere-egu2020-12178, 2020.

EGU2020-21327 | Displays | PS4.1

Daytime and nighttime turbulence on Mars monitored by InSight

Aymeric Spiga, Naomi Murdoch, Don Banfield, Ralph Lorenz, Claire Newman, Jorge Pla-Garcia, Raphael Garcia, Philippe Lognonné, Léo Martire, and Sara Navarro and the the InSight team

The InSight instrumentation for atmospheric science combines high frequency, high accuracy and continuity. This makes InSight a mission particularly suitable for studies of the variability in the Planetary Boundary Layer (PBL) of Mars -- all the more since this topic is of direct interest for quake detectability given that turbulence is the main contributor to atmosphere-induced seismic signal. For the strong daytime buoyancy-driven PBL convection, InSight significantly extends the statistics of dust-devil-like convective vortices and turbulent wind gustiness, both of which are of strong interest for aeolian science. For the moderate nighttime shear-induced PBL convection, InSight enables to explore phenomena and variability left unexplored by previous in-situ measurements on Mars. In both daytime and nighttime environments, how the gravity waves and infrasound signals discovered by InSight are being guided within the PBL is also a central topic to InSight's atmospheric investigations, with the tantalizing possibility to identify possible sources for those phenomena. InSight has been operating at the surface of Mars since 18 months, thus the seasonal evolution of the many phenomena occurring in the PBL will be an emphasis of this report. Comparisons with turbulence-resolving modeling such as Large-Eddy Simulations will be also discussed.

How to cite: Spiga, A., Murdoch, N., Banfield, D., Lorenz, R., Newman, C., Pla-Garcia, J., Garcia, R., Lognonné, P., Martire, L., and Navarro, S. and the the InSight team: Daytime and nighttime turbulence on Mars monitored by InSight, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21327, https://doi.org/10.5194/egusphere-egu2020-21327, 2020.

EGU2020-20481 | Displays | PS4.1

Seismic investigations of the Martian near-surface at the InSight landing site

Cedric Schmelzbach, Nienke Brinkman, David Sollberger, Sharon Kedar, Matthias Grott, Fredrik Andersson, Johan Robertsson, Martin van Driel, Simon Stähler, Jan ten Pierick, Troy Hudson, Kenneth Hurst, Mellanie Drilleau, Balthasar Kenda, Raphael Garcia, Naomi Murdoch, Domenico Giardini, Philippe Lognonne, W. Tom Pike, and Tilman Spohn and the InSight SEIS and Near Surface Team

The InSight ultra-sensitive broadband seismometer package (SEIS) was installed on the Martian surface with the goal to study the seismicity on Mars and the deep interior of the Planet. A second surface-based instrument, the heat flow and physical properties package HP3, was placed on the Martian ground about 1.1 m away from SEIS. HP3 includes a self-hammering probe called the ‘mole’ to measure the heat coming from Mars' interior at shallow depth to reveal the planet's thermal history. While SEIS was designed to study the deep structure of Mars, seismic signals such as the hammering ‘noise’ as well as ambient and other instrument-generated vibrations allow us to investigate the shallow subsurface. The resultant near-surface elastic property models provide additional information to interpret the SEIS data and allow extracting unique geotechnical information on the Martian regolith.

The seismic signals recorded during HP3 mole operations provide information about the mole attitude and health as well as shed light on the near-surface, despite the fact that the HP3 mole continues to have difficulty penetrating below 40 cm (one mole length). The seismic investigation of the HP3 hammering signals, however, was not originally planned during mission design and hence faced several technical challenges. For example, the anti-aliasing filters of the seismic-data acquisition chain were adapted when recording the mole hammering to allow recovering information above the nominal Nyquist frequency. In addition, the independently operating SEIS, HP3 and lander clocks had to be correlated more frequently than in normal operation to enable high-precision timing.

To date, the analysis of the hammering signals allowed us to constrain the bulk P-wave velocity of the volume between the mole tip and SEIS (top 30 cm) to around 120 m/s. This low velocity value is compatible with laboratory tests performed on Martian regolith analogs with a density of around 1500 kg/m3. Furthermore, the SEIS leveling system resonances, seismic recordings of atmospheric pressure signals, HP3 housekeeping data, and imagery provide additional constraints to establish a first seismic model of the shallow (topmost meters) subsurface at the landing site.

How to cite: Schmelzbach, C., Brinkman, N., Sollberger, D., Kedar, S., Grott, M., Andersson, F., Robertsson, J., van Driel, M., Stähler, S., ten Pierick, J., Hudson, T., Hurst, K., Drilleau, M., Kenda, B., Garcia, R., Murdoch, N., Giardini, D., Lognonne, P., Pike, W. T., and Spohn, T. and the InSight SEIS and Near Surface Team: Seismic investigations of the Martian near-surface at the InSight landing site, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20481, https://doi.org/10.5194/egusphere-egu2020-20481, 2020.

EGU2020-2238 | Displays | PS4.1

Evidence for a Wet Martian Interior from Magnetic Sounding with the InSight Magnetometer

Yanan Yu, Christopher Russell, Matthew Fillingim, and William Banerdt

The martian magnetic field oscillates at frequencies from once per day to periods of only 100s of seconds. The interior of Mars is electrically conducting, and the time-varying magnetic fields create induced currents in the electrically conducting subsurface of Mars. The diurnal periods are little affected by the interior conductivity, but at periods shorter than about 1000 sec, the reflection of the magnetic wave energy is strong, and the vertical component of the oscillating magnetic field approaches zero as the frequency increases. Electromagnetic waves at the shorter (<1000s) periods are produced by the nighttime currents such as those flowing on and within the Mars magnetotail. These fluctuations are weak in the vertical component of the waves associated with the restriction of the currents to flow horizontally as the wave period grows shorter. This phenomenon is also seen on Earth and has been well characterized there. The measure of the attenuation of the vertical component is referred to as the skin depth. The attenuation observed at the InSight landing site is consistent with a skin depth of 3.4 km for the expected conductivity of terrestrial seawater. We have not seen any variation of this skin depth with season. These observations are consistent with the many manifestations of the occasional presence of water on or near the surface of Mars and strengthen the case for permanent water in the soil only several kilometers beneath the surface.

How to cite: Yu, Y., Russell, C., Fillingim, M., and Banerdt, W.: Evidence for a Wet Martian Interior from Magnetic Sounding with the InSight Magnetometer, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2238, https://doi.org/10.5194/egusphere-egu2020-2238, 2020.

PS4.2 – Mars Science and Exploration

EGU2020-22390 | Displays | PS4.2

Mars Express Science Highlights and Future Plans

Dmitrij Titov, Jean-Pierre Bibring, Alejandro Cardesin, Thomas Duxbury, Francois Forget, Marco Giuranna, Francisco Gonzaìlez-Galindo, Mats Holmström, Ralf Jaumann, Anni Määttänen, Patrick Martin, Franck Montmessin, Roberto Orosei, Martin Pätzold, and Jeff Plaut

After 16 years in orbit Mars Express remains one of ESA’s most scientifically productive Solar System missions which publication record now exceeds 1270 papers. Characterization of the geological processes on a local-to-regional scale by HRSC, OMEGA and partner experiments on NASA spacecraft has allowed constraining land-forming processes in space and time. Recent studies suggest geological evidence of a planet-wide groundwater system on Mars and surface clay formation during short-term warmer and wetter conditions on a largely cold ancient Mars that might indicate a change in our understanding of early Mars climate. HRSC team released first set of multi-orbit Digital Elevation Model (DEM) of the MC-11 quadrangle and the Southern polar cap with 50 m/px resolution. Mars Express observations and experimental teams provided essential contribution to the selection of the Mars-2020 landing sites and supporting characterization of potential landing sites for the Chinese HX-1 mission. Following recent discovery of subglacial liquid water underneath the Southern polar layered deposits the MARSIS radar continues searching for subsurface water pockets.

One-and-half decade of monitoring of atmospheric parameters such as temperature, dust loading, water vapor and ozone abundance, water ice and CO2 clouds distribution, collected by SPICAM, PFS, OMEGA, HRSC and VMC together with subsequent modeling have provided key contributions to our understanding of the Martian climate. The observed ozone climatology demonstrate significant discrepancies with model predictions indicating the need for models improvement. In 2018 PFS confirmed observations of a methane abundance “spike” in the Gale crater observed in situ by the Curiosity Rover. Recent similar quasi-simultaneous observations were in disagreement, thus indicating that the methane “enigma” continues. This poses a significant challenge to both observers and modelers. The radio-science experiment MaRS revealed fine structure of the boundary layer. Its depth varies from 2 km in topographic lows to ~10 km over highlands.

Observations of the ion escape during complete solar cycle revealed that ion escape can be responsible for removal of about 10 mbar over Mars history that implies existence of other more effective escape channels.  

The structure of the ionosphere derived from MARSIS and MaRS sounding was found to be significantly affected by the solar activity, the crustal magnetic field. The observations suggest that the sunlit ionosphere over the regions with strong crustal fields is denser and extends to higher altitudes as compared to the regions with no crustal anomalies. Expansion of the ionosphere was also observed during the global dust storm. Ionospheric models aim at creating user-friendly data base of plasma parameters that would be of great service to the planetary community.

The “gyroless” attitude control and operations mode of the spacecraft operates flawlessly since April 2018. Aging batteries impose more and more limitations on science operations during eclipse seasons. The mission is now confirmed till the end of 2020 and notionally extended till the end of 2022. The talk will give the Mars Express status, review the recent science highlights, and outline future plans including synergistic science with TGO.

How to cite: Titov, D., Bibring, J.-P., Cardesin, A., Duxbury, T., Forget, F., Giuranna, M., Gonzaìlez-Galindo, F., Holmström, M., Jaumann, R., Määttänen, A., Martin, P., Montmessin, F., Orosei, R., Pätzold, M., and Plaut, J.: Mars Express Science Highlights and Future Plans, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22390, https://doi.org/10.5194/egusphere-egu2020-22390, 2020.

EGU2020-11414 | Displays | PS4.2 | Highlight

Phobos composition: a reappraisal, based on Omega/MEx observations

Brigitte Gondet and Jean-Pierre Bibring

The imaging spectrometer OMEGA [1] operates in the VIS-NIR range, covering the (0.35 µm to 5.1 µm) range in 352 contiguous spectral channels.  This spectral range has been chosen as it includes diagnostic signatures of most surface mafic and hydrated minerals, frosts and ices. With a 1.2 mrad IFOV, the footprint varies from 40 m when imaging from 40 kms, up to 4.8 km from an altitude of 4000 km: this allows a global spectral coverage of Phobos to be achieved, at various spatial resolution.

Along its 16 years of orbital operations, Mars Express has performed tens of close flybys of Phobos, at altitudes down to ~ 50 kms. OMEGA has acquired unprecedented compositional data sets, in both the visible and the near-infrared spectral range. We shall present and discuss these observations, as witnesses of Phobos origin, with their relevance to the upcoming MMX JAXA mission.

How to cite: Gondet, B. and Bibring, J.-P.: Phobos composition: a reappraisal, based on Omega/MEx observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11414, https://doi.org/10.5194/egusphere-egu2020-11414, 2020.

EGU2020-22228 | Displays | PS4.2

The ExoMars Trace Gas Orbiter – First Martian Year in Orbit

Håkan Svedhem, Oleg Korablev, Igor Mitrofanov, Daniel Rodionov, Nicholas Thomas, AnnCarine Vandaele, Jorge L. Vago, Francois Forget, and Colin Wilson

The Trace Gas Orbiter, TGO, has in March 2020 concluded its first Martian year in its 400km, 74 degrees inclination, science orbit. It has been a highly successful year, starting with the rise, plateau and decay of the major Global Dust Storm in the summer of 2018. This has enabled interesting results to be derived on the water vapour distribution, dynamic behaviour and upward transport as a consequence of the dust storm. The characterisation of the minor species and trace gasses is continuing and a large number of profiles is produced every day. A dedicated search of methane has shown that there is no methane above an altitude of a few km, with an upper limit established at about 20 ppt (2∙10-11). The solar occultation technique used by the spectrometers has definitely proven its strength, both for its high sensitivity and for its capability of making high resolution altitude profiles of the atmosphere. Climatological studies have been initiated and will become more important now that a full year has passed, even if the full potential will be visible only after a few Martian years of operation. The FREND instrument has characterised the hydrogen in the shallow sub-surface on a global scale at a spatial resolution much better than previous missions have been able. It has found areas at surprisingly low latitudes with significant amounts of sub-surface hydrogen, most likely in the form of water ice. The CaSSIS camera has made a high number of images over a large variety of targets, including the landing sites of the 2020 ESA and NASA rovers, Oxia Planum and the Jezero Crater. Stereo imaging has enabled topographic information and precise 3-D landscape synthesis.

This presentation will summarise the highlights of the first Martian year and discuss planned activities for the near and medium term future.

The ExoMars programme is a joint activity by the European Space Agency (ESA) and ROSCOSMOS, Russia. It consists of the ExoMars 2016 mission, launched 14 March 2016, with the Trace Gas Orbiter, TGO, and the Entry Descent and Landing Demonstrator, EDM, named Schiaparelli, and the ExoMars 2020 mission, to be launched in July/August 2020, carrying a Rover and a surface science platform to the surface of Mars.

How to cite: Svedhem, H., Korablev, O., Mitrofanov, I., Rodionov, D., Thomas, N., Vandaele, A., Vago, J. L., Forget, F., and Wilson, C.: The ExoMars Trace Gas Orbiter – First Martian Year in Orbit, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22228, https://doi.org/10.5194/egusphere-egu2020-22228, 2020.

EGU2020-8725 | Displays | PS4.2

Mapping of shallow subsurface water local variations at Mars’ moderate latitudes with FREND neutron telescope onboard ExoMars TGO

Alexey Malakhov, Igor Mitrofanov, Artem Anikin, Dmitry Golovin, Maya Djachkova, Denis Lisov, Maxim Litvak, Nikita Lukyanov, Sergey Nikiforov, and Anton Sanin

Fine Resolution Epithermal Neutron Detector, FREND, is an instrument onboard ExoMars’ Trace Gas Orbiter (TGO). It uses neutron measurements to detect hydrogen (and thus water) variations in the shallow subsurface of the Martian soil. Similar experiments have been performed in the past on Mars, but FREND’s main characteristic is its neutron collimator that significantly narrows down the field of view (FOV) to 28° full cone which corresponds to a 60-200 km diameter spot on the surface. This is considerably smaller than the spatial resolution of previous experiments and thus allows us to peek inside local features of hydrogen variations.

The instrument has been measuring for almost one full Martian year currently so what we present is a result of continuous observations of shallow subsurface water between May 2018 and present. A technique to locate the most prominent local spots, either very “dry” or very “wet”, was developed to analyze the planetary surface from 70° North down to 70° South. It yielded several such local spots of interest that are presented, characterized and associated with particular geomorphological features or/and with the selected landing sites candidates.

It is known that water or water ice is not stable at the surface of Mars, especially closer to equator, thus locating areas with enhanced subsurface hydrogen or water is of much interest both scientifically and in terms of future exploration. FREND is most sensitive to water in the shallow subsurface of about 1 m deep, which makes such deposits easily accessible and valuable.

How to cite: Malakhov, A., Mitrofanov, I., Anikin, A., Golovin, D., Djachkova, M., Lisov, D., Litvak, M., Lukyanov, N., Nikiforov, S., and Sanin, A.: Mapping of shallow subsurface water local variations at Mars’ moderate latitudes with FREND neutron telescope onboard ExoMars TGO, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8725, https://doi.org/10.5194/egusphere-egu2020-8725, 2020.

EGU2020-9303 | Displays | PS4.2

Variations of polar CO2 caps during the first Martian year of FREND onboard TGO

Dmitry Golovin, Igor Mitrofanov, Artem Anikin, Maya Djachkova, Denis Lisov, Maxim Litvak, Nikita Lukyanov, Alexey Malakhov, Sergey Nikiforov, and Anton Sanin

Fine Resolution Epithermal Neutron Detector (FREND) is an instrument onboard ExoMars’ Trace Gas Orbiter (TGO). It uses neutron measurements to detect hydrogen (and thus water) variations in the shallow subsurface of the Martian soil. In case of sub-polar regions, it is quite sensitive to the thickness of seasonal deposition of CO2, which it well-sees in neutrons, as “dry” layer on top of the hydrogen-rich polar permafrost soil.

This presentation is aimed to give a first look at variations of seasonal depositions of Carbone dioxide at winter vs summer seasons on Mars. Similar studies have been performed by neutron instruments earlier, however FREND’s major advantage is its much better spatial resolution: by shielding from the neutron flux coming from off-nadir directions, the instrument’s spatial resolution is improved down to a 60-200 km diameter spot. The orbiter’s inclination is currently 74 deg, so the experiment is capable to observe the rim of the polar permafrost northern and southern regions with seasonal coverages of atmospheric Carbone dioxide over them.

We re-define and improve the shape of polar CO2 caps boundaries and the column density of seasonal deposits thanks to improved spatial resolution and present data of FREND’s first Martian year of observations of high Martian latitudes.

How to cite: Golovin, D., Mitrofanov, I., Anikin, A., Djachkova, M., Lisov, D., Litvak, M., Lukyanov, N., Malakhov, A., Nikiforov, S., and Sanin, A.: Variations of polar CO2 caps during the first Martian year of FREND onboard TGO, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9303, https://doi.org/10.5194/egusphere-egu2020-9303, 2020.

EGU2020-12984 | Displays | PS4.2 | Highlight

Implications of the TGO results on potential surface emissions of methane on Mars

Sébastien Viscardy, Séverine Robert, Justin Erwin, Frank Daerden, Lori Neary, Ian Thomas, and Ann Carine Vandaele

As a potential biomarker, Martian methane has attracted attention through several reports of its detection over the last 15 years. Photochemical models predict that the lifetime of atmospheric methane should be of the order of 300 years, which implies that any detection would point to recent emissions. However, the very existence of this gas has been continuously questioned, in particular because the observed lifetime would be several orders of magnitude shorter than expected. Several fast removal processes have been hypothesized to explain the observations, but none of them has met a large consensus so far. It is in this context that the ESA-Roscomos ExoMars Trace Gas Orbiter (TGO) mission started its science operations in April 2018. The first highly sensitive measurements of methane in solar occultation were reported last year. No methane was detected over the first months of the TGO mission and an upper limit of 0.05 ppbv was obtained. The implications of this result on the methane problem on Mars will be addressed in this work.

Several model studies investigated the transport of methane in Mars’ atmosphere. In particular, simulations of surface emissions of the gas using General Circulation Models (GCM) for Mars predicted the formation of layers during the first weeks after the release. Therefore, any detection of a layer by TGO would point to a recent emission. As a corollary to this, methane should be found within a few days at higher altitudes after its emission from the surface.

The reported detection limit of 0.05 ppbv is a strong constraint on the background level of methane, i.e. on the total amount of the gas present in the atmosphere for a time exceeding the transport timescale (~3 months). However, locally, the retrieved detection limit from TGO strongly depends on the amount of atmospheric dust and, thus, on several factors such as the season, latitude, and altitude, which makes the problem much more complicated.

Hence, what are the surface emission scenarios that are consistent with the TGO results? To answer this question, a statistical analysis of GEM-Mars GCM simulations including a large range of theoretical lifetimes will be conducted to determine the realms of scenarios in agreement with the multifactor-dependent TGO upper limits. The positive detections reported over the last 15 years will also be discussed in the light of the results obtained from our study.

How to cite: Viscardy, S., Robert, S., Erwin, J., Daerden, F., Neary, L., Thomas, I., and Vandaele, A. C.: Implications of the TGO results on potential surface emissions of methane on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12984, https://doi.org/10.5194/egusphere-egu2020-12984, 2020.

EGU2020-14498 | Displays | PS4.2

Explanation for the increase in high altitude water on Mars observed by NOMAD during the 2018 global dust storm

Lori Neary, Frank Daerden, Shohei Aoki, James Whiteway, Robert Todd Clancy, Michael Smith, Sébastien Viscardy, Justin Erwin, Ian Thomas, and Ann Carine Vandaele and the Members of the NOMAD Team

Using the GEM-Mars three-dimensional general circulation model (GCM), we examine the mechanism responsible for the enhancement of water vapour in the upper atmosphere as measured by the Nadir and Occultation for MArs Discovery (NOMAD) instrument onboard ExoMars Trace Gas Orbiter (TGO) during the 2018 global dust storm on Mars.

Experiments with different prescribed vertical profiles of dust show that when more dust is present higher in the atmosphere, the temperature increases and the amount of water ascending over the tropics is not limited by saturation until reaching heights of 70-100 km. The warmer temperatures allow more water to ascend to the mesosphere. The simulation of enhanced high-altitude water abundances is very sensitive to the vertical distribution of the dust prescribed in the model.

The GEM-Mars model includes gas-phase photochemistry, and these simulations show how the increased water vapour over the 40-100 km altitude range results in the production of high-altitude atomic hydrogen which can be linked to atmospheric escape.

How to cite: Neary, L., Daerden, F., Aoki, S., Whiteway, J., Clancy, R. T., Smith, M., Viscardy, S., Erwin, J., Thomas, I., and Vandaele, A. C. and the Members of the NOMAD Team: Explanation for the increase in high altitude water on Mars observed by NOMAD during the 2018 global dust storm, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14498, https://doi.org/10.5194/egusphere-egu2020-14498, 2020.

EGU2020-8565 | Displays | PS4.2

Modeling of HDO in the Martian atmosphere

Loïc Rossi, Franck Montmessin, François Forget, Ehouarn Millour, Kevin Olsen, Margaux Vals, Anna Fedorova, Alexander Trokhimovskiy, and Oleg Korablev

Mars is known to have had a significant liquid water reservoir on the surface and the D/H ratio is an important tool to estimate the abundance of the early water reservoir on Mars and its evolution with time. The D/H ratio is a measure of the ratio of the current exchangeable water reservoir to the initial exchangeable water reservoir. Many observations from the ground have shown that the current ratio is five times that of the reference in Earth's oceans (Encrenaz et al. 2018, Krasnopolsky et al. 2015, Villanueva et al. 2015).

H and D atoms in the upper atmosphere are coming from H2O and HDO, their sole precursor in the lower atmosphere. The lower mass of H over D atoms and the fact that H2O is preferentially photolysed over HDO (Cheng et al. 1999) explain the differential escape of these two elements. Finally, due to differences in vapor pressure for HDO and H2O, the solid phase of water is enriched in deuterium compared to the vapor phase. This effect is known as the Vapor Pressure Isotope Effect (VPIE) and can reduce the D/H ratio above the condensation level to values as low as 10% of the D/H ratio near the surface (Bertaux et al. 2001, Fouchet et al. 2000).

These fractionation processes can affect the amount of HDO with latitude, longitude, altitude and with the season. In particular, previous models (Montmessin et al. 2005) have shown that an isotopic gradient should appear between the cold regions where condensation occurs and the warmer regions. This leads to a latitudinal gradient of D/H (with variations greater than a factor of 5) between the warm and moist summer hemisphere and the cold and dry winter hemisphere. Yet some observations (Villanueva et al. 2015, Khayat et al. 2019) also show longitudinal variations of H/D ratios which are not explained so far.

Previous work has been done on modeling HDO using 3D GCMs, in particular around the IPSL Mars GCM (Montmessin et al. 2005). Since the GCM has considerably evolved since this first HDO introduction in the modeled water cycle, a reappraisal of HDO predictions is needed to account for the detailed microphysics that control cloud formation and thus HDO fractionation. 

The Trace Gas Orbiter, part of the ExoMars mission, is currently in orbit around Mars. Onboard is the Atmospheric Chemistry Suite, a set of spectrometers designed to study the atmosphere of Mars with a specific focus on trace gases such as methane. With TGO now in its mission phase, very strong and precise constraints will be soon available to evaluate the GCM prediction capability.

We will describe here our work on the update of the HDO model in the IPSL Mars GCM and will attempt first comparison with the early TGO/ACS observations, in particular in the context of the global dust storm of 2018.

How to cite: Rossi, L., Montmessin, F., Forget, F., Millour, E., Olsen, K., Vals, M., Fedorova, A., Trokhimovskiy, A., and Korablev, O.: Modeling of HDO in the Martian atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8565, https://doi.org/10.5194/egusphere-egu2020-8565, 2020.

EGU2020-9223 | Displays | PS4.2

Trajectories of Major Martian Dust Storms

Huiqun (Helen) Wang, Mark Richardson, and Anthony Toigo

EGU2020-13394 | Displays | PS4.2

Water cycle at the Gale crater - More than three Martian years of in situ humidity observations by MSL/REMS

Ari-Matti Harri, Maria Genzer, Javier Gomez-Elvira, Hannu Savijärvi, Timothy McConnochie, Maria Hieta, Manuel de la Torre, Jouni Polkko, German Martinez, Mark Paton, and Luis Vazquez

The Mars  Science  laboratory  (MSL)  has been providing in situ Martian observations with excellent quality since  early  August  2012. MSL carries onboard the REMS-instrument, which has provided extremely valuable atmospheric observations of atmospheric pressure, temperature of the air, ground temperature, wind speed and direction, relative humidity (REMS-H), and UV measurements. The  REMS-H  relative  humidity  device  is  based  on  polymeric  capacitive  humidity  sensors  developed  by Vaisala Inc. and it makes use of three (3) humidity sensor heads. The humidity device is mounted on the REMS boom providing ventilation with the ambient atmosphere through a filter protecting the device from airborne dust.

The  annual  in  situ  water  cycle  based  on  more than three  full  Martian  years  at  the  Gale  crater  will  be  discussed.  We will  utilize  the  REMS-H  instrument’s  in  situ  observations  accompanied  by  orbital  observations  and  modeling efforts. We will infer the hourly atmospheric VMR from the REMS-H observations and compare these VMR measurements with predictions of VMR given by our 1D column Martian atmospheric/regolith model to investigate the local water cycle, exchange processes and the local climate in Gale Crater.

The  strong  diurnal  variation  suggests  there  are  surface-atmosphere  exchange  processes  at  Gale  Crater  during all seasons, which deplete moisture to the ground in the evening and nighttime and release the moisture back to the atmosphere during the daytime. Our modeling results presumably indicate that adsorption processes take place during the nighttime and desorption during the daytime. Other processes, e.g. convective turbulence play a significant role in the daytime in conveying the moisture into the atmosphere.

Atmospheric humidity shows clear increase during early mornings around the time when Curiosity  started  to  climb  up  Mt.  Sharp. Around that time there was also a major dust storm followed by a moderate storm. The  MSL  MastCam  pictures  from  this  time  show exposed bedrock scenery with sparse and thin layers of wind-blown dust. Our simulations indicate that a plausible explanation for the increase of the atmospheric humidity during early mornings could be the Mt Sharp bedrock material having a relatively high inertia and low porosity.  Overall, we will discuss the water cycle at gale crater during the period of more than three Martian years with specific focus on the effects of increased airborne dust and underlying changing terrain during the latter part of the current MSL mission.

How to cite: Harri, A.-M., Genzer, M., Gomez-Elvira, J., Savijärvi, H., McConnochie, T., Hieta, M., de la Torre, M., Polkko, J., Martinez, G., Paton, M., and Vazquez, L.: Water cycle at the Gale crater - More than three Martian years of in situ humidity observations by MSL/REMS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13394, https://doi.org/10.5194/egusphere-egu2020-13394, 2020.

EGU2020-10383 | Displays | PS4.2

3D multi-resolution mapping of Valles Marineris for better understanding of RSL formation

Yu Tao, Jan-Peter Muller, and Susan Conway

Recurring Slope Lineae (RSLs) are metre- to decametre-wide dark streaks found on steep slopes, which lengthen downslope during the warmest times of the year, fading during the cooler periods and reappearing again in the next Martian year. This behaviour has been linked to the action of liquid water, but as liquid water is thermodynamically unstable under current martian conditions this interpretation is under vigorous debate. A better understanding of the formation process of RSLs is therefore fundamental to constraining Mars’ water budget and habitability. One of the key components for studying the RSL process is accurate knowledge of the slopes and aspects.

 

The Valles Marineris (VM) area has the highest concentration of RSLs found on Mars as well as being a location where the triple point of water can be reached during the Martian summertime. This study focuses on multi-resolution 3D mapping of the whole VM area with all digital terrain models (DTMs) vertically referenced to the global standard Mars Orbiter Laser Altimeter (MOLA) surface. A multi-resolution DTM has been generated consisting of 82 Mars Express High Resolution Camera (HRSC) 50m DTMs and 1763 Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) 18m DTMs which will be presented. For 3 selected study areas (Coprates Montes, Capri Mensa, Nectaris Montes), terrain corrected and co-registered MRO High Resolution Imaging Science Experiment (HiRISE; at 0.25m), Compact Reconnaissance Imaging Spectrometer for Mars (CRISM; at 20/50m) and ExoMars Trace Gas Orbiter (TGO) Colour and Stereo Surface Imaging System (CaSSIS; at 2.5m) colour images and associated DTMs will be discussed.

 

Acknowledgements

The research leading to these results is receiving funding from the UKSA Aurora programme (2018-2021) under grant no. ST/S001891/1.

How to cite: Tao, Y., Muller, J.-P., and Conway, S.: 3D multi-resolution mapping of Valles Marineris for better understanding of RSL formation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10383, https://doi.org/10.5194/egusphere-egu2020-10383, 2020.

EGU2020-5493 | Displays | PS4.2

Deposition of Interior Layer Deposits within East and West Candor as well as Ophir chasms, Valles Marineris, Mars

Frank Fueten, Amanda Burden, Ariel van Patter, Josh Labrie, Jessica Flahaut, Robert Stesky, and Ernst Hauber

The Martian Valles Marineris, located on the eastern flank of the Tharsis region, is a 4000 km long linked system of troughs. The formation of the up-to-11 km deep chasmata of Valles Marineris is thought to have taken place during a two-stage process in which ancestral basins collapsed and were later linked by tectonism. Located within most chasmata are enigmatic layered deposits, referred to as interior layered deposits (ILDs), whose origin and mechanism of formation are uncertain. It has been estimated that ILDs cover 17% of the total area, representing 60% by volume of all deposits within Valles Marineris with several deposits nearly reaching the height of the surrounding plateau.

Here we present the results of a detailed study of the ILD mounds located within three of the presumed ancestral basins in the center of Valles Marineris.  In this study HiRISE and CTX images were used to measure layer attitudes of ILDs within East and West Candor and Ophir chasmata. Because only CTX images cover the entire chasms, the ILDs were grouped into distinct varities of bedding based on their appearance in CTX imagery.  In both East and West Candor and Ophir, the stratigraphically lowest unit is a massive unit which displays no layering in any available imagery.  Layered units with dips between 10° and 20° are deposited on top of this massive unit.  The lowest layered units in all three chasms appear to show multiple prominent benches, indicative of significant competency contrasts. These units can be shown in multiple places to be unconformably overlain by thinner layered units.  It is not possible to correlate or determine the number of thinner layered units because the unconformable contacts cannot be correlated. 

The general similarities of types of units and unit relationships between  the ILDs in these three chasms suggests that they share a similar depositional history. We believe that the ILD morphology is most compatible with an environmental setting in which the ancestral basins were lakes which may have been periodically frozen.  We suggest that the unconformities are the result of multiple erosional events indicating that ILD deposition was not continuous.   A general trend of massive units overlain by thinner layered units may reflect a change in the environment and sediment supply.  Associated with this change is a general observation that polyhydrated sulfate is most commonly found on top of the monohydrated material.  Work to correlate more closely units within these chasms, including their mineralogy, is currently ongoing.

How to cite: Fueten, F., Burden, A., van Patter, A., Labrie, J., Flahaut, J., Stesky, R., and Hauber, E.: Deposition of Interior Layer Deposits within East and West Candor as well as Ophir chasms, Valles Marineris, Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5493, https://doi.org/10.5194/egusphere-egu2020-5493, 2020.

Sulfur is transported to the surface and released in  volcanic effusive and explosive eruptions and is known to be concentrated in both time (acidic aqueous alteration environments in Late Noachian-Early Hesperian) and space (e.g., Valles Marineris-type layered deposits). Requirements necessary for formation, evolution and preservation of sulfates are highly specific due to high sulfate solubility and environmental sensitivity of sulfates to phase transitions (temperature and humidity). Can explosive volcanic eruptions under martian conditions help account for the characteristics of sulfate units in the Valles Marineris Interior Layered Deposits (VM-ILD)?

As a basis for understanding the nature of volcanic eruptions in the martian environment (e.g., low gravity, currently low and historically evolving atmospheric pressure) we developed a theoretical and predictive framework for the generation, ascent and eruption of magma. We have: 1) shown that basaltic plinian eruptions are highly favored (relative to Earth), 2) explored the characteristics/dispersal of tephra/gases in various locations and Patm conditions, and 3) assessed the behavior/fate of S species during eruptions including the role of sulfuric acid precipitates in surface melting and creation of aqueous acidic environments.

Observations consistent with volcanic eruptions under martian conditions accounting for characteristics of units in the VM-ILD include: 1) Volcanism is focused in Tharsis; 2) Explosive plinian basaltic volcanism is favored in general, and with increasing altitude (Tharsis) and decreasing Patm (time); 3) Finer ash is produced relative to Earth, enhancing dispersal; 4) Fine ash creates a profusion of nucleation sites for condensation of co-erupted water and S species; 5) Airfall products are tephra coated with condensed water and S species, producing extensive layered/graded deposits; 6) Tephra distribution is latitudinal (equatorial for Tharsis sources); 7) Temperatures of deposited tephra decrease with distance from vent; 8) Magmatic exsolution of sulfur is favored by lower Patm and enhanced by higher altitude eruption sites (Tharsis); 9) Sulfur speciation and atmospheric chemistry predictions favor sulfuric acid formation and widespread dispersal during and immediately following eruptions; 10) Condensation and ensuing precipitation of sulfuric acid is predicted to melt any existing surface snow and ice, and to provide acidic aqueous surface environments favoring sulfate precipitation; 11) Estimates of eruption duration and continuity readily predict km-thick accumulations; 12) Fluctuating eruption conditions and S speciation can lead to interbedding of phyllosilicates and sulfates. 

Explosive volcanism in the Tharsis region appears to meet the necessary requirements for the formation, evolution and preservation of sulfates in the VM-ILD, including: 1) sources of sulfur; 2) sources of liquid water; 3) cold climates; 4) resulting acidic environments (sulfur concentration in aqueous solutions); 5) mechanism to collect S-rich waters and then to evaporate water and concentrate/deposit sulfates; 6) varying climate conditions to permit observed interbedding of phyllosilicates and sulfates; 7) Tharsis environment accounts for concentration in certain locations; and 8) subsequent dry and cold climatic conditions preserve ancient sulfates to the present.  To test this model we are compiling predictive tephra/volatile dispersal stratigraphies to compare to the detailed characteristics/trends observed in the Valles Marineris ILDs.

How to cite: Head, J. and Wilson, L.: Sulfates on Mars: A Pyroclastic Airfall Model for the Origin and Emplacement of Valles Marineris Interior Layered Deposits (ILD). , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8777, https://doi.org/10.5194/egusphere-egu2020-8777, 2020.

EGU2020-11693 | Displays | PS4.2

Hydrothermal Alteration in the Frankenstein Gabbro Martian Analogue

Robert G. W. Seidel, John C. Bridges, Thomas Kirnbauer, Sarah C. Sherlock, and Susanne P. Schwenzer

We present results of an ongoing petrologic and modelling study of a new Martian analogue rock: The Frankenstein Gabbro (Odenwald, Germany). Our aim is to predict mineral reaction paths and fluid properties during hydrothermal alteration of basaltic host rocks on Mars – thought to be a common by-product of impact cratering – in order to assess the habitability of the fluids for the potential of Martian life, and establish a link between habitable fluid conditions and secondary mineral assemblages.

Primary minerals of the analogue are mostly plagioclase (~70 vol.%) and clinopyroxene (~20 vol.%) with lesser percentages of amphiboles and Fe-oxides. We focus on a chloritic-propylitic alteration event associated with hairline fault planes and mineral veinlets. The secondary mineralisation shows strong small-scale variability, depending on host mineral and type of fluid pathway: For plagioclase hosts, fault planes are dominated by chlorite with additional epidote and prehnite, while mineral veinlets consist of albite ± calcite ± chlorite ± epidote ± K-feldspar ± mica. For clinopyroxene hosts, fault planes consist of actinolite with additional chlorite or vermiculite, while mineral veinlets consist of prehnite and vermiculite.

We use the software CHIM-XPT to model mineral reaction paths, with published XRF bulk rock data, EMP analyses of single minerals, and a starting fluid enriched in Na, K, Mg and Si for input, the latter based on calculated element budgets of mineral replacement reactions. Our models reproduce secondary assemblages related to plagioclase-hosted fault planes (chlorite–epidote–prehnite) and veinlets (albite–chlorite–epidote–K-feldspar–mica), as well as alteration rims around clinopyroxene related to fault planes (actinolite–chlorite). Corresponding fluid conditions are ~200–250 °C, pH ~6.5–8.0, at water/rock ratios >3000, in agreement with pre-model constraints by mineralogy. The breakdown of clinopyroxene and plagioclase releases large amounts of Ca, with calcite inferred to be a late-stage product of cooling. Fluid redox state is shown to be largely controlled by host minerals, and in turn exerts strong influence on secondary mineral formation: clinopyroxene releases Fe2+ during alteration, which is taken up by chlorite; in contrast, plagioclase contains up to 0.5 wt.% Fe3+ substituting for Al, which is taken up by epidote. Prehnite, of the same elemental composition except for Fe, is inversely correlated with epidote. Thus, the relative percentages of chlorite, epidote and prehnite can serve as indicators of redox state in similar types of rock.

Our models match key petrological observations and provide information about the alteration process beyond what may be directly observed. They illustrate the need to account for small-scale variability, and to adjust models on a case-by-case basis. This has important implications for models of Martian habitability, where similar features may be expected. Next, we will apply these reaction pathways to Martian rocks (shergottitic basalts), focusing especially on small-scale distribution of dissolved iron species, a suggested energy source for hypothetical microbial Martian life.

How to cite: Seidel, R. G. W., Bridges, J. C., Kirnbauer, T., Sherlock, S. C., and Schwenzer, S. P.: Hydrothermal Alteration in the Frankenstein Gabbro Martian Analogue, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11693, https://doi.org/10.5194/egusphere-egu2020-11693, 2020.

EGU2020-10653 | Displays | PS4.2

Passive neutron sensing of martian subsurface from onboard rovers: results from MSL/DAN and expectations from ExoMars/Adron-RM

Sergey Nikiforov, Igor Mitrofanov, Maxim Litvak, Maya Djachkova, Dmitriy Golovin, Denis Lisov, Alexey Malakhov, Maxim Mokrousov, Anton Sanin, and Vladislav Tretyakov

During more than 7 years, the NASA MSL Curiosity rover is successfully traversing across the Mars surface exploring Gale crater with the Dynamic Albedo of Neutron (DAN) instrument installed onboard. This year, next generation neutron spectrometer Adron-RM is ready to be launched to Mars as a payload of the ExoMars 2020 rover. The main objectives of these instruments are analogous  and consist in the assessment of Water Equivalent Hydrogen (WEH) in the shallow martian subsurface.

The hydrogen presence significantly influences the neutron leakage spectrum because of  neutron moderation and thermalization through collisions with hydrogen nuclei. As a result, the variations of neutron flux detected onboard in different energy bands correlate with subsurface hydrogen/water abundance.

In our study, we will demonstrate scientific potential and latest results of natural neutron background measurements (called as passive measurements) by DAN. We will provide assessment on average WEH content in the area of the ExoMars 2020 landing site, which could be expected from first measurements of Adron-RM.

How to cite: Nikiforov, S., Mitrofanov, I., Litvak, M., Djachkova, M., Golovin, D., Lisov, D., Malakhov, A., Mokrousov, M., Sanin, A., and Tretyakov, V.: Passive neutron sensing of martian subsurface from onboard rovers: results from MSL/DAN and expectations from ExoMars/Adron-RM, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10653, https://doi.org/10.5194/egusphere-egu2020-10653, 2020.

EGU2020-10926 | Displays | PS4.2

Chlorine in Gale Crater, Mars: comparing data from DAN and APXS instruments onboard the Curiosity rover

Denis Lisov, Maya Djachkova, Ralf Gellert, Maxim Litvak, Igor Mitrofanov, and Sergey Nikiforov

The Dynamic Albedo of Neutrons (DAN) experiment onboard the MSL Curiosity rover performs active neutron measurements at the rover’s stops. It produces short pulses of high-energy neutrons and observes the time profile of slowed down neutrons leaking from the subsurface. Due to neutrons’ high penetrating power it is sensitive to the abundance of neutron moderating elements (mostly hydrogen) and neutron capturing elements (most significant are chlorine and iron) in approximately top 60 cm of the subsurface under the rover, a few tons of matter in total. The DAN data processing procedure is based on numerical simulations of neutron propagation, moderation and capture with the MCNPX software package and returns both the model acceptance probability and the best fit estimates for H2O mass fraction and equivalent Cl mass fraction. The latter corresponds to the total neutron absorption of the subsurface assuming a fixed Fe content. If external information on Fe content is available from other measurements, the DAN equivalent Cl mass fraction can be transformed into an estimate of the real Cl mass fraction in the subsurface.

We compare the DAN data on neutron absorption in the subsurface to the data on the Cl and Fe mass fractions on the surface as measured by the APXS instrument in different regions along the Curiosity path. Our analysis shows that the DAN and APXS measurements taken at the same location are in many cases not consistent with each other as the neutron absorption corresponding to the surface concentrations of chlorine and iron measured by APXS is too high to be accepted by the DAN data.

We investigate this finding in several regions along the Curiosity path. E.g., for the Glen Torridon region the DAN neutron absorption level for different measurements corresponds to the average chlorine mass fraction of 0.81% with a standard deviation of 0.18% and with typical measurement uncertainty of 0.10% (assuming the Fe mass fraction measured by APXS), while the chlorine mass fraction measured by APXS is 1.19% on average with a standard deviation of 0.43%. These two distributions are significantly different, and only 22% of the DAN measurements in the Glen Torridon region agree with the APXS-based neutron absorption for the same location.

We discuss several possible causes for this inconsistency, including either differences between Cl abundances in the martian dust particles and in rocks, or differences between Cl content in the very top surface layer and in the subsurface, or possible bias in APXS target selection.

How to cite: Lisov, D., Djachkova, M., Gellert, R., Litvak, M., Mitrofanov, I., and Nikiforov, S.: Chlorine in Gale Crater, Mars: comparing data from DAN and APXS instruments onboard the Curiosity rover, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10926, https://doi.org/10.5194/egusphere-egu2020-10926, 2020.

EGU2020-5880 | Displays | PS4.2

Enhancing the Science Return of Landed X-ray Spectrometers on the Mars Rovers

Scott VanBommel and Ralf Gellert

Alpha Particle X-ray Spectrometers (APXS) have flown on the Mars Exploration Rovers (MER) Spirit and Opportunity as well as the Mars Science Laboratory (MSL) rover Curiosity. The APXS was designed and calibrated for in situ interrogation of solid martian samples through the use of complementary particle-induced X-ray emission and X-ray fluorescence analysis techniques. Its compact and robust design, combined with low power and data demand, further suit the APXS instrument and method for lengthy missions to the surface of rocky bodies in our solar system. Since their three respective landings, the science derived from the latest APXS instruments has been expanded beyond its original scope through the integration of computational techniques and modest changes to how the instrument is utilized on Mars. We will discuss these new methods, operational considerations, as well as the enhanced science achieved, with a particular focus on the relevance and future application on the surface of Mars.

How to cite: VanBommel, S. and Gellert, R.: Enhancing the Science Return of Landed X-ray Spectrometers on the Mars Rovers, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5880, https://doi.org/10.5194/egusphere-egu2020-5880, 2020.

EGU2020-2480 | Displays | PS4.2

Ground scientific verification test for High Resolution Imaging Camera of China's First Mars Mission

Wei Yan, Jianjun Liu, Xiaoxia Zhang, Dawei Liu, and Donghao Liu

Mars is a planet in the solar system that is closer to the Earth and has the most similar natural environment to the Earth. It has always been the first choice for humans to go out of the Earth and Moon system for deep space exploration.

China’s First Mars Mission (HX-1) will be launched in 2020 with an orbiter and a lander rover. One of the scientific goals of our mission is to study the morphology and geologic structure of the Mars. In order to achieve this purpose, the orbiter is equipped with a High Resolution Imaging Camera (HiRIC) to obtain the high-resolution morphology data of typical regions and to study the formation and evolution of geologic structure. HiRIC consists of three TDI CCD line-scan detectors and two COMS area-array detectors. Each TDI CCD detector covers 5 spectral bands. Its main working mode is the panchromatic TDI CCD push-scan imaging with a maximum spatial resolution of 0.5m.

Ground scientific verification test is an effective way to comprehensively evaluate the performance, data quality of HiRIC, and to fully verify its on-orbit detection process and data processing methods. In this study, contents and results of ground scientific verification test for HiRIC is introduced. The engineering model is used here for image motion compensation effect evaluation test, focusing effect evaluation test, and outdoor field imaging test. The results show that, 1) HiRIC can calculate the image motion compensation parameters and control the camera imaging correctly according to the platform parameters of orbiter; 2) Focus processing is effective, and HiRIC can adapt to the high-resolution imaging needs of different orbit altitudes; 3) Clear image data can be obtained according to the on-orbit detection process in the outdoor field imaging test, and image data processing was correct. Image data quality, compression quality, and TDI CCD stitching accuracy all meet the requirements of the verification test. This test fully evaluated HiRIC's ability to obtain high-resolution image data of the surface of Mars.

How to cite: Yan, W., Liu, J., Zhang, X., Liu, D., and Liu, D.: Ground scientific verification test for High Resolution Imaging Camera of China's First Mars Mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2480, https://doi.org/10.5194/egusphere-egu2020-2480, 2020.

EGU2020-2525 | Displays | PS4.2

Ground Test for Multispectral Camera of China’s First Mars Mission

dawei liu, jianjun liu, wei yan, xiaoxia zhang, and donghao liu

China’s first Mars exploration mission will be launched in 2020 with an orbiter and a rover. Multispectral Camera (MC) is one payload onboard the rover. The main tasks of MC are to obtain multi-spectral images of the landing site and reconnaissance area of the rover, and to assess the mineralogy and composition of Mars surface. Multispectral imaging of MC is achieved via eight narrowband filters with their central wavelength at 480nm, 525nm, 650nm, 700nm, 800nm, 900nm, 950nm and 1000nm. The designed MC field of view is 24o and spatial resolution is higher than 0.15mrad.

In this study, we test two different experimental setups. The first one was dedicated to qualitatively evaluate the capabilities of MC in acquiring high quality images by observing the surface texture and structure of differing natural rocks at varying distance. The second one was to quantitatively assess the quality of the mineral spectra obtained by MC via comparison with that obtained simultaneously by a standard commercial equipment (ASD FieldSpec 4) under the same viewing geometry. The rock samples used for imaging capacity test include granite, rhyolite, basalt, andesite and peridotite. The mineral samples used for spectra quality evaluation include olivine, orthopyroxene, gypsum, chlorite, siderite and goethite. All these mineral and rock samples have been found on the Mars surface and are expected to be encountered when the rover reconnaissances.

Our results show that the images obtained by MC are quite clear. Detailed rock surface texture and structure such as vesicular and fluidal structure can be adequately captured by MC. RGB color composite image (R:650nm, G:525nm, B:480nm) of the rock targets generally consists with human perception. In addition, mineral spectra measured by MC agree well with that obtained by ASD. Absorption features of each mineral can be evidently revealed by the MC data, and the MC has the capacity to fully characterize the albedo and spectral shape of each mineral.

How to cite: liu, D., liu, J., yan, W., zhang, X., and liu, D.: Ground Test for Multispectral Camera of China’s First Mars Mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2525, https://doi.org/10.5194/egusphere-egu2020-2525, 2020.

EGU2020-21128 | Displays | PS4.2

ExoMars-2020 Landing Platform scientific payload

Daniel Rodionov, Lev Zelenyi, Oleg Korablev, Ilya Chulkov, Konstantin Anufreychik, Konstantin Marchenkov, and Jorge Vago

ExoMars is a joint project between ESA and Roscosmos to develop and launch two ExoMars missions - in 2016 and 2020. The first mission is currently in progress, studying Mars’ atmospheric composition in unprecedented details.

The second ExoMars mission is scheduled to be launched in Aug 2020 to target an ancient location at Oxia Planum interpreted to have strong potential for past habitability and for preserving physical and chemical biosignatures. The mission will deliver a Landing Platform with instruments for atmospheric and geophysical investigations and a Rover tasked with searching for signs of extinct life. The ExoMars rover will have the capability to drill to depths of 2 m to collect and analyze samples that have been shielded from the harsh conditions prevailing on the surface, where radiation and oxidants can destroy organic materials.

The Landing Platform is equipped with set of instruments (LPSP – Landing Platform Scientific Payload) to study the Martian environment at the landing site. After the Rover egress the Landing Platform will serve as long-lived stationary platform with expected lifetime of one Martian year.

LPSP consists of 13 instruments with total mass of 45 kg. LPSP is being developed by Space Research Institute of RAS (Moscow, Russia) with contribution from Belgium, Sweden, Spain, Finland, Czech Republic, France and Italy. LPSP will have strong synergies with other parts of ExoMars mission, thus extending the scientific output of whole project.

The main objectives of LPSP are:

  • Context imaging
  • Long-term climate monitoring and atmospheric investigations.
  • Studies of subsurface water distribution at the landing site.
  • Atmosphere/surface volatile exchange.
  • Monitoring of the radiation environment.
  • Geophysical investigations of Mars’ internal structure

LPSP Flight Models have been delivered and integrated on board of ExoMars 2020 descent module in TAS-F (Cannes, France).

How to cite: Rodionov, D., Zelenyi, L., Korablev, O., Chulkov, I., Anufreychik, K., Marchenkov, K., and Vago, J.: ExoMars-2020 Landing Platform scientific payload, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21128, https://doi.org/10.5194/egusphere-egu2020-21128, 2020.

EGU2020-22203 | Displays | PS4.2 | Highlight

Forward Planning for the Science of Mars Sample Return - Open Questions and Next Steps

Elliot Sefton-Nash, Michael A. Meyer, David W. Beaty, and Brandi L. Carrier

Introduction

Beginning with the April 2018 Statement of Intent regarding MSR, NASA and ESA initiated planning for a potential partnership to return the M-2020 samples from Mars to Earth.  A fundamental premise of the partnership is that scientists funded by NASA, or from ESA Member (and Associate) States or other partnership nations would equitably share in the planning for MSR science as well as have equal access to the samples for collective scientific benefits and discoveries.  As one component of that planning, the MSR Science Planning Group (MSPG) was chartered in late 2018 to begin addressing key outstanding science issues via a series of international workshops and to develop the framework for a science management plan.

Some of the major open science-related issues that have been defined so far include:

  1. Development of a complete science management plan starting from the MSPG “A Framework for Mars Returned Sample Science Management” [1].
  2. Five open issues were identified at the January, 2019 workshop “MSR Science in Containment” for which follow-up action was recommended at a high level of priority [2].
  3. Several areas requiring further work were also identified at the May, 2019 “Contamination Control” workshop [3].

The purpose of this conference presentation is to seek community discussion of the issues to be presented, and input into additional issues, if any, that are missing.  All of this will be input into planning for Mars Sample Return Science (MSR) over the next 1-2 years.

A Vision for What Needs to be Done Within the Next Year

  1. Using the October 2019 document “A Framework for Mars Returned Sample Science Management,” along with feedback from NASA and ESA, and the draft or final MSR MOU, MSPG-2 will prepare the “Mars Returned Sample Science Management Plan.”
  2. Address some or all of the technical by means of convening representatives from the scientific community, conducting workshops, establishing topical committees, directed work, and/or the MSPG-2’s own internal efforts. Emphasis is placed on the responsibility of this group to represent the view of the international science community and other stake-holders of Mars Sample Return science output.
  3. Formulate strategies to maintain engagement with the science research community during this early planning period.

References:

[1] MSPG (2019a), A Framework for Mars Returned Sample Science Management. https://mepag.jpl.nasa.gov/reports/MSPG_ScienceManagementReport_Final.pdf

[2] MSPG (2019b), The Relationship of MSR Science and Containment. Unpublished workshop report, https://mepag.jpl.nasa.gov/reports/Science%20in%20Containment%20Report.pdf.

[3] MSPG (2019c), Science-Driven Contamination Control Issues Associated with the Receiving and Initial Processing of the MSR Samples. Unpublished workshop report https://mepag.jpl.nasa.gov/reports/MSPG%20Contamination%20Control%20Report%20Final.pdf.

Disclaimer: The decision to implement Mars Sample Return will not be finalized until NASA’s completion of the National Environmental Policy Act (NEPA) process. This document is being made available for information purposes only.

How to cite: Sefton-Nash, E., Meyer, M. A., Beaty, D. W., and Carrier, B. L.: Forward Planning for the Science of Mars Sample Return - Open Questions and Next Steps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22203, https://doi.org/10.5194/egusphere-egu2020-22203, 2020.

EGU2020-10649 | Displays | PS4.2

Experimental approach to understand mineralogy and aqueous alteration history of Oxia Planum, ExoMars 2020 landing site

Agata Krzesinska, Benjamin Bultel, Jean-Christophe Viennet, Damien Loizeau, and Stephanie Werner

In 2020, ESA/ROSCOSMOS will launch ExoMars2020 rover mission to Mars. The selected landing site for the mission is Oxia Planum, a wide Noachian-aged clay mineral-bearing plain. The Fe,Mg-rich clay mineral deposits in Oxia are one of the largest exposures of this type on Mars, with a thickness of more than 10 m and as such are an important source of information about Martian Noachian (>3.9 Ga) water-mediated interactions between lithosphere, hydrosphere, and atmosphere. The regional compositional mapping of Oxia Planum conducted in spectroscopic studies by OMEGA and CRISM suggests that the clay minerals are mainly trioctahedral Fe,Mg-rich in nature, with a local presence of dioctahedral Al-rich varieties. Although no exact spectral match was found for Oxia clay minerals among terrestrial analog rocks, the closest consistency is revealed by vermiculite or Fe,Mg-rich di-trioctahedral smectite.

The mechanism by which vast deposits of vermiculite may have formed on Mars is, however, not entirely clear. Based on the preliminary geomorphological investigation at Oxia, five major environments of basement clay minerals formation are plausible: pedogenic, hydrothermal in shallow sub-surface, related to metamorphism or to diagenesis as well as connected to glacial alteration. However, it is not obvious whether these early Noachian environments may have provided conditions capable to form vermiculite-like minerals. Furthermore, understanding the mechanisms of alteration in specific environments does not bring sufficient information about fluid alteration conditions such as chemical composition, acidity, oxidation state and amount of fluid (i.e. water to rock ratio).

To better understand the plausible mechanism of the formation of vermiculitic-like clay minerals at Oxia Planum as well as fluid alteration conditions, we have been performing laboratory alteration experiments. Comprehended from terrestrial analog environments, we focus our research on possible alteration pathways of biotite and chlorite towards vermiculite. Additionally, considering geomorphological manifestations of plausible past aqueous environments at Oxia Planum, we test various conditions of surface weathering and hydrothermal activity.

Our results show that Fe,Mg-vermiculite may form via alteration of Fe-rich biotite in the CO2-rich atmosphere in Noachian Mars. However, critical factors governing the process are the saturation of solution in K dissolved from biotite and oxidation of solution. In laboratory conditions, vermiculitization occurred only under conditions providing relatively high water to rock ratios or in an open system. It implies that if vermiculite-like clay mineral deposits formed in Oxia Planum, a large amount of water must have been delivered to the subsurface to drive alteration through preferential removal of potassium from interlayer space of primary minerals.

How to cite: Krzesinska, A., Bultel, B., Viennet, J.-C., Loizeau, D., and Werner, S.: Experimental approach to understand mineralogy and aqueous alteration history of Oxia Planum, ExoMars 2020 landing site, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10649, https://doi.org/10.5194/egusphere-egu2020-10649, 2020.

EGU2020-13377 | Displays | PS4.2

Identification and characterization of new feldspar-bearing rocks in the walls of Valles Marineris, Mars

Jessica Flahaut, Marie Barthez, Vincent Payet, Frank Fueten, Martin Guitreau, Pascal Allemand, and Cathy Quantin-Nataf

VNIR spectroscopy has previously led to many discoveries pertaining to Mars geologic history (e.g., the discovery of hydrated minerals associated to ancient terrains with OMEGA, Bibring et al., 2006). Plagioclase feldspar minerals can also be identified with spectroscopic techniques thanks to a 1.3 microns absorption in the VNIR domain (e.g., Adams and Goullaud, 1978). Previous lunar analog studies show however that when mixing powders of Ca plagioclase and a mafic component (olivine or pyroxene), the feldspars absorption band is quickly masked (e.g., Cheek and Pieters, 2014). This study further demonstrates that the 1.3 micron feature is only detectable if the plagioclase abundance is > 90 %. Based on this observation, previous feldspar absorptions on Mars have been interpreted as evidence for nearly pure anorthositic rocks (e.g., Carter and Poulet, 2013). A recent study by Rogers and Nekvasil (2015) however suggests that phenocryst basalts with less than 90% plagioclase could reproduce the 1.3 micron feature if large crystals are involved, although no whole rock measurements were made.

In the present study, we describe new feldspar signatures detected with the CRISM VNIR spectral-imager in the walls of the Valles Marineris grand canyon, on Mars. The associated rock textures and elevations were assessed from CTX and HiRISE images and DTMs. In parallel, we are collecting VNIR spectra of various (uncrushed) terrestrial rocks containing a large range of feldspar abundances and grain sizes. Analyses are carried out between 0.35 and 2.5 microns with an ASD Fieldspec at CRPG Nancy, France, and will be presented at the conference time. By combining laboratory measurements of a range of possible terrestrial analog rocks with the study of Mars feldspar-bearing outcrops, we should bring more clues on the nature and origin of these feldspathic rocks.

How to cite: Flahaut, J., Barthez, M., Payet, V., Fueten, F., Guitreau, M., Allemand, P., and Quantin-Nataf, C.: Identification and characterization of new feldspar-bearing rocks in the walls of Valles Marineris, Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13377, https://doi.org/10.5194/egusphere-egu2020-13377, 2020.

EGU2020-21840 | Displays | PS4.2

Modeling the dose distribution in a human brain structure using CT images on the surface of Mars

Salman Khaksarighiri, Jingnan Guo, Robert Wimmer-Schweingruber, and Lennart Rostl

One of the most important steps in the near-future space age will be a manned mission to Mars. Unfortunately, such a mission will cause astronauts to be exposed to unavoidable cosmic radiation in deep space and on the surface of Mars. Thus a better understanding of the radiation environment for a Mars mission and the consequent biological impacts on humans, in particular the human brains, is critical. To investigate the impact of cosmic radiation on human brains and the potential influence on the brain functions, we model and study the cosmic particle-induced radiation dose in a realistic head structure. Specifically speaking, 134 slices of computed tomography (CT) images of an actual human head have been used as a 3D phantom in Geant4 (GEometry ANd Tracking) which is a Monte Carlo tool simulating energetic particles impinging into different parts of the brain and deliver radiation dose therein. As a first step, we compare the influence of different brain structures (e.g., with or without bones, with or without soft tissues) to the resulting dose therein to demonstrate the necessity of using a realistic brain structure for our investigation. Afterwards, we calculate energy-dependent functions of dose distribution for the most important (most abundant and most biologically-relevant) particle types encountered in space and on Mars such as protons, Helium ions and neutrons. These functions are then used to fold with Galactic Cosmic Ray (GCR) spectra on the surface of Mars for obtaining the dose rate distribution at different lobes of the human brain. Different GCR spectra during various solar cycle conditions have also been studied and compared.

How to cite: Khaksarighiri, S., Guo, J., Wimmer-Schweingruber, R., and Rostl, L.: Modeling the dose distribution in a human brain structure using CT images on the surface of Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21840, https://doi.org/10.5194/egusphere-egu2020-21840, 2020.

EGU2020-18532 | Displays | PS4.2

Leka Ophiolite Complex as analogy to the serpentinization-carbonation system on Mars

Benjamin Bultel, Agata M. Krzesińska, Damien Loizeau, Cateline Lantz, François Poulet, Håkon O. Austrheim, Elise M. Harrington, Jean-Christophe Viennet, Henning Dypvik, and Stephanie C. Werner

Jezero Crater is the landing site of the Mars2020 NASA rover. The crater in its early history hosted a paleolake with at least two deltas remaining. The Jezero lake belongs to a larger system - the Nili Fossae region – which exposes a mineralogical assemblage interpreted as a serpentinization/carbonation system [1].  While the main alteration minerals in Jezero are identified, little is known about the accessory minerals. The latter could reveal critical information about the conditions of serpentinization/carbonation [2; 3]. Moreover, several aspects are yet to be solved: Are the carbonates resulting of primary alteration or reworked origin [4]? Is the mineralogical assemblage modified after deposition in the lake (weathering)? What is the nature of the protolith that could contains up to 30% of olivine [5]?

The Nili Fossae-Jezero system has its potential analogue in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Leka Island, Norway, (PTAL collection, https://www.ptal.eu), which records complex weathering of serpentinite formed from mafic to ultramafic rock [6].

We perform petrological and mineralogical analyses on thin sections to characterize the weathering products in Leka samples, and combine with Near Infrared Spectroscopy measurements. We study the significance of the mineralogical assemblages including solid solution composition and nature of accessory minerals. The consequence for habitability potential might be important. Indeed, the amount of H2/CH4 production in mafic or ultramafic system vary significantly [2; 7]. This could represent crucial information that could guide future in-situ operations but could also help for a better interpretation of the remote sensing data.

 

References:

How to cite: Bultel, B., Krzesińska, A. M., Loizeau, D., Lantz, C., Poulet, F., Austrheim, H. O., Harrington, E. M., Viennet, J.-C., Dypvik, H., and Werner, S. C.: Leka Ophiolite Complex as analogy to the serpentinization-carbonation system on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18532, https://doi.org/10.5194/egusphere-egu2020-18532, 2020.

EGU2020-20648 | Displays | PS4.2

Geology of Isidis based on study of mascon and chains of cones

Natalia Zalewska, Leszek Czechowski, and Jakub Ciążela

Geology of Isidis based on study of mascon and chains of cones

 

Leszek CZECHOWSKI1, Natalia ZALEWSKA2,  Jakub CIĄŻELA2

 

1University of Warsaw, Faculty of Physics, Institute of Geophysics, ul. Pasteura 5, 02-093 Warszawa, Poland, lczech@op.pl.

2 Space Research Centre, Polish Academy of Sciences, ul. Bartycka 18A, 00-716 Warszawa, Poland


Introduction:

We consider the surface structures and geological history of Isidis Planitia on Mars. It is a plain located inside a large impact basin of ~1500 km in diameter. Its age is ~3.8 Ga ago [1, 2]. Geologic history of Isidis Planitia (or at least some of its parts) is quite complicated and many details remain unclear. We believe that better analysis of surface structures (especially chains of cones) and large deep structures (e.g. mascon) will allow a better understanding of the origin of Isidis.

 Formation of basin and mascon:

 One of the large Martian mascons is located under Isidis. This is an anomalously high mass concentration below the surface. Such structures were discovered during the Apollo missions on the Moon. The formation of mascon is possible only under special physical conditions. Therefore, its existence is an important source of information about past conditions and can help us determine thermal conditions in the past of the basin.

 We use numerical models to this problem. Our model is based on the equation of thermal conductivity and the equation of motion.  Preliminary results point that the model allows to determine thermal conditions and some tectonic processes in the period when the mascon was formed.

The possibility of comparing processes on different celestial bodies is important for our research. Mars is a body of intermediate mass and size between Earth and the Moon. Therefore, it can be expected that some geological processes on Mars are similar to processes on Earth (e.g. volcanism) or the Moon (e.g. mascon’s formation).

Role of distributed volcanism and chains of cones:

We are examining the volcanic system of cones on Isidis Planitia. Many of these chain forms have a characteristic furrow through the center, suggesting that fissure volcanism along circumferential dikes was common the Isidis area. The cones have diameters of 300–500 m and heights of ~30 m. These imply slopes of 7–11° consistent with explosive type of volcanism. Similar cones are known from Iceland. Some of the Isidis cones  keeping the cone shape without a furrow. We recognize this type of volcanism on the volcanic archipelago of the Canary Islands and in particular on Lanzarote. The cones on Isidis have been divided into three types depending on their building. Currently, we are working on determining the duration and age of this volcanic activity, as well as the size related magma plumbing system, which might be related to Syrtis Major.

Instability of water in the upper layers of the regolith could cause rapid degassing of the regolith. The result may be mud volcanism or geysers [3].

 References

[1] Ivanov, M.A., et al. 2012, Icarus.   https://doi.org/10.1016/j.icarus.2011.11.029

[2] Rickman, H., et al.  Planetary and Space Science, 166, 70–89, 2019.

[3] Czechowski, L., et al. 2020. Submitted for LPSC 2020 in The Woodlands, Tx

How to cite: Zalewska, N., Czechowski, L., and Ciążela, J.: Geology of Isidis based on study of mascon and chains of cones , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20648, https://doi.org/10.5194/egusphere-egu2020-20648, 2020.

EGU2020-4261 | Displays | PS4.2

Crustal magnetic field advection on Mars from MAVEN observations

Isabela de Oliveira, Markus Fränz, Adriane Franco, and Ezequiel Echer

The plasma environment of Mars is highly influenced by regions of remnant magnetism in the planetary crust, above which mini-magnetospheres are created. In this work, we study whether the ionospheric plasma flow can move crustal magnetic field lines, by the process of advection. According to this hypothesis, the magnetic field lines are dragged away in anti-solar direction, westward at dawn and eastward at dusk-side, due to the day-to-night flow of the ionospheric plasma. The altitude of interest is between 200 km and 1000 km, because the plasma flow velocity is significant in this region.

MAVEN (Mars Atmosphere and Volatile EvolutioN) data is used for a direct comparison between magnetic field data and a crustal magnetic field model. The difference between the observed and the model field at each point of the grid is a measure of the sum of the induced day magnetic field and the possible displacement of the crustal field lines by advection. The results of the analysis show that, except for the lowest altitude range, minimum value of this difference is always observed for westward shift at dawn-side and eastward shift at dusk-side, in agreement with the expected motion of the crustal magnetic field lines.

For a general idea of the relative forces between the moving plasma and the crustal fields, we use MAVEN data to analyze the pressures involved in the advection process. These are the dynamic pressure of the ionospheric plasma flow, the magnetic pressure of the field lines and the thermal pressure of the plasma related to the mini-magnetospheres. The balance between these quantities should dictate the occurrence of advection. This analysis suggests that advection could take place at low altitude (up to ~450 km) dawn-side regions above low intensity magnetic fields.

Although the global analysis results showed agreement with our hypothesis, we could not observe evidence of advection from the local observations in order to unambiguously prove the occurrence of this process. Future works include the investigation of single orbit data in regions of low intensity magnetic field, especially at dawn-side, and also magnetohydrodynamic modeling of the process using the plasma conditions prevalent in the Martian ionosphere.

How to cite: de Oliveira, I., Fränz, M., Franco, A., and Echer, E.: Crustal magnetic field advection on Mars from MAVEN observations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4261, https://doi.org/10.5194/egusphere-egu2020-4261, 2020.

EGU2020-5324 | Displays | PS4.2

The nutations of a rigid Mars

Rose-Marie Baland, Marie Yseboodt, Sébastien Le Maistre, Attilio Rivoldini, Tim Van Hoolst, and Véronique Dehant

The nutations of Mars are about to be estimated with unprecedented accuracy (a few milliarcseconds) with the radioscience experiments RISE (Rotation and Interior Structure Experiment, Folkner et al. 2018) and LaRa (Lander Radioscience, Dehant et al. 2020) of the InSight and ExoMars 2020 missions, allowing to detect the contributions due to the liquid core and tidal deformations and to constrain the interior of Mars.

To properly identify the non-rigid contribution, an accurate precession and nutation model for a rigidly behaving Mars is needed. We develop such a model, based on the Torque approach, and include the forcings by the Sun, Phobos, Deimos, and the other planets of the Solar System, as well as geodetic precession and nutations. Both semi-analytical developments (for the Solar and planetary torques) and analytical solutions (for Phobos and Deimos torques and the geodetic precession and nutations) are considered.

We identify 43 nutation terms with an amplitude above the chosen truncation criterion of 0.025 milliarcseconds in prograde and/or retrograde nutations. Uncertainties related to modelling choices are negligible in comparison to the uncertainty coming from the observational uncertainty on the current determination of the precession rate of Mars (7608.3+/-pm2.1 mas/yr, Konopliv et al. 2016). Our model predicts a dynamical flattening HD=(C-A)/C=0.00538017+/-0.00000148 and a normalized polar moment of inertia C/MR2=0.36367+/-0.00010 for Mars.

References:
Folkner et al., 2018. doi: 10.1007/s11214-018-0530-5.
Dehant et al., 2020. doi: 10.1016/j.pss.2019.104776.
Konopliv et al., 2016. doi: 10.1016/j.icarus.2016.02.052.

How to cite: Baland, R.-M., Yseboodt, M., Le Maistre, S., Rivoldini, A., Van Hoolst, T., and Dehant, V.: The nutations of a rigid Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5324, https://doi.org/10.5194/egusphere-egu2020-5324, 2020.

EGU2020-4971 | Displays | PS4.2

Ground scientific verification test for Moderate Resolution Imaging Camera of China’s First Mars Mission

Xiaoxia Zhang, Jianjun Liu, wei yan, Dawei Liu, and Donghao Liu

China's first Mars exploration mission (HX-1) is expected to launch in 2020 with an orbiter and a rover, to conduct a global and comprehensive exploration of Mars, and to carry out regional patrolling on the Mars surface. The orbiter will be equipped with a Moderate Resolution Imaging Camera (MoRIC) to produce a global map of the Mars and study the topography of the Mars surface. The MoRIC is a color camera, works at visible spectrum, the image resolution of the camera is 100m@400km, and the FOV is 64 o.

The purpose of the Ground scientific verification test for MoRIC is to evaluate its ability to obtainhigh quality image data of the Mars surface. In the test, we made a simulation of the on-orbit detection process of MoRIC and obtained different kinds of test data, which was used to evaluate the data processing method and analyze the quality of data. The test results show that the data processing method of the MoRIC is correct; the image quality, the color correction effect and compression quality of the MoRIC data meet the requirements of the verification test.

How to cite: Zhang, X., Liu, J., yan, W., Liu, D., and Liu, D.: Ground scientific verification test for Moderate Resolution Imaging Camera of China’s First Mars Mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4971, https://doi.org/10.5194/egusphere-egu2020-4971, 2020.

EGU2020-8812 | Displays | PS4.2

Observations of the Martian atmosphere by NOMAD on ExoMars Trace Gas Orbiter

Ann Carine Vandaele, Arianna Piccialli, Ian R. Thomas, Frank Daerden, Shohei Aoki, Cédric Depiesse, Justin Erwin, Lori Neary, Bojan Ristic, Séverine Robert, Loïc Trompet, Sébastien Viscardy, Yannick Willame, Jean-Claude Gérard, Giuliano Liuzzi, Geronimo Villanueva, Jon Mason, Manish Patel, Giancarlo Bellucci, and Jose-Juan Lopez-Moreno and the NOMAD Team

The NOMAD (“Nadir and Occultation for MArs Discovery”) spectrometer suite on board the ExoMars Trace Gas Orbiter has been designed to investigate the composition of Mars' atmosphere, with a particular focus on trace gases, clouds and dust probing the ultraviolet and infrared regions covering large parts of the 0.2-4.3 µm spectral range [1,2].

Since its arrival at Mars in April 2018, NOMAD performed solar occultation, nadir and limb observations dedicated to the determination of the composition and structure of the atmosphere. Here we report on the different discoveries highlighted by the instrument: investigation of the 2018 Global dust storm and its impact on the water uplifting and escape, its impact on temperature increases within the atmosphere as inferred by GCM modeling and observations, the dust and ice clouds distribution during the event, ozone measurements, dayglow observations and in general advances in the analysis of the spectra recorded by the three channels of NOMAD.

References

[1] Vandaele, A.C., et al., 2015. Planet. Space Sci. 119, 233-249.

[2] Vandaele et al., 2018. Space Sci. Rev., 214:80, doi.org/10.1007/s11214-11018-10517-11212.

How to cite: Vandaele, A. C., Piccialli, A., Thomas, I. R., Daerden, F., Aoki, S., Depiesse, C., Erwin, J., Neary, L., Ristic, B., Robert, S., Trompet, L., Viscardy, S., Willame, Y., Gérard, J.-C., Liuzzi, G., Villanueva, G., Mason, J., Patel, M., Bellucci, G., and Lopez-Moreno, J.-J. and the NOMAD Team: Observations of the Martian atmosphere by NOMAD on ExoMars Trace Gas Orbiter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8812, https://doi.org/10.5194/egusphere-egu2020-8812, 2020.

EGU2020-9035 | Displays | PS4.2

EXOFIT field trials: experience learned from the use of ExoMars/RLS Qualification Model and representative Raman prototypes

Guillermo Lopez-Reyes, Marco Veneranda, Jose Antonio Manrique Martinez, Jesus Saiz Cano, Jesus Medina García, Carlos Perez Canora, Laura Seoane, Sergio Ibarmia Huete, Andoni Moral, and Fernando Rull

The ESA/Roscosmos ExoMars mission to Mars is scheduled to be launched in 2020. Seeking to prepare the ExoMars operation team to manage the engineering and scientific challenges arising from the Rosalind Franklin rover soon operating at Oxia Planum, a rover prototype equipped with representative ExoMars navigation and analytical systems was recently used in two mission simulations (ExoFit trials)

The first field test was carried out in Tabernas (Spain), a desertic area characterized by the presence of clays, partially altered sedimentary rocks and efflorescence salts. The second ExoFit trial was performed in the Atacama Desert (Chile), in a sandy flat land displaying diorite-boulders, clays patches and evaporites.

The Raman Laser Simulator (RLS) team participated in both simulations: portable spectrometers were used to determine the mineralogical composition of subsoil samples collected by the rover-drill and to investigate the possible presence of biomarkers. In-situ analysis were carried out by means of the RAD 1 system (Raman Demonstrator), which is a portable spectrometer that follows the same geometrical concept and spectral characteristics of the RLS flight model (FM).

In the case of Tabernas trial, additional analysis were performed using the RLS qualification model (EQM2) which at the moment was the most reliable tool to understand the scientific outcome that could derive from the RLS operating on Mars.

Prior to analysis, geological samples were crushed and sieved to replicate the granulometry of the powdered material produced by the ExoMars crusher. After flattening, from 8 to 10 spots were analyzed and Raman data and interpreted.

From each site, two cores were drilled and analyzed. On one side, the main mineralogical phases detected in the first Atacama core are quartz and calcium carbonate. In addition to those, the mineralogy of the second core also includes hematite and calcium sulphate.

On the other side, RAD 1 spectra gathered from Almeria core-samples confirmed the presence of quartz as main mineralogical phase. However, peaks of medium intensity at 146 and 1086 cm-1 were also observed, confirming the detection of rutile and calcium carbonate respectively. The same samples were further characterized by means of the RLS-EQM2 system: beside confirming the detection of the abovementioned mineral phases, additional Raman biomarkers-related peaks were also found.

Even though deeper Raman analysis of ExoFit samples need to be performed, the preliminary results gathered in-situ suggests that Raman spectroscopy could play a kay role in the fulfillment of the ExoMars mission objectives.

How to cite: Lopez-Reyes, G., Veneranda, M., Manrique Martinez, J. A., Saiz Cano, J., Medina García, J., Perez Canora, C., Seoane, L., Ibarmia Huete, S., Moral, A., and Rull, F.: EXOFIT field trials: experience learned from the use of ExoMars/RLS Qualification Model and representative Raman prototypes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9035, https://doi.org/10.5194/egusphere-egu2020-9035, 2020.

EGU2020-18024 | Displays | PS4.2

Dynamical phenomena in the atmosphere of Mars imaged with the Visual Monitoring Camera onboard Mars Express

Teresa del Río-Gaztelurrutia, Agustín Sánchez-Lavega, Jorge Hernández-Bernal, Ricardo Hueso, Alejandro Cardesín-Moinelo, Eleni Ravanis, Patrick Martin, Simon Wood, and Dmitri Titov

The Visual Monitoring Camera on board Mars Express provides images of varied resolutions, covering a wide range of locations and seasons, and has been taking images for several Martian years. This large image database can be exploited to study various dynamical phenomena, and in this work, we concentrate on the study of cloud and dust storm activity in the polar regions, describing vortices, cloud evolution, and regional dust storms as well as the presence of gravity waves. Tracking the motions of details in the images, we estimate local winds, compare our results with predictions from the Mars Climate Database in different scenari, and study their seasonal evolution and potential inter annual variability. Further, resolution of images captured near pericenter is sufficient to allow the detection of gravity waves in the troposphere, identified as regular patterns in the cloud fields. We measure some of the basic properties of these waves, such as horizontal wave vector and extension of wave trains. We analyse those properties in relation to their aerographic location, local time and season, in the context of a recent study of the distribution of gravity waves on the lower atmosphere of Mars as inferred from the analysis of temperature fields by the Mars Climate Sounder onboard the Mars Reconnaissance Orbiter (MRO) (Heavens et al. ICARUS 2020).

How to cite: del Río-Gaztelurrutia, T., Sánchez-Lavega, A., Hernández-Bernal, J., Hueso, R., Cardesín-Moinelo, A., Ravanis, E., Martin, P., Wood, S., and Titov, D.: Dynamical phenomena in the atmosphere of Mars imaged with the Visual Monitoring Camera onboard Mars Express, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18024, https://doi.org/10.5194/egusphere-egu2020-18024, 2020.

EGU2020-16039 | Displays | PS4.2

Retrievals of dust and ozone from NOMAD-UVIS

Arianna Piccialli, Ann Carine Vandaele, Yannick Willame, Cedric Depiesse, Loic Trompet, Lori Neary, Sebastien Viscardy, Frank Daerden, Ian R. Thomas, Bojan Ristic, Jon P. Mason, Manish Patel, Giancarlo Bellucci, and Jose Juan Lopez Moreno

We will present two years of observation of dust and ozone vertical distribution obtained from NOMAD-UVIS solar occultations.

Atmospheric aerosols are ubiquitous in the Martian atmosphere and they strongly affect the Martian climate [1]. This is particularly true during dust storms. In June 2018, after a pause of 11 years, a planet-encircling dust storm took place on Mars that lasted two months.

Ozone, on the other hand, is a species with a short chemical lifetime and characterized by sharp gradients at the day-night terminator due to photolysis [2]. Odd hydrogen radicals play an important role in the destruction of ozone. This results in a strong anti-correlation between O3 and H2O [2].

The NOMAD (Nadir and Occultation for MArs Discovery) – operating onboard the ExoMars 2016 Trace Gas Orbiter satellite – started to acquire the first scientific measurements on 21 April 2018.

It is a spectrometer composed of 3 channels: 1) a solar occultation channel (SO) operating in the infrared (2.3-4.3 μm); 2) a second infrared channel LNO (2.3-3.8 μm) capable of doing nadir, as well as solar occultation and limb; and 3) an ultraviolet/visible channel UVIS (200-650 nm) that can work in the three observation modes [3,4]. The UVIS channel has a spectral resolution <1.5 nm. In the solar occultation mode it is mainly devoted to study the climatology of ozone and aerosols content [5].

Since the beginning of operations, on 21 April 2018, NOMAD-UVIS acquired more than 3000 solar occultations with a complete coverage of the planet. NOMAD-UVIS spectra are simulated using the line-by-line radiative transfer code ASIMUT-ALVL developed at IASB-BIRA [6]. In a preliminary study based on SPICAM-UV solar occultations (see [7]), ASIMUT was modified to take into account the atmospheric composition and structure at the day-night terminator. As input for ASIMUT, we used gradients predicted by the 3D GEM-Mars v4 Global Circulation Model (GCM) [8,9].

NOMAD will help us improve our knowledge of the climatology of ozone and aerosols. In particular, we will have the rare opportunity to analyze the distribution of aerosols during a dust storm.

References:

[1] Määttänen, A., Listowski, C., Montmessin, F., Maltagliati, L., Reberac, A., Joly, L., Bertaux, J.L., Apr. 2013. Icarus 223, 892–941.

[2] Lefèvre, F., et al., Aug. 2008. Nature 454, 971–975.

[3] Vandaele, A.C., et al., Planetary and Space Science, Vol. 119,  pp. 233–249, 2015.

[4] Neefs, E., et al., Applied Optics, Vol. 54 (28),  pp. 8494-8520, 2015.

[5] M.R. Patel et al., In: Appl. Opt. 56.10 (2017), pp. 2771–2782. DOI: 10.1364/AO.56.002771.

[6] Vandaele, A.C., et al., JGR, 2008. 113 doi:10.1029/2008JE003140.

[7] Piccialli, A., Icarus, in press, https://doi.org/10.1016/j.icarus.2019.113598.

[8] Neary, L., and F. Daerden (2018), Icarus, 300, 458–476, doi:10.1016/j.icarus.2017.09.028.

[9] Daerden et al., 2019, Icarus 326, https://doi.org/10.1016/j.icarus.2019.02.030

How to cite: Piccialli, A., Vandaele, A. C., Willame, Y., Depiesse, C., Trompet, L., Neary, L., Viscardy, S., Daerden, F., Thomas, I. R., Ristic, B., Mason, J. P., Patel, M., Bellucci, G., and Lopez Moreno, J. J.: Retrievals of dust and ozone from NOMAD-UVIS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16039, https://doi.org/10.5194/egusphere-egu2020-16039, 2020.

EGU2020-6566 | Displays | PS4.2

Lander Radioscience (LaRa) in ExoMars 2020 to obtain the rotation and orientation of Mars.

Véronique Dehant, Rose-Marie Baland, Sébastien Le Maistre, Ozgur Karatekin, Marie-Julie Péters, Attilio Rivoldini, Ertan Umit, Tim Van Hoolst, Marie Yseboodt, William M. Folkner, Alexander Kosov, and LaRa team

The Lander Radioscience (LaRa) experiment on the ESA-Roscosmos ExoMars 2020 mission is designed to obtain coherent two-way Doppler measurements from the radio link between a lander on Mars and the Earth over at least one Martian year. The Doppler measurements will be used to determine the orientation and rotation of Mars in space (precession, nutations, and length-of-day variations). LaRa, on another location on the Martian surface with respect to the InSight mission could allow to observe the polar motion of Mars, in addition to further increase the accuracy on precession, nutation, and length-of-day measurements. The ultimate objective of LaRa is to obtain information on the Martian interior and about the sublimation/condensation cycle of atmospheric CO2. Concerning the nutations, a knowledge of the rigid body nutation can be computed and shall be used to constrain the interior properties of Mars.

How to cite: Dehant, V., Baland, R.-M., Le Maistre, S., Karatekin, O., Péters, M.-J., Rivoldini, A., Umit, E., Van Hoolst, T., Yseboodt, M., Folkner, W. M., Kosov, A., and team, L.: Lander Radioscience (LaRa) in ExoMars 2020 to obtain the rotation and orientation of Mars., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6566, https://doi.org/10.5194/egusphere-egu2020-6566, 2020.

EGU2020-16604 | Displays | PS4.2

CO2 ice grain size retrievals from SPICAM IR/MEX spectra

Alexander Lomakin, Anna Fedorova, Jodi Berdis, Oleg Korablev, and Franck Montmessin

CO2 cycle on Mars defines fundamental processes both on the surface and in the atmosphere. On poles condensation of a large part of the atmosphere (up to 30%) results seasonal growth and retreat of polar caps, changing reflectance and emissivity of the surface, that has dramatic consequences for energy budget and changes local and global climate on the planet. SPICAM-IR is an AOTF-based infrared spectrometer onboard Mars Express mission operating in range 1-1.7 μm with middle resolving power about 2000. SPICAM provides continuous monitoring of the Martian surface in near IR since 2004 during already 8 Martian Years. Still, the surface albedo that can be derived from this dataset was never analyzed. In this work, we will focus on the retrieval of the CO2 ice properties (like grain size) from the SPICAM dataset based on the Hapke model. We will present the retrieval algorithm and results for a number of selected orbits over the South pole.

How to cite: Lomakin, A., Fedorova, A., Berdis, J., Korablev, O., and Montmessin, F.: CO2 ice grain size retrievals from SPICAM IR/MEX spectra, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16604, https://doi.org/10.5194/egusphere-egu2020-16604, 2020.

EGU2020-11071 | Displays | PS4.2

Chaotic Caldera collapse: a new interpretation for the origin of Chaotic terrains on Mars

Erica Luzzi, Angelo Pio Rossi, Matteo Massironi, Riccardo Pozzobon, Daniele Maestrelli, and Giacomo Corti

Chaotic terrains are broad regions on Mars characterized by the occurrence of angular-polygonal blocks separated by deep fractures and grabens, associated with collapse chains and with the overall mineralogy consisting mainly in basalts (Luzzi et al., submitted, 2020). Several mechanisms of formation for Chaotic terrains were proposed in the literature. While it is a shared opinion that the peculiar structures delineating the polygonal blocks of the Chaotic terrains are due to a collapse, the actual process at the origin of such collapse is still debated. Collapses due to the overpressure within a confined aquifer were proposed (Rodriguez et al., 2005; Andrews-Hanna & Phillips, 2007) as well as related to magma-ice/water interactions (Chapman & Tanaka, 2002; Leask et al., 2006; Meresse et al., 2008), or melting of a buried frozen lake (Zegers et al., 2010). We propose a new formation scenario for Chaotic Terrains: a Chaotic (or Piecemeal) Caldera collapse. In such a Caldera collapse the fragmentation of the floor is irregular and characterized by polygonal blocks. We reproduced this process in a series of analogue experiments similar to those performed by Troll et al. (2002): a rubber membrane was used to simulate the magma chamber with multiple cycles of inflation and deflation that generate the characteristic fractures in an overlying K-feldspar sand layer. We performed the experiments in different settings (different geometry of the magma chamber and different depth) and we found that the geometry of the basin is influenced mainly by the shape of the magma chamber. Moreover, after the second cycle of inflation and deflation, the deformation tends to be moderate, consisting only in the formation of minor fractures and not in deep structures, responsible for the polygonal blocks fragmentation, which are instead formed during the first cycles. From a morphological point of view, the reproduced geometry is strikingly similar to that of  Chaotic terrains on Mars. Further quantitative analyses on the DEMs are ongoing in order to assess the role played by each variable and refine a plausible collapse history for the specific case of study of Arsinoes Chaos.

REFERENCES

Andrews-Hanna, J. C., & Phillips, R. J. (2007). JGR: Planets, 112(E8).

Chapman, M. G., & Tanaka, K. L. (2002). Icarus, 155(2), 324–339.

Leask, H. J. et al. (2006). JGR: Planets, 111(E8).

Luzzi et al. (2020). EarthArXiv, DOI: 10.31223/osf.io/td297

Meresse, S. et al. (2008). Icarus, 194(2), 487–500.

Rodriguez, J. A. P. et al. (2005). Icarus, 175(1), 36–57.

Troll, V. R. et al. (2002). Geology, 30(2), 135–138.

Zegers, T. E. et al. (2010). Earth and Planetary Science Letters, 297(3–4), 496–504.

How to cite: Luzzi, E., Rossi, A. P., Massironi, M., Pozzobon, R., Maestrelli, D., and Corti, G.: Chaotic Caldera collapse: a new interpretation for the origin of Chaotic terrains on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11071, https://doi.org/10.5194/egusphere-egu2020-11071, 2020.

EGU2020-20278 | Displays | PS4.2

Evaluating the serpentinization degree of Martian analogues through the RLS ExoMars simulator: comparison between univariate and multivariate semi-quantification methods

Marco Veneranda, Guillermo Lopez Reyes, Elena Pascual Sanchez, Jose Antonio Manrique-Martinez, Aurelio Sanz-Arranz, Agata M. krzesinska, Henning Dypvik, Stephanie C. Werner, Jesus Medina, and Fernando Rull

As part of the ESA ExoMars rover payload, the Raman Laser Spectrometer (RLS) is scheduled to deploy on Mars in 2021. Together with MicrOmega (NIR) and MOMA (GC-MS), the instrument will analyze Martian subsoil samples to determine their mineralogical composition and investigate the potential presence of biomarkers. Beside the challenges associated with the development of the first Raman spectrometer to be validated for planetary exploration (together with Mars2020/ Sherloc and Supercam systems), to optimize the scientific outcome of RLS spectra gathered on Mars has a crucial importance in the fulfillment of the mission aims. Thus, the RLS team is developing tailored chemometric tools that, taking into account technical specifications and the operational mode of the RLS system, could be used to semi-quantify the main phases composing Martian samples.

Considering that 1) the serpentinization of olivine-bearing rocks on Earth plays a key role in the proliferation of microorganisms and in the preservation of biomarkers, and 2) remote sensing systems (e.g. CRISM) detected vast serpentine-bearing deposits on Mars, the present work seek to provide the chemometric tools necessary to correctly define the serpentinization degree of Martian rock samples through the interpretation of RLS data.

To do so, olivine and serpentine certified materials were mixed at different concentration ratios and 39 spot of analysis por sample were analyzed by means of the RLS ExoMars Simulator. Data sets were then analyzed using uni-variate (intensity ratio between olivine and serpentine main peaks) and multi-variate (a combination of principal component analysis and artificial neural networks PCA-ANN) methods.

The two uni-variate and multi-variate semi-quantification models were finally applied to the study of serpentinized rocks sampled from the Leka Ophiolite Complex (LOC), being those part of the Planetary Terrestrial Analogue Library (PTAL) collection. RLS-based semi-quantification results were finally compared to those obtained from the use of a state-of-the-art laboratory X-ray diffractometer (XRD).

Our study suggest that the uni-variate method provide excellent results when the analyzed rocks are mainly composed of olivine and serpentine. However, the estimation reliability decreases when the mineralogical heterogeneity of the sample increases (Raman features of additional mineral phase may overlap the selected olivine and serpentine peaks). In these cases, the multi-variate method based on the combination of PCA and ANN helps to more accurate estimate the serpentinization degree of the terrestrial analogs.

In conclusion, the preliminary results summarized in this work indicates that the study of terrestrial analogs is of crucial importance to test and validate RLS-dedicated semi-quantification models. In a broader perspective, it also highlights the importance of developing multiple chemometric tools, since the effectiveness of each of them varies according to mineralogical complexity of the sample under study.

How to cite: Veneranda, M., Lopez Reyes, G., Pascual Sanchez, E., Manrique-Martinez, J. A., Sanz-Arranz, A., krzesinska, A. M., Dypvik, H., Werner, S. C., Medina, J., and Rull, F.: Evaluating the serpentinization degree of Martian analogues through the RLS ExoMars simulator: comparison between univariate and multivariate semi-quantification methods, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20278, https://doi.org/10.5194/egusphere-egu2020-20278, 2020.

EGU2020-13373 | Displays | PS4.2

Faulting in Mars Polar Layered deposits modeled by HCA method

Paola Cianfarra, Costanza Rossi, Francesco Salvini, and Laura Crispini

The polar layered deposits (PLD) of Mars constitute the water ice stratigraphy of polar spiral troughs up to several kilometers thick (Phillips et al., 2011; Smith et al. 2015). PLD cross section profiles from the Shallow Subsurface Radar (SHARAD) instrument on NASA’s Mars Reconnaissance Orbiter, show the presence of internal discontinuities within these layers (Foss et al., 2017; Putzig et al., 2017). The mechanisms responsible for these deformations are still an open issue (Guallini et al., 2017) and this work represents the contribution of stress-related deformations. Layered ice is simulated by a mesh of cells within a HCA grid build replicating the physical properties and preserving volumes following balanced cross-section principles. Three major types of link exist among adjacent cells: 1. intra-layer relations link cells belonging to the same layer; 2. inter-layer relations regulate the relationships among adjacent layers; 3. discontinuity relations correspond to the presence of ruptures such as faults (Salvini et al., 2001). The HCA method allows to replicate the natural material anisotropies, such as rocks and ice sheet internal layering, and to simulate complex tectonic evolutionary paths (Cianfarra and Salvini, 2016; Cianfarra and Maggi, 2017). The models allow simulating the kinematics of the internal architecture of the layered deposits from both the north and the south Martian ice caps. In particular the observed stratigraphy (geometries and thickness of the ice layers) is replicated as resulting from the relative, normal movement among blocks separated by listric shaped normal faults and minor inversions.

The used HCA numerical methodology revealed an effective tool to support planetary geological mapping and 3D subsurface geological reconstructions. Through the integration of a net of spatially distributed along- and across- strike (balanced) sections it is possible to simulate the 4D (3D plus time) geological evolution of buried and/or topographic structures. Results have a wide range of applications including the optimal selection of landing sites for scheduled and future planetary exploration missions, as well as unravelling the geological and structural setting of enigmatic features on the planetary surfaces affected, for example, by salt tectonism, volcano-tectonics, tectonically-related hydrothermal activity, fluid storage and release, and ice tectonics.

How to cite: Cianfarra, P., Rossi, C., Salvini, F., and Crispini, L.: Faulting in Mars Polar Layered deposits modeled by HCA method, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13373, https://doi.org/10.5194/egusphere-egu2020-13373, 2020.

EGU2020-18376 | Displays | PS4.2

Investigation of inter-annual and seasonal variations of the Martian convective PBL by GCM simulations

Cem Berk Senel, Orkun Temel, Sara Porchetta, Hakan Sert, Ozgur Karatekin, and Jeroen van Beeck

The Martian planetary boundary layer (PBL) is an important component of the Martian climate. It is the lowest portion of the atmosphere where the strong buoyant and shear forces influence the interaction between surface and atmosphere [1]. The Martian PBL exhibits extreme events compared to the Earth's PBL, such as global dust storms, local dust devils, turbulent gusts and strong updraughts. Due to the thinner atmosphere of Mars and lower surface thermal inertia, the Martian planetary boundary layer shows stronger diurnal variations compared to its terrestrial counterpart. Moreover, as a result of the thinner atmosphere, radiative heat forcing is stronger, such that the Martian planetary boundary layer height can reach up to 10 km. Radiative forcing on Mars is affected by the atmospheric cycles, i.e. CO2, water and dust cycles. In this study, we perform GCM simulations, using dust climatologies corresponding to the last 10 Mars years and present the inter-annual and seasonal variations in the planetary boundary layer height, mixed-layer potential temperature, convective velocity scale, friction velocity and Richardson number. To perform these GCM simulations, the Mars version of planetWRF (MarsWRF) model [2] is utilized, that solves the fully-compressible, non-hydrostatic Euler equations in a finite difference framework.

[1] Hinson, D. P., Pätzold, M., Tellmann, S., Häusler, B., & Tyler, G. L. (2008). The depth of the convective boundary layer on Mars. Icarus, 198(1), 57-66.

[2] Richardson, M. I., Toigo, A. D., & Newman, C. E. (2007). PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics. Journal of Geophysical Research: Planets, 112(E9).

How to cite: Senel, C. B., Temel, O., Porchetta, S., Sert, H., Karatekin, O., and van Beeck, J.: Investigation of inter-annual and seasonal variations of the Martian convective PBL by GCM simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18376, https://doi.org/10.5194/egusphere-egu2020-18376, 2020.

EGU2020-20131 | Displays | PS4.2

On the horizontal currents over the Martian magnetic cusp

Tariq Majeed, Shahad Al Mutawa, Omar Al Aryani, Stephan Bougher, and Syed Haider

Localized crustal magnetization over heavily cratered southern hemisphere at Mars gives rise to open magnetic field configurations which interact with the solar wind magnetic field to form magnetic cusps.  The downward acceleration of energetic electrons in these cusps can produce aurora and an extended topside ionospheric structure over regions of magnetic anomalies.  We report plasma collisions with the neutral atmosphere at one of the Martian cusps located at 82oS and 108oE, where the crustal field is strong with a radial component ~30o from the local zenith.  We find that the dynamo region in the upper ionosphere of Mars is located between altitudes of 102 km and 210 km. The electrons in this region are constrained to gyrate along magnetic field lines while ions are dragged by neutrals and move along the direction of applied force.  In the absence of the electric field, the horizontal current in the Martian dynamo is generated by the differential motion of ions and electrons.  We find that the bulk of the current density is equatorward and confined within the Martian dynamo near the ionospheric peak with a magnitude of ~3.5 µA/m2.  We also find that the westward current density of magnitude ~0.4 µA/m2 peaking near the upper boundary of the Martian dynamo is generated by magnetized ions in the -F x B direction.  The model details and results in comparison with other studies will be presented.       

How to cite: Majeed, T., Al Mutawa, S., Al Aryani, O., Bougher, S., and Haider, S.: On the horizontal currents over the Martian magnetic cusp , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20131, https://doi.org/10.5194/egusphere-egu2020-20131, 2020.

EGU2020-19720 | Displays | PS4.2

Extremely Low Frequency laboratory investigation of moving sand and dust – a case of the Martian environment

Joanna Kozakiewicz, Andrzej Kulak, Mateusz Sobucki, and Jerzy Kubisz

We present first results of laboratory experiments on extremely low frequency (ELF) electromagnetic (EM) field generation by moving sand and dust. This work is a part of our ongoing project to design and manufacture an autonomous ELF Mars Station that will enable studying electric properties of the Martian ionosphere as well as the subsurface of Mars.

ELF waves are very weakly attenuated in the planetary environments and propagate in a cavity made of two high-conductivity spherical boundaries: a planetary ionosphere and a planetary ground. On Mars, as there is no liquid water at the planetary surface, the high-conductivity layer of the ground is expected to be located at greater depths than on Earth, and therefore, ELF investigation on Mars can be used as a tool for studying the subsurface layers. It can be especially useful for groundwater detection. However, the main aim in ELF studies on Mars is related to investigating ELF sources.

ELF sources on Mars can be generated by frequently occurring phenomena: dust storms and dust devils. However, up till now, electromagnetic activity of these dust events on Mars has not been investigated in situ, and remote sensing measurements have been inconclusive. On Earth, many works indicate that dust storms and dust devils generate electromagnetic field, and some ELF fields in dust devils were detected. Also, some aeolian tunnel experiments showed that electric fields can be produced by moving sand.

Our laboratory experiments were performed in an aeolian environmental tunnel located at the Jagiellonian University in Krakow, designed to study aeolian transport. The measurements were carried out by dedicated ELF detectors and using a developed technique of signal processing and analysis. Several aeolian materials, different in mineralogical and granulometric composition, were tested.

This work has been supported by the National Science Center under grant 2015/19/B/ST9/01710.

How to cite: Kozakiewicz, J., Kulak, A., Sobucki, M., and Kubisz, J.: Extremely Low Frequency laboratory investigation of moving sand and dust – a case of the Martian environment, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19720, https://doi.org/10.5194/egusphere-egu2020-19720, 2020.

EGU2020-20050 | Displays | PS4.2

The tectonic origin of Planum Boreum spiral troughs, Mars

Costanza Rossi, Paola Cianfarra, and Francesco Salvini

The spiral troughs of the North Polar Layered deposits on Mars are deep depressions that dissect the Planum Boreum ice cap. These are enigmatic structures whose puzzling origin is still under debate. Advanced hypotheses on their genesis and evolution range between erosional to structural scenario. In this work, a double approach was followed to explore the structural/tectonic origin of the spiral troughs by means of Hybrid Cellular Automata (HCA) numerical modelling and lineament domain analysis. The SHARAD profile data were used to replicate the ice internal layering architecture associated to buried troughs in Gemina Lingula. Analysis of the lineament domains automatically detected at the ice surface from satellite images of the Mars Orbiter Camera strengthened the structural/tectonic interpretation of their origin and evolution. Similar, twofold approach was used for the investigation of a terrestrial analog identified in the Antarctic ice sheet. It presents at depth blind structures recognized as fractures/faults produced by ice sheet dynamics. Radargrams of Operation IceBridge mission and images from Sentinel-2 were used to produce a tectonic model that was in turn compared with the Planum Boreum one. Obtained results, and their comparison, show that the troughs of Gemina Lingula result from the activity of low-angle normal faults with listric geometry. The activity of listric faults is modelled and compared with the antarctic analog. At the surface the detected lineament domains confirm the tectonic setting by tracing the buried trough/fault orientations. The proposed tectonic model refers to extensional regime characterized by the presence of a deep detachment connecting the troughs at depth. This represents an internal ductile layer placed at depth greater than 1000 m whose kinematics induces the troughs/faults deformation. The extensional tectonics developed in Planum Boreum is possibly related to the ice cap collapse that induces internal dynamics. In this way, katabatic winds play a secondary role by maintaining at the surface the troughs nearly orthogonal to their directions.

How to cite: Rossi, C., Cianfarra, P., and Salvini, F.: The tectonic origin of Planum Boreum spiral troughs, Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20050, https://doi.org/10.5194/egusphere-egu2020-20050, 2020.

EGU2020-19464 | Displays | PS4.2

WISDOM Calibration and Data Processing Pipeline for the ExoMars 2020 Mission

Dirk Plettemeier, Christoph Statz, Yun Lu, Wolf-Stefan Benedix, Sebastian Hegler, Yann Herve, Nicolas Oudart, Alice Legall, Charlotte Corbel, Svein-Erik Hamran, and Valerie Ciarletti

The WISDOM instrument is part of the 2020 ESA-Roscosmos ExoMars Rosalind-Franklin rover payload. It is a fully-polarimetric ground penetrating RADAR (GPR) operating as a stepped-frequency continuous-wave radar at frequencies between 500 MHz and 3 GHz yielding a centimetric resolution and a penetration depth of about 3 m in Martian soil. WISDOMs primary scientific objective is the detailed characterization the material distribution of the Martian subsurface as a contribution to the search for evidence of present and past life.

WISDOM  works by transmitting electromagnetic waves in the observable zone of the subsurface below the antenna. The transfer function of the observed zone is then recovered from the received signal. The processing of the WISDOM data involves several calibration steps, where environment and temperature as well as instrument influences are compensated in order to obtain interpretable results. The data processing involves several filters that are designed to extract and quantify features of interest w.r.t. the surface and subsurface. Calibration and processing are implemented in the WISDOM Data Processing Framework (WDPF). It can be operated manually (via GUI integration) as well as automatically as part of the ROCC processing pipeline yielding comparable and reproducible results from automatic and manual processing of WISDOM data. The capabilities of WDPF are validated on laboratory and field measurements performed with the WISDOM instrument.

How to cite: Plettemeier, D., Statz, C., Lu, Y., Benedix, W.-S., Hegler, S., Herve, Y., Oudart, N., Legall, A., Corbel, C., Hamran, S.-E., and Ciarletti, V.: WISDOM Calibration and Data Processing Pipeline for the ExoMars 2020 Mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19464, https://doi.org/10.5194/egusphere-egu2020-19464, 2020.

EGU2020-18615 | Displays | PS4.2

The Planetary Terrestrial Analogues Library (PTAL)

Stephanie C. Werner, Francois Poulet, and Fernando Rull and the The PTAL Team

The Planetary Terrestrial Analogues Library project aims to build and exploit a spectral data base for the characterization of the mineralogical and geological evolution of terrestrial planets and small Solar System bodies. Basis for the library is our collection of natural field-collected and artificial planetary (often Martian) analogue materials as well as materials, which have been altered in laboratory experiments. All samples were characterized by XRD, thin sections as base and as input for the spectral library with standard commercial and dedicated spacecraft instrumentation (NIR, RAMAN, LIBS) under laboratory conditions. The database will allow users to jointly interpret laboratory results and newly gathered in-situ or remote sensing data using instruments (LIBS, NIR, Raman) on board of current and future space missions (e.g., Hayabusa-2, Curiosity, ExoMars, Mars2020). The main aim of the database is the use of spectra stored for purposes related to comparison, identification, quantification and spectral calculation when spectroscopic instruments such as NIR, Raman and LIBS operate in planetary missions and/or analyzing materials in the field or in the laboratory. This database features spectral tools allowing for the spectral data treatment implementation plans are the integration of the database management and algorithms in an end-user platform with graphical interfaces for the use of the data and analyzing tools. The public release of the Planetary Terrestrial Analogues Library will be at the end of year 2020. We will have a demonstration and tutorial during the EGU-GA 2020.

Acknowledgements: This project is financed through the European Research Council in the H2020-COMPET-2015 programme (grant 687302).

How to cite: Werner, S. C., Poulet, F., and Rull, F. and the The PTAL Team: The Planetary Terrestrial Analogues Library (PTAL), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18615, https://doi.org/10.5194/egusphere-egu2020-18615, 2020.

EGU2020-740 | Displays | PS4.2

The Webcam around Mars: Supporting Science with the Mars Express Visual Monitoring Camera

Eleni Ravanis, Jorge Hernández-Bernal, Alejandro Cardesín-Moinelo, Agustín Sánchez-Lavega, Teresa del Río-Gaztelurrutia, Ricardo Hueso, Simon Wood, Dmitrij Titov, Miguel Almeida, Julia Marin-Yaseli de la Parra, Donald Merritt, Emmanuel Grotheer, Michel Breitfellner, Manuel Castillo, and Patrick Martin

The Visual Monitoring Camera (VMC), or “the ESA Mars Webcam” on board ESA’s Mars Express (MEX) orbiter was originally designed as an engineering camera whose purpose was to monitor the separation of the Beagle-2 lander in 2003. Later, in 2007, the camera was switched on again for outreach purposes, with images regularly posted to Twitter (@esamarswebcam) and Flickr. Following the subsequent use of VMC data for Mars atmospheric science (Sánchez-Lavega et al., AAS/DPS, 48, 2016; Sánchez-Lavega et al., Icarus 299, 194-205, 2018) the VMC was designated a scientific instrument in 2016. No on-ground calibration exists for the VMC, so the VMC team have had to take initiative in order to perform in-flight calibration of the instrument. New observation planning procedures have been developed, as well as a new data processing pipeline hosted at the European Space Astronomy Centre (ESAC) in Madrid to maximise the scientific return of the instrument. The data is currently in the process of being archived in the Planetary Science Archive, for its wider use by the community.

The MEX Science Ground Segment (SGS) team at ESAC maintains close collaboration with the VMC science team located at the University of the Basque Country (UPV-EHU) in Bilbao. The scientific studies undertaken with VMC camera data include monitoring of the global dust storm over the south pole in 2018 (Hernández-Bernal et al., J. Geophys. Res. Lett., 46, 10330–10337, 2019), analysis of twilight clouds (Hernández-Bernal et al., EPSC, 12, 2018), discovery of a seasonally recurrent double cyclone in the northern latitudes of Mars (Sánchez-Lavega et al., J. Geophys. Res., 123, 3020, 2018) and studies of an extremely elongated cloud over Arsia Mons (Hernández-Bernal et al., EGU, 2020). The scientific success of this “webcam” around Mars highlights how small cameras on planetary missions can yield high science return, which has implications for potential future CubeSat missions to Mars.

How to cite: Ravanis, E., Hernández-Bernal, J., Cardesín-Moinelo, A., Sánchez-Lavega, A., del Río-Gaztelurrutia, T., Hueso, R., Wood, S., Titov, D., Almeida, M., Marin-Yaseli de la Parra, J., Merritt, D., Grotheer, E., Breitfellner, M., Castillo, M., and Martin, P.: The Webcam around Mars: Supporting Science with the Mars Express Visual Monitoring Camera, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-740, https://doi.org/10.5194/egusphere-egu2020-740, 2020.

EGU2020-1001 | Displays | PS4.2

Seasonal cycle of methane on Mars could be produced by variations of the Hadley cell and differential hemispheric releases

Jorge Pla-Garcia, Scot C.R. Rafkin, Christopher R. Webster, Paul R. Mahaffy, Özgür Karatekin, Elodie Gloesener, and John E. Moores

The detection of methane at Gale crater by the Curiosity rover has garnered significant attention because it could be a signal from Martian organisms [Webster et al., 2015]. Although it is difficult to reconcile the measured peaks with the modeled transport and mixing unless invoking an unknown rapid destruction mechanism from the lower atmosphere before it spreads globally, the observed low background levels can be reproduced by the model under some circumstances [Pla-Garcia et al. 2019]. It appears to be a seasonal cycle in the background methane concentrations at Gale [Webster et al., 2018]. If ground temperature controls the release of methane on seasonal timescales then the methane flux should be higher during warmer seasons. Methane clathrates are one example where this mechanism could operate, assuming that clathrates could be preserved due to slow dissociation and diffusion rates. The rover weight effect on the soil could also favor the dissociation of these clathrates. Temperature-dependent metabolism of methanogens is another example. MRAMS [Rafkin et al., 2002] is used to study what the role of atmospheric transport and mixing may play in the seasonal cycle. An initial state mimicking the detection by [Mumma et al., 2009; M09] provides one scenario to explore how a large, methane-enriched air mass would be transported, mixed and diffused into the topographically complex Gale region. In order to characterize changes to seasonal transport, simulations were conducted with a continuous surface methane release at three key seasons: Ls155, when the high methane values by M09 were reported; Ls270 when there is a wholesale inundation of the crater by external air [Rafkin et al., 2016]; and Ls90, which is representative of the rest of the year. Ls155 has the highest methane values compared to other MRAMS scenarios. Around the equinoxes, the rising branch quickly crosses from one hemisphere into the other with individual Hadley cells in each hemisphere. Surface winds at the tropical location of Gale converge and help to contain and circulate methane-rich air from M09 release area. In contrast to the equinox, the mean meridional winds are northerly at Ls270 and southerly at Ls90 with no large-scale convergence of air in the tropics. An additional global tracers experiment, with 18 instantaneous tracers distributed three-dimensionally all over the martian atmosphere was performed to confirm the previous transport results and to highlight the difference emission of methane between hemispheres. The seasonal change in the global circulation combined with seasonal changes in the hemispheric release of methane could produce a seasonal methane signal at Gale. If there is a correlation between methane release and ground temperature, then one would expect a strong correlation between the local atmospheric methane value and the ground temperature in the absence of any transport. This is what was noted by [Webster et al., 2018], except during Ls216-298, when very high latitude northerly air penetrates into Gale. The air in Gale during this season is more representative of a source air mass deep in the northern hemisphere where it is cold and depleted in methane

How to cite: Pla-Garcia, J., Rafkin, S. C. R., Webster, C. R., Mahaffy, P. R., Karatekin, Ö., Gloesener, E., and Moores, J. E.: Seasonal cycle of methane on Mars could be produced by variations of the Hadley cell and differential hemispheric releases, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1001, https://doi.org/10.5194/egusphere-egu2020-1001, 2020.

EGU2020-7773 | Displays | PS4.2

Regional Geologic Mapping of the Oxia Planum Landing Site for ExoMars

Ernst Hauber, Samira Acktories, Sophie Steffens, Andrea Naß, Daniela Tirsch, Solmaz Adeli, Nicole Schmitz, Frank Trauthan, Katrin Stephan, and Ralf Jaumann

The ExoMars mission will deploy a stationary surface platform and a rover in Oxia Planum (OP), a region at the transition between the heavily cratered highlands of Mars and the ancient and filled impact basin, Chryse Planitia. While the fundamental geologic characteristics of the area have been investigated during the landing site selection process, detailed geologic or morpho-stratigraphic mapping is still missing. To fill this knowledge gap, two complementary mapping approaches were initiated by the ExoMars RSOWG: (1) Local HiRISE-scale mapping of the landing ellipse(s) area (reported elsewhere: Sefton-Nash et al., LPSC 2020). (2) Regional mapping at ~CTX-scale [this study] will provide a more synoptic view of the wider landing site within OP, enabling the contextualization of the units within the stratigraphy of western Arabia Terra and Chryse Planitia, and a comparison to other sites with similar key geologic and physiographic characteristics. It is also expected that this map will serve as a geologic reference throughout the mission and subsequent data analysis.

The study area is located between 16.5°N and 19.5°N, and 334°E to 338°E. The data sets used for mapping include HRSC, THEMIS IR (day and night), CTX, and CaSSIS. Mapping scale in a GIS environment is 1:100,000, which will result in a final printable map at a scale of 1:1M. Mapping started in mid-October 2019. Overall, the identified map units are very similar to those described by Quantin et al. (Astrobiology, submitted): The spatially most widespread units are the phyllosilicate-bearing unit that is the prime ExoMars target (with distinctly enhanced THEMIS nighttime temperatures when compared to its surroundings), a dark resistant unit of possibly volcanic or sedimentary origin, and a mantling unit that was likely emplaced by eolian processes. Multiple channels of various morphology and degradation state as well as sedimentary fan-shaped deposits (with low nighttime temperatures) imply a diverse and possibly long-lived history of surface runoff, perhaps accompanied or replaced by groundwater processes such as sapping. Inverted landforms (channels, impact craters) are the result of intense erosion. Additional mapped features include tectonic structures such as wrinkle ridges and lobate scarps (delineating a basin-like depression in the central mapping area), remnant erosional buttes in the northwestern portion of the mapping area (i.e. towards Chryse Planitia), craters and their ejecta blankets, and fields of eolian bedforms and secondary craters.

At the time of writing, the mapping is incomplete and only initial and limited conclusions can be drawn. Overall, the mapping confirms previous geologic analyses. However, some features (e.g., contractional structures, channels, possible sapping landforms) need further attention as the may provide important constraints on the tectonic and aqueous evolution of the ExoMars landing area. A comparison to a distant, but geologically very similar site in Xanthe Terra, southeast of the Hypanis fan-shaped deposits, may enable testing of hypotheses raised by the geologic mapping of OP.

How to cite: Hauber, E., Acktories, S., Steffens, S., Naß, A., Tirsch, D., Adeli, S., Schmitz, N., Trauthan, F., Stephan, K., and Jaumann, R.: Regional Geologic Mapping of the Oxia Planum Landing Site for ExoMars , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7773, https://doi.org/10.5194/egusphere-egu2020-7773, 2020.

The Dynamic Albedo of Neutrons (DAN) instrument designed to detect neutrons in order to determine hydrogen abundance in the Martian subsurface (down to 1 m deep) is successfully working onboard Mars Science Laboratory (MSL) Curiosity rover for more than seven years. The Curiosity rover covered more than 20 km on the Martian surface and crossed a range of terrain types and geological structures of different mineralogical composition.

We investigate the possible correlation between the water equivalent hydrogen (WEH) value, as measured by DAN along the Curiosity traverse, and the presence of hydrated minerals, as observed from the orbit by Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard Mars Reconnaissance Orbiter.  

Our analysis of the WEH value from DAN measurements in Gale crater and the CRISM data, reflecting the distribution of hydrated/hydroxylated minerals on the surface of this crater, shows a confident increase of the average WEH values for the surface elements, containing certain types of minerals, in comparison with surface elements, that do not contain any of them. This increase is shown to become higher for surface with more prominent spectral features of hydrated/ hydroxylated minerals on the surface. Thus, certain types of minerals being parts of the sedimentary deposits composing Gale crater, should have considerable thickness, which is sufficient for active neutron sensing in DAN measurements. To explain the correspondence, one may assume that large blocks of certain mineral composition are distributed over the traverse, the tops of which are observed by CRISM from the Martian orbit, and the volumes of which are detectable by DAN on the Martian surface.

The bottom of the crater is thought to be a composition of a uniform regolith and sedimentary blocks of minerals with different level of hydration. The fraction of the regolith contains a standard value of WEH, about 2.6 wt.%, and the  fraction of minerals, provided they are there, might contribute to some increase of the mean WEH values, up to 3.8 wt.%, as they are obtained at some spots from the DAN neutron sensing.

How to cite: Djachkova, M., Mitrofanov, I., Litvak, M., Lisov, D., Nikiforov, S., and Sanin, A.: Testing correspondence between areas with hydrated minerals, as observed by CRISM onboard MRO, and spots of enhanced subsurface water content, as found by DAN along the traverse of Curiosity, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9993, https://doi.org/10.5194/egusphere-egu2020-9993, 2020.

Three generations of the Alpha-Particle-X-ray-Spectrometer (APXS) have been part of the science suite on all four landed NASA Mars rovers so far. Using x-ray spectroscopy following excitation with alpha particles and x-rays from 244Cm radioactive sources, so far about 2000 samples have been investigated along the combined traverse of ~85km on the surface of Mars.

The APXS reports 16 standard elements in all samples and additional trace elements like Ge, Cu, Ga, Rb, Sr, As, Se, Y and Pb if at elevated levels. The sample spot of ~ 20 mm diameter is often large enough to represent bulk content, though small enough to reveal evidence for certain minerals through element correlations when oversampled in rasters. The results from all missions revealed large scale sedimentary formations, like Murray and Burns indicating specific environmental conditions in the past. The soil was found similar at all sites, representing a well mixed global crust component. APXS geochemical data were used for important constraints of complimentary mineralogy results, ground truth for orbiters and comparison to Martian meteorites.

Results from the ongoing Curiosity mission and the long living MER rovers will be discussed. Additionally, some very successful applications and investigations that were serendipitously developed after launch will be reviewed. Part of the presentation will be devoted to the unique challenges, trade-offs during design and lessons learned from the long operation of the instrument. The combination of APXS, XRD and Moesbauer results from MER and MSL with future fine scale XRF results of the soil at the Mars 2020 landing site might shed a light into the enigmatic amorphous phase, which could represent a record of the past alteration processes on Mars.

How to cite: Gellert, R.: Hindsight 2020: X-ray Spectroscopy on Mars, Challenges, Results and Future., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12226, https://doi.org/10.5194/egusphere-egu2020-12226, 2020.

EGU2020-18057 | Displays | PS4.2

Humidity calibration of relative humidity devices in Martian conditions

Maria Hieta, Maria Genzer, Jouni Polkko, Iina Jaakonaho, Andreas Lorek, Stephen Garland, Jean-Pierre de Vera, German Martinez, and Erik Fischer

Finnish Meteorological Institute (FMI) has developed relative humidity measurement devices for past and future Mars lander missions: REMS-H for Curiosity, MEDA HS for Mars 2020 and METEO-H for ExoMars 2020. The sensors used in these devices are HUMICAP® capacitive thin-film polymer sensors by Vaisala Inc. New calibration measurements are performed with ground reference models of these devices in the Mars Simulation Facility (MSF) and Planetary Analog Simulation Laboratory (PASLAB) at the German Aerospace Center (DLR) in spring 2020. The preliminary results will be given at the EGU 2020.

Calibration of relative humidity devices requires in minimum two humidity points over the expected operational temperature and pressure range of the device. With two-point calibration the relative humidity devices can be used for scientific measurements with satisfactory quality but the uncertainty is notable. Stable humidity conditions between dry and saturation humidity in Martian conditions can be achieved reliably in very few laboratories in the whole world and humidity measurements in Martian conditions have been previously performed for the same devices in FMI laboratory and in Michigan Mars Environmental Chamber (MMEC) at the University of Michigan.

The new measurement campaign will consist of stable humidity point measurements in multiple temperatures between +10°C to -70°C in CO2 gas and Martian pressure of approximately 7 hPa. The measurements are performed simultaneously for multiple devices in a small pressure vessel with continuous humidified carbon dioxide flow.

The new measurement campaign will improve the characterization of the existing relative humidity devices in Mars lander missions and define in more detail the measurement uncertainties.

How to cite: Hieta, M., Genzer, M., Polkko, J., Jaakonaho, I., Lorek, A., Garland, S., de Vera, J.-P., Martinez, G., and Fischer, E.: Humidity calibration of relative humidity devices in Martian conditions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18057, https://doi.org/10.5194/egusphere-egu2020-18057, 2020.

PS4.4 – Open Session on Moon, Mars, Mercury, Venus as terrestrial planets systems

EGU2020-8271 | Displays | PS4.4

Absolute Magnetometer Attitude Reconstruction using Magnetospheric Modelling

Johannes Z. D. Mieth, Daniel Heyner, and Karl-Heinz Glassmeier

One of the main goals of the magnetometer experiment MPO-MAG on board of the Magnetospheric Planetary Orbiter (MPO) during the BepiColombo mission is the determination of the Mercury main magnetic field, epecially in constraining the characteristics of the magnetic dipole offset.
In April 2020 BepiColombo had its Earth Gravity Assist manoeuvre on its way to planet Mercury.
The topocentric distance was lower than three Earth radii and offered a unique opportunity to compare the magnetometer measurements to a multitude of simultaneous measurements of the magnetospheric environment of the Earth performed by several other spacecraft like THEMIS and MMS.
Using a great number of probing points to constrain models of the Earh magnetosphere and compare models to actual measurements of the MPO-MAG sensors enables us to determine the absolute sensor attitude to an accuracy of only a few arc minutes.
Knowing the absolute attitude of a magnetometer sensor in planetary orbiter missions is a key component for the magnetic main field determination.
We present the modelling approach to compare to measurements from MPO-MAG and a study showing the dependence of a mainfield determination on the accuracy of the sensor orientation.

How to cite: Mieth, J. Z. D., Heyner, D., and Glassmeier, K.-H.: Absolute Magnetometer Attitude Reconstruction using Magnetospheric Modelling, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8271, https://doi.org/10.5194/egusphere-egu2020-8271, 2020.

EGU2020-9657 | Displays | PS4.4

Spectroscopy of gamma-rays of Earth, Venus and Mercury: MGNS instrument onboard BepiColombo mission

Alexander Kozyrev, Maxim Litvak, Alexey Malakhov, Igor Mitrofanov, Maxim Mokrousov, Anton Sanin, Vladislav Tretiyakov, Alan Owens, Rita Schulz, and Francesco Quarati

The Mercurian Gamma-ray and Neutron Spectrometer (MGNS) is a scientific instrument developed to study the elementary composition of the Mercury’s sub-surface by measurements of neutron and gamma-rays emission of the planet. MGNS measures neutron fluxes in a wide energy range from thermal energy up to 10 MeV and gamma-rays in the energy range of 300 keV up to 10 MeV with the energy resolution of 5% FWHM at 662 keV and of 2% at 8 MeV. The innovative crystal of CeBr3 is used for getting such a good energy resolution for a scintillation detector of gamma-rays.

During the BepiColombo long cruise to Mercury, it is planned that the MGNS instrument will operate practically continuously to perform measurements of neutrons and gamma-rays fluxes for achieving two main goals of investigations: monitoring of the local radiation background of the prompt spacecraft emission due to bombardment by energetic particles of Galactic Cosmic Rays and the participation in the Inter Planetary Network (IPN) program for the localization of sources of Gamma-Ray Bursts in the sky.

The MGNS instrument will also perform special sessions of measurements during flybys of Earth, Venus and Mercury with the objective to measure neutron and gamma-rays albedo of the upper atmosphere of Earth and Venus and of the surface of Mercury. Another objective is to test the computational model of the local background of the spacecraft using the data measured at different orbital phases of flyby trajectories. The low altitude flybys (such as the 700 km flyby for Venus and three 200 km flybys for Mercury) would be the most useful for such tests being BC maximally shadowed for cosmic radiation by the actual planet. Neutron and gamma-rays measurements during Earth flybys enable investigation of interaction between solar wind and Earth environments as well as studies of spacecraft neutron and gamma-rays background upon its passage through the Earth's radiation belts.

How to cite: Kozyrev, A., Litvak, M., Malakhov, A., Mitrofanov, I., Mokrousov, M., Sanin, A., Tretiyakov, V., Owens, A., Schulz, R., and Quarati, F.: Spectroscopy of gamma-rays of Earth, Venus and Mercury: MGNS instrument onboard BepiColombo mission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9657, https://doi.org/10.5194/egusphere-egu2020-9657, 2020.

EGU2020-3742 | Displays | PS4.4

The mass flux of volatiles from volcanic eruptions on Mercury

Ariel Deutsch, James Head, Stephen Parman, Lionel Wilson, Gregory Neumann, and Finnian Lowden

Mercury has been extensively resurfaced by large, effusive lava plains [1–2]. Similar lava plains on the Moon, the maria, are known to contain volatiles [3–4] and are estimated to have outgassed ~1016 kg of CO and S and ~1014 kg of H2O, with the bulk of volatiles being released during peak mare emplacement ~3.5 Ga ago [5]. If volcanic activity released substantial volatiles on the Moon [6–7], then it is possible that substantial volatiles were also volcanically released on Mercury, albeit with different chemical species [6–9]. Here we seek to understand the potential contribution of outgassing to volatile deposits, specifically for Mercury’s volatile species (S, CH4, Cl, and N-H).

We analyze the production function of volcanic plains deposits on Mercury and find that the volume of outgassed basalts on Mercury is 2 to 3 orders of magnitude larger than that predicted for the Moon [8]. We use a variety of experimental petrology studies [10–12] to predict the dominant species and their abundances associated with these eruptions on Mercury, providing estimates for both low-gas and high-gas scenarios for different oxygen fugacities (IW-3 and IW-7). The most prevalent volatile species predicted for Mercury (S, CH4, and Cl) are 1 to 4 orders of magnitude more abundant than what is predicted for the most abundant volatiles outgassed on the Moon (CO, S, and H2O) [5].

On the Moon, it has been predicted that volatiles outgassed from the formation of the maria may have been present in sufficient volumes to produce a transient atmosphere capable of aiding in the transport of H2O to cold-trapping regions [5]. At mantle pressures and Mercury’s extremely reducing conditions, H2O is not predicted to be present in the magma [e.g., 6–12]. Therefore, Mercury’s outgassed volatiles are of a different composition from the H2O ice observed at Mercury’s poles today [e.g., 13], and the polar H2O-ice deposits are better explained by some external delivery mechanism (likely cometary impacts). But the fate of large volumes of volatiles other than H2O is an important unanswered question for Mercury.

The large volumes of outgassed volatiles calculated here suggest that volcanism on Mercury may have resulted in the transient production of anomalously high atmospheric pressures of short lifetime due to solar proximity. If Mercury’s atmospheric loss rate was insufficient to lose all of the erupted gases, then it is possible that ancient, outgassed volatiles remain trapped in the planet’s subsurface today. The fate of Mercury’s outgassed volatiles is an important open question that we discuss in this work.

References: [1] Head et al. (2011). [2] Denevi et al. (2013). [3] Boyce et al. (2010). [4] McCubbin et al. (2010). [5] Needham and Kring (2017). [6] Nittler et al. (2011). [7] Zolotov et al. (2013). [8] Peplowski et al. (2016). [9] Greenwood et al. (2018). [10] Anzures et al. (2017). [11] Armstrong et al. (2015). [12] Libourel et al. (2003). [13] Lawrence et al. (2013).

How to cite: Deutsch, A., Head, J., Parman, S., Wilson, L., Neumann, G., and Lowden, F.: The mass flux of volatiles from volcanic eruptions on Mercury, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3742, https://doi.org/10.5194/egusphere-egu2020-3742, 2020.

EGU2020-18423 | Displays | PS4.4

Particle Induced X-ray Emission at Mercury and the Moon.

Manuel Grande and Rose Cooper

Mercury and the Moon are examples of terrestrial bodies which lack an atmosphere and therefore have surfaces which interact directly with the space environment. Thus the surfaces can be reprocessed by plasma impact, and in the process can emit X-rays via the Particle Induced X-ray Emission (PIXE) process. We will present and review existing measurements, particularly from SMART-1 and Chandrayaan at the Moon, and Messenger and Mercury, in order to predict opportunities for new science at Mercury by BepiColumbo. We will present predictions of PIXE signals from different regions of the Mercury surface, and examine the possibility of using the signal for direct diagnosis of particle interactions with the surface. These include the auroral signatures of substorm like behaviour, and interactions with coronal mass ejections.

How to cite: Grande, M. and Cooper, R.: Particle Induced X-ray Emission at Mercury and the Moon., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18423, https://doi.org/10.5194/egusphere-egu2020-18423, 2020.

EGU2020-3303 | Displays | PS4.4

Mineral powder samples for solar wind ion sputtering experiments relevant for Moon and Mercury

Noah Jäggi, André Galli, Peter Wurz, Herbert Biber, Paul S. Szabo, Friedrich Aumayr, and Klaus Mezger

The surfaces of Mercury and Moon are thought to be similar in terms of being rocky, regolith covered planetary bodies, dominated by pyroxene and plagioclase (Taylor et al. 1991, McCoy et al. 2018). Contrary to the Moon, Mercury possesses a global dipole magnetic field, resulting in a highly dynamic magnetosphere that varies surface exposure to solar wind ions and energetic electrons (Winslow et al. 2017, Gershman et al. 2015). The energy of these particles is thereby transferred and material is sputtered from the surface (Sigmund 2012), providing the main contributions to the exospheres of the Moon and Mercury. Parametrizing the underlying sputtering processes is of great interest for successfully linking exosphere observations with surface compositions (e.g. Wurz et al. 2010, Merkel et al. 2018).

The understanding of sputtering from the kinetic energy transfer is sufficient to predict sputter yields of singly charged impinging ions on conducting surfaces (e.g., Stadlmayr et al. 2018). Hijazi et al. (2017) and Szabo et al. (2018) have also made advancements on potential sputtering, investigating the interaction of multiply charged ions with glassy thin films. We expand on their studies and use mineral powder pellets as analogues for sputtering experiments relevant to the surfaces of the Moon and Mercury. The powder pellets include plagioclase, pyroxene, and wollastonite. The latter is a pyroxene-like Ca-rich mineral with Fe contents below detection limits, which allows investigating the effect on reflectivity during sputtering of Fe-free minerals. With these analogues, we strive to supply infrared spectra with a focus on the robust mid infrared (MIR) range for Mercury and sputter yields for both the Moon and Mercury. 

First results of irradiated mineral pellets include MIR spectra of the minerals before and after irradiation as well as sputtering yields and visual alteration effects. So far, no relevant changes in the MIR spectra were observed nor any visual alteration of wollastonite. The first irradiation with 4 keV 4He+ reached a fluence of about 29 E+20 ions per m2 at an angle of 30°. Presumably, the lack of visual alteration is due to the absence of Fe in wollastonite. Further results are expected to bring clarity in the reaction of pellets to irradiation and if their sputtering characteristics differ from those of glassy thin films.

Gershman, D. J., et al. (2015). J. Geophys. Res.-Space, 120(10).

Hiesinger, H., & Helbert, J. (2010). Planet. Space Sci., 58(1–2).

Hijazi, H., et al. (2017). J. Geophys. Res.-Planet, 122(7).

McCoy, T. J., et al. (2018). Mercury: The View after MESSENGER.

Sigmund, P. (2012). Thin Solid Films, 520(19).

Stadlmayr, R., et al. (2018). Nucl. Instrum. Meth. B, 430.

Szabo, P. S., et al. (2018). Icarus, 314.

Taylor, G. J., et al. (1991). Lunar sourcebook-A user’s guide to the moon.

Winslow, R. M., et al. (2017). J. Geophys. Res.-Space, 122(5).

 

How to cite: Jäggi, N., Galli, A., Wurz, P., Biber, H., Szabo, P. S., Aumayr, F., and Mezger, K.: Mineral powder samples for solar wind ion sputtering experiments relevant for Moon and Mercury, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3303, https://doi.org/10.5194/egusphere-egu2020-3303, 2020.

EGU2020-6112 | Displays | PS4.4

Deriving the ancient lunar pole path from impact induced gravity anomalies

David E Smith, Maria T Zuber, Sander J Goossens, Gregory A Neumann, and Erwan Mazarico

The large anomalies in the lunar gravity field are in most cases the result of large impacts that occurred more than 3 billion years ago.  Today those anomalies provide the stability of the lunar rotation and if removed would cause a change in the position of the intersection of the spin pole with the lithosphere. Thus, extracting a gravity anomaly from today’s gravity field can provide the approximate location of the pole of rotation prior to the impact that caused the anomaly.  By removing the gravity field of each anomaly in order of age, youngest first, we can estimate the path of the lunar pole back 3 to 4 billion years, to the beginning of the time of heavy bombardment.

Starting from the GRAIL gravity model we selectively remove large gravity anomalies by first determining the center and dimensions of the anomaly from the Bouguer gravity and then deriving the average free air gravity for the Bouguer location and dimensions. The anomaly field is expanded into spherical harmonics and the degree 2 terms used to derive the change in pole position caused by the anomaly. Removing each anomaly in order of increasing age provides an estimate of the pole path from before the time of the first anomaly, SP-A.  Since the pole path depends on the order of the gravity anomalies being created it is important to know when each impact induced anomaly occurred.  The results suggest the re-constructed motion of the lunar pole of rotation is within approximately 10 dgerees of the present pole.

How to cite: Smith, D. E., Zuber, M. T., Goossens, S. J., Neumann, G. A., and Mazarico, E.: Deriving the ancient lunar pole path from impact induced gravity anomalies, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6112, https://doi.org/10.5194/egusphere-egu2020-6112, 2020.

Planetary impact events eject large volumes of surface material.  Crater excavation processes are difficult to study, and in particular the details of individual ejecta fragments are not well understood.  A related, enduring issue in planetary mapping is whether a given crater resulted from a primary impact (asteroid or comet) or instead is a secondary crater created by an ejecta fragment.  With mapping and statistical analyses of six lunar secondary crater fields we provide three new constraints on these issues: 1) definition of the maximum secondary crater size as a function of distance from a primary crater on the Moon, 2) estimation of the size and velocity of ejecta fragments that formed these secondaries, and 3) estimation of the fragment size ejected at escape velocity. 

We mapped secondary craters around primary craters ranging in size from ~0.83–660 km in diameter using Lunar Reconnaissance Orbiter Camera (LROC) Narrow and Wide Angle Camera images.  Identification of secondary craters was based on expected secondary crater morphologies (e.g., v-shaped ejecta, clusters or chains, and elongation in the direction radial to the primary, similarity in degradation state across the secondary field) and secondaries were assigned a confidence level (as to whether they were likely a secondary crater) based on the number of expected morphologies they displayed.  Only the most confident features were utilized in this work, as there is no way to capture all secondary craters within a given lunar secondary field.  Scaling from secondary crater sizes to ejecta fragment sizes was carried out using the Housen-Holsapple-Schmidt formulations.                                                                                                                          

The largest secondaries and those made by the highest velocity fragments (up to ~1.4 km/s) were mapped around the Orientale basin.  The estimated size of fragments that could reach the lunar Hill-sphere escape velocity of 2.34 km/s varies by the size of the impact event, but could be as large as ~850 m for Orientale.  Note that these are not necessarily expected to be coherent fragments, they could also be loosely bound collections of smaller fragments.  However, the fragments/clumps mapped here remained in a form that resembles a single fragment in order to form the distinct secondary craters observed.  For low velocity secondaries, surprisingly, we found features that appear to be secondary craters formed from fragments with velocities as small as 50 m/s around the smallest primary.  

Through this analysis, we confirmed and extended a suspected scale-dependent trend in ejecta size-velocity distributions.  Maximum ejecta fragment sizes fall off much more steeply with increasing ejection velocity for larger primary impacts (compared to smaller primary impacts).  Specifically, we characterize the maximum ejecta sizes for a given ejection velocity with a power law, and find the velocity exponent varies between approximately -0.3 and -3 for the range of primary craters investigated here.  Data for the jovian moons Europa and Ganymede confirm similar trends for icy surfaces.  This result is not predicted by analytical theories of formation of Grady-Kipp fragments or spalls during impacts, and suggests that further modeling investigations are warranted to explain this scale-dependent effect.

How to cite: Singer, K., McKinnon, W., and Jolliff, B.: Lunar secondary craters: Results for secondary sizes across the Moon, and size-velocity distributions of ejected blocks, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1851, https://doi.org/10.5194/egusphere-egu2020-1851, 2020.

EGU2020-17704 | Displays | PS4.4

Pb-Pb ages and Pb initial isotopic composition of lunar meteorites: new constrains on the timing of lunar magmatism and its mantle sources
not presented

Renaud Merle, Alexander Nemchin, Martin Whitehouse, Joshua Snape, Gavin Kenny, Jeremy Bellucci, James Connelly, and Martin Bizzarro

Constraining the duration of magmatic activity on the Moon is essential to understand how the lunar mantle evolved chemically through time. Determining age and initial isotopic compositions of mafic lunar meteorites is a critical step in defining the periods of magmatic activity that occurred during the history of the Moon and to constrain the chemical characteristics of mantle components involved in the sources of the magmas.

We have used the in-situ Pb–Pb SIMS technique to investigate lunar gabbros and basalts, including meteorites from the Northwest Africa (NWA) 773 clan (NWA 2727, NWA 3333, NWA 2977, NWA 773 and NWA 3170), LAP 02224, NWA 4734 and Dhofar 287A. These samples have been selected as they all belong to the dominant chemical group of low-titanium mare basalts and there is no clear agreement on their age. We have obtained ages of 2978 ± 13 Ma for LAP02224, 2981 ± 12 Ma for NWA 4734 and 3208 ± 22 Ma for Dhofar 287. For the NWA 773 clan, four samples (NWA 2727, NWA 773, NWA 2977, NWA 3170) yielded isochron-calculated ages that are identical within uncertainties with an average age of 3086.1 ± 4.8 Ma. The gabbroic sample NWA 3333 yielded an age of 3038 ± 20 Ma suggesting that two distinct magmatic events are recorded in the meteorites of the NWA 773 clan.

The entire age dataset from lunar mafic meteorites was screened to identify data that are problematic from an analytical viewpoint and/or show evidence of resetting and terrestrial contamination. This refined dataset combines the ages of mafic lunar meteorites and Apollo samples and suggests pulses in magmatic activity, with two main phases between 3350 and 3100 Ma and between 3900 and 3550 Ma followed by a minor phase at ~3000 Ma.

The evolution of the Pb initial ratios of the low-Ti mare basalts between 3400 Ma and 3100 Ma suggests that these rocks were progressively contaminated by a KREEP-like component. Nevertheless, the ~3000 Ma mafic rocks (NWA4734 and LAP02224) show significant differences in terms of initial 204Pb/206Pb ratios that illustrates that the lunar mantle is probably more heterogeneous than has previously been assumed.

How to cite: Merle, R., Nemchin, A., Whitehouse, M., Snape, J., Kenny, G., Bellucci, J., Connelly, J., and Bizzarro, M.: Pb-Pb ages and Pb initial isotopic composition of lunar meteorites: new constrains on the timing of lunar magmatism and its mantle sources, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17704, https://doi.org/10.5194/egusphere-egu2020-17704, 2020.

EGU2020-4495 | Displays | PS4.4

Chemical composition of the Moon's 'primary' crust – a clue at a terrestrial origin

Audrey Vorburger, Peter Wurz, Manuel Scherf, Helmut Lammer, André Galli, and Vera Assis Fernandes

The Moon is one of the best characterized objects in space science, yet its origin still actively researched. Available orbital, geophysical, and geochemical information imposes clear restrictions on the origin and evolution of the Earth-Moon system (e.g., Canup 2008, 2012; Ćuk and Stewart 2012; Young et al. 2016). In regard to geochemical constraints, one of the most puzzling conundrums is posed by the similar isotopic fingerprints of the Earth and the Moon (e.g., Wiechert et al. 2001; Armytage et al. 2012; Zhang et al. 2012; Young et al. 2016; Schiller et al. 2018), together with the apparent lunar depletion in volatile elements (e.g., Ringwood and Kesson 1977; Wanke et al. 1977; Albarède et al. 2015; Taylor 2014). This apparent lunar volatile depletion is most notable in the low K content in comparison to U, a finding based on chemical analyses of samples collected from the lunar surface and lunar meteorites, and on spectroscopic observations of the lunar near-surface, despite both having been heavily processed in the past ~ 4.4 billion years.

In the past 4.4 billion years, space has been a harsh environment for our Moon, especially in the beginning, when the young Sun was still very active and the young Moon was continuously bombarded by meteorites of varying sizes. Solar wind and micro-meteoritic interactions with the lunar surface led to rapid and intensive processing of the lunar crust. Hence, the K/U depletion trend observable on today's lunar surface does not necessarily reflect a K/U ratio valid for the Moon in its entirety. We model the evolution of the abundances of the major elements over the past 4.3 to 4.4 billion years to derive the composition of the original lunar crust. Accounting for this processing, our model results show that the original crust is much less depleted in volatiles than the surface observable today, exhibiting a K/U ratio compatible with Earth and the other terrestrial planets, which strengthens the theory of a terrestrial origin for the Moon.

How to cite: Vorburger, A., Wurz, P., Scherf, M., Lammer, H., Galli, A., and Assis Fernandes, V.: Chemical composition of the Moon's 'primary' crust – a clue at a terrestrial origin, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4495, https://doi.org/10.5194/egusphere-egu2020-4495, 2020.

EGU2020-8685 | Displays | PS4.4 | Highlight

Updated Mapping of the Hydrogen Distribution in the Lunar Polar Regions

Anton Sanin, Igor Mitrofanov, Boris Bakhtin, and Maxim Litvak

It is well known that methods of nuclear physics allow one to study distribution of hydrogen-bearing compounds in the upper 1–2 m subsurface soil layer of atmosphereless celestial bodies or planets with thin atmospheres like Mars by measuring neutron spectra leak from the surface. For this study one needs not only to measure neutron spectra but to perform also a set of numerical simulations of the neutron production by the Galactic Cosmic Rays (GCRs) in subsurface soil, leakage of these neutrons from the surface, their transport to the neutron spectrometer on the orbit and processes of neutron interactions with the instrument’s detectors. These simulations make possible a model dependent deconvolution of the measured data to obtain the hydrogen concentration and/or other soil properties at a particular region of the planet.

Currently a number of numerical codes are being used for simulations of the neutron production and transport in planetary applications. All these codes provide a reasonable precision both in modeling of laboratory experiments and nuclear planetology tasks. However, the gravitational field description appropriate for simulation of a neutron propagation on planetary scales is not well addressed. For the planetary scales, it is not just enough to implement a uniform gravitational field (this option is available in some numerical codes). The planetary gravity should be described as a full-scale central force field with its potential depending from the distance from the center of planet.

We have developed a method of accounting effects of lunar gravity force and finite neutron lifetime on the spectral and angular distributions of neutron flux at different altitudes above Moon surface. This method was implemented to reprocess the data gathered by the collimated detectors of LEND instrument operated onboard NASA LRO spacecraft. The gravitational field description appropriate for simulation of a neutron propagation on planetary scales was not well addressed earlier.

As the result of the updated LEND data reprocessing with the discussed method, we obtained a new estimations of Water Equivalent Hydrogen (WEH) abundance in the lunar regolith and new maps of WEH distribution in the lunar polar regions. It is shown that difference of new derived values of WEH is about 0.08 wt% larger in comparison with the previously estimated value. The updated polar maps shows slightly different WEH distribution over the polar regions in comparison to the early published. The new polar maps will be used to select the landing sites of future landers.

How to cite: Sanin, A., Mitrofanov, I., Bakhtin, B., and Litvak, M.: Updated Mapping of the Hydrogen Distribution in the Lunar Polar Regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8685, https://doi.org/10.5194/egusphere-egu2020-8685, 2020.

EGU2020-11545 | Displays | PS4.4

Secondary Volcanically-Induced Lunar Atmosphere and Lunar Volatiles: 3-D Modeling and Analysis

Igor Aleinov, Michael Way, Kostas Tsigaridis, Eric Wolf, Chester Harman, Guillaume Gronoff, and Christopher Hamilton

The fact that the Moon could have a transient secondary atmosphere due to volcanic outgassing has been known for some time, though typically such an atmosphere was believed to be extremely thin (~10-8 bar) [1]. But recent research by Needham and Kring (NK) [2] suggests that during the peak of volcanic activity ~3.5 Ga such a volcanically-outgassed atmosphere could reach ~10-2 bar of surface pressure. In similar research Wilson et al. [3] proposed a more conservative estimate, arguing that the thickness of such an atmosphere would depend on the intervals between major eruptions and may not exceed microbar densities. In either case a collisional atmosphere could be present, which would control transport of outgassed volatiles (such as H2O) and their deposition in polar regions, where they could be preserved until modern day frozen in permanently shadowed regions (PSR) or buried beneath the regolith.

Here we study such a hypothetical atmosphere to investigate its stability, meteorological properties and the effect on transport of volatiles. We use the ROCKE-3D planetary 3-D General Circulation Model (GCM)[4]. The insolation and orbital parameters were set to conditions 3.5 Ga. The atmospheric composition, based on the list of outgassed species presented by NK in combination with our estimates for atmospheric escape, condensation and the results from our 1-D chemistry model, was chosen to be either CO-dominated or CO2-dominated (depending on atmospheric temperature). In this study we restricted ourselves to relatively "thick" lunar atmospheres of 1-10 mb, though we believe that our results will scale to thinner atmospheres as well.

We present the results for ground and atmospheric temperature for modeled atmospheres over a wide parameter space. In particular we consider  different atmospheric compositions (CO or CO2 dominated), a set of atmospheric pressures from 1 mb to 10 mb and a set of obliquities from 0o to 40o. We also present an experiment of a single major eruption [5] and show that in just 3 years ~80% of the outgassed water is deposited in polar regions. This demonstrates the efficiency of such an atmosphere in delivering volatiles. We argue that a secondary lunar atmosphere could play a significant role in forming volatile deposits currently observed in the polar regions of the Moon. 

References:
[1] Stern S. A. (1999) Rev. of Geophysics, 37, 453-492.
[2] Needham D. H. and Kring D. A. (2017) Earth and Planetary Sci. Lett., 478, 175-178.
[3] Wilson L. et al. (2019) LPSC 50, Abstract 1343. 
[4] Way M. J. et al. (2017) ApJS, 231, 12.
[5] Wilson L. and Head J. W. (2018) GRL, 45, 5852-5859.

 

How to cite: Aleinov, I., Way, M., Tsigaridis, K., Wolf, E., Harman, C., Gronoff, G., and Hamilton, C.: Secondary Volcanically-Induced Lunar Atmosphere and Lunar Volatiles: 3-D Modeling and Analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11545, https://doi.org/10.5194/egusphere-egu2020-11545, 2020.

Research on propagation of ELF waves in the ground-ionosphere waveguide has been conducted in order to develop methods for solving inverse problem, which enable measurement of physical parameters of the Marsian ground [1]. It was assumed that the Marsian ground has multi-layer structure with layers characterized by low conductivity. The ELF field penetrates the soil to the depth of several dozen kilometers, that is much more that at Earth. This has a strong impact on dispersive properties of group velocities and attenuation in the waveguide. It is assumed that dust storms and dust devils generate short impulses of ELF field that can propagate over long distances, on the order of megameters. They can be recorded by ELF observation station located on the Marsian surface. The waveforms of these impulses are closely connected with the propagation parameters of the waveguide and should enable identification of ground structure and its components.

Ground contribution to the parameters of the waveguide was examined using analytical solutions in [2]. Its contribution to the propagation of impulses and Schumann resonances on Mars was further studied in [3,4]. Studies presented here show impact of local ground structure on vertical electric dipole radiation in the ground-ionosphere waveguide. Modeling of impulse propagation in the time domain was performed using cylindrical coordinates. Solutions for large distances were corrected using the focusing factor. As approximation of the conductivity profile of ionosphere, a “double-knee” model [5] was used. Computation was performed with space steps dr = 10km, dz = 1 km and time step 1 us. Two examples of two-layer ground with different depth of the first layer (10km and 40km) were implemented. Impact of highly and weakly conducting plate on the radiation of the source was also studied. Validation of the model was based on a well studied analytical solution [3].

 

This work has been supported by the National Science Center under grant 2015/19/B/ST9/01710.

[1] A. Kułak, et al. (2015), Tomography of the Martian ground using inverse solutions for ELF waves generated by dust storms in the ground-ionosphere waveguide, National Science Center, Poland, under grant 2015/19/B/ST9/01710.

[2] A. Kulak, and J. Mlynarczyk (2013), ELF Propagation Parameters for the Ground-Ionosphere Waveguide With Finite Ground Conductivity, IEEE Transactions on Antennas and Propagations, 61, 4, doi: 10.1109/TAP.2012.2227445.

[3] A. Kulak, J. Mlynarczyk, J. Kozakiewicz (2013), An Analytical Model of ELF Radiowave Propagation in Ground-Ionosphere Waveguides With a Multilayered Ground, IEEE Transactions on Antennas and Propagations, 61, 9, 10.1109/TAP.2013.2268244.

[4] J. Kozakiewicz, A. Kułak, J. Młynarczyk (2015), Analytical modeling of Schumann resonance and ELF propagation parameters on Mars with a multi-layered Ground, Planetary and Space Science, 117, 127–135.

[5] O. Pechony, and C. Price (2004), Schumann resonance parameters calculated with a partially uniform knee model on Earth, Venus, Mars, and Titan, Radio Sci., 39, RS5007, doi:10.1029/2004RS003056.

How to cite: Rzonca, P., Kulak, A., and Mlynarczyk, J.: Studying the propagation of ELF waves in the Marsian ground-ionosphere waveguide using an FDTD method with application to the ground tomography, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20696, https://doi.org/10.5194/egusphere-egu2020-20696, 2020.

EGU2020-5003 | Displays | PS4.4

Fluctuation of recent large impact craters rate on Mars from automatic crater detection

Anthony Lagain, Misha Kreslavsky, Gretchen Benedix, David Baratoux, Phil Bland, Martin Towner, Jonathan Paxman, Sylvain Bouley, Chris Norman, Seamus Anderson, Konstantinos Servis, Eleanor Samson, Kevin Chai, and Shiv Meka

Knowledge of collision rates through time and space is essential because meteoritic impact crater counting is the only way to determine the ages of surface geological units and processes on the solid bodies of our Solar System. All chronology models assume a constant size distribution of impactors and an exponential decay of the impact flux between 4 Ga and 2.5 Ga before the present followed by a constant rate over the last 2.5 Ga. These two assumptions are challenged by recent evidence for an increase of the impact flux on the Moon and the Earth and probably on Mars associated with a decoupling between the flux of small and large impactors over the last billion years. Here, using the results of an automatic crater detection algorithm, we investigate the evolution of the rate of formation of large impact craters (Dc ≥ 20km) on Mars and thus infer the evolution of the flux of large impactors (Di > 5km) from the size-frequency distribution of small craters superposed to the ejecta blankets of large ones.

The dating of large impact craters on Mars is limited by several factors such as the degradation of ejecta blankets and the retention rate of small craters superposed to their ejecta. We therefore focused on craters ≥20km in diameter exhibiting an ejecta blanket according to the crater database and located on a latitudinal band between ±35°. We then selected those whom their ejecta are not affected by volcanic/tectonic processes or by the formation of another large nearby impact crater. The final set includes 590 impact craters.

If one can argue the impact flux cannot be fully recorded for the last 4Ga due to resurfacing processes erasing progressively the ejecta blanket and large craters themselves, Hesperian and Noachian terrains within the 35° latitudinal band should nevertheless have retained all D≥20km craters over a portion of the Amazonian period. The CSFD of craters younger than 600Ma (113 craters) superposed to these terrains is consistent with the 600Ma isochron, supporting the fact that the entire population of craters ≥20km formed over the last 600 million years on this portion of the Martian surface has been counted completely. We therefore focused on the analysis of the impact rate evolution over this range of time from this crater sub-sample.

The formation of large impact craters is not homogeneously distributed over the time range investigated here. Our data suggest an inconsistency between the flux used to date each crater and the rate inferred from these datings, thus implying that the small and large body impact fluxes are decoupled from one another. We note also sharp peaks centered around 480, 280 and 100Ma. Preliminary statistical test show that 280Ma peak is marginally significant whereas the two others are too small to be statistically significant. This pattern would be consistent with other independent arguments for increased rate with similar intensity and timing on the Moon and Mars for which the causes are probably collisions and potentially formation of asteroid families within the main asteroid belt.

How to cite: Lagain, A., Kreslavsky, M., Benedix, G., Baratoux, D., Bland, P., Towner, M., Paxman, J., Bouley, S., Norman, C., Anderson, S., Servis, K., Samson, E., Chai, K., and Meka, S.: Fluctuation of recent large impact craters rate on Mars from automatic crater detection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5003, https://doi.org/10.5194/egusphere-egu2020-5003, 2020.

EGU2020-4212 | Displays | PS4.4

New craters on Mars: Air shock wave traces

Boris Ivanov, Gwen Barnes, Ingrid Daubar, Colin Dundas, Alfred McEwen, and Jay Melosh

The idea of visualizing shock wave passage along a dusty (sooty) surface was first proposed and tested by Ernst Mach. High resolution HiRISE images of new impact craters on dusty areas of Mars gave in many cases revealed dark “fresh” halos around craters. In ~7% of cases they have low albedo/color contrasting curved strips near craters referred to as “parabolas” and “scimitars”. We analyze these albedo details as the possible surface footprints of atmospheric shock waves generated during atmospheric passage and shocks from impact cratering by small meteoroids and their fragments. In this approach “parabolas” are the trace of two colliding air shocks propagated from a pair of neighboring craters formed after a meteoroid fragmented during the atmosphere passage. The mechanism of the “scimitar’s” formation is more enigmatic and tentatively could be related to the interaction of the ballistic cone wave and a spherical wave from the point of impact. The study of images is accompanied by numerical modeling of impact of small projectiles at the atmosphere/rock boundary. This modeling constrains the minimum efficiency of an impact to generate the air shock wave in the rarified Martian atmosphere below of 0.1% of the kinetic energy for non-volatile targets. Targets with near surface volatiles could amplificated the air blast (if volatiles are presented in the shocked zone). The study is intended to estimate the air-shock wave parameters along the visible surface traces around impact craters. By constraining shock wave parameters opens new possibilities for investigating the mechanical properties of the Martian surface.
The work is supported by RAS program 12 “Universe Origin and Evolution from Earth-based Observations and Space Missions” (BAI), and a grant from the NASA Mars Data Analysis Program, number 80NSSC18K1368.

How to cite: Ivanov, B., Barnes, G., Daubar, I., Dundas, C., McEwen, A., and Melosh, J.: New craters on Mars: Air shock wave traces, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4212, https://doi.org/10.5194/egusphere-egu2020-4212, 2020.

EGU2020-11528 | Displays | PS4.4 | Highlight

BepiColombo – Status and first Results from Activities during Cruise and the Earth flyby

Johannes Benkhoff, Joe Zender, and Go Murakami

Mercury is a mysterious planet in many ways very different from what scientist were expecting. BepiColombo was launched on 20 October 2018 the BepiColombo from the European spaceport in French Guyana and is now on route to Mercury to unveil Mercury’s secrets. 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. BepiColombo is a joint project between the European Space Agency (ESA) and the Japanese Aerospace Exploration Agency (JAXA) and consists of two orbiters, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). 

The BepiColombo spacecraft is during its 7-year long journey to the innermost terrestrial planet in a so-called ‘stacked’ configuration: The Mio and the MPO are connected to each other, and stacked on-top of the Mercury Transfer Module (MTM). Only in late 2025, the ‘stack’ configuration is abandoned and the individual elements spacecraft are brought in to their final Mercury orbit: 480x1500km for MPO, and 590x11640km for Mio. The foreseen orbits of the MPO and Mio will allow close encounters of the two spacecraft throughout the mission. The mission has been named in honor of Giuseppe (Bepi) Colombo (1920–1984), who was a brilliant Italian mathematician, who made many significant contributions to planetary research and celestial mechanics.

On its way BepiColombo has several opportunities for scientific observations - during the cruise into the inner solar system and during nine flybys (one at Earth, two at Venus and six at Mercury). However, since the spacecraft is in a stacked configuration during the flybys only some of the   instruments on both spacecraft will perform scientific observations. In early April of 2020 BepiColombo will flyby Earth and later in October the first Venus flyby will follow.

A status of the mission and instruments and first results of measurements taken during the Earth flyby and the first year in cruise will be given.

How to cite: Benkhoff, J., Zender, J., and Murakami, G.: BepiColombo – Status and first Results from Activities during Cruise and the Earth flyby , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11528, https://doi.org/10.5194/egusphere-egu2020-11528, 2020.

EGU2020-12235 | Displays | PS4.4

Current status, initial results, and updated plans of BepiColombo/Mio: interplanetary cruise and planetary flybys

Go Murakami, Johannes Benkhoff, and Hajime Hayakawa

The ESA-JAXA joint mission BepiColombo is now on the track to Mercury. Two spacecraft for BepiColombo, "Mio" (Mercury Magnetospheric Orbiter: MMO) and "Bepi" (Mercury Planetary Orbiter: MPO), were successfully launched by Ariane-5 launch vehicle from Kourou in French Guiana on 20 October 2018. Mio is fully dedicated to investigating Mercury’s environment with a complete package of plasma instruments (particles, electric fields, and magnetic fields), a spectral imager of sodium exosphere, and a dust monitor. During the cruise to Mercury, in addition to two spacecraft MMO Sunshield and Interface Structure (MOSIF) and Mercury Transfer Module (MTM) are all integrated together. After the commissioning operations of spacecraft, we are focusing on preparing science operations for interplanetary cruise and planetary flybys. Some science instruments can be used even in the composite spacecraft configuration. The first and second flybys will happen at the Earth in April 2019 and at Venus in October 2019, respectively. In addition, during the interplanetary cruise BepiColombo can contribute to inner heliospheric science by measuring the solar wind and solar energetic particles. Thanks to NASA’s Parker Solar Probe and ESA’s Solar Orbiter, multi-spacecraft observations of the inner heliosphere will soon be possible and provide us deeper knowledge of this region. Here we report the updated status of BepiColombo mission, initial results of the commissioning operations, and the future plans for interplanetary cruise and planetary flybys.

How to cite: Murakami, G., Benkhoff, J., and Hayakawa, H.: Current status, initial results, and updated plans of BepiColombo/Mio: interplanetary cruise and planetary flybys, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12235, https://doi.org/10.5194/egusphere-egu2020-12235, 2020.

EGU2020-10707 | Displays | PS4.4

Solar Wind Measurements from the Planetary Magnetometer Onboard the BepiColombo Spacecraft

Daniel Heyner, Ingo Richter, Ferdinand Plaschke, David Fischer, Johannes Mieth, Hans-Ulrich Auster, and Karl-Heinz Glassmeier

BepiColombo is en-route to Mercury. The boom carrying the planetary magnetometers (MPO-MAG instrument) was deployed in space on 25th of October in 2018. After the deployment, the magnetic disturbances arising from the spacecraft have been greatly decreased. Since the deployment, the fluxgate sensors have been monitoring the magnetic field continuously except for the solar electric propulsion phase. Extensive calibration and data processing activities have since enabled us to greatly decrease spacecraft-generated
disturbances in the magnetic field observations; these activities constitute a key step towards making the data
suitable for scientific analysis. We present a few cases of identified magnetic disturbances, discuss the challenges
they pose, and compare methods to clean the data. We also compare MPO-MAG measurements to observations by the
Advanced Composition Explorer (ACE) solar wind monitor, thereby highlighting the small-scale nature and rapid
evolution of interplanetary magnetic field (IMF) variations. We conclude with an overview of the scientific
goals of the instrument team for the in-orbit mission phase.

How to cite: Heyner, D., Richter, I., Plaschke, F., Fischer, D., Mieth, J., Auster, H.-U., and Glassmeier, K.-H.: Solar Wind Measurements from the Planetary Magnetometer Onboard the BepiColombo Spacecraft, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10707, https://doi.org/10.5194/egusphere-egu2020-10707, 2020.

EGU2020-13932 | Displays | PS4.4

Magnetometer in-flight offset accuracy for the BepiColombo spacecraft

Daniel Schmid, Ferdinand Plaschke, Daniel Heyner, Johannes Z.D. Mieth, Brian J. Anderson, Wolfgang Baumjohann, Ayako Matsuoka, and Yasuhito Narita

Recently ESA and JAXXA launched the two-spacecraft mission BepiColombo to explore the plasma and magnetic field environment of Mercury. Both spacecraft, the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (MMO, also referred to as Mio), are equipped with fluxgate magnetometers, to provide in-situ data for the characterization of the internal magnetic field origin as well as its dynamic interaction with the solar wind. To achieve this goal, accurate magnetic field measurements are thus of crucial importance, which require proper in-flight calibration. In particular the magnetometer offset, which relates relative fluxgate readings into an absolute value, needs to be determined with high accuracy. Usually, the magnetometer offsets are evaluated from Alfvénic fluctuations observed in the pristine solar wind. However, while Mio's orbit will indeed partially reside in the solar wind, MPO will remain within the magnetosphere at most times during the main mission phase. Therefore, we examine an alternative offset determination method, based on the observation of highly compressional fluctuations, the so-called Mirror Mode Method. To evaluate the method performance in the Hermean environment, we analyze four years of MESSENGER magnetometer data, which are calibrated by the Alfvénic fluctuation method, and compare it with the accuracy and error of the offsets determined by the Mirror Mode Method in different plasma environments around Mercury. We show that the Mirror Mode Method yields the same offset estimates and thereby confirms its applicability. Furthermore, we also evaluate the spacecraft observation time within different regions necessary to obtain reliable offset estimates. Although the lowest percentage of strong compressional fluctuations are observed in the solar wind, this region is most suitable for an accurate offset determination with the Mirror Mode Method. 132 hours of solar wind data are sufficient to determine the offset to within 0.5nT, while thousands of hours are necessary to reach this accuracy in the magnetosheath or within the magnetosphere. We conclude that in the solar wind the Mirror Mode Method might be a good complementary approach to the Alfvénic fluctuation method to determine the (spin-axis) offset of the Mio magnetometer. However, although the Mirror Mode Method requires considerably more data within the magnetosphere, it might also be for the MPO magnetometer one of the most valuable tools to determine the offsets accurately.

How to cite: Schmid, D., Plaschke, F., Heyner, D., Mieth, J. Z. D., Anderson, B. J., Baumjohann, W., Matsuoka, A., and Narita, Y.: Magnetometer in-flight offset accuracy for the BepiColombo spacecraft, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13932, https://doi.org/10.5194/egusphere-egu2020-13932, 2020.

EGU2020-13847 | Displays | PS4.4

The effect of a strongly stratified layer in the upper part of Mercury’s core on its magnetic field

Patrick Kolhey, Daniel Heyner, Johannes Wicht, and Karl-Heinz Glassmeier

In the 1970’s the flybys of NASA’s Mariner 10 spacecraft confirmed the existence of an internally generated magnetic field at Mercury. The measurements taken during its flybys already revealed, that Mercury‘s magnetic field is unique along other planetary magnetic fields, since the magnetic dipole moment of ~190 nT ∙ RM3 is very weak, e.g. compared to Earth’s magnetic dipole moment. The following MESSENGER mission from NASA investigated Mercury and its magnetic field more precisely and exposed additional interesting properties about the planet’s magnetic field. The tilt of its dipole component is less than 1°, which indicates a strong alignment of the field along the planet’s rotation axis. Additionally the measurement showed that the magnetic field equator is shifted roughly 0.2 ∙ RM towards north compared to Mercury‘s actual geographic equator.

Since its discovery Mercury‘s magnetic field has puzzled the community and modelling the dynamo process inside the planet’s interior is still a challenging task. Adapting the typical control parameters and the geometry in the models of the geodynamo for Mercury does not lead to the observed field morphology and strength. Therefore new non-Earth-like models were developed over the past decades trying to match Mercury’s peculiar magnetic field. One promising model suggests a stably stratified layer on the upper part of Mercury’s core. Such a layer divides the fluid core in a convecting part and a non-convecting part, where the magnetic field generation is mainly inhibited. As a consequence the magnetic field inside the outer core is damped very efficiently passing through the stably stratified layer by a so-called skin effect. Additionally, the non-axisymmetric parts of the magnetic field are vanishing, too, such that a dipole dominated magnetic is left at the planet’s surface.

In this study we present new direct numerical simulations of the magnetohydrodynamical dynamo problem which include a stably stratified layer on top of the outer core. We explore a wide parameter range, varying mainly the Rayleigh and Ekman number in the model under the aspect of a strong stratification of the stable layer. We show which conditions are necessary to produce a Mercury-like magnetic field and give a inside about the planets interior structure.

How to cite: Kolhey, P., Heyner, D., Wicht, J., and Glassmeier, K.-H.: The effect of a strongly stratified layer in the upper part of Mercury’s core on its magnetic field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13847, https://doi.org/10.5194/egusphere-egu2020-13847, 2020.

EGU2020-18513 | Displays | PS4.4

Asymmetric magnetic anomalies over two young impact craters on Mercury

Valentina Galluzzi, Joana S. Oliveira, Jack Wright, Lon L. Hood, and David A. Rothery

In the last months of its mission, MESSENGER was able to obtain measurements at low altitude (< 120 km). This has made it possible to measure small magnetic field signals, probably of crustal origin (Johnson et al, 2015). Maps of the crust signatures at 40 km altitude were produced by Hood (2016) and Hood et al. (2018), showing that the strongest anomalies are about 14 nT in the Caloris basin. Some of the anomalies are associated with impact craters, and it has been demonstrated that this is not a coincidence (Hood et al., 2018). It is believed that these anomalies are the result of impactor materials rich in magnetic carriers (e.g., metallic iron) that were incorporated on the surface acquiring remanent magnetic fields during the cooling of the material. We intend to analyze whether the anomalies of the crustal field are related to geological characteristics by examining two Hermean craters in order to test this impactor hypothesis. Anomalies associated with Rustaveli and Stieglitz craters are slightly or totally asymmetric with respect to the crater center. The morphology and geological setting of these two fresh impact craters that still maintain a well-preserved ejecta blanket and visible secondary crater chains are investigated to constrain the overall impact dynamics. Both impact angles were likely > 40°. In both cases, slight asymmetries in the morphology and ejecta distribution show that the magnetic anomalies correlate well with the location of impact melt. For the large basin Rustaveli, the melt emplaced SE in the downrange direction, whereas in the case of the smaller crater Stieglitz, downrange direction remains uncertain; in one scenario the melt naturally migrated to the northern topographic lows away from a SW downrange direction, while in the other the downrange direction corresponds to the location of the melt to the north. Rustaveli is associated with a ~5 nT crustal magnetic anomaly centered close to the crater’s midpoint, although offset ~20 km east-southeast. This offset is somewhat consistent with the downrange direction implied by Rustaveli’s impact melt and crater chains distribution. For Stieglitz, all anomalies are offset from the crater’s center. An anomaly larger than 3 nT includes most of the ejecta melt locations towards southwest. The ejecta melt cluster to the north of the crater corresponds to an anomaly of ~5 nT, while the largest anomaly of ~7 nT is found further north and closely corresponds to the crater’s deepest chain, making the second scenario of a N downrange direction more realistic. For both craters, the melt likely recorded the prevailing magnetic field of Mercury after quenching. For Stieglitz, also some solid impactor fragments likely contribute to the anomaly. Hence, both impactors brought magnetic carriers to the surface that could record the past magnetic field of Mercury.


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

References: Hood, J. Geophys. Res. Planets 121, 2016; Hood et al., J. Geophys. Res. Planets 123, 2018; Johnson et al., Science 348, 2015.

How to cite: Galluzzi, V., Oliveira, J. S., Wright, J., Hood, L. L., and Rothery, D. A.: Asymmetric magnetic anomalies over two young impact craters on Mercury, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18513, https://doi.org/10.5194/egusphere-egu2020-18513, 2020.

EGU2020-6542 | Displays | PS4.4

Seasonal variation of Mercury's exosphere deduced from MESSENGER data and simulation study

Yudai Suzuki, Kazuo Yoshioka, Go Murakami, and Ichiro Yoshikawa

Celestial bodies with surface-bound exosphere are valuable because we can directly see the interaction between the bodies and space environment to which they are exposed. This interaction is especially expected to be clearly observed around Mercury. This research aims to clarify the generation process of neutral sodium exosphere, through the comparison between the data from MASCS onboard MESSENGER spacecraft and 3-D model calculation considering generation, transportation and dissipation processes.

First, seasonal variability of the amount of sodium exosphere is analyzed for each local time (LT) using MASCS data. Previous research has shown that the amount of sodium above LT12 reaches a maximum at aphelion, and it is found that this maximum is seen only above LT12. In addition, two hypotheses proposed by the research: the increase in the surface sodium density of the dayside due to fast rotation of terminator, and the expansion of exosphere owing to weaker radiation pressure, were turned out to be inconsistent with seasonal variability above LT06 and the results of test particle calculations.

Following these results, in order to understand the key process of the seasonal variation of the amount of sodium especially around LT12, 3-D sodium exosphere model including release from the surface, transport due to gravity and solar radiation pressure, and dissipation due to ionization caused by solar radiation is constructed. The results from numerical calculation is consistent with the observations by MASCS in terms of the vertical profile and the seasonal variability above LT06 and LT18, but the maximum at aphelion above LT12 could not be reproduced. Then, when the existence of the impact of comet dust stream is assumed as a local and short-term sodium source, the model with impact of 108kg comets per Mercury year could reproduce observations.

Using the model constructed in this study, the sodium distribution which would be observed by MSASI onboard MIO spacecraft is predicted. The comparison between the calculation and observation by MSASI will provide us new insights into the interaction between the celestial bodies and space environment.

In this presentation, we will summarize the results of comparison between observations by MASCS and 3-D Monte Carlo simulation about the seasonal variability of Mercury’s sodium exosphere.

How to cite: Suzuki, Y., Yoshioka, K., Murakami, G., and Yoshikawa, I.: Seasonal variation of Mercury's exosphere deduced from MESSENGER data and simulation study, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6542, https://doi.org/10.5194/egusphere-egu2020-6542, 2020.

EGU2020-18363 | Displays | PS4.4

An independent solution for the precise orbit determination of Mercury planetary orbiter (MPO)

Alireza HosseiniArani, Stefano Bertone, Daniel Arnold, Adrian Jäggi, and Nicolas Thomas

Navigation of deep space probes is most commonly operated using the spacecraft Doppler
tracking technique. Orbital parameters are determined from a series of repeated measurements of the frequency shift of a microwave carrier over a given integration time. This study addresses the work that is done on Doppler orbit determination of MPO - one of the two spacecraft of the European Space Agency’s BepiColombo mission- using Bernese software.

For modelling the orbit of MPO around Mercury, we use a full force model, including Mercury gravity field GGMES-100V07 (up to degree and order 50), solid tides and third body perturbations. We also have an extensive modelling of non-gravitational forces that act on the orbit of spacecraft. This modelling includes the solar radiation pressure and planetary IR and albedo radiation together with a 33-plates macromodel of MPO. We propagate the orbit using this force model. Our simulations of Doppler tracking measurements include 2-way X-band and K-band Doppler measurements, station and planetary eclipses and the relativistic corrections. 

The imperfect knowledge of the non-gravitational forces due to the proximity of Mercury to the Sun, together with the effect of desaturation maneuvers uncertainties, makes the use of the accelerometer necessary. Therefore, in our modelling of the orbit recovery, the models for the non-conservative forces were replaced by the noisy simulated accelerometer measurements. We find out that the modelling of the accelerometer noise has a huge impact on the results of the POD.

We perform several orbit reconstruction tests using daily arcs with noise modulated Doppler data with different settings on the arc lengths, arcs initial conditions, dynamical model, observation mode and orbit determination process and we solve for the initial state vector of each arc. We also run sensitivity analysis with respect to the different accelerometer model. The final goal of this study is to provide an independent solution for the precise orbit determination of Mercury planetary orbiter (MPO) using the planetary extension of the Bernese GNSS software. We present out latest results and then compare our results with the existing ones from the MORE team.

How to cite: HosseiniArani, A., Bertone, S., Arnold, D., Jäggi, A., and Thomas, N.: An independent solution for the precise orbit determination of Mercury planetary orbiter (MPO), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18363, https://doi.org/10.5194/egusphere-egu2020-18363, 2020.

EGU2020-13020 | Displays | PS4.4

Effects of the Solar Wind Conditions on Mercury's Exosphere: Hybrid Simulations

Pavel M. Travnicek, Dave Schriver, Thomas Orlando, and James A. Slavin

How to cite: Travnicek, P. M., Schriver, D., Orlando, T., and Slavin, J. A.: Effects of the Solar Wind Conditions on Mercury's Exosphere: Hybrid Simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13020, https://doi.org/10.5194/egusphere-egu2020-13020, 2020.

EGU2020-13099 | Displays | PS4.4

Deconvolution of Laboratory IR Spectral Reflectance Measurements of Olivine-Pyroxene Mineral Mixtures.

Karin E. Bauch, Iris Weber, Maximilian P. Reitze, Andreas Morlok, Harald Hiesinger, Aleksandra N. Stojic, and Jörn Helbert

The imaging spectrometer MERTIS (Mercury Radiometer and Thermal Infrared Spectrometer) is part of the payload of ESA/JAXA’s BepiColombo mission, launched in 2018 [1,2]. The instrument consists of an IR-spectrometer and radiometer, which will observe the surface in the wavelength range of 7–14µm and 7–40μm, respectively. In preparation of the mission, we are investigating Mercury analog minerals at the IRIS (Infrared and Raman for Interplanetary Spectroscopy) laboratory of the Institut für Planetologie at the Westfälische Wilhelms-Universität Münster. We study typical rock-forming minerals, e.g., pyroxenes, olivines, and feldspars, as well as mineral mixtures.

Here we present results of a deconvolution model used to quantify mineral specific abundances of mineral mixtures [4,5]. Planetary surfaces are composed of a variety of different minerals, therefore the obtained spectral data reflects a mixture of these minerals. In order to quantify the mineral abundances a non-linear unmixing model is necessary. Our model is based on the Hapke reflectance theory [6-8] and is applied to data obtained at the IRIS laboratory [9]. Results of olivine and pyroxene mixtures, as well as grain size mixtures, will be presented at the meeting.

We used olivine (Fo91) from Dreiser Weiher, Germany, and pyroxene (En87) from Bamble, Norway and a range of mineral mixtures for IR measurements. Samples are sieved in grain size fractions of <25µm, 25-63µm, 63-125µm, and 125-250µm. For the mineral mixing analysis presented here, we focus on the 63-125µm fraction, which was also used by [10,11] for further investigations. Samples are analyzed by a Bruker Vertex 70v spectrometer with an A513 variable mirror reflectance stage for various incidence/emergence angles. A total of 512 single channel scans of the sample and the background (diffuse gold standard INFRAGOLD™) were accumulated to ensure a high signal-to-noise ratio.

The pure pyroxene and olivine spectra clearly show characteristic Christiansen features and Reststrahlen bands for all applied geometries and increasing phase angles result in decreased intensities. The reflectance increases from pyroxene and pyroxene-rich mixtures to olivine and olivine-rich mixtures. Moreover, the olivine-rich mixtures exhibit more olivine reflectance features, compared to pyroxene-rich mixtures [11].

Our studies of pyroxene grain size analysis focus on pyroxene mixtures of 50%fine/50%coarse and 30%fine/70%coarse material. Generally, the intensities increase with increasing grain sizes. The transparency feature is evident for small grain sizes and the 50%fine/50%coarse mixture.

At IRIS laboratory, we will further investigate planetary analog material and their mineral mixtures applying various analytical techniques. With these data we are establishing a database that will enable the correct interpretation of MERTIS results.

 

This work has been funded by DLR grant 50 QW 1701 in the framework of the BepiColombo mission.

 

[1] Hiesinger H. et al. (2010) PSS58, 144-165. [2] Benkhoff J. et al. (2010) PSS58, 2-20. [3] Grumpe A. et al (2017) Icarus299, 1-14. [4] Rommel D. et al. (2017) Icarus284, 126-149. [5] Hapke B. (1981), JGR86(B4), 3039-3054. [6] Hapke B. (2002), Icarus157, 523-534. [7] Hapke B. (2012), 2ndCambr. Univ. Press., NY. [8] Bauch, K.E. et al. (2019) LPSC L, Abstract#2521. [9] Weber I. et al. (2019) LPSC L, Abstract#2326. [10] Weber, I. et al. (2020) LPSC LI, Abstract#1889.

How to cite: Bauch, K. E., Weber, I., Reitze, M. P., Morlok, A., Hiesinger, H., Stojic, A. N., and Helbert, J.: Deconvolution of Laboratory IR Spectral Reflectance Measurements of Olivine-Pyroxene Mineral Mixtures., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13099, https://doi.org/10.5194/egusphere-egu2020-13099, 2020.

EGU2020-733 | Displays | PS4.4

Geological mapping of an interesting lunar site: Tsiolkovskiy crater

Gloria Tognon, Riccardo Pozzobon, and Matteo Massironi

Tsiolkovskiy is a 180 km diameter late Imbrian crater located at 20.4° S, 129.1° E on the far side of the Moon [Whitford-Stark & Hawke, 1982].

Compared to the extensive mare deposits present of the lunar side facing the Earth, Tsiolkovskiy crater represents one of the few basaltic exposures on the far side [Pieters & Tompkins, 1999]. Along with its particularly dark and smooth crater floor, the impact crater is also characterized by a morphologically well-shaped central peak on which has been detected both olivine [Corley et al., 2018] and PAN [Ohtake et al., 2009; Lemelin et al., 2015].

The area represents thus a potential scientific site of interest for a safe landing. The production of geological maps aiming at characterize Tsiolkovskiy crater will allow the definition of interesting locations for rover exploration.

A geomorphological mapping of the crater has been performed using the ~100m/pixel LRO-WAC [Robinson et al., 2010] global mosaic along with the ~59m/pixel LRO-LOLA and Kaguya TC DEM merge which has a vertical resolution of 3-4m [Barker et al., 2016]. The mapping defined six units corresponding to the well-recognizable central peak and the texturally different smooth and hummocky materials constituting the crater floor units, and by scarps with slopes >40°, isolated ponds of smooth material discernible from the rough material constituting the crater rim and constituting the crater walls units.

The geomorphological mapping has then been coupled with a spectral characterization of Tsiolkovskiy crater performed on the basis of the ~200m/pixel Clementine UVVIS false color composite (Red 750/415nm; Green 750/1000nm; Blue 415/740nm) [Lucey et al., 2000]. The spectral mapping allowed to discriminate different units characterized by different origin and composition. In particular, the morphologically smooth crater floor unit is composed by fresher basalts and basaltic soils, the steep scarps and the central peak units are mostly composed by norites, troctolites and anorthosites, while the remaining smooth ponds, crater rim and the hummocky crater floor units are generally composed by mature highland soils.

In order to define landing ellipses and broad traverses for a rover exploration of the site, the geological mapping is also been supported by an ongoing high-resolution mapping of a quarter of Tsiolkovskiy crater by means of a mosaic of ~0.5m/pixel LRO-NAC [Robinson et al., 2010] images here scaled to 3m/pixel.

Finally, a radar investigation for the presence of deep structures will be performed to possibly detect lava pile emplacements and voids in the crater subsoil.

Acknowledgments

This research was supported by the European Union’s Horizon 2020 under grant agreement No 776276-PLANMAP.

References

Whitford-Stark, J.L. & Hawke, B.R., XXXIII LPSC, pp. 861-862, 1982Barker, M.K. et al., Icarus, Vol. 273, pp. 346-355, 2016

Pieters, C.M. & Tompkins, S., JGR, Vol. 104, pp. 21935-21949, 1999

Corley, L.M. et al., Icarus, Vol. 300, pp. 287-304, 2018

Ohtake, M. et al., Nature, Vol. 461, pp. 236-241, 2009

Lemelin, M. et al., JGR: Planets, Vol. 120, pp. 869-8878, 2015

Robinson, M.S. et al., Space Sci. Rev., Vol. 150, pp. 81–124, 2010

Barker, M.K., et al., Icarus, Vol. 273, pp. 346-355, 2016

Lucey, P.G. et al., JGR, Vol. 105, pp. 20377-20386, 2000

How to cite: Tognon, G., Pozzobon, R., and Massironi, M.: Geological mapping of an interesting lunar site: Tsiolkovskiy crater, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-733, https://doi.org/10.5194/egusphere-egu2020-733, 2020.

EGU2020-20201 | Displays | PS4.4

Mineralogical and morphological characterization of a suspected lunar silicic construct: The Wolf crater

Himela Moitra, Sumit Pathak, Mamta Chauhan, Saibal Gupta, and Satadru Bhattacharya

The Wolf crater is an irregularly shaped crater situated within the central part of Mare Nubium in the southern hemisphere on the lunar near side (16.573°W, 22.904°S). With an approximate diameter of about 25 km, this crater has been recently suspected to be a lunar silicic construct, hinting at a felsic composition that is more silicic than pure, immature anorthite. These suspicions have mainly been triggered by the high thorium anomaly in this region, and Christiansen Feature (CF) and Concavity Index (CI) mapping using Diviner multispectral data from the Lunar Reconnaissance Orbiter (LRO) mission. Many areas in the Wolf crater show CF values lower than 7.84 µm (CF for pure, immature anorthite). This study adopts a more holistic approach by studying the mineralogical composition and morphology of this crater complex using Moon Mineralogy Mapper (M3) data for mineralogical analysis and LROC WAC (wide angle camera) and NAC (narrow angle camera) data for morphological analysis. The whole complex can be divided into two parts- highland massif and mare basalt regions. CSFD analyses show that the outer part of the massif is older than the mare basalt, whereas the inner part have relatively younger surfaces. Analysis of the M3 data reveals the presence of pyroxene exposures on the massif as well as the mare basalt. However, their compositions are distinctly different, the massif pyroxenes being low-Ca pyroxene while the mare pyroxenes are High-Ca pyroxenes in composition. It can be inferred that the pyroxene exposures on the massif are not related to any ejecta deposits from the mare basalts. The highly silicic compositions implied by the CF and CI maps are limited to only certain parts of the massif, indicating a compositional heterogeneity in the massif region as well. Morphologically, the highland massif shows an extremely knobby structure which surrounds the mare basalt in a topographically depressed central part. The massif is discontinuous and the mare-highland boundary is very irregular, suggesting that the central depression is not of an impact-related origin. Extensional deformation features near the mare-highland boundaries also support this. In some parts, dome like features can be identified, with fresh rock fragments being visible on the surface. The rock fragments seem to be of two different tones- one very bright tone, and another comparatively darker tone. These rock fragments cannot be related to any nearby cratering activity, and they seem to be embedded in their locations. Pyroclastic deposits can also be identified around some of these domes, by their characteristic low albedo and smooth appearance. Overall, the Wolf crater complex shows signatures of non-mare volcanic activity and can be of non-impact related volcanic origin.

How to cite: Moitra, H., Pathak, S., Chauhan, M., Gupta, S., and Bhattacharya, S.: Mineralogical and morphological characterization of a suspected lunar silicic construct: The Wolf crater, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20201, https://doi.org/10.5194/egusphere-egu2020-20201, 2020.

EGU2020-10248 | Displays | PS4.4

Impact-induced crustal dichotomy on Mars: from SPH to long-term mantle convection models

Kar Wai Cheng, Antoine B. Rozel, Harry Ballantyne, Martin Jutzi, Gregor J. Golabek, and Paul J. Tackley

The formation process of the crustal dichotomy of Mars has remained elusive since its discovery more than three decades ago.  Workers put forward different theories including (i) an endogenic origin, where the dichotomy is formed by degree-1 mantle convection [1, 2]; (ii) an exothermic origin, where the northern crust is excavated by an impact [3]; and (iii) a hybrid origin, where an impact generated large amounts of melt, followed by crust production shaping the crustal dichotomy [4]. 

In this study we focus on the last hypothesis. Our previous results using a parameterized impact show that a dichotomy can be formed in this manner.  In order to confirm whether these results still hold when using a realistic impact, and to consider the most probable impact angles and velocities, a SPH code [5] is used to model both the impact itself and the first 24 hours of post-impact evolution. The result is then transferred into mantle convection code StagYY [6] in order to simulate the long-term evolution of both crust and mantle for 4.5 Gyrs.  Due to the different physical nature and assumptions between the SPH impact models and long-term mantle convection models, care in data treatment is required when coupling the two simulations.  In this study, different setups regarding the transfer of data are tested and explored, including the treatment of temperature profiles, the choice of density and viscosity of materials, and the time of transfer.

Preliminary results from coupled SPH-geodynamics evolution models are presented, involving the crust thickness and topography maps after 4.5 Gyrs of evolution.

 

[1] Roberts, J., & Zhong, S. (2006). Degree-1 convection in the Martian mantle and the origin of the hemispheric dichotomy. Journal Of Geophysical Research, 111(E6).

[2] Keller, T., & Tackley, P. (2009). Towards self-consistent modeling of the martian dichotomy: The influence of one- ridge convection on crustal thickness distribution. Icarus, 202(2), 429-443.

[3] Andrews-Hanna, J., Zuber, M., & Banerdt, W. (2008). The Borealis basin and the origin of the martian crustal dichotomy. Nature, 453(7199), 1212-1215.

[4] Golabek, G., Keller, T., Gerya, T., Zhu, G., Tackley, P., & Connolly, J. (2011). Origin of the martian dichotomy and Tharsis from a giant impact causing massive magmatism. Icarus, 215(1), 346-357.

[5] Emsenhuber, A., Jutzi, M., Benz, W. (2018). SPH calculations of Mars-scale collisions: The role of the equation of state, material rheologies, and numerical effects. Icarus, 301, 247-257

[6] Tackley, P. (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.

How to cite: Cheng, K. W., Rozel, A. B., Ballantyne, H., Jutzi, M., Golabek, G. J., and Tackley, P. J.: Impact-induced crustal dichotomy on Mars: from SPH to long-term mantle convection models, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10248, https://doi.org/10.5194/egusphere-egu2020-10248, 2020.

EGU2020-22354 | Displays | PS4.4

Equation of state of the [Fe,Ni]3Si system at conditions relevant to small terrestrial planets

Andrew Jamieson, Lidunka Vočadlo, and Ian Wood

The detailed composition of terrestrial planetary cores is still unknown. The nature of the ‘light element’ alloying with Fe-Ni in planetary cores can affect a large range of properties, such as its melting temperature and the stable crystal structures it exhibits. While geophysical and geodetic parameters of a planet can provide first order information, mineral physics can also be used to investigate the compositional space.

We present ab initio simulations on the [Fe,Ni]3Si system (at ~7wt% and 14wt% Ni) to determine stable crystal structures and thermoelastic properties at PT conditions relevant to smaller terrestrial planets (central pressure <45 GPa). This will allow for comparisons to be made to any future seismic profile of Mars (from InSight or otherwise), and other research on the [Fe,Ni]3[Si,S] system. The overall aim to produce a compositional model for the core of Mars and place it in the context of the evolution of planetary cores, including the state and structure of Mars’ core.

How to cite: Jamieson, A., Vočadlo, L., and Wood, I.: Equation of state of the [Fe,Ni]3Si system at conditions relevant to small terrestrial planets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22354, https://doi.org/10.5194/egusphere-egu2020-22354, 2020.

EGU2020-16875 | Displays | PS4.4

Determining the Thermal Inertia of the UTPS-TB simulant for different grain sizes and densities

Bernadett Pál, Hideaki Miyamoto, Takafumi Niihara, Naoya Sakatani, Amiko Takano, and Ákos Kereszturi

The Martian moons, Phobos and Deimos are exciting new targets for future in-situ, and possibly future human explorations. The mission of JAXA, Martian Moons eXplorer (MMX), is scheduled to launch in 2024 to perform observations of both moons, landing on one of them. How the landing modules should be designed depends greatly on the surface conditions, thus studying the surface of Phobos (the likely candidate for landing) is highly important. The exact composition of the regolith covering the surface of the moon is still under debate; but even with the chemical compositions and size distributions of the grains established, numerous mechanical properties remain problematic to estimate. The thermal inertia of the regolith determines the amount of heat the soil can store, as well as how quickly the heat is reradiated. It is also possible to estimate the particle diameter and porosity of the regolith, if thermal inertia is measured, however, the Hayabusa2 and OSIRIS-REx missions showed that the actual grain sizes can vary greatly. In our study we work with the Tagish Lake-based simulant developed at the University of Tokyo (UTPS-TB). Using a thermostatic chamber and a vacuum chamber at the ISAS/JAXA laboratory in Sagamihara, we measure and calculate the thermal inertia of UTPS-TB samples with different grain sizes and densities. This work was supported by the by Campus Mundi short scientific research programme, and the ÚNKP-19-3 New National Excellence Program of the Ministry for Innovation and Technology. 

How to cite: Pál, B., Miyamoto, H., Niihara, T., Sakatani, N., Takano, A., and Kereszturi, Á.: Determining the Thermal Inertia of the UTPS-TB simulant for different grain sizes and densities, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-16875, https://doi.org/10.5194/egusphere-egu2020-16875, 2020.

PS5.1 – Ice Giant System Exploration

EGU2020-10443 | Displays | PS5.1

Monitoring Neptune's atmosphere with a combination of small and large telescopes

Ricardo Hueso, Imke de Pater, Amy Simon, Mike Wong, Larry Sromovsky, Erin Redwing, Erandi Chavez, Agustín Sánchez-Lavega, Vik Dhillon, Patrick Fry, Stuart Littlefair, Joshua Tollefson, Marc Delcroix, Iñaki Ordonez-Etxeberria, Peio Iñurrigarro, Jorge Hernández-Bernal, Santiago Pérez-Hoyos, Jose Félix Rojas, and Tom Marsh

Neptune’s atmosphere is covered by tropospheric clouds and elevated hazes that are highly contrasted in hydrogen and methane absorption bands that dominate the red and near-infrared spectrum of the planet. The major cloud systems observed in these wavelengths evolve in time-scales of days, months and years. However, the differential rotation of the atmosphere, and the vertical wind shear implied by the motion of some of these systems, result in challenges in identifying common cloud systems observed in images obtained with a time difference of only a few weeks. Given the small apparent size of Neptune’s disk (2.3 arc sec at best) there are outstanding difficulties in obtaining sufficient high-resolution data to trace Neptune’s atmospheric dynamics and study the variability in the atmosphere.

In 2019 Neptune has been observed by a battery of different large telescopes and techniques including: Adaptive Optics observations from the Keck, Lick and other telescopes, observations from Hubble Space Telescope in two different dates, and lucky-imaging observations with the GranTeCan 10.4m, Calar Alto 2.2m and the 1.05m Pic du Midi telescope. In addition, some ground-based observers using small telescopes of 30-40 cm have been successful to image Neptune’s major clouds completing a dense time-line of observations. We will present comparative results of Neptune’s major cloud systems observed with these facilities at a variety of spatial resolutions and long-term drift rates of some of these cloud systems. These will be compared with similar multi-telescope results obtained in the past with several of these telescopes since 2015. Future punctual observations achievable with new observational facilities such as the JWST will benefit from ground-based coordinated campaigns and will require a combination of several telescopes to understand drift rates and evolutionary time-lines of major cloud systems in Neptune.

How to cite: Hueso, R., de Pater, I., Simon, A., Wong, M., Sromovsky, L., Redwing, E., Chavez, E., Sánchez-Lavega, A., Dhillon, V., Fry, P., Littlefair, S., Tollefson, J., Delcroix, M., Ordonez-Etxeberria, I., Iñurrigarro, P., Hernández-Bernal, J., Pérez-Hoyos, S., Rojas, J. F., and Marsh, T.: Monitoring Neptune's atmosphere with a combination of small and large telescopes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10443, https://doi.org/10.5194/egusphere-egu2020-10443, 2020.

EGU2020-4492 | Displays | PS5.1

Chemical and Isotopic Composition Measurements on Atmospheric Probes for Giant Planets

Peter Wurz, Audrey Vorburger, Hunter Waite, and Olivier Mousis

The ice giants Uranus and Neptune are the least understood class of planets in our solar system but the most frequently observed type of exoplanets. Unfortunately, no designated mission to either of the two ice giants exists so far. Almost all of our gathered information on these planets comes from remote sensing. Whereas information provided by remote sensing is undoubtedly highly valuable, remote sensing of a planet's atmosphere also has limitations. In recent years, NASA and ESA have started planing for future missions to Uranus and Neptune, with both agencies focusing their attention on orbiters and atmospheric probes. A mass spectrometer experiment is a favored science instrument for an atmospheric probe for in situ composition measurements in most of these studies. Mass spectrometric measurements can provide unique scientific data, i.e., sensitive and quantitative measurements of the chemical composition of the atmosphere, including isotopic, elemental, and molecular abundances. Of major interest for the formation and evolution process of our Solar System are the species including the major volatiles CH4, CO, NH3, N2; the noble gases He, Ne, Ar, Kr, Xe; and the isotopic ratios D/H,13C/12C, 15N/14N, 3He/4He, 20Ne/22Ne, 38Ar/36Ar, 36Ar/40Ar, as well as those of Kr and Xe. We will review the state-of-the-art mass spectrometry with respect to an application on such an atmospheric probe.  

How to cite: Wurz, P., Vorburger, A., Waite, H., and Mousis, O.: Chemical and Isotopic Composition Measurements on Atmospheric Probes for Giant Planets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4492, https://doi.org/10.5194/egusphere-egu2020-4492, 2020.

EGU2020-2024 | Displays | PS5.1

Quadrupole Ion Trap Mass Spectrometer for ice giant atmospheres exploration

Jurij Simcic, Dragan Nikolic, Anton Belousov, David Atkinson, and Stojan Madzunkov

To date a variety of different types of Mass Spectrometers has been utilized on missions to study the composition of atmospheres of many solar system bodies including Venus, Mars, Jupiter, Titan, the moon and several comets. For in-situ exploration of ice giant atmospheres, the highest priority composition measurements are helium and the other noble gases, noble gas isotopes, and other key isotopes including 3He/4He and D/H. Other important but lower priority composition measurements include abundances of volatiles C, N, S, and P, isotopes 13C/12C, 15N/14N, 18O/17O/16O and disequilibrium species PH3, CO, AsH3, GeH4, and SiH4. Required measurement accuracies are largely defined by the accuracies achieved by the Galileo (Jupiter) probe Neutral Mass Spectrometer and Helium Abundance Detectors, and current measurement accuracies of solar abundances[1].

The Jet Propulsion Laboratory’s Quadrupole Ion Trap Mass Spectrometer (QITMS)[2] is a compact, wireless instrument with a mass of only 7.5 kg, designed to meet these requirements and challenges specific to the planetary probe missions. It is currently the smallest flight MS available, capable of making measurements of all required constituents in the mass range 1-600Da, with a sensitivity of up to 1013 counts/mbar/sec and resolution of m/∆m=12000 at 40Da.

During a fly-by or a descent mission, the time available to perform an in-situ measurement is usually short. This makes it challenging to measure the abundances of minor constituents for which long integration times are needed. Mass spectrometers largely employ a non-discriminatory electron impact ionization of sampled gas mixtures for creating ions, which means the probability to create and trap ion fragments of trace species is very low and further destabilized by space charge effects due to an excessive number of ions from dominant species. A selective resonant ejection technique was employed to lower the amount of major constituent species, while keeping the minor constituents intact, which resulted in higher accuracy measurements of minor species.

Another inherent challenge of planetary entry probe mass spectrometers is the introduction of material to be sampled into the instrument interior, which operates at vacuum. Atmospheric entry probe mass spectrometers typically require a specially designed sample inlet system, which ideally provides highly choked, nearly constant mass-flow intake over a large range of ambient pressures. An ice giant descent probe would have to operate over a range of atmospheric pressures covering 2 or more orders of magnitude, 100 mb to 10+ bars, in an atmospheric layer of ~120 km at Neptune to ~150 km at Uranus. The QITMS features a novel MEMS based inlet system driven by a piezo-electric actuator that continuously regulates gas flow at inlet pressures of up to 100 bar.

In this paper, we present an overview of the QITMS capabilities including instrument design and characteristics of the inlet system, as well as the most recent results from laboratory measurements in different modes of operation.

[1] Mousis, O., et al., Pl. Sp. Sci., 155 12–40, 2018.

[2] Madzunkov, S.M., Nikolic, D., J. Am. Soc. Mass Spectrom. 25(11), 2014.

How to cite: Simcic, J., Nikolic, D., Belousov, A., Atkinson, D., and Madzunkov, S.: Quadrupole Ion Trap Mass Spectrometer for ice giant atmospheres exploration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2024, https://doi.org/10.5194/egusphere-egu2020-2024, 2020.

EGU2020-3495 | Displays | PS5.1

The LONSCAPE instrument, a Light Optical Nephelometer Sizer and Counter for Aerosols in Planetary Environments

Jean-Baptiste Renard, Olivier Mousis, Gwenaël Berthet, Jean-Michel Geffrin, Anny-Chantal Levasseur-Regourd, Pascal Rannou, and Nicolas Verdier

            Liquid and solid particles are present in the atmosphere of many Solar System objects. Measuring aerosol properties can provide major constraints about both atmospheric composition and dynamics. While some bulk aerosol properties can be estimated using remote measurements, the size distributions and the typologies of the aerosols, which are related to their formation process, their origin and their evolution, are often poorly known. We propose a new concept of optical instrument dedicated to in situ measurements of aerosols as part of the science payload of an atmospheric entry probe or of a surface module. It relies the Earth atmospheric light aerosol counter LOAC used since 2013 under various types of balloons. This instrument measures the aerosol concentrations in 19 size classes between 0.2 and 50 micrometers, and estimates their typology

            The LONSCAPE (Light Optical Nephelometer Counter Sizer and Counter for Aerosols in Planetary Environments) concept combines counter measurements and nephelometric measurements at several phase angles, particle by particle, to retrieve for all size classes the concentrations and the scattering functions. This approach is the novelty of the instrument concept. The scattering functions can be compared to results of theoretical calculations but also to laboratory databases obtained for levitating particles and from the microwave analogy technics, to retrieve the refractive indices of the liquid and solid particles to better identify their nature and origin. Up to 10 angles measurements for the scattering function and one angle measurement for the counting provide an optimal configuration to distinguish between liquid, icy and possibly solid particles in the Uranus or Neptune atmosphere. Such an instrument must be able to detect up to tens of particles greater than 0.1 micrometer within 1 cm3.

            For ice giants, the instrument must work for pressures up to 10 bars. No pumping system should be needed since the aerosols will be injected in the optical chamber by an inlet parallel to the descent motion of the probe under parachutes. Considering the relative velocity between the atmosphere and the probe, the electronics must be able to detect particles crossing the laser beam up to several tens of m/s, which can be done by “conventional” electronics. Preliminary studies show that the instrument could have a total mass of about 2 kg and an electric consumption of about 2W.

How to cite: Renard, J.-B., Mousis, O., Berthet, G., Geffrin, J.-M., Levasseur-Regourd, A.-C., Rannou, P., and Verdier, N.: The LONSCAPE instrument, a Light Optical Nephelometer Sizer and Counter for Aerosols in Planetary Environments, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3495, https://doi.org/10.5194/egusphere-egu2020-3495, 2020.

EGU2020-11891 | Displays | PS5.1

Accessible Latitudes for Planetary Entry Probe Missions to Saturn, Uranus or Neptune

Alena Probst, Linda Spilker, Tom Spilker, David Atkinson, Olivier Mousis, Mark Hofstadter, and Amy Simon

In-situ probe measurements of planetary atmospheres add an immense value to remote sensing observations from orbiting spacecraft or telescopes, as highlighted and justified in numerous publications [1,2,3]. Certain key measurements such as the determination of noble gas abundances and isotope ratios can only be made in situ by atmospheric entry probes, but represent essential knowledge for investigating the formation history of the solar system as well as the formation and evolutionary processes of planetary atmospheres. Following the above rationale, a planetary entry mission to one of the outer planets (Saturn, Uranus and Neptune) has been identified as a mission of high priority by international space agencies. In particular, an entry probe mission proposal to Neptune has been selected as a flagship mission study in the next NASA decadal survey.

Within the scientific frame of atmospheric planetary sciences, a two- to three-year research study called IPED (Impact of the Probe Entry Zone on the Trajectory and Probe Design) investigates the impact of the interplanetary and approach trajectories on the feasible range of atmospheric entry sites as well as the probe design, considering Saturn, Uranus and Neptune as target bodies. The objective is to provide a decision matrix for entry site selection by comparing several mission scenarios for different science cases.

In this presentation, the focus is on approach circumstances of the planetary entry probe upon arrival at a normalized, spherical planet. Science objectives are organised in four (planetocentric) latitude ranges: (1) low latitudes < 15°, (2) mid latitudes between 15° and 45°, (3) high latitudes between 45° and 75° and (4) polar latitudes of > 75°. The latitude ranges are considered as potential entry zones for the implementation. The implementation strategy will be explained and discussed. Astrodynamically accessible latitudes are presented as a function of the approach velocity  vector v(both declination of the approach asymptote and magnitude). A roadmap is shown that explains the next implementation step to include the physical characteristics of the destination planet such as the planet’s size, rotation period, shape, ring geometries and obliquity.

The presented research was supported by an appointment to the NASA Postdoctoral Program (NPP) at the Jet Propulsion Laboratory (JPL), California Institute of Technology, administered by Universities Space Research Association (USRA) under contract with National Aeronautics and Space Association (NASA). © 2020 All rights reserved.

[1] Mousis, O. et al., Scientific Rationale for Saturn’s in situ exploration, Planetary and Space Science 104 (2014) 29-47.

[2] Mousis, O. et al., Scientific Rationale for Uranus and Neptune in situ explorations, Planetary and Space Science 155 (2018) 12-40.

[3] Hofstadter, M. et al., Uranus and Neptune missions: A study in advance of the next planetary science decadal survey, Planetary and Space Science 177 (2019) 104680.

How to cite: Probst, A., Spilker, L., Spilker, T., Atkinson, D., Mousis, O., Hofstadter, M., and Simon, A.: Accessible Latitudes for Planetary Entry Probe Missions to Saturn, Uranus or Neptune, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11891, https://doi.org/10.5194/egusphere-egu2020-11891, 2020.

The REASON ground penetrating radar (GPR) on Europa Clipper and the RIME GPR on JUICE will produce radargrams for Europa to determine the nature and depth of the ice overlying a putative ocean. The REASON radar is dual frequency, 9 MHz and 60 MHz, and the RIME frequency is 9 MHz. The surface temperature of Europa is between 50 and 100 Kelvin. At 9 MHz, the REASON GPR could map relative permittivity to about 30 km with a resolution of 150 m. These two GPRs may be able to spot pockets of water within the ice shell that could serve as a passageway for chemicals between the surface and the ocean below. The upper ice crust is expected to contain magnesium and sodium sulfates, and perhaps calcium sulfate [J. Moore, 1999].

To fill this gap in knowledge about the properties of the ice crust on Europa, we will make laboratory measurements of the relative permittivity (complex dielectric coefficient using impedance spectroscopy) and thermal properties (thermal conductivity and specific heat) of ice-salt mixtures at 9 and 60 MHz, over the temperature range 50 to 100 Kelvin, for the ice-salt mixtures given in Table X. This Table was provided by Kevin Collins (UCF). We do not plan to include any dust content in these ice-salt mixtures. These laboratory data may assist in the interpretation of future radargrams from RESSON and RIME

 

   TABLE 1, Europan ice-salt specimens for electrical and thermal property measurements.

Experiment NumberSalt SpeciesSalt Concentration (wt. %)Physical Texture1Sulfuric acid hydrate5Dispersed in particulate ice2Magnesium sulfate5Dispersed in particulate ice3Magnesium chloride5Dispersed in particulate ice4Sodium chloride5Dispersed in particulate ice5Magnesium sulfate1Dispersed in particulate ice6Magnesium sulfate10Dispersed in particulate ice7Magnesium sulfate25Dispersed in particulate ice8Magnesium sulfate + sulfuric acid hydrate5 (each)Dispersed in particulate ice9Magnesium sulfate5Solid block10Magnesium sulfate5Layered structure

 

We are planning also to make similar measurements of the electrical and thermal properties of ice on Titania (moon of Uramus), over temperature range of 60 to 90 Kelvin, and at 9 MHz. The surface of Titania is mainly water ice, with some frozen carbon dioxide and possibly salts. We will devise a table of salt-ice mixtures that is appropriate for Titania, based on available information on surface content.

How to cite: Frampton, R.: Icy Moon Ice-Salt Measurements for Dielectric and Thermal Properties, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12460, https://doi.org/10.5194/egusphere-egu2020-12460, 2020.

EGU2020-11828 | Displays | PS5.1

Aerothermal Modeling Challenges for Ice Giant Entry Probes

Michael Wright, Louis Walpot, Brett Cruden, Aaron Brandis, and Chris Johnston

In June 2017, NASA published the Ice Giants Pre-Decadal Survey Mission Study Report which took a fresh look at science priorities and mission concepts for missions to the Uranus and Neptune systems. In addition to science objectives, the team explored the state of required technologies for remote and in-situ science exploration. Notably, three of the four mission architectures considered in the study included an atmospheric probe. More recently, interest has grown within ESA for outer planet exploration. In support of this objective, ESA has performed two CFD studies (January & July 2019) which analyzed the feasibility of stand-alone elements (orbiter and probes) provided by ESA as a part of a NASA led mission to the Uranus or Neptune systems. The first study was carried out by ESA experts with active participation of NASA/JPL. ESA highlighted the necessity to deepen the knowledge characterizing the aerothermal environment of the probes.

 

Entry environments for the NASA study were estimated using an aeroheating correlation that was calibrated to data returned from the Galileo probe entry to Jupiter. For the ESA concept study, aeroheating estimates were made using correlations employed during the design of the Galileo probe. Importantly, these correlations show large discrepancies in predicted total aeroheating (in some cases more than 100%), largely due to differences in the predicted radiative heat load. The magnitude of the disagreement is disconcerting in and of itself, but the problem is made worse by the fact that both correlations are being extrapolated from the extreme Galileo entry conditions to the (relatively) more benign Uranus and Neptune entry. It is likely that neither correlation is providing an accurate assessment of the true aeroheating loads at this time. Given that current NASA predictions are near the limits of existing TPS test capability, and that ESA predictions are more severe, improving the accuracy and associated margins of the prediction is critical to better assess mission feasibility.

 

Recent work in NASA by Cruden (AIAA Paper No. 2015-0380) and Erb (AIAA Paper No. 2019-3360) have substantially improved our fundamental understanding of aerothermodynamics in Hydrogen-Helium atmospheres. Similar work is planned in ESA as well. However, these recent data have not been incorporated into updated design models for Outer Planet probes. In addition, this work does not address the problem of trace atmospheric constituents (such as Methane) that are known to be present in Ice Giant atmospheres and may substantially alter the resulting shock layer radiation signal by providing a ready source of free electrons to initiate excitation processes. The proposed presentation will review the current status of aerothermal modeling for Ice Giant entries and propose a path forward to reduce key uncertainties and enable optimized thermal protection system designs.

How to cite: Wright, M., Walpot, L., Cruden, B., Brandis, A., and Johnston, C.: Aerothermal Modeling Challenges for Ice Giant Entry Probes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11828, https://doi.org/10.5194/egusphere-egu2020-11828, 2020.

EGU2020-1146 | Displays | PS5.1 | Highlight

Modelling the dielectric properties of the geyser deposited snow layer on Enceladus

Pia Friend, Alexander Kyriacou, and Klaus Helbing

Saturn’s icy moon Enceladus is with its roughly 500 km diameter a differentiated geological active body that harbours a liquid ocean between its rocky core and icy mantle. This ocean is among the most promising places to host extraterrestrial life in our solar system.

At Enceladus’ south pole terrain, active geysers form a passage from the ocean to the surface; erupting ice, dust and gas particles. Most of those particles escape the moon’s gravity, but some portion falls back to the surface. Considering the current output, about 10 m of snow gets sedimented at a distance of about 100 m away from the geyseres within 105-106 years. Hence, depending on the timescale the geysers are active at the same location, the snow layer would have a thickness of some km already, assuming no densification.

A first model of the density profile of the snow layer as a function of the ice/vacuum ratio will be provided at the conference. To investigate the density at the surface, mainly the distribution of the ice grain shapes and the grain sizes have to be considered and put into a state equation. For modelling the density change in respect to the depth, also the pressure from the overlying weight has to be accounted for. As temperatures at Enceladus’ surface are too low, neither sintering nor processes such as melting and re-freezing can thereby contribute to densification. These processes however are acting in terrestrial glaciers. We propose therefore, because the temperatures on Enceladus are far below the melting point of ice, to consider the ice grains on Enceladus rather as sand than as snow in respect to these materials on Earth, when modelling the density within the snow layer.

After obtaining the ratio between ice and vacuum, it is possible to define the dielectric properties of the snow layer. The dielectric profile in turn is the primary diagnostic property for radar based geophysical investigation. It determines the velocity of radio waves in a medium as well as their reflection and refraction at interfaces.
Because of the above mentioned possibility that primitive extraterrestrial life might exist in Enceladus’  hidden ocean, there will likely be future space missions with the aim to reach a water reservoir and probe it. A well-defined density profile could then help to radar navigate a melting probe through the ice.

 

How to cite: Friend, P., Kyriacou, A., and Helbing, K.: Modelling the dielectric properties of the geyser deposited snow layer on Enceladus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1146, https://doi.org/10.5194/egusphere-egu2020-1146, 2020.

EGU2020-6131 | Displays | PS5.1

The chemical composition of impact craters on Titan

Anezina Solomonidou, Catherine Neish, Athena Coustenis, Michael Malaska, Alice Le Gall, Rosaly Lopes, Nico Altobelli, Olivier Witasse, Kenneth Lawrence, Ashley Schoenfeld, Christos Matsoukas, Ioannis Baziotis, Bernard Schmitt, and Pierre Drossart

We investigate nine Titan impact craters using Visual and Infrared Mapping Spectrometer (VIMS) data and a radiative transfer code (RT) [e.g. 1] in addition to emissivity data, in order to constrain the spectral behavior and composition of the craters. Past studies have looked at the chemical composition of impact craters either by using qualitative comparisons between craters [e.g. 2;3] or by combining all craters into a single unit [4], rather than separating them by geographic location or degradation state. Here, we use a radiative transfer model to first estimate the atmospheric contribution to the data, then extract the surface albedos of the impact crater subunits, and finally constrain their composition by using a library of candidate Titan materials. Following the general characterization of the impact craters, we study two impact crater subunits, the ‘crater floor’, which refers to the bottom of a crater, and the ‘ejecta blanket’, which is the material thrown out of the crater during an impact event. The results show that Titan’s mid-latitude plain craters: Afekan, Soi, and Forseti, in addition to Sinlap and Menrva are enriched in an OH-bearing constituent (likely water-ice) in an organic based mixture, while the equatorial dune craters: Selk, Ksa, Guabonito, and Santorini, appear to be purely composed of organic material (mainly unknown dune dark material). This follows the pattern seen in [4], where midlatitude alluvial fans, undifferentiated plains, and labyrinths were found to consist of a tholin-like and water-ice mixture, while the equatorial undifferentiated plains, hummocky terrains, dunes, and variable plains were found to consist of a dark material and tholin-like mixture in their very top layers. These observations also agree with the evolution scenario proposed by [3], wherein the impact cratering process produces a mixture of organic material and water ice, which is later “cleaned” through fluvial erosion in the midlatitude plains; a cleaning process that does not appear to operate in the equatorial dunes, which seem to be quickly covered by a thin layer of sand sediment. This scenario agrees with other works that suggest that atmospheric deposition is similar in the low-latitudes and midlatitudes on Titan, but with more rain falling onto the higher latitudes causing additional processing of materials in those regions [e.g. 5]. In either case, it appears that active processes are working to shape the surface of Titan, and it remains a dynamic world in the present day.

[1] Hirtzig, M., et al. (2013). Icarus, 226, 470–486; [2] Neish, C.D., et al. (2015), Geophys. Res. Lett. 42, 3746–3754; [3] Werynski, A., et al. (2019), Icarus, 321, 508-521; [4] Solomonidou, A., et al. (2018), J. Geophys. Res, 123, 2, 489-507; [5] Neish, A.C., et al. (2016), Icarus, 270, 114–129.


How to cite: Solomonidou, A., Neish, C., Coustenis, A., Malaska, M., Le Gall, A., Lopes, R., Altobelli, N., Witasse, O., Lawrence, K., Schoenfeld, A., Matsoukas, C., Baziotis, I., Schmitt, B., and Drossart, P.: The chemical composition of impact craters on Titan, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6131, https://doi.org/10.5194/egusphere-egu2020-6131, 2020.

EGU2020-6150 | Displays | PS5.1

Gravity constraints on the interior structure of Europa

Isamu Matsuyama and Antony Trinh

We assess the gravity constraints on the interior structure of Europa in anticipation of the Europa Clipper mission.

Moore and Schubert (2000) illustrated that the diurnal tide amplitude, quantified by the diurnal (tidal) Love numbers, k2d and h2d, can be used to determine the presence of a subsurface liquid ocean due to the significant increase in tidal amplitudes associated with the mechanical decoupling of the shell with a subsurface ocean.  However, they considered a limited range of possible interior parameters except the ice shell rigidity, which was assumed to be in the range of 1-10 GPa. We consider a wider range of possible interior structure parameters and a more realistic ice shell rigidity range of 1-4 GPa. Inferring the presence of a subsurface ocean is slightly easier than previously thought (Verma & Margot 2018), with required absolute precisions of 0.08 for k2d , and 0.44 for h2d .

Previous work have considered diurnal (tidal) gravity constraints alone or static gravity constraints alone using a forward modeling approach (e.g.  Anderson et al., 1998; Moore and Schubert, 2000; Wahr et al., 2006). We evaluate constraints on interior structure parameters using Bayesian inversion with the mass, static gravity, and diurnal gravity as constraints, allowing a probabilistic view of Europa's interior structure. Given the same relative uncertainties, the static Love numbers provide stronger constraints on the interior structure relative to those from the mean moment of inertia (MOI). Additionally, the static Love numbers can be inferred directly from the static gravity field whereas inferring the MOI requires the Radau-Darwin approximation.

Jointly considered with the static shape, the static gravity field can constrain the average and long-wavelength thickness of the shell. For an isostatically compensated shell, it is usual to conceptualize the crust as a series of independently floating columns of equal cross-sectional area which, by application of Archimedes' principle, should have equal mass above the depth of compensation. However, this approach is unphysical in the presence of curvature and self-gravitation. We consider alternative prescriptions of Airy isostasy: the equal-pressure prescription (Hemingway and Matsuyama, 2017), and the minimum-stress prescription (Dahlen 1982; Beuthe et al., 2016; Trinh et al., 2019).  The gravitational coefficients are more sensitive to shell thickness than would be expected from the classical (equal-mass) approach, illustrating that the equal-mass prescription can lead to large errors in the inferred average shell thickness and its lateral variations.

Diurnal gravity data alone can only constrain the product of the shell rigidity and thickness (Moore and Schubert, 2000; Wahr et al., 2006). An additional observational constraint that is sensitive to these parameters is the libration amplitude, which can be obtained from direct imaging or from altimeter data. We show that a joint gravity and libration analysis is able to separately constrain the shell thickness and rigidity.

How to cite: Matsuyama, I. and Trinh, A.: Gravity constraints on the interior structure of Europa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6150, https://doi.org/10.5194/egusphere-egu2020-6150, 2020.

EGU2020-10146 | Displays | PS5.1

Development of a three-dimensional global circulation model for Uranus

Orkun Temel and Özgür Karatekin

In this study, we present the Uranus implementation of the planetWRF model [1]. For the determination of the radiative heat fluxes in our three-dimensional global circulation model, we make use of a simple analytic radiative model. This model is based on two-stream approximation and using a power-law scaling for the relationship between the optical depth and the pressure [2]. Preliminary results are compared to the zonal wind [3] and vertical temperature observations [4]. The effect of model's resolution, both vertical and horizontal, on the representation of the strong zonal transport in the Uranian atmosphere, is investigated. Moreover, we discuss the seasonal wind speed variations predicted by our model, assessing its potential to predict the changes in the zonal transport before and after the equinox in 2007. Possible implications for the Entry, Descent, and Landing applications are also presented. The devleoped GCM can also be potentially applied to the atmosphere of Neptune. 


[1] Richardson, Mark I., Anthony D. Toigo, and Claire E. Newman. "PlanetWRF: A general purpose, local to global numerical model for planetary atmospheric and climate dynamics." Journal of Geophysical Research: Planets 112.E9 (2007).
[2] Robinson, Tyler D., and David C. Catling. "An analytic radiative-convective model for planetary atmospheres." The Astrophysical Journal 757.1 (2012): 104.
[3] L.A. Sromovsky, I. de Pater, P.M. Fry, H.B. Hammel, P. Marcus, High S/N Keck and Gemini AO imaging of Uranus during 2012–2014: new cloud patterns, increasing activity, and improved wind measurements. Icarus 258, 192–223 (2015).
[4] Marley, Mark S., and Christopher P. McKay. "Thermal structure of Uranus' atmosphere." Icarus 138.2 (1999): 268-286.

How to cite: Temel, O. and Karatekin, Ö.: Development of a three-dimensional global circulation model for Uranus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10146, https://doi.org/10.5194/egusphere-egu2020-10146, 2020.

EGU2020-10500 | Displays | PS5.1

Laboratory experiments in support of the Dragonfly space mission : Simulation of the photochemical aging process of benzene-containing clouds in Titan's stratosphere

Julie Mouzay, Isabelle Couturier-Tamburelli, Nathalie Pietri, Grégoire Danger, and Thierry Chiavassa

Context: After more than thirteen years of exploration, Cassini-Huygens space mission provided a large amount of data about the atmosphere of Saturn’s largest moon, Titan. It is the only satellite in the solar system to house such a diversified chemistry triggered by the dissociation of N2and CH4under the action of different sources of energy (electrons, ions, solar photons, …)1that reach the highest atmospheric layer. It results in the formation of complex carbon and nitrogen-based molecules. At lower altitudes, depending on temperature profile and saturation vapor pressures variations, these same compounds condense, thereby forming icy clouds in the stratosphere. In particular, between 2013 and 2017, two distinct benzene-containing clouds have been identified by the Cassini Composite Infrared Spectrometer for the first time during the mission, at the south pole at high stratospheric altitudes that are crossed by long-UV solar photons (λ>230nm). For the highest cloud located below 300km, the spectral signature of icy benzene is mixed with the ones of other molecules unassigned yet2. The second cloud detected around 250km of altitude3, comes from a more complex process consisting in the simultaneous condensation of benzene with hydrogen cyanide. Thereafter in the mission, a significant warming-up in the stratosphere was reported, contributing to the sublimation of these same ices photo-processed.

 

Aim: Laboratory experiments have demonstrated that stratospheric ices evolve photo-chemically under long-UV solar photons and contribute to the formation of polymeric materials and volatile photo-products that will subsequently sediment at the surface. This work has been realized in the context of the preparation of the future Dragonfly space mission dedicated to analyze the organic layer that recovers the surface of Titan. We have chosen to simulate experimentally the photochemical aging process undergone by these benzene-containing icy clouds to characterize the chemical composition of the polymers photo-produced - to determine if their spectroscopic signature can match the one of the stratospheric aerosols layer observed by VIMS instrument - as well as the nature of the volatile photo-products released during the warming-up of the stratosphere. To do so, we irradiated pure benzene (C6H6) and hydrogen cyanide (HCN) ices, first isolated and then condensed simultaneously, with a high-pressure vapor mercury lamp (λ>230nm) - energetic conditions similar to Titan’s stratospheric ones - in a high vacuum chamber. This experimental set-upis designed to characterize the solid phase via in situ FT-IR spectroscopy and the volatile photo-products by a GC-MS instrument.

 

References :

  1. Waite, J. H. et al. Science 316, 870–875 (2007).
  2. Vinatier, S. et al. Icarus (2017) doi:10.1016/j.icarus.2017.12.040.
  3. Anderson, C. et al. in vol. 49 304.10 (2017).
  4. Abou Mrad, N., Duvernay, F., Theulé, P., Chiavassa, T. & Danger, G. Anal. Chem. 86, 8391–8399 (2014).

How to cite: Mouzay, J., Couturier-Tamburelli, I., Pietri, N., Danger, G., and Chiavassa, T.: Laboratory experiments in support of the Dragonfly space mission : Simulation of the photochemical aging process of benzene-containing clouds in Titan's stratosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10500, https://doi.org/10.5194/egusphere-egu2020-10500, 2020.

EGU2020-5263 | Displays | PS5.1 | Highlight

Key Atmospheric Signatures for Identifying the Source Reservoirs of Volatiles in Uranus and Neptune

Olivier Mousis, Artyom Aguichine, David H. Atkinson, Sushil K. Atreya, Thibault Cavalié, Jonathan I. Lunine, Kathy E. Mandt, and Thomas Ronnet

We investigate the enrichment patterns of several delivery scenarios of the volatiles to the atmospheres of ice giants, having in mind that the only well constrained determination made remotely, i.e. the carbon abundance measurement, suggests that their envelopes possess highly supersolar metallicities, i.e. close to two orders of magnitude above that of the PSN. In the framework of the core accretion model, only the delivery of volatiles in solid forms (amorphous ice, clathrates, pure condensates) to these planets can account for the apparent supersolar metallicity of their envelopes. In contrast, because of the inward drift of icy particles through various snowlines, all mechanisms invoking the delivery of volatiles in vapor forms predict subsolar abundances in the envelopes of Uranus and Neptune. Alternatively, even if the gravitational instability mechanism remains questionable in our solar system, it might be consistent with the supersolar metallicities observed in Uranus and Neptune, assuming the two planets suffered subsequent erosion of their H-He envelopes. Because current technologies do not enable entry probes to reach levels deeper than a few dozens of bars in the atmospheres of giant planets, subsequent probe measurements should focus on the determination of the abundances of the noble gases since these latter never condense in the envelopes of Uranus and Neptune and are expected to be well mixed, even in the top layers at the ~1-bar level. Because these species are highly sensitive to the considered mechanism of volatiles delivery, they should be considered in the top priority of the measurements to be made by an ice giant entry probe.

How to cite: Mousis, O., Aguichine, A., Atkinson, D. H., Atreya, S. K., Cavalié, T., Lunine, J. I., Mandt, K. E., and Ronnet, T.: Key Atmospheric Signatures for Identifying the Source Reservoirs of Volatiles in Uranus and Neptune, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5263, https://doi.org/10.5194/egusphere-egu2020-5263, 2020.

The Galileo Probe was designed to measure the abundances of the heavy elements (mass >helium) and helium in Jupiter since they are key to understanding the planet’s formation and heat balance. Broadly speaking, the same formation scenarios presumably apply also to the Icy Giant Planets (IGP), Uranus and Neptune, so the determination of their heavy elements and He is equally important. We will show that the bulk of C, N, S, and O are sequestered in condensible volatiles whose well-mixed regions in the atmospheres of the IGP’s are extremely deep compared to Jupiter. That poses formidable challenges to their direct in situ measurements. On the other hand, being non-condensible and chemically inert, the noble gases − He, Ne, Ar, Kr and Xe – are expected to be uniformly mixed all over the planet, unlike the condensibles whose distribution is governed by dynamics, convection and purported deep oceans. Thus the noble gases would provide the most critical set of data for constraining the IGP formation models. Although the noble gases should be well-mixed everywhere below the homopause, measurements at and below the 1-bar level are needed considering their low mixing ratios, except for He. That depth also gets around any potential cold trapping of the heavy noble gases at the tropopause or adsorption on methane ice aerosols. Entry probes deployed to relatively shallow pressure levels of 5-10 bars would allow a robust determination of the abundances and isotopic ratios of the noble gases, amongst other things. A measurement of CO from orbit, along with other disequilibrium species has the potential of estimating the O/H ratio. Microwave radiometry from orbiter and the Earth have the potential of measuring the depth profiles of NH3 and H2O, which would be important for understanding the atmospheric dynamics and weather in the deep atmosphere. Combined with the above data and the data on the interior and the magnetic field, the probe results on the noble gases would provide essential constraints to the formation, migration and evolution models of the Icy Giant Planets. 

How to cite: Atreya, S. K., Mousis, O., and Reh, K. R.: Synergistic Probe-Orbiter Science and Measurements for Understanding the Formation and Evolution of the Icy Giant Planets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2232, https://doi.org/10.5194/egusphere-egu2020-2232, 2020.

EGU2020-2410 | Displays | PS5.1 | Highlight

Science Payload for Ice Giant Entry Probes

David H. Atkinson, Olivier Mousis, and Thomas R. Spilker

To discern the origin and evolution of the solar system including the formation of the terrestrial planets, an understanding of giant planet formation and evolution is needed. Among the most important measurements are the atmospheric composition, structure, and processes of the ice giant. Noble gas abundances in particular are diagnostic of the conditions under which the giant planets formed, and the abundances of cloud-forming (condensable) species are indicators of both the characteristics of the protosolar nebula at the time and location of planetary formation as well as the mechanisms by which additional heavy elements might have been delivered to the planets. Although many key properties of ice giant systems can be accessed by remote observations from flyby and orbiting spacecraft, measurements of the abundances of the noble gas and key isotopes as well as deeper thermal structure, dynamics, clouds, and other atmospheric processes require direct in situ exploration by an atmospheric entry probe.


Entry probe measurements can be classified as either Tier 1 or Tier 2. Tier 1 represents the minimum, threshold science required to justify the probe mission. Tier 2 is high value science that would complement and enhance the Tier 1 measurements, but alone are not enough to justify the entry probe mission.


Tier 1 measurements include atmospheric abundances of noble gases (including helium), key noble gas isotope ratios 22Ne/20Ne, 36Ar/38Ar, 129Xe/total Xe, 131Xe/total Xe, and 132Xe/total Xe, additional key isotopic ratios D/H, 3He/4He, and 15N/14N, and the atmospheric thermal structure along the probe descent trajectory. To achieve the Tier 1 measurements, the probe payload must include a mass spectrometer, a helium abundance detector, and an atmospheric structure instrument including pressure and temperature sensors and an atmospheric acoustic properties sensor for speed of sound measurements from which the ratio of ortho- to para- molecular hydrogen can be determined. Depending on mission architecture and probe-carrier telecom design, Tier 1 science can be achieved with a relatively shallow probe descending to several bars.


Tier 2 science includes additional key isotopic ratios such as 13C/12C and 18O/17O/16O, abundance of condensables, and additional atmospheric structure and processes including the dynamics of the atmosphere (winds and waves), the net balance of upwelling thermal infrared and downwelling solar visible radiative fluxes, and the location, structure, composition and properties of the clouds. The presence of the disequilibrium species such as PH3, CO, AsH3, GeH4, and SiH4 is primarily due to atmospheric convective upwelling, and abundance measurements would help constrain both the composition of the very deep atmosphere and deep atmosphere chemistries. Additional instrumentation necessary to fully achieve the Tier 2 objectives includes a net flux radiometer, a Nephelometer, and an ultrastable oscillator (USO) as part of the telecommunications system to enable probe Doppler tracking for measurements of atmospheric dynamics.


To address all the Tier 1 and Tier 2 science objectives, a deep probe to 10 bars and beyond would provide measurements of atmospheric thermal structure, dynamics, and processes at levels beyond the direct influence of sunlight that are out of reach of remote sensing.

How to cite: Atkinson, D. H., Mousis, O., and Spilker, T. R.: Science Payload for Ice Giant Entry Probes, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2410, https://doi.org/10.5194/egusphere-egu2020-2410, 2020.

EGU2020-12733 | Displays | PS5.1

Tidal-librational dissipation within volcanic and cryovolcanic worlds

Antony Trinh and Isamu Matsuyama

Tidal dissipation is thought to power volcanism or cryovolcanism on a number of moons, most notably Io and Enceladus. The amount and distribution of tidal heating within the moon are however still misunderstood, and intricately related to surface observations like heat flow and distribution of volcanic activity. From an extensive benchmark between a set of numerical and semi-analytical models, we show that, in the presence of a subsurface (magma or water) ocean, librations (i.e. spin rate variations) along the orbit trigger additional deformation mechanisms, enhancing the amount of dissipation compared to traditional tidal dissipation (by at least 25% for Enceladus), and affecting the distribution of dissipation within the moon. We illustrate these mechanisms with numerous animations, and identify librational loading as the most relevant process.

How to cite: Trinh, A. and Matsuyama, I.: Tidal-librational dissipation within volcanic and cryovolcanic worlds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12733, https://doi.org/10.5194/egusphere-egu2020-12733, 2020.

EGU2020-18372 | Displays | PS5.1

The Origin of Saturn’s Rings Revisited

Luis Teodoro, Paul Estrada, Jacob Kegerreis, Jeff Cuzzi, Vincent Eke, and Matija Cuk

A set of key observations over the Cassini spacecraft's tenure has constrained Saturn's rings' age to be less than a few 100 Myr effectively ruling out currently accepted ring origin scenarios, all of which require that the rings are ancient or primordial. We propose a new scenario motivated from evidence of a comparably recent dynamical instability ~100 Myr ago which would have led to collisions between Saturn's pre-existing mid-size icy moons, opening the door to possible ring formation during that epoch. Successfully testing this scenario requires better  understanding of collisional outcomes. Toward that end, we introduce a new suite of simulations modeling impacts between Saturn's icy moons using the next generation smoothed hydrodynamical and gravity code SWIFT. The unprecedented spatial resolution achieved in these simulations (108.5 particles within the simulation box) allows us to depict the myriad of gravitationally bound objects formed during icy moon collisions which may afterwards evolve both thermally and dynamically to re-accrete or collide with other bodies. Our unprecedented high resolution further allows us to determine a size distribution of fragments which can be used to inform crater impact distributions on newly accreted or remaining moons.

 

How to cite: Teodoro, L., Estrada, P., Kegerreis, J., Cuzzi, J., Eke, V., and Cuk, M.: The Origin of Saturn’s Rings Revisited, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18372, https://doi.org/10.5194/egusphere-egu2020-18372, 2020.

EGU2020-18541 | Displays | PS5.1

Activity of Enceladus and proto-Enceladus

Leszek Czechowski

Introduction: Enceladus, a satellite of Saturn, is the smallest celestial body in the Solar System where endogenic activity is observed. Since its accretion, Enceladus has lost about 20% of its mass.  This is the base of hypothesis about proto-Enceladus [1, 2]. It means that this satellite should be treated as new type of the celestial body, the body that is losing its mass as a result of internal activity.

 

Present activity:  Activity of Enceladus is concentrated in the South Polar Terrain (SPT). The mass of matter ejected into space by volcanic activity of Enceladus is 200 kg s-1 [e.g. 1, 2, 3].  We have suggested that this mass loss is a main driving mechanism of the present Enceladus’ tectonics [1, 2]. Usually the loss of matter from the body’s interior (or thermal contraction) lead to global compression of the crust. Typical effects of compression are: thrust faults, folding and subduction [5]. However, such forms are not dominant on Enceladus. We proposed tectonic model that could explain this paradox [1, 2, 5].

 

Proto-Enceladus: Just after the accretion, Enceladus could be substantially larger. Its radius was ~300 km. We  refer here this body as proto-Enceladus [2]. Two assumptions could be used for calculation of the size of proto-Enceladus. Both approaches give similar results [2]. Note also possible biological role of proto-Enceladus [6].

 

Past activity: There are some traces of past activity on the surface of Enceladus [4]. The traces could be interpreted as indication that the past activity was similar to the present one (similar features like ‘tiger stripes’), but we do not know how old are these traces.   

 

Model of activity: We found some places where signs of the past activity are observed. However, we need a better model of this activity. The only known type of activity is the center in SPT. Are other forms of activity possible? We uses numerical model to find these other possible forms. Preliminary results indicate some possibility of smaller centers. Calculations indicate also that that the activity could be periodic.

 

Future activity center: We suggested that ovoid-shaped depression down to 2 km deep, of size 200×140 km with the centre at 200E, 15S is a good candidate for the future center [5]. However, our recent calculations using numerical model are presently inconclusive.

 

Acknowledgements: The research is partly supported by BST funds of the University of Warsaw. We are grateful also to the ICM.

 

References

[1] Czechowski, L. (2014)  EGU 2014, Vienna.

[2] Czechowski, L. (2014) Planet. Sp. Sc. 104, 185-199

[3] Kargel, J.S. (2006) Science 311, 1389–1391.

 [4] Spencer, J. R., et al. (2009), Enceladus: An Active Cryovolcanic Satellite, in: M.K. Dougherty et al. (eds.), Saturn from Cassini-Huygens, Springer, Sciencep. 683.

[5] L. Czechowski (2017) Presented in EPSC 2017.

[6] L. Czechowski (2018) Geological Quarterly 62, 1, 172-180.

How to cite: Czechowski, L.: Activity of Enceladus and proto-Enceladus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18541, https://doi.org/10.5194/egusphere-egu2020-18541, 2020.

EGU2020-18970 | Displays | PS5.1

Compositional heterogeneity amongst salt-rich grains emitted from Enceladus’ subsurface ocean

Zenghui Zou, Frank Postberg, Jon Hillier, Nozair Khawaja, Fabian Klenner, and Lenz Nölle

Salt-rich icy particles within Saturn’s E-Ring are relatively young (<~200 years), and originate from frozen aerosolized droplets of the salty seawater of Enceladus’ subsurface ocean, ejected into space, through fractures in the moon’s south polar region, within a plume of gas and ice particles. The salt-rich grains are therefore believed to reflect the composition of the ocean water. In situ mass spectra of the plume and E-ring icy particles, obtained by the Cosmic Dust Analyzer (CDA) impact ionization mass spectrometer onboard the Cassini spacecraft, indicate significant compositional diversity within the salt-rich population. Understanding the compositions of dissolved salts within the grains, and thus the ocean, can provide important constraints for geochemical models of Enceladus’ core/ocean environment.

To investigate and quantify variations in grain composition, a Laser Induced Liquid Beam Ion Desorption (LILBID) technique has been used to desorb and ionize a wide range of Enceladean ocean-like solutions containing dissolved salts. The resulting ions were then measured by a reflectron-type time of flight mass spectrometer. As the laser desorption mechanism simulates the ice grain impact process occurring on the CDA target, spectra produced in the laboratory from a large range of well-characterized salt solutions can be used to determine the CDA-applicable spectral appearances of substances within the ice grains emitted from Enceladus’ ocean.

Here we present the results of an investigation of CDA E-ring spectra, supported by laboratory analogue experiments, which show significant compositional heterogeneity within the salt-rich grains originating from Enceladus’ subsurface ocean. Two main spectral subtypes, representing endmember compositions within the salt-rich grains, are identified. These mass spectra are dominated by features from chloride-rich or carbonate-rich compounds and the laboratory detectability of other, additional, compounds within these brines is discussed.

How to cite: Zou, Z., Postberg, F., Hillier, J., Khawaja, N., Klenner, F., and Nölle, L.: Compositional heterogeneity amongst salt-rich grains emitted from Enceladus’ subsurface ocean, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18970, https://doi.org/10.5194/egusphere-egu2020-18970, 2020.

EGU2020-21273 | Displays | PS5.1

Stability of the subsurface ocean of Pluto

Jun Kimura and Shunichi Kamata

We explore the long-term evolution of Pluto’s subsurface ocean in the absence of an insulating clathrate hydrate layer. Numerical simulations of the thermal history of the interior are performed using a 1D model assuming Pluto was initially differentiated into an outer hydrosphere (H2O shell) and an inner rocky core. We consider two endmember initial conditions: the hydrosphere was either entirely molten or frozen. We also consider different radiogenic heating rates, core sizes, ice reference viscosities, and ammonia concentrations. Our results indicate that the present-day Pluto can possess a subsurface ocean if the ice shell is purely conductive or only weakly convective. Our results also indicate that the initial state affects only little on the evolution scenario. These results strengthen previous conclusions obtained based on thermal evolution studies with limited calculation conditions. The thickness of the present-day ocean can be up to ~130 km, depending on the radiogenic heating rate and ice reference viscosity. The reference viscosity of ice required to maintain an ocean until today for the case of a CI chondritic core is approximately an order of magnitude higher than that for the case of an ordinary chondritic core. We also find that a thick subsurface ocean can be maintained until relatively recently for a dense small core case, which allows the formation of high-pressure ice at the seafloor. An inclusion of ammonia in the ocean increases the possibility of the current presence of a subsurface ocean even in the case of 1 wt% NH3 at the initial.

How to cite: Kimura, J. and Kamata, S.: Stability of the subsurface ocean of Pluto, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21273, https://doi.org/10.5194/egusphere-egu2020-21273, 2020.

EGU2020-6977 | Displays | PS5.1

Cosmic ray ionization of Ice Giant atmospheres

Karen Aplin, Tom Nordheim, James Sinclair, and Jamie Jasinski

Galactic cosmic rays (GCRs) represent a major ionization source in planetary atmospheres, particularly within deeper layers that are largely unaffected by solar UV and charged particle precipitation. When GCR particles undergo inelastic collisions with atmospheric nuclei they create large numbers of secondary interactions, resulting in extensive nuclear and electromagnetic particle cascades. In thick atmospheres, such as those of the giant planets, these cascades can develop much more extensively than what is the case on Mars and Earth. Furthermore, GCRs are strongly modulated by the heliosphere, and therefore GCR fluxes are significantly higher at the Ice Giants than in the inner Solar System. Intriguingly, observations of Uranus and Neptune show brightness variations that appear to be associated with known variability in the background GCR flux (Aplin and Harrison 2016;2017).

Using a full 3D Monte Carlo particle physics code, we have carried out the first detailed study of cosmic ray ionization within the atmospheres of Uranus and Neptune. We will show preliminary results of this study and discuss the possible importance of GCR ionization to atmospheric chemistry and atmospheric electricity. We will also discuss GCR shielding by the planetary magnetic fields of Uranus and Neptune, and what effect this has on predicted GCR ionization rates at different locations. 

References

Aplin K.L. and Harrison R.G. (2016), Determining solar effects in Neptune's atmosphere, Nature Communications, 7, 11976 doi:10.1038/ncomms11976

Aplin K.L. and Harrison R.G (2017), Solar-driven variability in the atmosphere of Uranus, Geophys. Res. Letts. 44, doi: 10.1002/2017GL07374

How to cite: Aplin, K., Nordheim, T., Sinclair, J., and Jasinski, J.: Cosmic ray ionization of Ice Giant atmospheres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6977, https://doi.org/10.5194/egusphere-egu2020-6977, 2020.

EGU2020-22682 | Displays | PS5.1

The Icy Giants & Triton’s Ionospheres – lessons learned from Cassini observations within Saturn’s and Titan’s ionospheres

Jan-Erik Wahlund, Michiko W. Morooka, David Andrews, Mats André, Jan Bergman, Niklas Edberg, Anders I. Eriksson, Lina Hadid, Yuri Khotyaintsev, Andris Vaivads, and Erik Vigren

We discuss the importance to determine the structure and composition of the upper atmospheres and ionospheres of the Icy Giants (Uranus & Neptune) as well as Triton’s ionosphere in the light of numerous recently obtained Cassini results. The ionizing radiation and charging environment within the upper atmospheres of Saturn and Titan creates a very complex organic chemistry leading to charged sub-nm-sized to 100 nm-sized aerosols. The charged dust has a profound effect on the ionospheric structure and related chemistry, enhancing the ion number density well above photochemical equilibrium levels, while the electrons tend to become attached to the dust population. The organic chemistry leads to compounds reaching above 50,000 amu diffusing downward and possibly creating a pre-biotic chemistry. This process, involving nitrogen, methane and water may very well be a more general process, also applicable for the cases of Uranus, Neptune and Triton, were all have these starting species abundant in their upper atmospheres. We therefore propose that a future mission to the Ice Giants and the moon Triton has Langmuir probe, electron spectrometer, dust, ion- and neutral mass spectrometers onboard to make detailed in-situ measurements on both the orbiter and atmospheric probe in order to investigate this fundamental chemistry and aerosol formation.

How to cite: Wahlund, J.-E., Morooka, M. W., Andrews, D., André, M., Bergman, J., Edberg, N., Eriksson, A. I., Hadid, L., Khotyaintsev, Y., Vaivads, A., and Vigren, E.: The Icy Giants & Triton’s Ionospheres – lessons learned from Cassini observations within Saturn’s and Titan’s ionospheres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22682, https://doi.org/10.5194/egusphere-egu2020-22682, 2020.

PS5.2 – Jupiter and Saturn: Results from Juno and Cassini

EGU2020-11829 | Displays | PS5.2

The innermost ion radiation belts of Jupiter and Saturn

Peter Kollmann, Barry Mauk, George Clark, Chris Paranicas, Quentin Nenon, Yuri Shprits, Nikita Aseev, Rob W. Ebert, Thomas Kim, Elias Roussos, Dennis Haggerty, Abi M. Rymer, Angelica Sicard, and John E. P. Connerney

The ion radiation belts just above the surface of the giant planets Jupiter and Saturn have recently been observed for the first time with Juno and Cassini. The relevant physical processes differ from Earth’s inner proton belt. Jupiter’s innermost ion belt consists of protons, oxygen, and sulfur ions. A comparison of Juno particle and plasma data with numerical modeling supports that these ions are occasionally transported from the magnetosphere across the main ring of Jupiter. It has been suggested earlier that this ring is populated through the stripping of energetic neutral atoms that are produced in the magnetosphere. This process is found to be too slow to populate the belt. After radial transport, the new ions lose energy in the tenuous ring halo inward of the main ring. This gives rise to an unusual spectral shape that rises from 100keV to 1MeV. Neutralization of the ions in the ring grains acts slower and eventually removes <100keV ions until the next transport across the ring.

Saturn’s innermost belt differs from Jupiter’s and Earth’s inner belts in the sense that Saturn’s rings are too dense and extended to allow radial transport of magnetospheric ions into the innermost belt. Saturn’s ion belts are therefore thought to be exclusively populated by cosmic ray tertiary particles from the CRAND process. While the source is different, the losses are similar as at Jupiter, namely interaction with the tenuous D-ring and the planetary exosphere. This interaction shows in the proton pitch angle distribution and has been used to constrain the scale height of Saturn’s exosphere that is difficult to do otherwise.

How to cite: Kollmann, P., Mauk, B., Clark, G., Paranicas, C., Nenon, Q., Shprits, Y., Aseev, N., Ebert, R. W., Kim, T., Roussos, E., Haggerty, D., Rymer, A. M., Sicard, A., and Connerney, J. E. P.: The innermost ion radiation belts of Jupiter and Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11829, https://doi.org/10.5194/egusphere-egu2020-11829, 2020.

EGU2020-10615 | Displays | PS5.2

Saturn’s Auroral Field-Aligned Currents: Observations from the Northern Hemisphere Dawn Sector During Cassini’s Proximal Orbits

Greg Hunt, Emma Bunce, Hao Cao, Stan Cowley, Michele Dougherty, Gabrielle Provan, and David Southwood

We examine the azimuthal magnetic field signatures associated with Saturn’s northern hemisphere auroral field-aligned currents observed in the dawn sector during Cassini’s Proximal orbits (April 2017 and September 2017). We compare these currents with observations of the auroral currents from near noon taken during the F-ring orbits prior to the Proximal orbits. First, we show that the position of the main auroral upward current is displaced poleward between the two local times (LT). This is consistent with the statistical position of the ultraviolet auroral oval for the same time interval. Second, we show the overall average ionospheric meridional current profile differs significantly on the equatorward boundary of the upward current with a swept-forward configuration with respect to planetary rotation present at dawn. We separate the planetary period oscillation (PPO) currents from the PPO-independent currents and show their positional relationship is maintained as the latitude of the current shifts in LT implying an intrinsic link between the two systems. Focusing on the individual upward current sheets pass-by-pass we find that the main upward current at dawn is stronger compared to near-noon. This results in the current density been ~1.4 times higher in the dawn sector. We determine a proxy for the precipitating electron power and show that the dawn PPO-independent upward current electron power is ~1.9 times higher than at noon. These new observations of the dawn auroral region from the Proximal suggest the possibility of an additional upward current at dawn likely associated with strong flows in the outer magnetosphere. These findings provide new insights into the dawn sector of giant planet magnetospheres.

How to cite: Hunt, G., Bunce, E., Cao, H., Cowley, S., Dougherty, M., Provan, G., and Southwood, D.: Saturn’s Auroral Field-Aligned Currents: Observations from the Northern Hemisphere Dawn Sector During Cassini’s Proximal Orbits, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10615, https://doi.org/10.5194/egusphere-egu2020-10615, 2020.

EGU2020-3651 | Displays | PS5.2

The Pulsating Magnetosphere at Jupiter

Harry Manners and Adam Masters

The magnetosphere of Jupiter is the largest planetary magnetosphere in the solar system, and plays host to internal dynamics that remain, in many ways, mysterious. Prominent among these mysteries are the ultra-low-frequency (ULF) pulses ubiquitous in this system. Pulsations in the electromagnetic emissions, magnetic field and flux of energetic particles have been observed for decades, with little to indicate the source mechanism. While ULF waves have been observed in the magnetospheres of all the magnetized planets, the magnetospheric environment at Jupiter seems particularly conducive to the emergence of ULF waves over a wide range of periods (1-100+ minutes). This is mainly due to the high variability of the system on a global scale: internal plasma sources and a powerful intrinsic magnetic field produce a highly-compressible magnetospheric cavity, which can be reduced to a size significantly smaller than its nominal expanded state by variations in the dynamic pressure of the solar wind. Compressive fronts in the solar wind, turbulent surface interactions on the magnetopause and internal plasma processes can also all lead to ULF wave activity inside the magnetosphere.

To gain the first comprehensive view of ULF waves in the Jovian system, we have performed a heritage survey of magnetic field data measured by six spacecraft that visited the magnetosphere (Galileo, Ulysses, Voyager 1 & 2 and Pioneer 10 & 11). We found several-hundred wave events consisting of wave packets parallel or transverse to the mean magnetic field, interpreted as fast-mode or Alfvénic MHD wave activity, respectively. Parallel and transverse events were often coincident in space and time, which may be evidence of global Alfvénic resonances of the magnetic field known as field-line-resonances. We found that 15-, 30- and 40-minute periods dominate the Jovian ULF wave spectrum, in agreement with the dominant “magic frequencies” often reported in existing literature.

We will discuss potential driving mechanisms as informed by the results of the heritage survey, how this in turn affects our understanding of energy transfer in the magnetosphere, and potential investigations to be made using data from the JUNO spacecraft. We will also discuss the potential for multiple resonant cavities, and how the resonance modes of the Jovian magnetosphere may differ from those of the other magnetized planets.

How to cite: Manners, H. and Masters, A.: The Pulsating Magnetosphere at Jupiter, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3651, https://doi.org/10.5194/egusphere-egu2020-3651, 2020.

EGU2020-13656 | Displays | PS5.2

Factors Controlling the Thickness of the Jovian Current Sheet

Krishan Khurana, Chris Paranicas, and George Hospodarsky

The Jovian current sheet is the main repository of Jupiter’s magnetospheric plasma. Spatial variations in its thickness and therefore its plasma content are poorly understood because thickness determination requires a knowledge of the motion of the current sheet relative to the observing spacecraft which is hard to get. Recently, we have developed a new technique that uses the timings of any three consecutive current sheet crossings to determine the instantaneous motion of Jupiter’s current sheet relative to the spacecraft. Next by using this technique and modeling the magnetic field and electron density dataset in terms of Harris current sheet type equilibria we can estimate the thickness and plasma content of the Jovian current sheet over all local times and radial distances. Our modeling of Juno and Galileo magnetic field data shows that in all local times the current sheet thickness increases with radial distance. We also find that the Jovian current sheet is highly asymmetric in local time, being at its thinnest in the dawn sector and the thickest in the dusk sector. The current sheet thickness on the dayside is comparable to that in the dusk sector. The nightside current sheet is intermediate in its thickness to the dawn and the dusk sectors.

We show that the increase in the thickness of the current sheet with radial distance can be explained in terms of the increasing temperature and therefore the plasma beta of the current sheet with radial distance. However what causes the sharp local time variations of the current sheet is not yet fully understood. We will discuss several models of plasma transport and redistribution in Jupiter’s magnetosphere that can create local time differences in the plasma content and therefore the current sheet thickness. These models have testable implications for the structure of the magnetosphere (open versus closed, convective versus diffusive transport of plasma etc.).

How to cite: Khurana, K., Paranicas, C., and Hospodarsky, G.: Factors Controlling the Thickness of the Jovian Current Sheet , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13656, https://doi.org/10.5194/egusphere-egu2020-13656, 2020.

EGU2020-5437 | Displays | PS5.2

Electron density and temperature over Jupiter’s main auroral emission

Frederic Allegrini, William Kurth, Joachim Saur, Randy Gladstone, Fran Bagenal, Scott Bolton, George Clark, Jack Connerney, Rob Ebert, George Hospodarsky, Vincent Hue, Masafumi Imai, Steve Levin, Philippe Louarn, Barry Mauk, Dave McComas, Ali Sulaiman, Jamey Szalay, Philip W. Valek, and Rob J. Wilson

Jupiter’s ultraviolet (UV) aurora, the most powerful and intense in the solar system, is caused by energetic electrons precipitating from the magnetosphere into the atmosphere where they excite the molecular hydrogen. Electrons from ~50 eV to ~100 keV are characterized over the auroral regions by the Jovian Auroral Distributions Experiment (JADE) on Juno. Investigating the characteristics of electron distributions at these energies is critical for understanding the source population for the electrons that produce Jupiter’s UV aurora and the mechanisms that accelerated them to keV and MeV energies. In this study, we present a survey of electron distributions and moments derived from JADE in Jupiter’s polar magnetosphere. We quantify the electron properties (e.g. density and temperature) and explore similarities and differences in their distributions over several Juno perijove passes, focusing on regions near the main emission.

How to cite: Allegrini, F., Kurth, W., Saur, J., Gladstone, R., Bagenal, F., Bolton, S., Clark, G., Connerney, J., Ebert, R., Hospodarsky, G., Hue, V., Imai, M., Levin, S., Louarn, P., Mauk, B., McComas, D., Sulaiman, A., Szalay, J., Valek, P. W., and Wilson, R. J.: Electron density and temperature over Jupiter’s main auroral emission, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5437, https://doi.org/10.5194/egusphere-egu2020-5437, 2020.

EGU2020-17995 | Displays | PS5.2

Global current systems in Jupiter’s polar magnetosphere

Stavros Kotsiaros, John E P Connerney, John L Jørgensen, and Matija Herceg

The Juno spacecraft has been in polar orbit around Jupiter since July 4, 2016 sampling Jupiter's environment from ~1.05 Jovian radii outwards, extending to the distant reaches of the Jovian magnetosphere. Juno’s polar orbit makes it possible to acquire direct observations of the Jovian magnetosphere and auroral emissions above the poles for the first time. We have quantitatively measured magnetic field-aligned (Birkeland) currents which are associated with Jupiter's auroral emissions and have modelled the morphology of the currents based on observations collected along one of Juno’s polar periJove passes. The structure of the field-aligned currents seems to be more complex than expected showing a dynamic filamentation in the azimuthal direction and strong asymmetries between the northern and southern regions. This complexity indicates a non-steady state generation of field-aligned currents possibly with non-linear processes involved. We present a way towards modeling the field-aligned currents more systematically extending the analysis with data from multiple periJove passes. We also show the development of a composite map of field-aligned current regions above the polar aurorae. This map gives us important information on the global structure of the field aligned currents and therefore on how angular momentum is transferred between Jupiter’s atmosphere and magnetosphere.

How to cite: Kotsiaros, S., Connerney, J. E. P., Jørgensen, J. L., and Herceg, M.: Global current systems in Jupiter’s polar magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17995, https://doi.org/10.5194/egusphere-egu2020-17995, 2020.

EGU2020-10992 | Displays | PS5.2

Juno’s Exploration of Jupiter’s Magnetic Field and Magnetosphere

Jack Connerney, Ron Oliverson, Stavros Kotsiaros, Dan Gershman, Yasmina Martos, John Joergensen, Peter Joergensen, Jose Merayo, Matija Herceg, Mathias Benn, Troelz Denver, Jeremy Bloxham, Kimberly Moore, Scott Bolton, and Steven Levin

The Juno spacecraft was inserted into polar orbit about Jupiter on July 4th, 2016, performing close passes (to ~1.05 Rj radial distance at periJove) every 53 days. By the end of its prime mission, Juno will have circled the planet 34 times, uniformly sampling longitudes separated by less than 11 at the equator. The Juno magnetic field investigation is equipped with two magnetometer sensor suites, located at 10 and 12 m from the spacecraft body at the end of one of Juno’s three solar arrays. Each contains a vector fluxgate magnetometer (FGM) sensor and a pair of co-located non-magnetic star tracker camera heads that provide accurate attitude determination for the FGM sensors. A moredetailed view of Jupiter’s planetary dynamo is emerging as Juno acquires more periJove passes, providing spatial resolution beyond that already evident in the preliminary model (JRM09, a degree 10 spherical harmonic) derived from Juno’s first 9 periJoves. A complex and very non-dipolar magnetic field dominates the northern hemisphere, while a mostly dipolar magnetic field is observed south of the equator, where the enigmatic “Great Blue Spot” resides within an equatorial band of opposite polarity. The Jovian magnetodisc, formed by a washer-shaped disc of azimuthal (“ring”) currents, stretches magnetic field lines outward along the magnetic equator. With 26 equally spaced longitudes now available we can begin to address magnetodisc variability, finding a more or less stable system of azimuthal ring currents (few % variability) and a more variable (~50%) system of radial currents that supply torque to outflowing plasma. A new magnetodisc model greatly improves knowledge of the field geometry, independently verified via observations of the particle absorption signatures of Galilean satellites. A more systematic mapping of Birkeland currents above the polar aurorae also emerges from multiple passes. These and other developments will be presented with Juno now about ¾ of the way towards completion of its primary mission.

How to cite: Connerney, J., Oliverson, R., Kotsiaros, S., Gershman, D., Martos, Y., Joergensen, J., Joergensen, P., Merayo, J., Herceg, M., Benn, M., Denver, T., Bloxham, J., Moore, K., Bolton, S., and Levin, S.: Juno’s Exploration of Jupiter’s Magnetic Field and Magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10992, https://doi.org/10.5194/egusphere-egu2020-10992, 2020.

EGU2020-3622 | Displays | PS5.2

Jupiter’s polar auroral bright spots as seen by Juno-UVS

Kamolporn Haewsantati, Bertrand Bonfond, Suwicha Wannawichian, and George R Gladstone

The instruments on board the NASA Juno mission provides scientists with a wealth of unprecedented details about Jupiter. In particular, the Ultraviolet Spectrograph (UVS) is dedicated to the study of Jupiter’s aurora in the 60-200 nm wavelength range. The images taken by Juno-UVS reveals for the first time a complete view of Jupiter’s aurora, including the nightside part hidden from the Earth-orbiting Hubble Space Telescope (HST). This work aims to study Jupiter’s polar aurora using images obtained from the UVS instruments. Here we present the systematic analysis of one of the most spectacular features of Jupiter’s polar-most aurora, called the bright spot. The emitted power of the bright spots ranges from a few to a hundred GWs. Within a Juno perijove, the spots reappear at almost the same positions in system III. The time interval between two consecutive brightenings is a few tens of minutes, comparable to Jupiter’s X-ray pulsation. The comparison of the time interval with X-ray observation is under the investigation. Comparing the difference perijove sequences, the system III positions of bright spots in the northern hemisphere are concentrated in a region around 175 degrees of system III longitude and 65 degrees of latitude. On the other hand, the positions of bright spot aurora the southern hemisphere are scattered all around the pole. Previous studies suggested that the bright spot could correspond to noon facing magnetospheric cusp. However and surprisingly, we have discovered that the bright spots could map to any magnetic local time, putting this interpretation into question.

How to cite: Haewsantati, K., Bonfond, B., Wannawichian, S., and Gladstone, G. R.: Jupiter’s polar auroral bright spots as seen by Juno-UVS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3622, https://doi.org/10.5194/egusphere-egu2020-3622, 2020.

EGU2020-18093 | Displays | PS5.2

A profile of the Io dust cloud and plasma torus as observed from Juno

John L. Jørgensen, Troelz Denver, Mathias Benn, Peter S. Jørgensen, Matija Herceg, Jose M. G. Merayo, and John E. P. Connerney

The Juno MAG investigation’s dedicated star tracker, the Advanced Stellar Compass (ASC), has continuously monitored high energy particles fluxes in Jupiter’s magnetosphere subsequent to Juno’s orbit insertion on July 4, 2016. The ASC primary function is to provide an accurate inertial attitude reference, however, the most energetic particles in Jupiter’s trapped population is capable of penetrating the radiation shield of the ASC where they are registered. Such particles have energy >15MeV for electrons, >80MeV for protons, and >~GeV for heavier elements. With a sample cadence of 250ms, the ASC renders a detailed mapping of the trapped particles throughout space traversed by Juno. The particles travelling along the magnetic field lines crossing near the orbit of Io will be strongly influenced by interaction with any matter, moon, dust or plasma, which happens to be in their trajectory. The relativistic particle flux monitored, is highly relativistic, and has as such a modest retention time in any drift shell. The short lifetime of the trapped particles, and the constant scanning of field lines connecting to the Io environment enables a detailed profiling of the dust and plasma density, as well as the effect to/from Io itself. We present the measurement and their implications for the azimuthal and radial dust cloud and plasma torus.

How to cite: Jørgensen, J. L., Denver, T., Benn, M., Jørgensen, P. S., Herceg, M., Merayo, J. M. G., and Connerney, J. E. P.: A profile of the Io dust cloud and plasma torus as observed from Juno , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18093, https://doi.org/10.5194/egusphere-egu2020-18093, 2020.

The strong zonal flows observed at the cloud-level of the gas giants extend thousands of kilometers deep into the planetary interior, as indicated by the Juno and Cassini gravity measurements. However, the gravity measurements alone, which are by definition an integrative measure of mass, cannot constrain with high certainty the detailed vertical structure of the flow below the cloud-level. Here we show that taking into account the recent magnetic field measurements of Saturn and past secular variations of Jupiter's magnetic field, give an additional physical constraint on the vertical decay profile of the observed zonal flows in these planets. In Saturn, we find that the cloud-level winds extend into the planet with very little decay (barotropically) down to a depth of around 7,000 km, and then decay rapidly, so that within the next 1,000 km their value reduces to about 1% of that at the cloud-level. This optimal deep flow profile structure of Saturn matches simultaneously both the gravity field and the high-order latitudinal variations in the magnetic field discovered by the recent measurements. In the Jupiter case, using the recent findings indicating the flows in the planet semiconducting region are order centimeters per second, we show that with such a constraint, a flow structure similar to the Saturnian one is consistent with the Juno gravity measurements. Here the winds extend unaltered from the cloud-level to a depth of around 2,000 km and then decay rapidly within the next 600 km to values of around 1%. Thus, in both giant planets, we find that the observed winds  extend unaltered (baroctropically) down to the semiconducting region, and then decay abruptly. While is it plausible that the interaction with the magnetic field in the semiconducting region is responsible for winds final decay, it is yet to be understood whether another mechanism is involved in the process, especially in the initial decay form the strong 10s meter per seconds winds.

How to cite: Galanti, E. and Kaspi, Y.: Synergized magnetic and gravity measurements probe the detailed structure of the gas giants' deep atmospheres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4037, https://doi.org/10.5194/egusphere-egu2020-4037, 2020.

EGU2020-3441 | Displays | PS5.2 | David Bates Medal Lecture

From storms to planetary-scale disturbances in the atmospheres of Jupiter and Saturn

Agustín Snchez-Lavega

EGU2020-4702 | Displays | PS5.2

The range of flow structures fitting Jupiter's asymmetric gravity field

Keren Duer, Eli Galanti, and Yohai Kaspi
Jupiter's North-South asymmetric gravity field, measured by the Juno spacecraft, allowed estimating the depth of the zonal jets trough the relation between the measured density anomaly and the flow. This analysis was based on a combination of all four measured odd gravity harmonics, so the direct effect of each of them on the flow profile has not been investigated. Moreover, past calculations assumed that the cloud-level zonal wind maintains its meridional structure with depth; However, the Juno microwave radiometer measurements imply that a vertically dependent meridional profile might be more suitable, due to the reasonable relation between the Nadir brightness temperature profile and the zonal wind. In this study, we analyze in detail the possible range of structures of Jupiter’s deep jet-streams, fitting each of the Juno's measured asymmetric gravity harmonics. Specifically, we examine the possible vertical structure of Jupiter’s deep jet streams, different meridional structures of the cloud-level zonal wind and depth-dependent meridional profile compatible with the Nadir temperature tendency. We find that each odd gravity harmonic constrains the flow at a different depth, with J3 being the most dominant at depths below 3000 km, where the electrical conductivity becomes significant. J5 is the most restrictive harmonic overall, and J9 does not constrain the flow at all if the other odd harmonics are within the measurement range. Deep flow profiles constructed from perturbations to the cloud-level winds allow a more extensive range of solutions, yet when the patterns differ substantially from the cloud-level observed wind profile, the ability to match the gravity data reduces significantly. Random zonal wind profiles, unconnected to the cloud-level profile allow almost no solutions for the gravity data, and only 1% of the tested wind profiles yield any solution. Overall, we find that while interior wind profiles that diverge considerably from those at the cloud-level are possible, they are statistically unlikely. Finally, we find that meridional smoothing of the wind with depth, according to the Juno MWR brightness temperature profile, still allows fitting the measured gravity signal within the uncertainty range.

How to cite: Duer, K., Galanti, E., and Kaspi, Y.: The range of flow structures fitting Jupiter's asymmetric gravity field, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4702, https://doi.org/10.5194/egusphere-egu2020-4702, 2020.

EGU2020-5948 | Displays | PS5.2

Simulating vortices and jets in deep atmospheres of gas giant planets

Rakesh Yadav, Jeremy Bloxham, and Moritz Heimpel

Decades of observations have painted a dynamic and rich picture of the atmosphere on Saturn and Jupiter. Both planets have a dominant prograde equatorial jet, and strong zonal flows that alternate in direction at higher latitudes, with Saturn also having a mysterious hexagon shape embedded in one of the polar jets. Both planets also have numerous vortices or storms of different sizes scattered on their surface. All these features are striking examples of turbulent self-organization. While observations abound, the physics behind the formation of these dynamical features is still uncertain. Two interpretations have emerged over time: In one, the surface features are shallow, extending to depths ranging from 10s to 100s of kilometers, while, in the other, they extend to 1000s of kilometers. Here we utilize the deep interpretation and investigate the properties of rotating convection in deep spherical shells. We present three cases: In the first case a giant polar cyclone, alternating zonal flows, and a high latitude eastward jet having polygonal patterns form simultaneously; The second case generates alternating zonal flows as well as numerous cyclones and anticyclones on various latitudes; And, the third case exclusively generates anticyclones with few being as large as Jupiter's great red spot. We discuss what drives these features in these turbulent simulations, and what can we learn from these cases about the interior and surface dynamics of Saturn and Jupiter. 

How to cite: Yadav, R., Bloxham, J., and Heimpel, M.: Simulating vortices and jets in deep atmospheres of gas giant planets, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-5948, https://doi.org/10.5194/egusphere-egu2020-5948, 2020.

EGU2020-9585 | Displays | PS5.2

Recent results from the imagery of Juno’s Stellar Reference Unit

Heidi Becker, James Alexander, Sushil Atreya, Scott Bolton, Martin Brennan, Shannon Brown, Meghan Florence, Alexandre Guillaume, Tristan Guillot, Andrew Ingersoll, Steven Levin, Jonathan Lunine, Paul Steffes, and Youry Aglyamov

The Juno Mission has recast its spacecraft engineering star camera as a visible wavelength science imager. Developed and primarily used to support onboard attitude determination, Juno’s Stellar Reference Unit (SRU) has been put to use as an in situ high energy particle detector for profiling Jupiter’s radiation belts and as a low light sensitive camera for exploring multiple phenomena and features of the Jovian system. Juno’s unprecedented polar orbit and closest approach of ~4000 km have yielded high resolution SRU imagery of Jupiter’s lightning and aurorae from as little as 50,000 km from the 1 bar level and unique Jovian dust ring and satellite images. We will present recent SRU results and discuss the implications for Jupiter’s atmosphere that stem from the SRU lightning observations.

How to cite: Becker, H., Alexander, J., Atreya, S., Bolton, S., Brennan, M., Brown, S., Florence, M., Guillaume, A., Guillot, T., Ingersoll, A., Levin, S., Lunine, J., Steffes, P., and Aglyamov, Y.: Recent results from the imagery of Juno’s Stellar Reference Unit, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9585, https://doi.org/10.5194/egusphere-egu2020-9585, 2020.

EGU2020-19958 | Displays | PS5.2

Measured Elevation of Lightning and Aurora in the Jovian Atmosphere

Mathias Benn, John L. Jørgensen, Troelz Denver, Peter S. Jørgensen, Matija Herceg, and John E. P. Connerney

As part of the Juno MAG investigation, each magnetometer features dedicated star trackers providing accurate bias free attitude information continuously throughout the mission. These optical sensors are optimized for low-light scenarios, which enables detection of stars and objects as faint as 7-8Mv. The Juno mission features a highly elliptical polar orbit with a period of ~53 days, with periapsis as close as 3.300km above the cloud tops. In combination with the 13° off pointing of the star tracker cameras from the Juno spin axis in anti-sun direction, the Jovian night side high latitude regions regularly enters the field of regard of these star trackers. This geometry facilitates imaging low light phenomenas as lightning and aurora at a large slanted angle in the upper parts of Jupiter’s atmosphere. The large slant angle enables estimation of the vertical structure, by combining the detections with accurate attitude and spacecraft position information. We present up-to-date images of detected lightning events, visible wavelength aurora and the measured vertical structure, and discuss implications of these measurements for the Jovian atmosphere at the resulting altitudes

How to cite: Benn, M., Jørgensen, J. L., Denver, T., Jørgensen, P. S., Herceg, M., and Connerney, J. E. P.: Measured Elevation of Lightning and Aurora in the Jovian Atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19958, https://doi.org/10.5194/egusphere-egu2020-19958, 2020.

EGU2020-10704 | Displays | PS5.2

Contributions to Jupiter's gravity field from dynamics in the dynamo region and deep atmosphere

Laura Kulowski, Hao Cao, and Jeremy Bloxham

The antisymmetric part of Jupiter's zonal flows is responsible for the large odd gravity harmonics measured by the Juno spacecraft. Here, we investigate the contributions to Jupiter's odd gravity harmonics (J3, J5, J7, J9) from dynamics in the dynamo region and the deep atmosphere. First, we estimate the odd gravity harmonics produced by zonal flows in the dynamo region. Using Ferraro's law of isorotation, we construct physically motivated profiles for dynamo region zonal flow. We use the vorticity equation to determine the density perturbations associated with the flows and then calculate the odd gravity harmonics. We find that dynamo zonal flows with root mean square (RMS) velocities of 10 cm/s would produce J3 values on the same order of magnitude as the Juno measured value, but would not significantly contribute to J5, J7, and J9. Next, we examine the gravitational contribution from zonal flows above the dynamo region. We consider a simple model where the observed surface winds are barotropic (i.e., z-invariant) until they are truncated at some depth by some dynamical process, such as stable stratification and/or MHD processes. We find that barotropic zonal flow in the strongly antisymmetric northern (13°-26°N) and southern (14°-21°S) jets extending to the likely depth of a rock cloud layer or deep radiative zone can account for a significant fraction of the observed gravity signal.

How to cite: Kulowski, L., Cao, H., and Bloxham, J.: Contributions to Jupiter's gravity field from dynamics in the dynamo region and deep atmosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-10704, https://doi.org/10.5194/egusphere-egu2020-10704, 2020.

EGU2020-12025 | Displays | PS5.2

Fluid Dynamical 2D Simulations of Jupiter's South Polar Region Based On JunoCam Image Data

Gerald Eichstädt, Candice Hansen, and Glenn Orton

During almost every perijove pass in more than three years of Juno's ~53-day polar orbits around Jupiter, its wide-angle visible-light camera, JunoCam [1], has imaged Jupiter's south polar region [2].

We sought to determine whether these images could be used for prognostic “weather forecasts” in Jupiter. One of the simplest fluid dynamical models suitable for forecasting dynamical behavior of essentially barotropic incompressible flows of very low viscosity is the 2D Euler fluid. Vortex methods [3] are particularly suitable for modeling the resulting turbulence.

Sequences of images taken with a cadence of several minutes reveal small motions of the cloud tops within the illuminated area of the pole. The south pole itself has been visible in the twilight.

Raw JunoCam image data are transformed into an equidistant south-polar azimuthal map, roughly illumination-adjusted, high-passed with local contrast-normalization, and registered.
A streamfunction describing the velocity field approximately is derived from a sequence of consecutive maps of a common perijove flyby. Running a Monte-Carlo approach for stereo correlation repeatedly with different pseudo-random number sets returns an ensemble of streamfunctions.
The Laplacian of a streamfunction returns the vorticity values for a randomized 2D vortex particle seed as initial conditions of a grid-free vortex method. Applying the Biot-Savart law [3, p.19ff] on a 2-spherical geometry to the vorticity field returns the velocity field. A single-step explicit Runge-Kutta method of order 4 or 5 and fixed time steps advects the 4th-degree Gaussmollified vortex particles. Measuring the area of their Voronoi cells (Dirichlet/Thiessen polygons) reassesses the radius of the vortex particles. The method allows for some divergence. An approximately inviscid and incompressible 2D-flow is simulated over 2 up to 54 real-time days or about one Juno orbital period. The randomized nature of the method induces simulation ensembles for a given streamfunction by repeated runs.

Reducing the streamfunction to a Morse-Smale complex returns idealized model vortex seeds.

JunoCam images of the south polar region taken during a perijove pass provide an ensemble of dynamical data. These initial conditions extend to ensembles of forecast runs of the 2-spherical dynamics of the visible cloud tops in Jupiter's south polar region. We find that JunoCam images of
Jupiter's south polar region allow for reasonably plausible forecasts of the dynamics of the observed area with grid-free 2D vortex methods over at least a few days.

[1] C.J. Hansen, M.A. Caplinger, A. Ingersoll, M.A. Ravine, E. Jensen, S. Bolton, G. Orton.
Junocam: Juno’s Outreach Camera. Space Sci Rev 2013:475-506, 2017
[2] F.Tabataba-Vakili,J.H.Rogers,G.Eichstädt,G.S.Orton,C.J.Hansen,et al. Long-term Tracking of
Circumpolar Cyclones on Jupiter From Polar Observations with JunoCam. Icarus 335, 113405,
2020.
[3] G.-H. Cottet, P. D. Koumoutsakos, Vortex Methods: Theory and Practice, Cambridge University
Press, 2000

How to cite: Eichstädt, G., Hansen, C., and Orton, G.: Fluid Dynamical 2D Simulations of Jupiter's South Polar Region Based On JunoCam Image Data, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12025, https://doi.org/10.5194/egusphere-egu2020-12025, 2020.

EGU2020-12997 | Displays | PS5.2

Jupiter As Seen By The Juno Microwave Radiometer: A Progress Report

Steven Levin and the Juno Microwave Radiometer Team

Juno is a spin-stabilized, solar-powered spacecraft in a highly eccentric 53.5-day polar orbit about Jupiter, with perijoves at about 5000 km above the cloud tops. From this unique vantage point, the Juno Microwave Radiometer (MWR) measures the radio emission in 6 channels, at wavelengths ranging from 1.4 to 50 cm, with 100 mS sampling throughout each spin of the spacecraft.  This data set covers the Jovian atmosphere over a wide range of latitudes, longitudes and emission angles, resulting in discoveries, puzzles, and fresh insights related to the distribution and concentration of ammonia and water, atmospheric dynamics, lightning, and other aspects of the atmosphere at depths as deep as 100 bars or more. We will present an overview of MWR results to date, incorporating data from 22 perijove passes.

How to cite: Levin, S. and the Juno Microwave Radiometer Team: Jupiter As Seen By The Juno Microwave Radiometer: A Progress Report, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12997, https://doi.org/10.5194/egusphere-egu2020-12997, 2020.

EGU2020-4794 | Displays | PS5.2

Statistics of Zebra stripes at Saturn magnetosphere

Yixin Sun, Ying Liu, Yixin Hao, Elias Roussos, Qiugang Zong, Xuzhi Zhou, Chongjing Yuan, and Norbert Krupp

Multi bands electron flux enhancement are found via Cassini /LEMMS PHA measurements.  The enhancement extends extremely large Lshells from L=10 to even L=5 at energy from 100 keV to 1 MeV, which is quite different from previously recognized injection events at Saturn but similar to Zebra Stripes identified at Earth.  Cases are presented by Hao et al showing the evolution of a Zebra Stripe event, and statistics here will show the spatial distribution of stripe events . The result shows that Zebra Stripe is indeed universal at Saturnian inner magnetosphere, although there exists a day-to-night asymmetry. The evolution time of stripes observed by Cassini is around 40 hours indicating the occurrence frequency  of impulsive electric field which lead to this convection process. The existence of Zebra Stripes provides an insight into the formation and dynamics of giant planets' radiation belts and magnetosphere.

How to cite: Sun, Y., Liu, Y., Hao, Y., Roussos, E., Zong, Q., Zhou, X., Yuan, C., and Krupp, N.: Statistics of Zebra stripes at Saturn magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4794, https://doi.org/10.5194/egusphere-egu2020-4794, 2020.

EGU2020-7182 | Displays | PS5.2

Analysis of short large amplitude magnetic structures at the Kronian bow shock

Zsofia Bebesi, Geza Erdos, Melinda Dosa, and Karoly Szego

            We present a comprehensive statistical analysis of Short Large Amplitude Magnetic Structures (SLAMS) upstream of the quasi-parallel bow shock of Saturn. During its mission Cassini extensive surveyed the quasi-parallel regime. For this study we used the measurements of the Cassini Plasma Spectrometer (CAPS) and the Magnetometer (MAG).

            The SLAM structures locally act as fast mode shock waves, and we observed possible ion beam reflection, multiple ion beams, deceleration and plasma heating of the solar wind protons. These features are in agreement with the near Earth observations. We also detected whistler precursor waves multiple times, which was also documented in studies of the Earth's foreshock region. Since the frequency of the upstream ULF waves detected at Saturn is lower than it is at Earth, it also has an effect on the spatial extension of the SLAM structures, which arise from these waves. With only one spacecraft's measurements it is not possible to study the SLAMS with the same efficiency as with the four-point measurements of the CLUSTER probes, but the basic observational features and the description of their evolutional characteristics are summarized.

How to cite: Bebesi, Z., Erdos, G., Dosa, M., and Szego, K.: Analysis of short large amplitude magnetic structures at the Kronian bow shock, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7182, https://doi.org/10.5194/egusphere-egu2020-7182, 2020.

EGU2020-7318 | Displays | PS5.2

Jupiter dayside as seen by JIRAM-Juno: current status and examples of spectral data analysis

Davide Grassi, Giuseppe Sindoni, Alberto Adriani, Alessandro Mura, Christina Plainaki, and Scott Bolton

The JIRAM instrument on board of the Juno spacecraft includes a spectrometer that operates in the range 2-5 μm with a spectral resolution of about 15 nm.
The signal measured between 2 and 3.1 um is due to the scattering of solar photons by aerosols in the daytime Jupiter atmosphere and, as such, it has been partially exploited in [1] to study the structure of "white ovals" vortexes in the southern hemisphere.
This contribution reviews the current status and issues of analysis of JIRAM data in this solar-dominated spectral range, with several examples from different latitudes. Modeling of vertical density profile of clouds is largely based on recent results of [2].
In JIRAM spectra, the region between 2.7 and 3.1 does not show any firm evidence of ammonia ice, that would be expected to produce clear spectral features here even when massively coated with contaminants such as tholines. It is therefore difficult to properly model the data assuming the optical properties of aerosols of any given realistic composition.


[1] Sindoni, G., et al. (2017) doi: 10.1002/2017GL072940
[2] Braude, A. S., et al. (2020) doi: 10.1016/j.icarus.2019.113589

How to cite: Grassi, D., Sindoni, G., Adriani, A., Mura, A., Plainaki, C., and Bolton, S.: Jupiter dayside as seen by JIRAM-Juno: current status and examples of spectral data analysis, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-7318, https://doi.org/10.5194/egusphere-egu2020-7318, 2020.

EGU2020-9813 | Displays | PS5.2

On the effective recombination coefficient in Saturn's ionosphere

Joshua Dreyer, Erik Vigren, Michiko Morooka, Jan-Erik Wahlund, Stephan Buchert, and J. Hunter Waite

The present study combines RPWS/LP and INMS data from Cassini's orbit 292, which reached an altitude of 1685 km at the lowest point, to constrain the effective recombination coefficient α300 from measured densities and electron temperatures at a reference electron temperature of 300 K. Assuming photochemical equilibrium at these low altitudes and linking established methods to calculate the electron production rate and the dissociative recombination rate results in a formula to calculate an upper limit for α300. This is then compared against rate constants of individual recombination reactions as measured in the laboratory.
We derive upper limits for α300 of ∼ 2.5∗10-7cm3 s-1, which suggest that Saturn's ionospheric positive ions are dominated by species with low recombination rate coefficients. An ionosphere dominated by water group ions or complex hydrocarbons, as previously suggested, is incompatible with this result, as these species have recombination rate constants > 5∗10-7 cm3 s-1 at an electron temperature of 300 K. The results do not give constraints on the nature of the negative ions.

How to cite: Dreyer, J., Vigren, E., Morooka, M., Wahlund, J.-E., Buchert, S., and Waite, J. H.: On the effective recombination coefficient in Saturn's ionosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9813, https://doi.org/10.5194/egusphere-egu2020-9813, 2020.

EGU2020-11791 | Displays | PS5.2

Wave-particle interaction in the Io flux tube

Sascha Janser, Joachim Saur, Jamey Szalay, and George Clark

Observations by the JUNO spacecraft revealed energetic, bidirectional particle populations with broadband energy distributions in the high-latitude region of Jupiter. These measurements indicate that an acceleration mechanism of stochastic nature plays a dominant role for the generation of the intense main auroral oval. In our current work, we investigate the heating of an energetic upward proton population recently observed by JUNO in the Io flux tube wake near Jupiter. We try to infer on the relevant physical acceleration process by considering a resonant as well as a non-resonant wave-particle interaction mechanism, both based on Alfven waves. We focus on necessary temporal scales to drive these mechanisms efficiently and also on the released wave energy by means of the transported Poynting flux along the flux tube.

How to cite: Janser, S., Saur, J., Szalay, J., and Clark, G.: Wave-particle interaction in the Io flux tube, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11791, https://doi.org/10.5194/egusphere-egu2020-11791, 2020.

EGU2020-12090 | Displays | PS5.2

Role of coupled processes on the radial and angular distributions of > 1 keV electrons at Saturn

Daniel Santos-Costa, Emma Woodfield, Doug Menietti, George Hospodarsky, George Clark, Peter Kollmann, Chris Paranicas, and Wei-Ling Tseng
We present results from a three-dimensional diffusion theory model, which solves the time dependent Fokker-Planck equation with physical terms representing energizing, source and loss processes to interpret key features in the radial and angular distributions of > 1 keV-energy electrons at Saturn. Cassini observations of eV-keV electron Pitch-Angle Distributions (PADs) at Saturn have revealed a spatial structuring, with little temporal and longitudinal dependence, that can be broken up into three distinct regions [1]: (1) a region dominated by field-aligned PADs from ~12-15 Rs, (2) a transition region from ~8-12 Rs in which butterfly distributions are typically observed, and (3) a region inside ~8 Rs dominated by trapped PADs. Past studies have explained field-aligned PADs by the presence of field aligned currents and acceleration mechanisms in the auroral region [2], while pancake profiles would be the result of inward adiabatic transport [3]. It was argued that energetic electrons are adiabatically energized during inward motion and their PADs would radially evolve from field-aligned (> 15 Rs) to butterfly to pancake/isotropic inside ~8 Rs [4,5,6]. Although Cassini had unveiled Enceladus' dense and extended neutral cloud, little had been done regarding the role of neutrals on the distributions of electrons. We have subsequently combined multi-instrument data analyses of Cassini observations (particle, field and waves) and a diffusion theory model of charged particle fluxes to test the scenarios of the origins and radial evolution of electrons' PADs in the region ~2-15 Rs. In our work, Cassini CAPS/ELS, MIMI/LEMMS and MAG are used to both constrain the model at its boundary conditions and discuss our simulation results with in-situ data. Our radial transport is initially constrained by MIMI/LEMMS observations of micro-signatures [7] and assumed to be adiabatic [8]. Our simulation results show that the adiabatic transport cannot entirely explain the radial and angular features of energetic electrons within the ~2-15 Rs region. The coupling of different mechanisms is required into our model to obtain better agreements with in-situ data. The implementation of a supra-thermal electron population at high-latitudes appears to be a reasonable source of magnetospheric particles beyond ~9 Rs. While impact-ionization and Bremsstrahlung are insignificant mechanisms for > 1 keV-energy electrons, coulomb collisions with neutrals efficiently alter the electron distributions inside ~9 Rs. The drastic depletion observed in the electron fluxes inside ~9-10 Rs is partially explained by the interaction of electrons with neutrals. To pursue our understanding of radial and angular distributions of > 1 keV electrons inside ~7-8 Rs, we are currently investigating the role of dust, cold plasma and waves. Interactions with dust and plasma particles seem to have limited effects. Past studies showed that wave-particle interactions at Saturn are inconclusive [9,10]. Nonetheless, we propose to revisit the role of waves at Saturn as only the interaction with whistler mode chorus waves was examined and the role of coupled processes not discussed. We will thus present our latest results of the interactions of neutrals, dust and plasma environments, and electromagnetic waves with Saturn’s energetic electron population from a physics-based modeling approach. 
 
[1] Clark et al., PSS, Volume 104, 2014
[2] Saur et al, Nature, Volume 439 (7077), 2006
[3] Paranicas et al., GRL, Volume 34 (2), 2007
[4] Rymer et al., JGR, Volume 113 (A1), 2008
[5] Schippers et al., JGR, Volume 113 (A7), 2008
[6] Rymer et al, PSS, Volume 57 (14-15), 2009
[7] Roussos et al., JGR, Volume 112 (A6), 2007
[8] Kollmann et al., JGR, Volume 123, 2018
[9] Lorenzato et al., JGR, Volume 117, 2012
[10] Shprits et al., JGR, Volume 117, 2012

How to cite: Santos-Costa, D., Woodfield, E., Menietti, D., Hospodarsky, G., Clark, G., Kollmann, P., Paranicas, C., and Tseng, W.-L.: Role of coupled processes on the radial and angular distributions of > 1 keV electrons at Saturn, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12090, https://doi.org/10.5194/egusphere-egu2020-12090, 2020.

EGU2020-13221 | Displays | PS5.2

Modelling the electron density distribution in the Io Plasma Torus using Juno radio occultations

Marco Zannoni, Alessandro Moirano, Luis Gomez Casajus, Paolo Tortora, Daniele Durante, and Luciano Iess

The innermost galileian moon Io hosts an intense volcanic activity, which ejects about 103 kg/s of gas into Jupiter's magnetosphere. Here these neutrals are ionized by interaction with the background plasma and they are accelerated from keplerian velocity to corotation velocity thanks to Alfvén's theorem. This plasma cloud around the planet (the so-called Io Plasma Torus or IPT) slowly diffuses across Jupiter's magnetic field, but high electron densities (>1000-2000 cm-3) are found between 5-8 RJ.

Juno is travelling along highly eccentric, polar orbits around the planet and flies very close to Jupiter's surface during each perijove. Thus, the radio links used for ground communication and radio science cross the IPT both in the uplink and the downlink leg. Being a dispersive medium, the torus introduces a different path delay on the X/X and Ka/Ka links established between the Ground Station and the spacecraft. Thus, the path delay can be extracted through a linear combination of the two links, and then quantitatively analyzed and fitted to different parametric models of the IPT.

In this work we have used almost all the available Juno radio occultations of the IPT in order to improve an already existing model by introducing both longitudinal and temporal variations of the electron density. To this end, we looked for the 2D Fourier expansion in longitude and time of the parameters of this model with the goal of minimizing the residuals of the fit and pointing out periodicities in the morphology of the torus.

How to cite: Zannoni, M., Moirano, A., Gomez Casajus, L., Tortora, P., Durante, D., and Iess, L.: Modelling the electron density distribution in the Io Plasma Torus using Juno radio occultations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13221, https://doi.org/10.5194/egusphere-egu2020-13221, 2020.

EGU2020-20400 | Displays | PS5.2

Corotating drift resonant electrons in Saturn's radiation belt: theory and observational evidence

Yixin Hao, Yixin Sun, Elias Roussos, Ying Liu, Chongjing Yuan, Norbert Krupp, and Qiugang Zong

Corotating drift resonant (CDR) electrons, of which the gradient and curvature drift could cancel the corotation around the Saturn, could get efficiently radial transported when exposed to the Saturnian global convective electric field. Such fast radial transport could lead to significant adiabatic acceleration and therefore supply for the electron radiation belt population. In this work, the nonlinear trapping nature of the corotating drift resonance is investigated. Electrons trapped inside the resonant island preform a banana-like orbit in the equatorial plane. We present an estimation of the trapping limit in L shell and energy for the resonant electrons with varying first adiabatic invariant, which could be directly compared to CASSINI observations. The estimation of the trapping period also indicates that trapped electrons takes times of more hours to close their orbit than the traveling electrons. The evolution in energy spectrogram driven by Saturn's convection and corotation has also been predicted by our test particle simulations. We suggest  that the bifurcation of the 'zebra stripes' near the corotation drift resonant energy could be a diagnostic feature of the nonlinear CDR. Observations from MIMI/LEMMS with similar zebra stripes and the bifurcation have been found as predicted, proving that the electrons in Saturn's radiation belt are being transported radially by the convection and that corotating drift resonant could be a significant candidate for the plenishing of the Saturn's electron radiation belt.   

How to cite: Hao, Y., Sun, Y., Roussos, E., Liu, Y., Yuan, C., Krupp, N., and Zong, Q.: Corotating drift resonant electrons in Saturn's radiation belt: theory and observational evidence, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20400, https://doi.org/10.5194/egusphere-egu2020-20400, 2020.

EGU2020-21724 | Displays | PS5.2

Finding the drivers for a non-steady state and large-scale stresses acting on the Saturnian magnetosphere

Ned Staniland, Michele Dougherty, and Adam Masters

In the inner region of Saturn’s rotationally-dominated magnetosphere, the governing magnetic field contributors are the internal magnetic field and the magnetodisc current sheet. The equatorially confined plasma sourced predominantly by the moon Enceladus stretches Saturn’s magnetic field lines into the characteristic ‘magnetodisc’ geometry. The extent of this effect varies due to both external and internal dynamical processes that perturb the system.

In this study, we use the complete dataset collected by the Cassini spacecraft to determine whether the magnetosphere is compressed, stretched or near some prescribed ground state. We find that there is an underlying dawn-dusk asymmetry in the ground state of Saturn’s magnetosphere, where the field is more compressed at dusk compared to dawn. Whilst Saturn spent a significant period of the Cassini mission near its ground state, we find evidence for large-scale stresses acting on the system, including large compression events that coincide with the declining phase of the solar cycle. These results are then compared to propagated solar wind data. In addition, approximately two thirds of our dataset is well described by the internal field and current sheet models, signifying the system was in steady-state during these passes. We further discuss the drivers for the non-steady state periods at Saturn and what this implies for the global dynamics of Saturn's magnetosphere.

How to cite: Staniland, N., Dougherty, M., and Masters, A.: Finding the drivers for a non-steady state and large-scale stresses acting on the Saturnian magnetosphere, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21724, https://doi.org/10.5194/egusphere-egu2020-21724, 2020.

EGU2020-21953 | Displays | PS5.2

Investigating the effects of the planetary rings on the azimuthal magnetic field at Saturn

Omakshi Agiwal, Michele Dougherty, Gregory Hunt, Hao Cao, and Hsiang-Wen Hsu

Magnetic field observations from the 22 Cassini Grand Finale orbits have shown a mean lagging azimuthal magnetic field configuration on magnetic field lines mapping from Saturn to its main rings in the equatorial plane, with some orbit to orbit variability. A prominent feature is observed in the southern hemisphere on field lines connecting to the B-ring on 70% of the orbits, which is spatially consistent with the location of in-falling dust indicated by the Cosmic Dust Analyser instrument. In our work, we examine the possible connection between the in-falling charged dust and the B-ring magnetic field feature. We also use a simple steady-state model to couple the planetary ionosphere to a weakly conducting ring ionosphere over the main rings, where the model output shows an expected leading field configuration associated with the rings. The discrepancy between the simple theoretical model and the data indicates the presence of additional processes (e.g. departure from Keplerian velocity of the charged ring particles), which will be discussed. We will further discuss the likely connection between the observed lagging field configuration in the middle magnetosphere and in the inner magnetosphere.  

How to cite: Agiwal, O., Dougherty, M., Hunt, G., Cao, H., and Hsu, H.-W.: Investigating the effects of the planetary rings on the azimuthal magnetic field at Saturn , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21953, https://doi.org/10.5194/egusphere-egu2020-21953, 2020.

EGU2020-11306 | Displays | PS5.2

Saturn’s ring current observed during Cassini’s Grand Finale

Gabrielle Provan, Tom Bradley, Emma Bunce, Stan Cowley, Michele Dougherty, Greg Hunt, Elias Roussos, Ned Staniland, and Chihiro Tao

The presence of a substantial azimuthal current sheet in Saturn’s magnetosphere was identified in Voyager and Pioneer magnetometer data.  Data from these spacecraft showed depressions in the strength of the field below that expected for the internal field of the planet alone.  This ring current was  modelled  as a simple axisymmetric current system by Connerney et al. [1980, 1983].  In this study we utilise the Connerney ring current model to look at the size, shape, current density and total current of Saturn’s ring current as observed during the Cassini proximal orbits.  We compare the variations in these parameters with the phases of the planetary period oscillations and with the occurrence of magnetospheric storms as determined from propagated solar wind data and LEMMS electron and proton data. Overall, we find that Saturn’s ring current is a dynamical environment which varies in size and magnitude due to  both  planetary period oscillations and solar-driven storms.  

How to cite: Provan, G., Bradley, T., Bunce, E., Cowley, S., Dougherty, M., Hunt, G., Roussos, E., Staniland, N., and Tao, C.: Saturn’s ring current observed during Cassini’s Grand Finale, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11306, https://doi.org/10.5194/egusphere-egu2020-11306, 2020.

EGU2020-100 | Displays | PS5.2

Cassini observations of magnetic holes in the solar wind and Saturn magnetosheath

Tomas Karlsson, Lina Hadid, Michiko Morooka, and Jan-Erik Wahlund

We present the first Cassini observations of magnetic holes on the near-Saturn solar wind and magnetosheath, based on data from the MAG magnetometer. We conclude that magnetic holes (defined as isolated decreases of at least 50% compared to the background magnetic field strength) are common in both regions. We present statistical properties of the magnetic holes, including scale size, depth of the magnetic field reduction, orientation, change in magnetic field direction over the holes, and solar cycle dependence. For magnetosheath magnetic holes, also high-time resolution density measurements from the LP Langmuir probe are available, allowing us to study the anti-correlation of density and magnetic field strength in the magnetic holes. We compare to recent results from MESSENGER observations from Mercury orbit, and finally discuss the possible importance of magnetic holes in solar wind-magnetosphere interaction at Saturn.

How to cite: Karlsson, T., Hadid, L., Morooka, M., and Wahlund, J.-E.: Cassini observations of magnetic holes in the solar wind and Saturn magnetosheath, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-100, https://doi.org/10.5194/egusphere-egu2020-100, 2020.

EGU2020-18599 | Displays | PS5.2

High Energy (>10 MeV) Oxygen and Sulfur Ions Observed at Jupiter from Pulse Width Measurements of the JEDI Sensors

Joseph Westlake, George Clark, Dennis Haggerty, Stephen Jaskulek, Peter Kollmann, Barry Mauk, Donald Mitchell, Kenneth Nelson, Chris Paranicas, and Abigail Rymer

The Jovian polar regions produce X-rays that are characteristic of very energetic oxygen and sulfur that become highly charged on precipitating into Jupiter’s upper atmosphere.  Juno has traversed the polar regions above where these energetic ions are expected to be precipitating revealing a complex composition and energy structure. Energetic ions are likely to drive the characteristic X-rays observed at Jupiter (Haggerty et al., 2017; Houston et al., 2018; Kharchenko et al., 2006). Motivated by the science of X-ray generation, we describe here Juno JEDI measurements of ions above 1 MeV, and demonstrate the capability of measuring oxygen and sulfur ions with energies up to 100 MeV. We detail the process of retrieving ion fluxes from pulse width data on instruments like JEDI (called “puck’s”; Clark et al., 2016; Mauk et al., 2013) as well as details on retrieving very energetic particles (>20 MeV) above which the pulse width also saturates. The Juno JEDI instrument is shown to have the unplanned capability to measure heavy ions to energies as high as 100 MeV. As such, the JEDI instrument has the capability to measure those ions needed to generate polar X-rays at Jupiter. (> 10’s of MeV O and/or S). We present analysis that involves separating these very energetic ions into the group that is trapped (i.e., part of the very high latitude radiation belts) and the group that is precipitating and might be linked to observed X-rays.

How to cite: Westlake, J., Clark, G., Haggerty, D., Jaskulek, S., Kollmann, P., Mauk, B., Mitchell, D., Nelson, K., Paranicas, C., and Rymer, A.: High Energy (>10 MeV) Oxygen and Sulfur Ions Observed at Jupiter from Pulse Width Measurements of the JEDI Sensors, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18599, https://doi.org/10.5194/egusphere-egu2020-18599, 2020.

EGU2020-14619 | Displays | PS5.2

Trapped particles around Jupiter detected by Advanced Stellar Compass

Matija Herceg, John L. Jørgensen, Peter S. Jørgensen, Jose M. G. Merayo, Mathias Benn, Troelz Denver, and John E. P. Connerney

The Advanced Stellar Compass (ASC), attitude reference for the MAG investigation onboard Juno, has continuously monitored high energy particles fluxes in Jupiter’s magnetosphere since Juno’s orbit insertion. The instrument performs this function by tracking the effects of radiation with sufficient energy to transit the instrument’s radiation shielding. Particles that Juno ASC observes have energy >15MeV for electrons, >80MeV for protons, and >~GeV for heavier elements.

Completing 24 highly elliptical orbits around Jupiter, results in a fairly detailed mapping of the trapped high energy flux at up to 20 Jupiter radius distances.

Traveling at velocities close to the speed of light, electrons measured by the ASC, maintain the motion governed by the three adiabatic invariants: gyrating motion around the magnetic field line, a north-south magnetic pole particle bounce, and a charge dependent drift around the planet.

The bounce period is much smaller than the Jovian rotation period, and a large east-west drift component is caused by the magnetic field gradient. For these reasons, the drift shell description traditionally used for dipolar fields, are far from adequate to describe the behavior of energetic particles travelling close to Jupiter.

In this work, we present the distribution of the trapped high energy electrons around Jupiter. Furthermore, we have constrained the spatial extent of the stable trapped regions and are presenting the distinctive pitch angle and its correlation with ”life” of a particle. At certain distances from Jupiter, pitch angle dependency is not as important to keep the particle trapped as is the injected energy. We also develop an adiabatic map which describes the radial bands for stable trapped particles as a function of the pitch angle and energy.

 

How to cite: Herceg, M., Jørgensen, J. L., Jørgensen, P. S., Merayo, J. M. G., Benn, M., Denver, T., and Connerney, J. E. P.: Trapped particles around Jupiter detected by Advanced Stellar Compass, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-14619, https://doi.org/10.5194/egusphere-egu2020-14619, 2020.

EGU2020-17851 | Displays | PS5.2

Jupiter polar cap high energy particle acceleration observed from Juno

Peter S. Jørgensen, John L. Jørgensen, Jose M. G Merayo, Mathias Benn, Matija Herceg, Troelz Denver, John E. P. Connerney, and Barry Mauk

The Juno mission carries the Advanced Stellar Compass (ASC) as primary attitude reference for the MAG investigation. Since Jupiter Orbit Insertion on July 4, 2016, the ASC has continuously monitored high energy particles fluxes in Jupiter’s magnetosphere. In the attitude determination process, the energetic particles with sufficient energy to penetrate the heavily shielded focal plane CCD are detected and characterized to facilitate their removal in the stellar attitude match. Thus highly energetic particles, >15MeV for electrons, >80MeV for protons, and >~GeV for heavier elements, are detected and reported every 250ms. The ASC’s highly optimized radiation shield design enables directional sensitivity, since shielding encountered by particles entering via the optics aperture is less efficient. The directionality offers preferential detection to electrons with energies between 15 and 25MeV and protons with energies between 80 and 100MeV (i.e operates as a particle telescope), whereas particles with energies above these limits may penetrate from any direction. The Juno spacecraft, rotates at 2 RPM, thus particles with energies in the band mentioned, and velocities pointing to the lens exhibit particle flux variation with the spin phase of Juno. Every periJove, Juno traverses a section of the north and south polar caps, and now, past the midpoint of nominal mission, high energetic particles in the aurora regions have been mapped with a high degree of detail. A significant feature is that very intense beams of particles are regularly measured at field lines reaching well beyond L=50, i.e. on distant closed or open field lines. These features are rapidly varying, signifying either a very limited extent, or, high time variability. In the cases where these beams contain particles with energies in the directional sensitive range of the ASC, the source of the beam is from the aurora region, suggesting a polar cap mechanism, capable of accelerating a particle directly to 20MeV. We present examples of flux profiles on open field lines.

How to cite: Jørgensen, P. S., Jørgensen, J. L., Merayo, J. M. G., Benn, M., Herceg, M., Denver, T., Connerney, J. E. P., and Mauk, B.: Jupiter polar cap high energy particle acceleration observed from Juno, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-17851, https://doi.org/10.5194/egusphere-egu2020-17851, 2020.

EGU2020-22108 | Displays | PS5.2

Evolution of the atmospheric organic content on Titan with seasons

Athena Coustenis, Donald Jennings, Richard Achterberg, Panayotis Lavvas, Conor Nixon, F. Michael Flasar, and Georgios Bampasidis

Titan is one of the most promising bodies in the solar system from the astrobiological perspective in particular because of its large organic content in the atmosphere and on the surface. These chemical species evolve with time. We performed an analysis of spectra acquired by Cassini/CIRS at high resolution which cover the far-IR range from 10 to 1500 cm-1 since the beginning and until the last year of the Cassini mission in 2017 and describe the temperature and composition variations near Titan’s poles and at the equator over almost two Titan seasons ([1-3]. By applying our radiative transfer code (ARTT) to CIRS data and to the 1980 Voyager 1 flyby values inferred from the re-analysis of the Infrared Radiometer Spectrometer (IRIS) spectra, as well as to the intervening ground- and space-based observations (such as with ISO), we study the stratospheric evolution over a Titanian year (V1 encounter Ls=9° was reached in mid-2010) [1,2]. CIRS nadir and limb spectral together show variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE) and also during one Titan year.

After the 2010 equinox we have thus reported on monitoring of Titan’s stratosphere near the poles and in particular on the observed strong temperature decrease and compositional enhancement above Titan’s southern polar latitudes since 2012 and until 2014 of several trace species, such as complex hydrocarbons and nitriles, which were previously observed only at high northern latitudes. This effect followed the transition of Titan’s seasons from northern winter in 2002 to northern summer in 2017, while at that latter time the southern hemisphere was entering winter.

Our data show a continued decrease of the abundances which we first reported to have started in 2015. The 2017 data we have acquired and analyzed here are important because they are the only ones recorded since 2014 close to the south pole in the far-infrared nadir mode at high resolution. A large temperature increase in the southern polar stratosphere (by 10-50 K in the 0.5 mbar-0.05 mbar pressure range) is found and a change in the temperature profile’s shape. The 2017 observations also show a related significant decrease in most of the abundances which must have started sometime between 2014 and 2017 [3]. In our work, we show that the equatorial latitudes remain rather constant throughout the Cassini mission.

We have thus shown that the south pole of Titan is now losing its strong enhancement, while the north pole also slowly continues its decrease in gaseous opacities. It would have been interesting to see when this might happen, but the Cassini mission ended in September 2017. Perhaps future ground-based measurements can pursue this investigation and monitor Titan’s atmosphere to characterize the seasonal events. We have obtained thus significant results which set constraints on GCM and photochemical models.

 [1] Coustenis et al., 2016, Icarus 270, 409-420; [2] Coustenis et al., 2018, Astroph. J., Lett., 854, no2; [3] Coustenis et al., 2019, Icarus in press, https://doi.org/10.​1016/​j.​icarus.​2019.​113413.

How to cite: Coustenis, A., Jennings, D., Achterberg, R., Lavvas, P., Nixon, C., Flasar, F. M., and Bampasidis, G.: Evolution of the atmospheric organic content on Titan with seasons, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22108, https://doi.org/10.5194/egusphere-egu2020-22108, 2020.

EGU2020-10858 | Displays | PS5.2

Juno’s Microwave Imaging of Jupiter’s Atmosphere at Multiple Depths

Scott Bolton, Steve Levin, Michael Janssen, Fabiano Ovafuso, Zhimeng Zhang, John Arballo, Cheng Li, Michael Wong, and Glenn Orton

EGU2020-13596 | Displays | PS5.2

Fluid planetary dynamics in Jupiter and Saturn

Simranjeet Singh

EGU2020-18349 | Displays | PS5.2

Jupiter’s gravity field updates from Juno

Daniele Durante, Marzia Parisi, Daniele Serra, Marco Zannoni, Virginia Notaro, Paolo Racioppa, Dustin R. Buccino, Giacomo Lari, Luis Gomez Casajus, Luciano Iess, William M. Folkner, Giacomo Tommei, Paolo Tortora, and Scott Bolton

The Juno spacecraft arrived at Jupiter’s system on July 4th, 2016 and reached the mid-point of its nominal mission in December 2018, after completing 17 perijove passes. Juno is currently orbiting Jupiter in a highly eccentric orbit, with a perijove altitude of about 4000 km that provides great sensitivity to the gravitational field of the planet. The radioscience instrumentation on board Juno enables very accurate radial velocity (Doppler) measurements, with noise as low as 10 micron/s at an integration time of 60 s. The gravity field of the planet is recovered though detailed reconstruction of Juno’s motion and observation model, performed with JPL’s and University of Pisa’s latest precise orbit determination codes, MONTE and ORBIT14 respectively.

We provide an update on Jupiter’s gravity field, its tidal response and spin axis motion over the first half of Juno’s mission. Although the Doppler data collected during the first two gravity-dedicated perijove passes have been reduced to the noise level by assuming a purely axially symmetric field for the gas giant, the current dataset, which includes ten passes, hints to a non-static and/or non-axially symmetric field, possibly related to several different mechanisms, such as normal modes, localized atmospheric or deeply-rooted dynamics.

How to cite: Durante, D., Parisi, M., Serra, D., Zannoni, M., Notaro, V., Racioppa, P., Buccino, D. R., Lari, G., Gomez Casajus, L., Iess, L., Folkner, W. M., Tommei, G., Tortora, P., and Bolton, S.: Jupiter’s gravity field updates from Juno, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18349, https://doi.org/10.5194/egusphere-egu2020-18349, 2020.

EGU2020-13182 | Displays | PS5.2

Jupiter atmosphere in the infrared

Alessandro Mura, Alberto Adriani, Davide Grassi, Alessandra Migliorini, Marisa Moriconi, and Francesca Altieri and the JIRAM TEAM

The Jovian InfraRed Auroral Mapper (JIRAM) on board the Juno spacecraft, is equipped with an infrared camera and a spectrometer working in the spectral range 2-5 μm. JIRAM was built to study both the infrared aurora of Jupiter and its atmosphere. The imager observations are used for studying atmospheric dynamical structures, while spectroscopic ones are used for studying atmospheric dynamical structures and for investigating the abundance of some chemical species relevant for the atmosphere’s chemistry, microphysics and dynamics, such as water, ammonia, phosphine, germane and arsine.
Since the orbit insertion, JIRAM has performed several observations of the planet from the equator to poles. Unprecedented views of the polar atmospheric structures have been acquired for the 1st time thanks to the unique orbital design of the Juno mission. Spectral measurements provided the opportunity to measure abundances of minor atmospheric species at all latitudes down to pressures of 4-5 bars.  Limb observations at the low latitudes permit to probe abundances of methane and trihydrogen cation in the stratosphere and the thermosphere of the planet. 
In the north polar region, Juno discovered, in 2016, the presence of a regular eight-cyclone structure around a single polar cyclone; in the south, one polar cyclone is encircled by five circumpolar cyclones. Now, recent observations, performed in late 2019, showed that this configuration has significantly changed: the south structure is now more similar to a hexagon, while in the north there are significant hints that the octagonal shape may have been destroyed.

How to cite: Mura, A., Adriani, A., Grassi, D., Migliorini, A., Moriconi, M., and Altieri, F. and the JIRAM TEAM: Jupiter atmosphere in the infrared, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13182, https://doi.org/10.5194/egusphere-egu2020-13182, 2020.

EGU2020-6197 | Displays | PS5.2

Small-Scale Waves and Wave-Like Features in Jupiter’s Atmosphere Detected by JunoCam

Glenn Orton, Fachreddin Tabataba-Vakili, Gerald Eichstaedt, John Rogers, Candice Hansen, Thomas Momary, Andrew Ingersoll, Shawn Brueshaber, Michael H. Wong, Amy Simon, Leigh Fletcher, Michael Ravine, Michael Caplinger, Dakota Smith, Scott Bolton, Steven Levin, James Sinclair, Chloe Thepenier, Hamish Nicholson, and Abigail Anthony

Within the first 26 orbits of the Juno spacecraft around Jupiter, we have identified a variety of wave-like features in images made by its public-outreach camera, JunoCam.  Because of Juno’s unprecedented and repeated proximity to Jupiter’s cloud tops during its close approaches, JunoCam has detected more wave structures than any previous surveys.  Most of the waves appear in long wave packets, oriented east-west and populated by narrow wave crests.  Spacing between crests were measured as small as ~30 km, shorter than any previously measured.  Some waves are associated with atmospheric features, but others are not ostensibly associated with any visible cloud phenomena and thus may be generated by dynamical forcing below the visible cloud tops.    Some waves also appear to be converging and others appear to be overlapping, possibly at different atmospheric levels.  Another type of wave has a series of fronts that appear to be radiating outward from the center of a cyclone.  Although we have detected wave-like phenomena covering latitudes between 20°S and 45°N, most appear within 5° of latitude from the equator. Most waves appear in regions associated with prograde motions of the mean zonal winds.   Although Juno was unable to measure the velocity of wave features to diagnose the wave types due to its close and rapid flybys, both by our own upper limits on wave motions and by analogy with previous measurements, we expect that the waves JunoCam detected near the equator are inertia-gravity waves.

How to cite: Orton, G., Tabataba-Vakili, F., Eichstaedt, G., Rogers, J., Hansen, C., Momary, T., Ingersoll, A., Brueshaber, S., Wong, M. H., Simon, A., Fletcher, L., Ravine, M., Caplinger, M., Smith, D., Bolton, S., Levin, S., Sinclair, J., Thepenier, C., Nicholson, H., and Anthony, A.: Small-Scale Waves and Wave-Like Features in Jupiter’s Atmosphere Detected by JunoCam, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6197, https://doi.org/10.5194/egusphere-egu2020-6197, 2020.

PS6.1 – New mission concepts, instruments and enabling technologies for planetary exploration in the next decade

EGU2020-8739 | Displays | PS6.1 | Highlight

Luna-28 mission for polar samples return, as the key element of the initial stage of Russian Lunar Program

Igor Mitrofanov, Lev Zelenyi, and Vladislav Tretyakov

The most interesting sites for future lunar outposts are thought to be located closely to poles, and South one is found to be more preferable.  But before humans could land there, the sequence of robotic missions should be implemented to study the natural environment at the selected sites, to deliver some supporting systems for ensuring conditions of habitability and also to test the innovated technology for Earth-Moon-Earth round trip.

Therefore, the Russian Lunar Program will be ignited by four robotic missions, which Russian Academy of Science has selected for the initial stage of this Program. Their names Luna-25 -28 were selected taking into account the name of the last Soviet lander Luna-24 of 1976. The objectives of these missions are critically important for accomplishment of the future polar expeditions of humans. The missions will conduct orbital mapping of polar regions with fine spatial resolution, measurements of radiation environment at the selected landing sites, testing of water and space volatiles in the polar regolith, and, in particular – testing presence of complex molecules and pre-biotic molecular complexes, the lunar dust and exosphere, etc. Mobile elements of landing missions will investigate local areas around the landing sites to determine the best spots for the future habitation modules of human missions. In addition, the researches for the basic science will also be accomplished by these missions, such as the experiments for lunar-based astronomy at long wavelengths and at gamma-rays, the experiments for lunar seismology, for monitoring of interplanetary plasma and solar wind, etc.

The talk presents in details the concept of the key mission of the first stage of the Lunar Program, the Luna-28 mission for lunar polar sample return. The mission concept is based on the several basic requirements. The mission should have the return module for direct flight from Moon to Earth. The module should be able to deliver to the Earth a set of samples of polar regolith with the total mass of about 2 kilograms. They should be quarried from different depths of the shallow subsurface from several cm down to 1 meter. Samples should be delivered to the Earth with all volatiles, including water, in the frozen state. Small moonrover “Lunokhod” with mass below 100 kg should be delivered to the Moon by the lander. Before the launch of the return module, the rover could deliver remotely selected stones for return at the nearest vicinity of the lander, after the launch, the rover should conduct scientific studies of the area around the landing site.

The mission of Luna-28 will also be supported by the ground segment for proper curation of delivered samples and for their studies in the leading domestic and international research centers. The complex molecules and organic molecular complexes will be the main objects for these studies.   

How to cite: Mitrofanov, I., Zelenyi, L., and Tretyakov, V.: Luna-28 mission for polar samples return, as the key element of the initial stage of Russian Lunar Program , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-8739, https://doi.org/10.5194/egusphere-egu2020-8739, 2020.

EGU2020-12937 | Displays | PS6.1 | Highlight

Introduction to Mars Analog Mission: AMADEE20 and Exploration Cascade

Seda Ozdemir, Gernot Groemer, and Stefanie Garnitschnigg

Analog missions are the windows to future exploration to different planetary surfaces, e.g., Mars, the Moon, and asteroids, by playing a tremendous role in problem-solving, know-how and lesson learned in space research. AMADEE-20 is the Mars Analog Mission of the Austrian Space Forum (OEWF), will be held in Ramon Crater-Negev Desert, Israel between 15 October and 15 November 2020. The mission is mainly in fields of geosciences, astrobiology, engineering, life sciences, communications, and medical applications. Moreover, it provides data on the limitations and strengths of human-robotic exploration at every stage of the mission and, presents how to combine those two significant components for the scientific explorations. 

Ramon crater provides similarities to various Mars surface features, e.g., typical terrain with a wide range of sand-rocky surface and inclination, for the 13th mission of OeWF. AMADE-20 has already come forward with its mission architecture development and its evolving algorithm “Exploration Cascade” which is defining an efficient deployment sequence, providing a framework for the search of life on Mars (space analogies). It was first demonstrated at the last mission AMADEE-18 (Oman, February 2018) and became a critical methodological tool for AMADEE-20. Notably, this model provides a solid layout for all future analog missions by bridging different parties to avoid the human-robotic missions’ complexities, taking into account instrument requirements, flight planning border conditions, environmental dynamics and (ground-based) data processing pipeline limitations. This workflow defines when and where to deploy instruments, expected data transfer times to the Mission Support Center on Earth and how fast the data processing can lead to knowledge influencing the decision-making processes of the flight planning teams.

Here, we would like to present our upcoming analog mission; AMADEE-20 and discuss the mission development processes with all aspects including the Exploration Cascade.

How to cite: Ozdemir, S., Groemer, G., and Garnitschnigg, S.: Introduction to Mars Analog Mission: AMADEE20 and Exploration Cascade, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12937, https://doi.org/10.5194/egusphere-egu2020-12937, 2020.

EGU2020-20691 | Displays | PS6.1 | Highlight

EuroMoonMars programme & field campaigns

Bernard Foing and the ILEWG EuroMoonMars Team

EuroMoonMars is an ILEWG programme  following up ICEUM declarations as a collaboration between ILEWG, space agencies, academia, universities and research institutions and industries. The ILEWG EuroMoonMars programme includes research activities for data analysis, instruments tests and development, field tests in MoonMars analogue, pilot projects , training and hands-on workshops , and outreach activities. EuroMoonMars includes a programme of grants for Young Professional Researchers.  EuroMoonMars field campaigns have been organised in specific locations of technical, scientific and exploration interest. Field tests have been conducted in ESTEC, EAC, at Utah MDRS station , Eifel, Rio Tinto, Iceland, La Reunion,  LunAres base at Pila Poland , and HiSEas base in Hawaii. These were organised by ILEWG in partnership with ESTEC, VU Amsterdam, NASA Ames, GWU in Utah MDRS (EuroGeoMars 2009, and then yearly for EuroMoonMars 2010-2013). Other EuroMoonMars analogue field campaigns using selected instruments from ExoGeoLab suite were conducted in other MoonMars extreme analogues such as Eifel volcano, Rio Tinto, Iceland, La Reunion, Hawaii. 

EuroMoonMars field campaigns started with EuroGeoMars2009  (Utah MDRS, 24 Jan-1 Mar 2009) with ILEWG, ESA ESTEC , NASA Ames, VU Amsterdam , GWU  and continued with yearly EuroMoonMars Field campaigns in Utah (2010-2014), and in other Moon-Mars terrestrial analogues (Eifel volcanic area, Rio Tinto, Iceland, La Reunion,  LunAres base in  Poland , and HiSEAS base in Hawaii ). 

EMMIHS campaigns (EuroMoonMars-IMA International Moonbase Alliance- HiSEAS): EuroMoonMars 2018-19 supported field campaigns at  IMA HISEAS base on Mauna Loa volcano in Hawaii . The Hawaii - Space Exploration Analog and Simulation (HI-SEAS) habitat is located at 8,200’ (2,500 meters) in elevation on the largest mountain in the world, Mauna Loa, on the Big Island of Hawai'i. As of 2018, the International Moonbase Alliance (IMA), an organization dedicated to building sustainable settlements on the Moon, has been organising regular simulated missions to the Moon, Mars or other planetary bodies at HI-SEAS.  In 2019, the EuroMoonMars campaigns were launched at HI-SEAS. Six scientists, engineers, journalists and photographers spent two weeks at the HI-SEAS station performing research relevant to both the Moon and Mars there.  Furthermore, the research and technological experiments conducted at HI-SEAS are going to be used to help build a Moonbase in Hawai’i, and ultimately to create an actual Moonbase on the Moon, as part of IMA’s major goals. The campaigns were remote;y supported from Blue Planet Lab (; support@ BluePlanet/IMA: Ponthieux, Cox, Rogers, Foing et al ) & ESTEC/ILEWG/VU Amsterdam (Ageli, Foing, Beniest, Sitnikova, Preusterink et al ) and had analog astronaut crew: 2018 EMMIHS0 EMM-IMA-HISEAS  scouting campaign May 2018  ( Crew: Rogers H&A, Foing, Wilhite, Machida); 2019 EMMIHS1 February (crew: Musilova, Sirikan, Mulder, Weert, Burstein, Pothier); 2019 EMMIHS2  8-22 December in Moonbase , (crew: Musilova, Kerber, Castro, Wanske, Pouwels, d’Angelo) ; 2020 EMMIHS3   18 Jan- 1 Feb  in Moonbase, (crew: Heemskerk M&H, Rajkakati, Musilova, Brasileiro, Edison); 2020 EMMIHS4    1-15 Feb in MoonbaseEMMIHS0 , (crew: Boross, Musilova, Neidlinger, Pantazidis, Sheini) . 

Other EuroMoonMars 2020 campaigns are planned in ESTEC, Lunares Poland , Iceland ,  Etna (ARCHES with DLR/ESA) & IMA HISEAS.

How to cite: Foing, B. and the ILEWG EuroMoonMars Team: EuroMoonMars programme & field campaigns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20691, https://doi.org/10.5194/egusphere-egu2020-20691, 2020.

EGU2020-18245 | Displays | PS6.1 | Highlight

Semi-privacy and Color Application as Elements of Habitability in Concept Designs for Extra-terrestrial Habitation

Sabrina Kerber, Ariane Wanske, Michaela Musilova, and Bernard Foing

Introduction
Concepts for designs of extra-terrestrial habitats are experiencing a growing importance in the space industry. New technologies and innovative materials bring the need for novel spatial arrangements in these habitats. Two of the most important components to improve habitability in extra-terrestrial habitats - the situation of privacy and color application - have been addressed in a lunar simulation (EMMIHS-II) at the Hawai´i Space Exploration Analog and Simulations (HI-SEAS) habitat. This analog astronaut mission was initiated by the European Space Agency’s (ESA) EuroMoonMars (EMM) and International Lunar Exploration Working Group (ILEWG) in cooperation with the International MoonBase Alliance (IMA).
The question of how much privacy is necessary to create a liveable environment in an extra-terrestrial habitat has engaged space architects for the last decades. [1] The same keen interest has been attributed to the importance of color in guiding architectural conceptions in the often colour-less environment of outer space. [2] 
Less attention has been paid to the issue of semi-private space. Past analog astronaut missions at the HI-SEAS facility came across not only a lack of private space but also a scarcity of areas crew members could retreat to without completely leaving the common space. [2] Such semi-private areas bear great potential both from a spatial and psychological point of view.

Methodology
The research results presented here are based on several experiments conducted during the EMMIHS-II lunar simulation at the HI-SEAS Mars/Moon Research Facility.Potential benefits on crew cohesion, work effectiveness and personal mood were studied through setting up a semi-private area and assessing its use by the crew.
Further experiments investigated the analog astronauts’ reaction to disparate color situations inside the habitat and this semi-private space.
The findings will serve as a basis for future architectural design concepts in extra-terrestrial habitats and also offer the potential for further investigations during future analog missions.

Acknowledgements
First, we would like to thank our fellow EMMIHS-II crew members (M. Musilova, A. J. D’Angelo, A. P. Castro de Paula Nunes, C.R. Pouwels) and the EMMIHS-II mission sponsors. In addition, our gratitude goes out to the HI-SEAS Mission Control, ground support at ESA/ESTEC and the ILEWG EuroMoonMars manager, Prof. B. H. Foing, for enabling this research.

 

References
[1] K. Kennedy, S. Capps (2000). Designing Space Habitation. Space 2000. 10.1061/40479(204)6.
[2] I. Schlacht, H. Birke (2011). Space design: Visual interface of space habitats. Personal and Ubiquitous Computing. 15. 497-509. 10.1007/s00779-010-0326-4.
[3] S. Häuplik-Meusburger, K. Binsted et al (2017). Habitability Studies and Full Scale Simulation Research: Preliminary themes following HISEAS mission IV.
[4] Musilova, M., Rogers, H., Foing, B.H. et al (2019). EMM IMA HI-SEAS campaign February 2019. EPSC-DPS2019-1152.
[5] EuroMoonMars Instruments, Research, Field Campaigns and Activities 2017-2019. Foing, B.H., EuroMoonMars 2018-2019 Team. 2019 LPI Contrib. No. 3090.

How to cite: Kerber, S., Wanske, A., Musilova, M., and Foing, B.: Semi-privacy and Color Application as Elements of Habitability in Concept Designs for Extra-terrestrial Habitation, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18245, https://doi.org/10.5194/egusphere-egu2020-18245, 2020.

EGU2020-11096 | Displays | PS6.1

Chemical identification and automatic spectral classification of Microfossils from the Gunflint chert (1,88 Ga)

Rustam Lukmanov, Marek Tulej, Andreas Riedo, Niels Ligterink, Valentine Riedo, Coenraad de Koning, and Peter Wurz

The identification of microbial remains on planetary bodies is an extremely challenging endeavor, requiring the utilization of novel measurement techniques and modern analytical approaches.  We performed an extensive study of the chert sample from Gunflint formation (1.88 Ga) containing populations of Precambrian microfossils with a laser ablation ionization mass spectrometer (LIMS) (Riedo et al., 2013; Wiesendanger et al., 2018) intended for application in space. Chemical characterization on microscale can open a new perspective in the identification of microbial remains, where morphological features might be lost and provide additional lines of evidence towards proving biogenicity of a given putative sample. Chert from the Gunflint formation in this study is considered as a Martian analogue where remains of microfossils are mainly concentrated within circular and tubular structures, which are primarily made from collapsed cell walls entombed within silica.

We sampled the microfossils and surrounding chert (host area) with fs UV laser with a spot size of 8 μm and retrieved intensities of 180 consecutive single mass peaks from each mass spectrum. We collected 60’000 mass spectra and build an intensity-based classifier, intended to process large datasets from cherts and identify their classes in an automatic regime. Using elemental pair-to-pair correlation analysis, we identified relevant masses for each given mineralogical class.  Additionally, we will present results of chemical imaging of the sample and discuss in details the chemical composition of microfossils and surrounding chert as well as technical aspects of the identification of spectra from the microfossils.

We will show how rich spectral information can be reduced to the low dimensional domain using principal components analysis and used for successful classification. Moreover, we will present the established workflow and discuss possibilities to extend this approach to other astrobiologically relevant formations, such as phosphates, carbonates, hydrothermal silicates. Future Mars exploration with enabling technologies as machine learning and big data processing coupled with high-output instrumentation such as laser ablation ionization time-of-flight mass spectrometry has the capacity to improve scientific return and achieve stated objectives and therefore should be given appropriate attention in the future missions. 

 

Riedo, A., Neuland, M., Meyer, S., Tulej, M., & Wurz, P. (2013). Coupling of LMS with a fs-laser ablation ion source: Elemental and isotope composition measurements. Journal of Analytical Atomic Spectrometry, 28(8), 1256–1269.

Wiesendanger, R., Wacey, D., Tulej, M., Neubeck, A., Ivarsson, M., Grimaudo, V., … Wurz, P. (2018). Chemical and Optical Identification of Micrometer-Sized 1.9 Billion-Year-Old Fossils by Combining a Miniature Laser Ablation Ionization Mass Spectrometry System with an Optical Microscope. Astrobiology, 18(8), 1071–1080.

 

 

How to cite: Lukmanov, R., Tulej, M., Riedo, A., Ligterink, N., Riedo, V., de Koning, C., and Wurz, P.: Chemical identification and automatic spectral classification of Microfossils from the Gunflint chert (1,88 Ga), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11096, https://doi.org/10.5194/egusphere-egu2020-11096, 2020.

EGU2020-20179 | Displays | PS6.1

Gan De: Science Objectives and Mission Scenarios For China’s Mission to the Jupiter System

Michel Blanc, Chi Wang, Lei Li, Mingtao Li, Linghua Wang, Yuming Wang, Yuxian Wang, Qiugang Zong, Nicolas Andre, Olivier Mousis, Daniel Hestroffer, and Pierre Vernazza

To answer key scientific questions about Planetary Systems, it is particularly fruitful to study the Jupiter System, the most complex “secondary” planetary system in the solar system, using the power of in situ exploration. Two key questions should be addressed by future missions:

A-How did the Jupiter System form? Answers can be found in the most primitive objects of the system: Callisto seems to have been only partly differentiated; its bulk composition, interior and surface terrains keep records of its early eons; the 77 or so irregular satellites, wandering far out beyond the region occupied by the Galilean satellites, are unique and precious remnants of the populations of planetesimals which orbited the outer Solar System at the time of Jupiter’s formation.

B-How does it work? One can address this question by studying and understanding the chain of energy transfer operating today in the Jupiter System: how is gravitational energy from Jupiter transferred to Io’s interior via tidal heat dissipation to power its volcanic activity? How does this activity in turn store energy into the Io plasma torus to drive the whole magnetosphere into motion? How does the interplay between the Io torus and the solar wind dump energy into heating of Jupiter’s upper atmosphere, or release it into the tail and interplanetary space?

Starting from the measurement requirements derived from these two objectives, we propose two ambitious mission scenarios, named JCO and JSO, to meet these requirements. Both use the combination of a main spacecraft and one or several specialized small platforms.

JCO, the Jupiter Callisto Orbiter, first flies by and characterizes several irregular satellites during its Jovian orbital tour. It is then injected into Callisto orbit to characterize its surface and interior, investigate its degree of differentiation and search for the possible existence of an internal ocean.  As an option, JCO could release a lander to Callisto’s surface to perform key measurements of chemical composition, clues to understanding the formation scenario of the Galilean moons.

JSO, the Jupiter System Observer, performs several fly-bys of Io and visits several irregular satellites during its Jovian orbital tour. As an option, JSO could release one or several small satellites to perform multi-point studies of the dynamics of the Jovian magnetosphere. At the end of its tour it could be injected into a halo orbit around the L1 Lagrangian point of the Sun-Jupiter system to monitor the solar wind upstream of the Jovian magnetosphere, measure Jovian seismic oscillations, and perform a comprehensive survey of the irregular satellites.

Led by China under the name of GAN De, the first astronomer to have claimed an observation of a moon of Jupiter four centuries BC, and broadly open to international collaboration, a mission flying to Jupiter in the 2030’s according to either one of these scenarios will be able to capitalize on the legacy of previous missions to Jupiter (Juno, JUICE, Europa Clipper) and to trigger a very exciting international collaboration to unravel the mysteries of the origins and workings of the Jupiter system.

How to cite: Blanc, M., Wang, C., Li, L., Li, M., Wang, L., Wang, Y., Wang, Y., Zong, Q., Andre, N., Mousis, O., Hestroffer, D., and Vernazza, P.: Gan De: Science Objectives and Mission Scenarios For China’s Mission to the Jupiter System, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20179, https://doi.org/10.5194/egusphere-egu2020-20179, 2020.

EGU2020-11339 | Displays | PS6.1

Detection, Analysis, and Mapping of Surface Material from Europa

William Goode, Sascha Kempf, and Juergen Schmidt

Europa Clipper, NASA’s next flagship mission launching in 2024, will closely study Jupiter’s icy ocean moon in order to determine if it has conditions favorable for life. Among the nine scientific instruments will be the Surface Dust Analyzer (SUDA), a state-of-the-art instrument for in situ chemical analysis of dust grains. During a series of close flybys of Europa (~25 to 100 km at closest approach), SUDA will collect and measure the chemical composition of thousands of ice and dust particles ranging from ~200 nm to 100 microns in radius, which will be direct samples from Europa’s surface. This is possible due to the flux of interplanetary micrometeoroids impacting the surface producing a cloud of ejecta particles, which SUDA detects and analyzes. Knowing the spacecraft trajectory, instrument pointing, and particle velocity through the instrument aperture, SUDA’s in situ chemical measurements will be linked to their site of origin on Europa’s surface near the spacecraft ground-track, thereby offering geological context for chemical composition. This method implements established models of impact ejecta dynamics and derives distributions for each measurement’s site of origin on the surface using Monte Carlo simulations. These studies are especially useful for evaluating the science return for particular tour designs since we can simulate SUDA’s effectiveness at mapping the composition of geologically interesting areas. With well targeted flybys by Europa Clipper, SUDA will be help constrain the chemical composition of surface material originating from various geological features, particularly those characterized by non-icy materials. This will enhance our understanding of the exchange processes between the icy surface and subsurface ocean as well as assess the habitability of Europa.

How to cite: Goode, W., Kempf, S., and Schmidt, J.: Detection, Analysis, and Mapping of Surface Material from Europa, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11339, https://doi.org/10.5194/egusphere-egu2020-11339, 2020.

EGU2020-6100 | Displays | PS6.1

Spirit of pionieers, economy and Solar System exploration

Leszek Czechowski

SpaceX’s lesson: SpaceX presents a new approach to astronautics. Its success is a result of the simple application of a commercial approach. Similar breakthroughs were observed when government funding became unnecessary for new technology.

 

SpaceX’s recipes:

Reusability: Falcon 9 – a reusable rocket.

Simplicity: Contrary to most of other rockets, Falcon 9 uses one type of engine only – Merlin 1 (in different versions).

Steady improvements: Initial versions of Merlin had rather moderate parameters. Presently, the engine represents one of the best achievement in technology of RP-1/LOX engines (high specific impulse, high ratio thrust/weight).

Precooling of fuel allows more fuel in the same volume.

 

“Mass” production: A few hundreds of Merlin engines are produced per year. It could be not impressive but it is more than many other rocket engines.

 

Special taxes? Given the high public support for space research, probably politicians may be convinced to introduce a special "space tax"? Currently, the average European spends the equivalent of a can of beer monthly on space research!

 

One-copy? The cost of the rocket is usually less than 10% of the total cost of the interplanetary mission. Most of the money is spent for development of unique devices, produced in one copy.

The second copy of Curiosity Rover evidently would be much cheaper than the R&D + first copy’s production cost (about US$ 2.5 billion). Probably no more than US$ 1 billion. At least six Curiosity class rovers could be useful for Mars research.

 

Better cooperation: Better cooperation between space agencies can be beneficial. Instead of independent attempts to develop technology already developed by others, decisions makers should consider buying ready products, licences, exchanging of technology, etc.

 

Achievements from previous decades: Just as in our wardrobe there are old attractive outfits, so in NASA's wardrobe there are past achievements. NERVA nuclear engine (developed 50 years ago) has specific impulse twice as high as the best chemical engines! Fortunately, US Congress recently has approved funds for the development of nuclear engines.

 

The spirit of pioneers: During the Apollo program, there was enthusiasm and a creative spirit typical of pioneering times. Presently, outstanding people still inspire others by pointing out that the conquest of space does not have to be just the domain of large agencies.

 

Conclusions: The current attitude towards space exploration is often the result of irrational political and nationalistic pressure. SpaceX's success still seems to be ignored by many decision makers. A commercial approach and common sense seem to be the best remedies for many of the problems. Outstanding scientists, engineers and technology entrepreneurs can inspire others and restore the spirit of pioneering times known from the Apollo program.

 

How to cite: Czechowski, L.: Spirit of pionieers, economy and Solar System exploration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6100, https://doi.org/10.5194/egusphere-egu2020-6100, 2020.

EGU2020-6204 | Displays | PS6.1

EUV observation for Earth’s plasmasphere from EML2 by nano-spacecraft

Kazuo Yoshioka, Masaki Kuwabara, Reina Hikida, and Ichiro Yoshikawa

The nano-spacecraft (6U) mission named EQUULEUS will be launched in 2020 as one of the sub-payloads of NASA’s Space Launch System. EQUULEUS will fly to a liberation orbit around the Earth-Moon L2 point and demonstrate trajectory control techniques within the Sun-Earth-Moon region for the first time as a nano-spacecraft. A small telescope for extreme ultraviolet (EUV) named PHOENIX will be boarded on the spacecraft. It consists of multilayer-coated mirror (diameter of 6 cm with Mo/Si coating), metallic thin filter, and photon counting device with microchannel plate and resistive anode. The reflectance of the mirror and transmittance of the filter are optimized for the emission line of ionic helium (wavelength of 30.4 nm) which is the important component of the plasmasphere of the Earth. By flying far from the Earth, the entire image of plasmasphere can be obtained. In this presentation, the mission concept and the design of the telescope, and the status of the latest development will be shown.

How to cite: Yoshioka, K., Kuwabara, M., Hikida, R., and Yoshikawa, I.: EUV observation for Earth’s plasmasphere from EML2 by nano-spacecraft , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6204, https://doi.org/10.5194/egusphere-egu2020-6204, 2020.

EGU2020-4255 | Displays | PS6.1

A Double Hemispherical Probe for the Advancement of In Situ Plasma Measurements

Joseph Samaniego and Xu Wang

Langmuir probes are conductors of simple geometries (spheres, disks, cylinders, etc.) inserted into a plasma. By sweeping a voltage on the probe and measuring the current collected or emitted, a current-voltage (I-V) relationship can be found and interpreted to derive the density, temperature, and potential of the ambient plasma. Over the past 50 years, Langmuir probes have been flown on spacecraft missions for in-situ measurements of the local plasma environment. However, even after decades of use, there are still challenges in the analysis and interpretation of Langmuir probe measurements due to local plasmas created around the probe as a result of plasma interactions with the probe itself and spacecraft.

The Double Hemispherical Probe (DHP) is a directional Langmuir probe made of two hemispheres that are electrically isolated from each other and swept with a voltage together to get two separate I-V curves. The DHP uses the I-V curve differences between the two hemispheres to gain information of the asymmetry of the local plasma around the probe to retrieve the true ambient plasma parameters. Specifically, the DHP is intended to improve the plasma measurements in the following scenarios: i) Low-density plasmas; ii) flowing plasmas; iii) high-surface-emission environments; and iv) dust-rich plasmas. The following discusses the current progress of the DHP development.

Low-density plasmas create large Debye sheaths around the spacecraft that may engulf the Langmuir probe attached to a boom with a finite length. The potential drop in the sheath can change the characteristics of charged particles collected by the probe, causing mischaracterization of the ambient plasma. As expected, the I-V curves of both hemispheres match in the bulk plasma. It was found that as the DHP is moved ‘deeper’ into the sheath of the spacecraft, the currents of the two hemispheres diverge. The saturation current ratio of the hemispheres of the DHP was found to have monotonic relationships with the plasma characteristics measured in the sheath. A technique was created to retrieve the ambient plasma parameters.

In space ions generally have relative velocities with respect to the spacecraft due to flowing plasmas or fast-moving spacecraft, creating an ion wake behind the probe itself. This self-wake can cause issues in interpreting the I-V curves for both ion and electron species. The ion saturation current of either hemisphere of the DHP is dependent on the ion Mach number (the ratio of the ion flow speed to the thermal speed). Electrons are generally in the thermal state. However, depending on the ratio of the probe size to the Debye length, ambipolar electric fields can be created at the wake boundaries, causing the reduction of the electron density in the downstream side of the probe and its subsequent underestimation measured by traditional single Langmuir probes. It was shown that the DHP can identify this self-wake effect and properly measure the true ambient plasma parameters.    

Future work will explore the effects of high-surface-emission environments and dust-rich plasmas on DHP measurements and to develop techniques to resolve the true ambient plasma parameters in these environments. 

How to cite: Samaniego, J. and Wang, X.: A Double Hemispherical Probe for the Advancement of In Situ Plasma Measurements, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4255, https://doi.org/10.5194/egusphere-egu2020-4255, 2020.

EGU2020-18025 | Displays | PS6.1

Operation Plan of Geostationary Environmental Monitoring Spectrometer (GEMS)

Jaehoon Jeong, Goo Kim, Kyung-Jung Moon, Minseok Nam, Deokrae Kim, and Dongwon Lee

The Geostationary Environmental Monitoring Spectrometer (GEMS), which is the world's first geostationary environmental satellite, is scheduled to be launched in February of this year. Observing more than 8 times a day (up to 10 times), GEMS is expected to play an important role for regional and periodic monitoring of air quality and pollution in East Asia. In this study, we report the status of GEMS operation readiness and the overall operation plan after launch. The design and development of a ground station system for GEMS operation and utilisation are now completed. The GEMS ground system will generate level 1B (L1B) data through radiometric and geometric correction after receiving the signal and produce a level 2 (L2) product by using L1B as input data. In the case of L2 data, it will produce 20 kinds of output, including ozone, aerosol, volatile organic compounds (VOCs) such as formaldehyde and glyoxal, gas products such as nitrogen dioxide and sulphur dioxide, surface information, and more. All algorithms for L2 product generation have been developed and verified. Currently, we are continuing to work toward stabilisation and speed improvement and plan to produce L2 products within one hour of observation. All processing must be completed within one hour before the next observation begins, specifically 30 minutes for L1B generation and the remaining 30 minutes for L2 generation. GEMS L2 processing is scheduled day and night. In the daytime, the goal is to produce L2 products within one hour for real-time distribution. In the night operation, on the other hand, the goal is to produce L2 products with a main purpose of improving the quality of L2 products through the use of additional information. GEMS will have an in-orbit test (IOT) period of approximately eight months following launch for radiometric and geometric calibration. During this period, many efforts will be made to ensure the quality of GEMS data, including comparative verification with reference data obtained from various observation methods and cross-calibration and -validation with the organisations that have made an agreement in advance. Suggestions from institutions interested in mutual collaboration for GEMS calibration are still welcome (note that proposals for mutual collaboration remain open). We also plan to verify the effectiveness of the night-time operation during the IOT period. The products will be distributed in stages after IOT according to the internally established distribution regulations. In this study, the overall operation of GEMS and the data distribution plan are presented. Although the schedule may change slightly depending on various situations after launch, this information is expected to be useful for many institutions and researchers in related fields who are very interested in GEMS data.

How to cite: Jeong, J., Kim, G., Moon, K.-J., Nam, M., Kim, D., and Lee, D.: Operation Plan of Geostationary Environmental Monitoring Spectrometer (GEMS), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18025, https://doi.org/10.5194/egusphere-egu2020-18025, 2020.

EGU2020-21809 | Displays | PS6.1

Towards a time-gated Raman spectrometer with VIS-NIR SPAD camera for stand-off planetary surface exploration

Luca Ciaffoni, Pavel Matousek, Iain Sedgwick, and Nick Waltham

Single-photon avalanche diode (SPAD) arrays are solid-state detectors that offer imaging capabilities at the level of individual photons. Very recently, time-gated cameras based on solid-state CMOS SPAD technology have been proposed for improving the performance and field applicability of Raman spectrometers for on-surface planetary geoscience through addressing the largely unmet challenge of suppression of fluorescence interference in highly fluorescent rocks (e.g. minerals containing phosphate, one of the chemical nutrients thought to be essential for life).

The effectiveness of Raman SPAD cameras currently proposed in the literature, however, is at present restricted to a small subset of samples and regimes of operations. This is largely owed to two main limitations. Firstly, their performance is optimised only for the VIS spectral region (typically around 532 nm), where the fluorescence issue tends to be exacerbated due to increased likelihood of electronic excitation for most molecular species compared to Raman excitation above 775 nm. Secondly, their 2D architecture is limited to few pixel rows, which reduces their light-gathering capability and consequently the detection performance of the Raman spectrometer.

We present the preliminary work towards the development of a novel time-gated Raman spectrometer that relies on a large format NIR-optimised SPAD camera prototype with time resolution better than 200 ps. This technology promises to deliver unsurpassed dual-wavelength Raman detection capabilities that would be transformative for stand-off sample analysis in surface exploration of Mars and Icy moons.

A performance analysis model for predicting the fluorescence and ambient light suppression performance levels in relation to the properties of various samples, environmental conditions and specifications of the laser and camera is presented, followed by the preliminary designs of the SPAD camera module and Raman spectrometer.

How to cite: Ciaffoni, L., Matousek, P., Sedgwick, I., and Waltham, N.: Towards a time-gated Raman spectrometer with VIS-NIR SPAD camera for stand-off planetary surface exploration, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21809, https://doi.org/10.5194/egusphere-egu2020-21809, 2020.

The procedures for detecting fossils on Mars can be derived from the methods that are already used in terrestrial paleobiology (Cady et al., 2003). Here fossils preserving regions are visually located, then inspected for morphological features that might imply fossilised biology (Cady and Noffke, 2009; Westall et al., 2015). Morphological evidence of microfossils on its own is not a completely reliable biosignature (García Ruiz et al., 2002).  However, evidence of biological activity may be implanted within the molecular and isotopic composition of organic compounds, which can serve as biosignatures (Summons et al., 2008). Thus, combining both morphological with organo-geochemical evidence could strengthen any argument that a given geological feature could be associated with biological activity. The results from the simultaneous morphological and geochemical analysis of geobiological structures on Earth could provide evidence that any comparable structures that may be observed on Mars, are potentially connected to biological activity, and therefore, may be suitable for collection for return to the Earth, for further analysis.

As a proof of concept, the distribution of the organic material that is associated with distinctive microtubules in the glassy volcaniclastic shards within tuff, that have been suggested to be putative ichnofossils (Banergee and Muehlenbachs, 2003), these were analysed by us using X-ray photoelectron spectroscopy, nanoSIMS and the Ionoptika J105 time of flight secondary ion mass spectrometer, with  an argon gas cluster ion beam. This indicated that nitrogenous organic material occurred in regions of the sample that were rich in microtubule textures and in the surrounding microfractures (Sano et al., 2016). 

These results demonstrated that the J105 ToF-SIMS combined with XPS and GC/MS analysis is able to match geomorphological features with their organic and inorganic composition at the µm scale, which may be a useful approach for the identification of fossilised life on Mars.

References:

Banerjee et al., (2003). Geochemistry, Geophysics, Geosystems, 4(4).

Cady et al., (2003). Astrobiology, 3(2), pp.351-368.

Cady et al., (2009). GSA Today, 19(11).

García Ruiz et al., (2002). Astrobiology, 2(3), pp.353-369.

Summons et al., (2008) Astrobiology, 90, 1151–1154.

Westall, F., et al., (2015). Astrobiology, 15(11), pp.998-1029.

Sano, N et al., (2016). J. of Vac Sci & Tech A: 34(4), p.041405

How to cite: Purvis, G., van der Land, C., Sano, N., Cumpson, P., and Gray, N.: Combining morphological and organic geochemical evidence for investigating putative ichnofossils: A case study for an approach for the detection of fossilised life on Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22041, https://doi.org/10.5194/egusphere-egu2020-22041, 2020.

EGU2020-9105 | Displays | PS6.1

A Method to Discriminate between Abiotic and Biotic Processes on Cryovolcanically Active Ocean Worlds

Fabian Klenner, Frank Postberg, Jon Hillier, Nozair Khawaja, Morgan L. Cable, Bernd Abel, Sascha Kempf, Jonathan Lunine, and Christopher R. Glein

Discriminating between abiotic and biotic signatures of amino acids and fatty acids on extraterrestrial ocean worlds is key to the search for life and its emergence on these bodies. Cryovolcanically active ocean worlds, such as Enceladus and potentially Europa, eject water ice grains formed from subsurface water into space. The ejected ice grains can be sampled by impact ionization mass spectrometers onboard spacecraft – such as Cassini’s Cosmic Dust Analyzer (CDA) – thereby exploring the habitability of the subsurface oceans. Complex organic macromolecules [1], as well as nitrogen- and oxygen-bearing organics that could act as amino acid precursors [2], were recently detected by the CDA in Enceladean ice grains. The next step is to determine whether potential biosignatures, such as amino acids and fatty acids, may also be detected using impact ionization mass spectrometry and whether abiotic and biotic signatures can be distinguished after a hypervelocity ice grain impact.

Previous experiments with an analogue Laser Induced Liquid Beam Ion Desorption (LILBID) spectrometer, proven to accurately reproduce the mass spectra of water ice grains at different impact speeds in space [3], have shown that most amino acids, fatty acids and peptides in pure water ice grains can be detected at nanomolar concentrations [4]. Here, we investigate the mass spectral appearance and detection limits of amino acids and fatty acids, in proportions representative of either biotic or abiotic formation processes, in a more realistic, Enceladus-like scenario. The analytes are mixed with over twenty additional organic (e.g., carboxylic acids) and inorganic background components (e.g., salts) suitable for ice grains formed from Enceladean ocean water which has interacted with the moon’s rocky core.

We find it is possible to distinguish and identify abiotic and biotic mass spectral fingerprints of potential biosignatures from the background even under these difficult conditions. In contrast to our previous work, we here find that amino acids and fatty acids form characteristic sodium-complexed molecular cations in a salty matrix. Detection limits of the organic biosignatures depend strongly on their Pka values and the salinity of the ice grains. Amino acid and fatty acid concentrations realistic for abiotic and biotic processes in the Enceladus ocean can be detected and characteristic abiotic and biotic mass spectral signatures can be clearly distinguished from each other [5]. We infer from our experiments that ice grain encounter velocities of 3 – 6 km/s are most appropriate for the detection of the distinctive signatures of the biomolecules. In this work, we established a standard methodology to detect and discriminate between abiotic and biotic processes in ice grains from extraterrestrial water environments.

 

References:

[1] Postberg et al. (2018) Nature 558, 564-568, [2] Khawaja et al. (2019) Mon Not R Astron Soc 489, 5231-5243, [3] Klenner et al. (2019) Rapid Commun Mass Spectrom 33, 1751-1760, [4] Klenner et al. (2020a) Astrobiology 20, in press, [5] Klenner et al. (2020b) Astrobiology, under review

How to cite: Klenner, F., Postberg, F., Hillier, J., Khawaja, N., Cable, M. L., Abel, B., Kempf, S., Lunine, J., and Glein, C. R.: A Method to Discriminate between Abiotic and Biotic Processes on Cryovolcanically Active Ocean Worlds, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9105, https://doi.org/10.5194/egusphere-egu2020-9105, 2020.

EGU2020-11952 | Displays | PS6.1

The in-situ exploration of Jupiter's radiation belts

Elias Roussos and the JUPITER_BELTS_TEAM

Jupiter has the most energetic and complex radiation belts in our solar system. Their hazardous environment is the reason why so many spacecraft avoid rather than investigate them, and explains how they have kept many of their secrets so well hidden, despite having been studied for decades. We believe that these secrets are worth unveiling, as Jupiter’s radiation belts and the vast magnetosphere that encloses them constitute an unprecedented physical laboratory, suitable for both interdisciplinary and novel scientific investigations: From studying fundamental high energy plasma physics processes which operate throughout the universe, such as adiabatic charged particle acceleration and nonlinear wave-particle interactions; to exploiting the astrobiological consequences of energetic particle radiation. The in-situ exploration of the uninviting environment of Jupiter’s radiation belts presents us with many challenges in mission design, science planning, instrumentation and technology development. We address these challenges by reviewing the different options that exist for direct and indirect observation of this unique system. We stress the need for new instruments, the value of synergistic Earth and Jupiter-based remote sensing and in-situ investigations, and the vital importance of multi-spacecraft, in-situ measurements. While simultaneous, multi-point in-situ observations have long become the standard for exploring electromagnetic interactions in the inner solar system, they have never taken place at Jupiter or any strongly magnetized planet besides Earth. We conclude that a dedicated multi-spacecraft mission to Jupiter’s radiation belts is an essential and obvious way forward. Besides guaranteeing many discoveries and outstanding progress in our understanding of planetary radiation belts, it offers a number of opportunities for interdisciplinary science investigations. For all these reasons, the exploration of Jupiter’s radiation belts deserves to be given a high priority in the future exploration of our solar system. A White Paper on this subject was submitted in response to ESA's Voyage 2050 call.

How to cite: Roussos, E. and the JUPITER_BELTS_TEAM: The in-situ exploration of Jupiter's radiation belts, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11952, https://doi.org/10.5194/egusphere-egu2020-11952, 2020.

EGU2020-19621 | Displays | PS6.1

Potential of a Multimodal Orbital Radar Mission for the Exploration of Enceladus

Andreas Benedikter, Marc Rodriguez-Cassola, Gerhard Krieger, Rolf Scheiber, Gustavo Martin del Campo Becerra, Ralf Horn, Michael Stelzig, Alberto Moreira, and Martin Vossiek

An Enceladus mission launched within a realistic time frame (e.g., launch between 2025 and 2040 and a transfer time of about ten years) would likely arrive as the sun is departing or gone from the most interesting South Polar Region marked by its active jets erupting through the ice crust. This almost drives the need for a radar instrument enabling the imaging, mapping and characterization of the moon independent of sunlight illumination. The known ice penetration capability of radar waves in the tens of MHz up to few GHz range allows for the exploration of subsurface features, whereas the surface may be imaged with high level of detail in higher frequencies up to several tens of GHz. In the frame of the Enceladus Explorer Initiative (EnEx) of the German Aerospace Center (DLR), we are currently investigating the potential of a multimodal orbital radar instrument to be used as a companion to a lander mission and to contribute in the understanding of the structure, composition and temporal variation of the Enceladean ice crust and the involved geophysical processes.

The considered orbit geometries, strongly constrained by the presence of Saturn, allow for global coverage and offer half-daily revisit of the South Polar Region. We suggest a multi frequency system working concurrently in high frequency (e.g., Ka-band) and lower frequency (e.g., P-band) for surface and subsurface exploration, respectively, both capable of operating in a variety of modes: i) high resolution imaging used as a synthetic aperture radar (SAR), ii) SAR interferometer for topography, permittivity and surface and volume deformation estimates, iii) nadir looking configuration operating as an altimeter for elevation estimates and as a sounder for subsurface exploration with great penetration capability, iv) radiometer for surface temperature estimates and inversion of temperature profiles, and v) bistatic measurements between the radar instrument and an ice penetrating probe deployed by the lander with similarities to the CONSERT instrument of ESA's Rosetta mission.

In this presentation, we evaluate the potential of the different modes concerning their scientific output and their usefulness for supporting the success of a lander mission. In particular the performance of SAR imaging and interferometry (single- and repeat-pass) modes are analysed, which are expected to provide key information for landing site selection such as structure, composition and topography of the surface and subsurface with metric resolution. For validation, we present results of a SAR campaign conducted using DLR's airborne sensor F-SAR over an alpine glacier, with simultaneous X- and L-band acquisitions. The campaign incorporates repeat- and single-pass acquisitions, as well as circular flights, which provide interferometric and tomographic measurements with observation geometries similar to those of an Enceladus mission. Furthermore, we provide an analysis towards a bistatic sounding experiment. Utilizing the transmission line between the radar instrument and a transponder integrated in an ice penetrating probe allows for the inversion of the spatial distribution of the dielectric ice properties and associated geophysical parameters (e.g., density, grain size, temperature, and salinity).

How to cite: Benedikter, A., Rodriguez-Cassola, M., Krieger, G., Scheiber, R., Martin del Campo Becerra, G., Horn, R., Stelzig, M., Moreira, A., and Vossiek, M.: Potential of a Multimodal Orbital Radar Mission for the Exploration of Enceladus, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19621, https://doi.org/10.5194/egusphere-egu2020-19621, 2020.

EGU2020-13250 | Displays | PS6.1

MiniPINS - Miniature Planetary In-situ Sensors

Maria Genzer, Maria Hieta, Antti Kestilä, Harri Haukka, Ignacio Arruego, Victor Apéstigue, Jose Antonio Manfredi, Cristina Ortega, Manuel Dominiguez, Servando Espejo, Héctor Guerrero, Matti Palin, Jarmo Kivekäs, Petri Koskimaa, and Matti Talvioja

MiniPINS is an ESA study led by the Finnish Meteorological Institute to develop and prototype miniaturised surface sensor packages (SSPs) for Mars and the Moon. The study aims at miniaturising the scientific sensors and subsystems, as well as identifying and utilizing commonalities of the packages, allowing to optimise the design, cut costs and reduce the development time. We present the Preliminary Mission Plan and possible concepts for the landers for this mission. 

The Mars SSP will be a small 25 kg penetrator deployed from Mars orbit. Maximally four (4) penetrators will be carried to the Martian orbit by an Orbiter and the Orbiter will be oriented for deployment of each penetrator. In the Martian atmosphere the penetrators undergo aerodynamic braking until they reach the target velocity for entering the Martian surface. 

The SSPs will start their scientific observations after landing and stay stationary throughout their mission (2 years). The SSPs have an ambitious science program to study for example the Martian atmosphere, seismology, magnetic field and chemistry. Theri payloads consist of a camera, a visual spectrometer, a meteorological package, an accelerometer, thermoprobes, a magnetometer, a chemistry package and a radiation monitor. The SSP will also provide positioning signal and communications link to the Orbiter. 

The Moon SSP will be a miniature 5 kg station deployed on the Moon surface by a rover. Maximum four (4) SSPs are deployed with low velocity and small impact depth (max. 0.05 m). All SSPs can be deployed from a single rover on the same sortie. The SSPs will start their scientific observations after landing and study for example radiation, seismology, magnetic field and chemistry. SSP will also provide communications link either to the rover or to a relay orbiter. 

Both Mars and Moon SSPs will be miniaturised, light and robust, and still capable of surviving high G loads and extreme thermal environments. SSPs are capable of working on the surface of Mars or Moon and to produce high quality science data with state of art instrumentation. The output of this work will enable ESA to prepare and plan for technology development programs required to implement such ambitious planetary missions. 

How to cite: Genzer, M., Hieta, M., Kestilä, A., Haukka, H., Arruego, I., Apéstigue, V., Manfredi, J. A., Ortega, C., Dominiguez, M., Espejo, S., Guerrero, H., Palin, M., Kivekäs, J., Koskimaa, P., and Talvioja, M.: MiniPINS - Miniature Planetary In-situ Sensors, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13250, https://doi.org/10.5194/egusphere-egu2020-13250, 2020.

EGU2020-15130 | Displays | PS6.1

GAUSS - A Sample Return Mission to Ceres

Xian Shi and the GAUSS Project Team

Ceres, the largest resident in the main asteroid belt and the innermost dwarf planet of the solar system, shares characteristics with a broad diversity of solar system objects, making it one of the most intriguing targets for planetary exploration. The recently completed Dawn mission through its 3.5 years of in-orbit investigation has furthered our understanding of Ceres, yet at the same time opened up more questions. Remote sensing data revealed that Ceres is rich in volatiles and organics, with fresh traces of cryovolcanic and geothermal activities. There is potential evidence of Ceres’ past and present habitability. Findings by Dawn suggest that Ceres might once be an ocean world and have undergone more complicated evolution than originally expected. Thus, Ceres encapsulates key information for understanding the history of our solar system and the origin of life, which has yet to be explored by future missions.

We present the GAUSS project (Genesis of Asteroids and EvolUtion of the Solar System), recently proposed as a white paper to ESA’s Voyage 2050 program. GAUSS is a mission concept of future exploration of Ceres with sample return as the primary goal. It aims to address the following top-level scientific questions concerning: 1) the origin and migration of Ceres and its implications on the water and volatile distribution and transfer in the inner solar system; 2) the internal structure and evolution of Ceres; 3) Ceres’ past and present-day habitability; and 4) mineralogical connections between Ceres and collections of primitive meteorites. We will discuss scientific objectives of Ceres exploration in post-Dawn era as well as instrumentation required for achieving them. We will explore candidate landing and sampling sites of high scientific interest based on Dawn results. We will also consider technical and financial feasibility of different mission scenarios in the context of broad international collaboration.

How to cite: Shi, X. and the GAUSS Project Team: GAUSS - A Sample Return Mission to Ceres, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-15130, https://doi.org/10.5194/egusphere-egu2020-15130, 2020.

EGU2020-4190 | Displays | PS6.1

Exploration of resources in permanently shadowed lunar polar regions

Mihaly Horanyi, Edwin Bernardoni, Sascha Kempf, Zoltan Sternovsky, and Jamey Szalay

Our understanding of the lunar dust exosphere is based on  NASA’s Lunar Atmosphere and Dust Environment Explorer. Its findings provide a unique opportunity to map the composition of the lunar surface from orbit and identify regions that are rich in volatiles, providing opportunities for future in situ resource utilization (ISRU), which is a key element in establishing human habitats on the Moon. The expected availability of water ice, and other volatiles, in Permanently Shadowed Regions (PSR) makes the lunar poles of prime interest. However, the relative strength of the various sources, sinks, and transport mechanisms of water into and out of PSRs remain largely unknown. The quantitative characterization of the temporal and spatial variability of the influx of IDPs to the polar regions of the Moon is critical to the understanding the evolution of volatiles in PSRs. A dust instrument onboard a polar orbiting lunar spacecraft could make fundamental measurements to assess the availability and accessibility of water ice in PSRs. Water is thought to be continually delivered to the Moon through geological timescales by water-bearing comets and asteroids and produced continuously in situ by the impacts of solar wind protons of oxygen-rich minerals on the surface. IDPs are an unlikely source of water due to their long UV exposure in the inner solar system, but their high-speed impacts can mobilize secondary ejecta dust particles, atoms and molecules, some with high-enough speed to escape the Moon. Other surface processes that can lead to mobilization, transport and loss of water molecules and other volatiles include solar heating, photochemical processes, and solar wind sputtering. Since the efficiency of these are reduced in PSRs, dust impacts remain the dominant process to dictate the evolution of volatiles in PSRs.
The continually present dust ejecta cloud was observed by LADEE/LDEX. A more capable dust instrument, in addition to the size and speed of an impacting particle, can also measure the composition of secondary ejecta particles, resulting in a surface composition map with a spatial resolution comparable to the height of the spacecraft.
This talk will describe the available instrumentation, its testing and calibration using the SSERVI /IMPACT dust accelerator  facility at the University of Colorado, Boulder, and conclude with the recognition that a polar-orbiting spacecraft could directly sample lunar ejecta, providing the critical link between IDP bombardment and the evolution of water ice in PSRs.

How to cite: Horanyi, M., Bernardoni, E., Kempf, S., Sternovsky, Z., and Szalay, J.: Exploration of resources in permanently shadowed lunar polar regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-4190, https://doi.org/10.5194/egusphere-egu2020-4190, 2020.

EGU2020-6753 | Displays | PS6.1

Russian Lunar Landers Luna-25 and Lna-27: goals of the missions and scientific investigations at Moon Polar Regions

Vladislav Tretyakov, Igor Mitrofanov, and Lev Zeleniy

Scientific goals, current status and nearest plans for Russian Landers missions with Luna-25 (project Luna-Glob) and Luna-27 (project Luna-Resource) will be presented. Both projects aimed on search for volatiles and water ice in upper layer of regolith, study structure and content of regolith and investigate of Moon’s near-surface dust and plasma exosphere at lunar polar regions.

The scientific experiments which were selected in accordance to the main goals of these missions, will be described. Main and spare landing sites for Luna-25 will be presented selected on the base both of engineering suitability (flatness and roughness of surface, radio visibility, solar irradiation and so on) and of scientific motivation. Criteria for landing sites selection for Luna-27 will be discribed shortly too. The plan of surface operations during the first lunar days for Luna-25 and Luna-27 will be presented and discussed.

The content of international cooperation for Luna-25 and Luna-27 missions will be described.

It will be shown that Luna-25 and Luna-27 shell provide the necessary scientific and technological ground for future long life-time Landers at the Moon polar regions.

How to cite: Tretyakov, V., Mitrofanov, I., and Zeleniy, L.: Russian Lunar Landers Luna-25 and Lna-27: goals of the missions and scientific investigations at Moon Polar Regions, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6753, https://doi.org/10.5194/egusphere-egu2020-6753, 2020.

EGU2020-11795 | Displays | PS6.1

Geophysical Exploration of the Dynamics and Evolution of the Solar System (GEODES)

Nicholas Schmerr, Jacob Richardson, Rebecca Ghent, Matthew Siegler, Kelsey Young, and Laurent Montési and the The GEODES Team

The Moon, near Earth asteroids, and the martian moons Phobos and Deimos are all Solar System Exploration Research Virtual Institute (SSERVI) target bodies as they present a wide variety of natural wonders and are potential hosts to resources that will one day enable human exploration of the Solar System. Our SSERVI project, Geophysical Exploration of the Dynamics and Evolution of the Solar System (GEODES) is exploring a suite of natural resources on these bodies through multidisciplinary geophysical investigations. Geophysical methods have been incredibly successful in identifying resources on Earth as they provide a means of characterizing and mapping the sub-surface using data gathered on and above the surface. We focus our geophysical investigations on four essential resources that will enable future human space exploration: I) Lava tubes and void spaces, capable of hosting people and infrastructure; II) Ice deposits, subsurface bodies that can be used for volatile extraction; III) Regolith, which covers the surface of all target bodies, potentially serving as a building material but also presenting a hazard to human and robotic operations and health; and IV) Magma-tectonic Systems, which mobilize, concentrate, and trap volatiles, unique rocks, and ore minerals.

Our investigations use an "orbit to outcrop" approach by analyzing existing geophysical data, conducting geophysical exploration of field analog sites on Earth, and creating models that link these analog studies to SSERVI target bodies. Analog sites enable the development, ground-truthing, and integration of (a) exploration strategies, (b) multiple geophysical methods, and (c) modeling capabilities. The GEODES team is integrating field methods and results to create a scientific modeling framework that facilitates the joint inversion of data sets and will share these results with the community via cyber infrastructure, data management, and outreach. The unifying goal behind GEODES is to develop geophysical detection and exploration methods to characterize these natural resources and enable in situ resource utilization at SSERVI target bodies.

How to cite: Schmerr, N., Richardson, J., Ghent, R., Siegler, M., Young, K., and Montési, L. and the The GEODES Team: Geophysical Exploration of the Dynamics and Evolution of the Solar System (GEODES) , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11795, https://doi.org/10.5194/egusphere-egu2020-11795, 2020.

EGU2020-13646 | Displays | PS6.1

Lunar and Mars analogue research performed at the HI-SEAS research station in Hawaii, part of the EuroMoonMars - IMA - HI-SEAS campaigns

Michaela Musilova, Bernard Foing, Anouk Beniest, and Henk Rogers

As of 2018, the International MoonBase Alliance (IMA), has been organizing regular simulated missions to the Moon and Mars at the Hawaii Space Exploration Analog and Simulation (HI-SEAS) habitat. HI-SEAS is a lunar and Martian analog research station located on the active volcano Mauna Loa in Hawaii. The missions that take place at HI-SEAS can be of varied duration, from several days to several months, depending on the needs of the researchers. They are open to space agencies, organizations and companies worldwide to take part in, provided their research and technology testing will help contribute to the exploration of the Moon and Mars. The crews are supported by a Mission Control Center based on the Big Island of Hawaii as well. A series of EuroMoonMars IMA HI-SEAS (EMMIHS) missions have been taking place at HI-SEAS since 2019. These missions bring together researchers from the European Space Agency (ESA), IMA, the International Lunar Exploration Working Group (ILEWG), European Space Research and Technology Centre (ESTEC), VU Amsterdam and many other international organizations. Crews on these missions perform geological, astrobiological and architectural research; technological tests using drones, 3Dprinters and rovers; as well as performing outreach and educational projects. The EMMIHS missions typically last for two weeks each. During this time, the crew is isolated within the HI-SEAS habitat, which they cannot leave without performing EVAs (Extra-Vehicular Activities) in analog space-suits and with the permission of Mission Control. The EMMIHS campaigns aim to increase the awareness about the research and technology testing that can be performed in analogue environments, in order to help humans become multiplanetary species. Furthermore, the research and technological experiments conducted at HI-SEAS are going to be used to help build a Moon base in Hawaii, and ultimately to create an actual Moon base on the Moon, as part of IMA’s major goals. Future missions at HI-SEAS include more EMMIHS campaigns, collaborative missions with ESA, NASA, University of Hawaii, University of South Florida and with companies, such as SIFT and Ketone Technologies.

How to cite: Musilova, M., Foing, B., Beniest, A., and Rogers, H.: Lunar and Mars analogue research performed at the HI-SEAS research station in Hawaii, part of the EuroMoonMars - IMA - HI-SEAS campaigns, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13646, https://doi.org/10.5194/egusphere-egu2020-13646, 2020.

EGU2020-1849 | Displays | PS6.1

BASALT – A Science-Based Mars Con-Ops Astronaut Field Simulation

John Hamilton and the BASALT RESEARCH PROJECT team

BASALT (Biologic Analog Science Associated with Lava Terrains) was a NASA PSTAR funded field research program. The goal was to understand the habitability of terrestrial volcanic terrains as analog environments for early and present-day Mars.

A key objective was to merge the oftimes disparate field techniques and protocols of biologists, geologists and geochemists.   worked together on this project to understand microbial lifeforms, like bacteria, that grow on these rocks and the factors that allow them to thrive.

Deployments of 21 days at each of its three analog research sites performing field studies of the science operations and technology it had developed.  The first field work was conducted at the Craters of the Moon National Monument, Idaho.  In Hawai’i, operations were conducted twice at Hawai`i Volcanoes National Park (Mauna Ulu, Kilauea Iki and Keanakakoi ). The science targeted active and relict magmatic fumaroles to examine the relationship between meteoric (a condition sampled for in 2016) and magmatic influences on basalt alteration and associated microbial diversity.

These were conducted under simulated Mars mission constraints (5/20 minute light-travel time delay and low/high communication bandwidth conditions) to evaluate strategically selected concepts of operations (ConOps) and capabilities with respect to their anticipated value for the joint human and robotic exploration of Mars.

How to cite: Hamilton, J. and the BASALT RESEARCH PROJECT team: BASALT – A Science-Based Mars Con-Ops Astronaut Field Simulation , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-1849, https://doi.org/10.5194/egusphere-egu2020-1849, 2020.

EGU2020-19877 | Displays | PS6.1

GEOs experiments in MARS ANALOG MISSION: AMADE20

Seda Ozdemir, Ania Losiak, and Izabela Golebiowska

Analog missions are a unique opportunity to test methods and equipment in the field on Earth before they are used in space. AMADEE-20 is a Mars analog simulation in Negev Desert, Israel, managed by the Austrian Space Forum similar to the previous missions (Morocco2013 Groemer et al. 2014, Oman2018 Groemer et al. 2019). The test site is located within the erosional structure of the Ramon Crater. It has a variety of terrain types relevant to Mars exploration.

GEOS experiment is a suite of geology-related experiments that will be performed during the AMADEE-20, it is built on experiences from previous missions (e.g., Losiak et al. 2014). The aim of the GEOS experiments is to study how to optimise the future geological exploration on Mars.

The GEOs is divided into four parts:

(1) Geo-mapping: The aim is to optimise the process of preparing and using the geologic map of the exploration area. A map will be prepared before the mission, and later it will be improved using the data collected by a drone, rover and AAs observations. After the mission pre- and post-mission maps will be compared to optimize and improve the mission preparation phase.

(2) Geo-sampling: The aim is to compare the geological understanding of the area based on sampling and field observations performed by analog astronauts with the one obtained by a proper research performed by trained geologists in the past.

(3) Geo-compare: The aim of the study is to determine strategies of spatial information acquisition from thematic maps and the environment. In other words, we will study how people learn about the spatial relationships between objects and their attributes from thematic maps and while working in the field by using a mobile and stationary eye tracking. The results can be used to create a more efficient way of teaching spatial information acquisition skills to all the people that work in the field, including astronauts to be sent within the next couple tens of years to the Moon and Mars. 

(4) Micrometeorite: The aim is to search for micrometeorites within the collected sand samples in the field, aiming to find these highest flux extraterrestrial materials on the earth's surface. This experiment might provide a practical and achievable application which may also provide information about Mars' history as well as the solar system.

Groemer et al. 2014. The MARS2013 Mars Analog Mission. Astrobiology, 14(5), 360–376.

Groemer et al. 2019. The AMADEE-18 Mars Analog Expedition in the Dhofar region of Oman. Astrobiology.

Losiak et al. 2014. Remote Science Support during MARS2013: Testing a Map-Based System of Data Processing and Utilization for Future Long-Duration Planetary Missions. Astrobiology, 14(5), 417–430.

How to cite: Ozdemir, S., Losiak, A., and Golebiowska, I.: GEOs experiments in MARS ANALOG MISSION: AMADE20, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19877, https://doi.org/10.5194/egusphere-egu2020-19877, 2020.

EGU2020-20507 | Displays | PS6.1

Food for Extra-Terrestrial Astronaut Missions on Native Soil

Charlotte Pouwels, Wieger Wamelink, Michaela Musilova, and Bernard Foing

Introduction:   Food demand and the lack of plant nutrients are the main reasons to establish a sustainable agricultural ecosystem on celestial bodies, such as Mars and the Moon. Different kinds of fresh crops, grown in a greenhouse, deliver essential macro and micro nutrients, which have a positive impact on the well-being  of humans. Thus, they will also heavily influence the social interactions of future astronauts. Food development is therefore one of the main activities that will need to be established as soon as possible upon the landing of a human-led mission on another planetary body.

In addition, crops can be used for air purification and thus oxygen production. Experimental research has been conducted, during a two-week analogue astronaut mission (EMMIHS-II: the second of the EuroMoonMars-IMA-HI-SEAS missions), to grow crops, from garden cress seeds, sown in soil that resembles the regolith on Mars and the Moon. This plant was used because it is easy and fast to grow, which is a priority for research projects during these short-duration missions. In addition, this research will help in reducing compost and fertilizer payloads for upcoming space missions involving human crewmembers.

Methodology:  In a remote volcanic region in Hawai’i, United States, the geology and therefore its soil is quite similar to the regolith on Mars and the Moon. For these reasons, the Hawai’i Space Exploration Analog and Simulations (HI-SEAS) habitat was constructed and is being used in this area for space-related research purposes.

In this habitat, a greenhouse setting had been built with basic requirements for plant growth. The local soil in each of the 70 pots had pre-determined ratio’s with a compost mixture: 0%, 1%, 2%, 3%, 5%, 10%, 25%, 50%, 75%, 100%.  For these settings, the assumption was made that shielding from Solar Energetic Particles (SEP) and Galactic Cosmic Rays (GCR’s) was present. These types of radiation, and thus shielding from the radiation, would be of high relevance on Mars and the Moon to protect the crops there from malformations and death. Future habitats may be located in lava tubes or covered by regolith to address these requirements.

Here, the presented results focus on the needed ratio of compost to ‘Martian’ simulant soil for garden cress. The results indicate that coarse ‘Martian’ soil with 2% of compost is sufficient for establishing sufficient germination and plant growth in the first stage of plant development. This result leads to promising expectations for other nutrient-soil ratio experiments. In particular for the growth of potatoes and beans, as they are high in nutrients per m3.

Studies on different kinds of soil ratio’s, nutrients delivered per m3, radiation shielding and the architecture of an indoor greenhouse setting are of significant relevance to future missions to the Moon and Mars and thus deserve further investigation.

 

How to cite: Pouwels, C., Wamelink, W., Musilova, M., and Foing, B.: Food for Extra-Terrestrial Astronaut Missions on Native Soil, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20507, https://doi.org/10.5194/egusphere-egu2020-20507, 2020.

PS6.3 – Planetary Cartography, Mapping and GIS

EGU2020-13023 | Displays | PS6.3

Beyond Earth – Lessons learned and Challenges of Planetary Cartography

Andrea Naß, Stephan van Gasselt, Kaichang Di, Trent Hare, Irina Karachevtseva, Angelo Pio Rossi, Jim Skinner, Elke Kersten, Stefan Elgner, Nicolas Manaud, and Thomas Roatsch

The standardization of cartographic methods and data products is critical for accurate and precise analysis and scientific reporting. This is more relevant today than ever before, as researchers have easy access to a magnitude of digital data as well as to the tools to process and analyze these various products. The life cycle of cartographic products can be short and standardized descriptions are needed to keep track of different developments.

Planetary Cartography does not only provide the basis to support planning (e.g., landing-site selection, orbital observations, traverse planning) and to facilitate mission conduct during the lifetime of a mission (e.g., observation tracking and hazard avoidance). It also provides the means to create science products after successful termination of a planetary mission by distilling data into maps and map-related products. After a mission’s lifetime, data and higher level products such as mosaics and digital terrain models (DTMs) are stored in archives and are eventually re-used and transformed into maps and higher-level data products to provide a new basis for research and for new scientific and engineering studies. The complexity of such tasks increases with every new dataset that has been put on this stack of information, and in the same way as the complexity of autonomous probes increases, also tools that support these challenges require new levels of sophistication. In the planetary sciences, cartography and mapping have a history dating back to the roots of telescopic space exploration and are now facing new technological and organizational challenges with the rise of innovative missions, improved instruments, global data initiatives, new organizations and opening research markets. A general aim for this Planetary Cartography community is to develop concepts and approaches to foster future cooperation between scientists, cartographers and non-cartographers.

The focus of this contribution is to summarize recent activities in Planetary Cartography, highlighting current issues the community is facing, and to derive future opportunities in this field in order to address technical and scientific objectives. Furthermore, we focus on (1) identifying and prioritizing needs of the planetary cartography community along with a strategic timeline to accomplish such goals, (2) keeping track of ongoing work across the globe in the field of Planetary Cartography, and (3) identifying areas of evolving technologies and innovations that deal with mapping strategies as well as output media for the dissemination and communication of cartographic results.

By this we would like to invite cartographers, researchers and map-enthusiasts to join this community and to start thinking about how we can jointly solve some of these challenges.

How to cite: Naß, A., van Gasselt, S., Di, K., Hare, T., Karachevtseva, I., Rossi, A. P., Skinner, J., Kersten, E., Elgner, S., Manaud, N., and Roatsch, T.: Beyond Earth – Lessons learned and Challenges of Planetary Cartography , EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13023, https://doi.org/10.5194/egusphere-egu2020-13023, 2020.

The project of the International Quaternary Map of Europe project (IQUAME 2500) is a major international initiative coordinated by BGR under the auspices of the CGMW (Commission of the Geological Map of the Word, Sub-Commission Europe) and with support of INQUA (International Union for Quaternary Research). It started in 2011 at the INQUA congress in Bern and aims to show the distribution of Quaternary features at the land surface and general marine deposits across the entire European continent. The map is planned as web-based geographical information system (GIS) and is going to include the Quaternary on- and off-shore information on e.g. glaciogenic elements, geomorphologic features, age and lithology of Quaternary units, last extent of ice sheets (Weichselian, Saalian, if possible Elsterian), faults, active faults off-shore Quaternary information (in cooperation with the European Union EMODnet Geology project) and more.

Partner institutions from more than 30 countries including geological survey organisations from Russia in the East, Portugal in the West, Norway in the North and Cyprus in the South are participating; a scientific board of Quaternary researchers ensures the high scientific quality of resulting map. For a multinational and cross-boundary project like this, international collaboration is the key to success. This project requires that data originally set up in a plethora of regional and national classifications need to be adapted, integrated and harmonized in respect to semantics, structure and geometry. To achieve this aim common rules needed to used such as those defined by the European INSPIRE Directive or be set up and applied by all participants:  structured vocabularies (incl. definitions of terms) to describe the above contents, cartographic guidelines to suite the scale and last but not least generally applicable tools to aid the partners to submit their data to the project.

Ultimately, the aim is to create an pan-European, internationally harmonized, comprehensive, spatial geological database where relevant properties of the Quaternary layers can be retrieved, combined, selected and cross-referenced across political boundaries and also to provide a summary of the current status of European Quaternary geological research.

Looking at planetary mapping, e.g. of Mars and Moon, there are several similarities. The surfaces of terrestrial planets are shaped by geologic processes that are similar to those operating on Earth, therefore endogenic and exogenic landforms (such as lava flows, glacial deposits, and impact craters) are regularly mapped by the scientific community.  Beside specific scientific mapping projects conducted by individual researchers and groups different organisations and institutes are producing planetary maps, such as NASA, ESA, ROSCOSMOS and MIIGAiK (Russia), USGS (USA), CAS/NOAC/SGCAS/RADI (China), DLR (Germany), or the British Ordnance Survey. This presentation aims to introduce the small-scale Quaternary mapping of one part of planet Earth, i.e. Europe, to present its collaborative aspects, to highlight the parallels to planetary mapping and to suggest potentially useful aspects for planetary geological mapping projects.

How to cite: Asch, K., Naß, A., and van Gasselt, S.: Under the ice and over the sky – aspects of building the International Quaternary Map of Europe and potentially useful parallels to planetary geological map projects, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22610, https://doi.org/10.5194/egusphere-egu2020-22610, 2020.

EGU2020-18839 | Displays | PS6.3 | Highlight

PLANMAP data packaging: lessons learned towards FAIR planetary geologic maps

Carlos Henrique Brandt, Angelo Pio Rossi, Luca Penasa, Riccardo Pozzobon, Erica Luzzi, Jack Wright, Cristian Carli, and Matteo Massironi

Geologic mapping is a key element of planetary exploration for mission planning, orbital and rover reconnaissance, and target selection for in-situ analysis and sample return, as well as for understanding the formation and evolution of planetary surfaces. The PLANMAP project (http://www.planmap.eu) aims at produce high-level, standardized geological maps of the Moon, Mars, and Mercury (Massironi M. et al., 2018). The project is integrating different types of data as images, spectral-cubes, chemical data, Digital Terrain Models and three-dimensional geological models to produce geological maps suitable to planetary exploration at different levels. The process results in rich datasets composed by a variety of datatypes encapsulated in open standards and released to the community as freely accessible packages (https://maps.planmap.eu).
To accomplish the complexity of deploying PLANMAP packages, considering reliability and automation as key components of a data release workflow, we arranged a data management framework respecting the FAIR (findable, accessible, interoperable, and reusable) guidelines. Geographic data are stored and served by a multi-layered Web-GIS allowing easy information discovery. Particular attention has been paid in designing the user interface and in the definition of the underlying data structure. Different data query services are also provided to properly address different user needs (Luzzi E. et al., 2020). PLANMAP’s datasets can be downloaded in the form of fully contained packages (https://data.planmap.eu) fulfilling a specifically designed standard. Once a data package is ready for publication, validation and summary information extraction take place and the results are published together within the packages.
We will here present an overview of the PLANMAP’s deployed data system, and the technical solutions that were adopted with the final goal of improving the quality standards of planetary geological maps.

References:

- Luzzi E. et al., 2020, “Tectono-magmatic, Sedimentary and Hydrothermal History of Arsinoes and Pyrrhae Chaos, Mars.”, EarthArXiv, doi:10.31223/osf.io/td297

- Massironi M. et al., 2018, “Towards integrated geological maps and 3D geo-models of planetary surfaces: the H2020 PLANetary MAPping project”, EGU General Assembly 2018

How to cite: Brandt, C. H., Rossi, A. P., Penasa, L., Pozzobon, R., Luzzi, E., Wright, J., Carli, C., and Massironi, M.: PLANMAP data packaging: lessons learned towards FAIR planetary geologic maps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-18839, https://doi.org/10.5194/egusphere-egu2020-18839, 2020.

There is no perfect global map projection. A projection may be area preserving or conformal (shape preserving on small scales) in some regions, but it will inevitably exhibit considerable distortions in others. An oblique version of a projection (where the globe is rotated before projecting) can be optimized to avoid major distortions in specific regions of interest.
We present two global map projections of the Earth which either display all continents (including Antarctica) or the complete world ocean with minimal distortion and without any intersection. These are the triptychial projection and the Spilhaus projection, respectively.
The triptychial projection is original work and has been published by Grieger (2019). While that paper comprises complete information on the definition of the projection, the details of its application need to be collected from literature referenced therein. The triptychial projection is an oblique and rearranged version of the Peirce quincuncial projection of the world (Peirce, 1879).
Instances of the Spilhaus projection went viral on the internet in fall 2018. The projection is mostly attributed to a publication from 1942, but in fact it seems to appear for the first time in Spilhaus (1979). The projection is shown in that paper (and in a few later ones), but no information on its definition is provided. Developers of ArcGIS did some reverse engineering and could identify the Spilhaus projection as an oblique version of the Adams projection of the world in a square II (Adams, 1929).
The triptychial and the Spilhaus projection both imply several steps in their application. While the two projections look very different, they have one step in common: the conformal mapping of a hemisphere onto a square, which requires tabulated Jacobi elliptic functions. We review both projections, describe them in full detail, and provide all formulas and data needed to apply them. The algorithms employed may also be interesting for planetary applications.

How to cite: Grieger, B.: Optimized global map projections for specific applications: the triptychial projection and the Spilhaus projection, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-9885, https://doi.org/10.5194/egusphere-egu2020-9885, 2020.

Studying and mapping of faults in the Earth’s crust is one of the priority objectives in structural geology and tectonophysics. Generally, faults are associated with mineral deposits, thermal springs, and earthquakes, and fault zones are areas of the most dangerous geological processes and various geophysical anomalies. In this regard, databases of faults are highly demanded by both science and practical applications. In this work, we present an on-line geospatial database containing faults, which were active in the Pliocene‐Quaternary within the territory between 96–124°E to 49–58°N. The locations of the faults were mapped with using MapInfo GIS based on the extensive analysis of cartographic, published and own structural materials. The data about each fault were input via ActiveTectonics Information System developed by us. The interactive version of the database put out in the open (http://www.activetectonics.ru/) in Russian and English and anyone may get available information about a fault by a click. The geoportal is constantly developing and constitutes a base for the creation of an automated system for modeling geological hazards (seismic soil liquefaction, secondary rupturing, subsidence and slope processes) in the Baikal region.

Currently, as part of the modernization of the ActiveTectonics geographic information product, we are developing models and schemes of data and metadata to create a detailed geospatial database of seismogenic ruptures of the Baikal region. A modern user-friendly interface is being developed to automate the data collection process.

The creation of such a publicly accessible catalog of seismogenic ruptures will be useful for applied and fundamental research.

The reported study was partly funded by RFBR and the Government of the Irkutsk Region, project number 20-45-385001.

How to cite: Gladkov, A. and Oxana, L.: Upgrade of the “ActiveTectonics” on-line database of Pliocene-Quaternary fautls in the Baikal Region and adjacent areas, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12450, https://doi.org/10.5194/egusphere-egu2020-12450, 2020.

EGU2020-6269 | Displays | PS6.3

Automatic crater detection over the Jezero crater area from HiRISE imagery

Konstantinos Servis, Anthony Lagain, Gretchen Benedix, David Flannery, Chris Norman, Martin Towner, and Jonathan Paxman

Impact craters are used to determine the ages of planetary surfaces. Absolute dating of meteorites or in situ geochronology provide a few essential reference points, but these techniques are rare and not yet applicable at the planetary scale. Therefore, impact crater counting techniques will remain the major tool to decipher planetary surface history. This approach requires a tedious mapping and morphological inspection of a large number of circular features to distinguish true and primary impact craters. The most complete database of Martian craters includes a catalog of more than 384,000 impact structures larger than 1 km in diameter. This database is considered to be complete for this diameter range. A requirement to determine young surface ages on Mars must include smaller impact craters, typically a hundred meters in diameter, found on the area of interest.

To access to the crater population of this size range at a planetary scale we built a Crater Detection Algorithm (CDA) trained on THEMIS images where impact craters larger than 1 km from the Robbins & Hynek database have been identified. Our model offer a true detection rate of 0.9. We then applied our CDA on the global CTX mosaic within the ±45º latitudinal band leading to ~17 million of detection >100m in diameter.

The ultimate goal of our work is now to automatically compile smaller impact craters (5m<D<100m) visible on HiRISE imagery dataset offering a resolution of 25cm/px. We trained our algorithm on a part of the HiRISE mosaic (NASA/JPL/MSSS/The Murray Lab) covering a part of the Jezero crater (E77-5_N18_0) where 1650 craters have been manually identified. A portion of this population of craters has then be selected in order to be sure to include the most confident impact features in the training dataset, finally resulting to 1624 craters over this entire image.

Our model has been applied over the entire HiRISE mosaic covering the Jezero crater where more than 27,298 craters >3m have been detected. In order to validate our results, we compared the detection obtained on 30 tiles of 960px x 960px randomly chosen on a part of the mosaic (E77-25_N18-25) which have not been included into the training dataset with a manual identification, thus constituting the ground truth. For this purpose, we decided to categorize each tile according to the type of terrain mostly represented on each of them: rocky terrain, smooth terrain and dunes fields. We have also specified when the image exhibited some vertical stripes leading to the fourth category.

On rocky and smooth terrains, the CDA produce very good results: only 5% of detection on the average are false detection and 16% of craters on average have not been detected by the CDA. However, the CDA is less efficient on dune fields since 35% of detection are false detection and 15% of craters have not been identified. Finally, images exhibiting some vertical stripes significantly decrease the detection rate of the CDA since 56% of detection are false negative and 20% of craters have not been detected.

How to cite: Servis, K., Lagain, A., Benedix, G., Flannery, D., Norman, C., Towner, M., and Paxman, J.: Automatic crater detection over the Jezero crater area from HiRISE imagery, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-6269, https://doi.org/10.5194/egusphere-egu2020-6269, 2020.

EGU2020-19072 | Displays | PS6.3

HRSC 3D Image products of the North Polar Layered Terrain of Mars

Alfiah Rizky Diana Putri, Yu Tao, and Jan-Peter Muller

The NASA Mars Orbital Laser Altimeter (MOLA) Digital Terrain Model (DTM) has the greatest coverage available for Mars with an average resolution of 463 m/pixel (128pixel/ degree) globally and 112 m/ pixel (512 pixels/degree) for the polar regions [1]. The ESA Mars Express High-Resolution Stereo Camera (HRSC) is currently orbiting Mars and continuously mapping the surface, 98% with resolutions finer than 100 m/pixel, and 100% at lower resolutions [2]. Previously, 50m/pixel DTMs were produced using a NASA-VICAR-based pipeline developed by the German Aerospace Centre, with modifications from Kim and Muller [3] for the south polar region, using an image matcher based on the Gruen-Otto-Chau (Gotcha) algorithm [4].

 

In this research, we demonstrate application of the same method to the North Polar [5] region. Forty single strip DTMs have been processed and corrected to produce a north polar HRSC DTM mosaic at 50m/pixel. The assessment of the dataset to MOLA will be discussed. Moreover, a large number (~50) of the North polar HRSC images are co-registered and orthorectified using the DTM mosaic. We also demonstrate observations of the seasonal ice cap growth and retreat using the orthorectified images for Martian Year (MY) 27-32. In addition, the results for MY28-31 are compared against the observations from the Mars Colour Imager (MARCI)[6].

 
ACKNOWLEDGEMENT: Part of the research leading to these results has received partial funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) under iMars grant agreement n ̊ 607379; The first author is supported by the Indonesian Endowment Fund for Education. We would also like to express gratitude to the HRSC team and the MOLA team for the usage of HRSC and MOLA data, and Alexander Dumke for the exterior orientation processing results used within this research.

[1] Smith, David, et al. 2001. “Mars Orbiter Laser Altimeter: Experiment summary after the first year of global mapping of Mars.” Journal of Geophysical Research: Planets 106(E10):23689–23722

[2] Gwinner, et al. 2016. “The High Resolution Stereo Camera (HRSC) of Mars Express and Its Approach to Science Analysis and Mapping for Mars and Its Satellites.” Planetary and Space Science 126:93–138

[3] Kim and J-P. Muller, 2009. “Multi-resolution topographic data extraction from Martian stereo imagery.” Planetary and Space Science, 57(14-15):2095-2112.

[4] D. Shin and J-P. Muller, 2012. “Progressively weighted adaptive correlation matching for quasi-dense 3d reconstruction.” Pattern Recognition, 45(10):3795-3809.

[5] Putri, A.R.D., et al., 2019. “A New South Polar Digital Terrain Model of Mars from the High-Resolution Stereo Camera (HRSC) onboard the ESA Mars Express.” Planetary and Space Science.

[6] Calvin, W.M., et al., 2015. “Interannual and seasonal changes in the north polar ice deposits of Mars: Observations from MY 29–31 using MARCI.” Icarus, 251, pp.181-190.

 

How to cite: Putri, A. R. D., Tao, Y., and Muller, J.-P.: HRSC 3D Image products of the North Polar Layered Terrain of Mars, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19072, https://doi.org/10.5194/egusphere-egu2020-19072, 2020.

EGU2020-3427 | Displays | PS6.3

OpenPlanetaryMap Updates: Planetary Basemaps and Geocoding Web Services

Nicolas Manaud, Jérôme Gasperi, Andrea Nass, Stephan van Gasselt, Angelo Pio Rossi, and Trent Hare

OpenPlanetaryMap (OPM) is a collaborative project to build the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. We want to make it easy for anyone to create and share maps and locations on any planets or bodies in our Solar System [1].

Our platform architecture is based on four main service-oriented components: (1) an open repository of geospatial datasets; containing information used to create basemaps and to enable location-based searches, (2) basemaps that are needed to build any types of web mapping applications or geospatial data visualisation, (3) geocoding and geo-referencing APIs/web services to enable location-based searches and crowdsourcing of our datasets repository, (4) Web app, Python module and CLI interfaces to search, add and share places on planetary bodies.

Since the project started as an initiative funded by Europlanet in 2017, we have consolidated our network of collaborators and we published our first planetary basemaps and design concept [2]. Instructions on how to use our basemaps are available from our new website [3]. External projects have started to use OPM basemaps, for example: PLANMAP Stories [4] and CaSSIS Map Interface [5]. While we continue to improve our basemaps and create new ones, we have been working on providing an open planetary geocoding API/web service and user interfaces.

The purpose of our planetary geocoding API is to provide a common and consistent way of defining and searching for places on the surface of bodies in the Solar System, including the Earth. We are first implementing our geocoding API as a JavaScript module, along with our first web map interface that demonstrates its use. We will then focus on implementing our geocoding API as a Python module.

We introduce the project and present recent updates on OPM planetary basemaps, geocoding APIs and user interfaces.

[1] Manaud et al. (2018). OpenPlanetaryMap: Building the first Open Planetary Mapping and Social platform for researchers, educators, storytellers, and the general public. European Planetary Science Congress 2018, 12, EPSC2018-78. [2] Nass et al. (2019). Towards a new face for Planetary Maps: Design and web- based Implementation of Planetary Basemaps. Adv. Cartogr. GIScience Int. Cartogr. Assoc., 1, 15, 2019. https://doi.org/10.5194/ica-adv-1-15-2019 [3] http://openplanetarymap.org [4] https://stories.planmap.eu/mars/gale [5] http://cassis.halimede.unibe.ch

How to cite: Manaud, N., Gasperi, J., Nass, A., van Gasselt, S., Pio Rossi, A., and Hare, T.: OpenPlanetaryMap Updates: Planetary Basemaps and Geocoding Web Services, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3427, https://doi.org/10.5194/egusphere-egu2020-3427, 2020.

EGU2020-19741 | Displays | PS6.3

Intergrating morpho-stratigraphic and spectral units on Mercury and the Moon: Updates from the PLANMAP project

Cristian Carli, Francesca Zambon, Francesca Altieri, Carlos Brandt, Angelo Pio Rossi, and Matteo Massironi

The numerous past and present space missions dedicated to the Solar System planetary bodies exploration, provided a huge amount of data so far. In particular, data acquired by cameras and spectrometers allowed for producing morpho-stratigraphic and mineralogical maps for many planets, satellites and minor bodies. Despite the considerable progresses, the integration of these products is still poorly addressed. To date, no geological maps of planetary bodies other than the Earth, containing both the information, are available yet. In this context, one of the main goals the “European Union's Horizon 2020 - PLANetary MAPping (PLANMAP)” project [1] is to provide, for the first time, highly informative geological maps of specific regions of interest on the Moon, Mercury and Mars, taking into account datasets publicly available in the Planetary Data System (PDS) database [2].

Here, we show the results achieved during the first two years of the project by the PLANMAP “Compositional unit definition Work Package”. In particular, we focused on specific areas, such as Hokusai quadrangle (22°-60° N, 0°-90°W) and Beethoven (13.24°S- 28.39° S; 116.1°- 132.32°W, 630 km diameter) and Rembrandt (24.58°S- 41.19°S, 261.72°- 282.73°W, 716 km diameter) basins on Mercury, and the Apollo basin (10 ° –60 ° S, 125 ° –175 ° W, 492 km diameter) within the northeastern edge of the ~ 2500 km South Pole-Aitken (SPA) basin on the Moon [3]. For this work, we considered the multi-color images acquired by the Mercury Dual Imaging System - Wide Angle Camera (MDIS-WAC) [3] onboard the MESSENGER mission and hyperspectral data provided by the Moon Mineralogy Mapper (M3) [4] onboard the Chandrayaan-1 mission. After data calibration and the instrumental artifacts removal, we have photometrically corrected the data to derive multi- and hyper-spectral reflectance maps, afterwards we defined appropriate spectral indices to eventually obtain the spectral unit maps of these regions of interest. In next step, we will integrate the spectral unit maps obtained with the morpho-stratigraphic ones provided by other PLANMAP work packages [5, 6, 7] to merge the information and finally retrieve geological units.

 

This work is funded by the European Union’s Horizon 2020 research grant agreement No 776276- PLANMAP and by the Italian Space Agency (ASI) within the SIMBIO-SYS project (ASI-INAF agreement 2017-47-H).

 

References

 

[1] https://planmap.eu/

[2] https://pds.nasa.gov/

[3] S. Edward Hawkins III et al., 2007, Space Science Reviews, 131, 247–338.

[4] Pieters, C. E. et al., 2009, CURRENT SCIENCE, 96 (4).

[5] Brandt, C. et al., 2020 EGU General Assembly 2020.

[6] Ivanov, M.A., et al., 2018, Journal of Geophysical Research, 123 (10), 2585-2612.

[7] Wright, J., et al., 2019, 50th Lunar and Planetary Science Conference.

How to cite: Carli, C., Zambon, F., Altieri, F., Brandt, C., Rossi, A. P., and Massironi, M.: Intergrating morpho-stratigraphic and spectral units on Mercury and the Moon: Updates from the PLANMAP project, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19741, https://doi.org/10.5194/egusphere-egu2020-19741, 2020.

EGU2020-11206 | Displays | PS6.3

A Proposed Planetary Extension for FGDC Geospatial Metadata

Marc Hunter, Mark Bailen, and Trent Hare

As part of USGS Astrogeology’s ongoing efforts to support planetary spatial data infrastructures (PSDI), this extension seeks to codify common descriptions of planetary geoscience data that do not have an equivalence in the Federal Geographic Data Committee (FGDC) Content Standard for Digital Geospatial Metadata (CSDGM) core standard [1, 2]. This profile will be submitted for adoption by the FGDC so that it may be used by the community and will be revised as necessary to ensure it remains useful to the broadest base of planetary scientists.

Those active in supporting metadata efforts will point out that many users of FGDC CSDGM are transitioning to the more robust International Standards Organization (ISO) geospatial data standards, which is also officially endorsed by FGDC itself. Fortunately, the USGS is actively leading in this migration, but it is expected to take years, and support for the current FGDC CSDGM standard remains widespread.  

The basis for our proposed <solarsys> metadata extension is the need to 1) represent planetary coordinate reference systems and 2) capture supplemental fields unique to planetary science. Many of these fields are used in Astrogeology’s Astropedia, which has evolved over years to support the discovery of a wide variety of planetary data products, from global mosaics to rover observations [3].

It is the recommendation of these authors that a group representative of the broader planetary science community should assume stewardship of the metadata profile so that it can be of greatest accessibility and use, and be responsive to changes needed by the user base.

The first plans are to work with USGS developers of the Metadata Wizard Toolkit to integrate the extension along with controlled vocabularies for planetary bodies, space exploration missions and their instruments [4]. This will also posture the project to participate in the transition from FGDC to ISO. The authors encourage European colleagues who wish to develop a complementary profile with ISO or another standards body to collaborate with USGS. Maintaining alignment during the developmental phase will both accelerate progress and promote interoperability as they are put into use.

<solarsys>

    <hostsrc></hostsrc>

    <body>

        <system></system>

        <target></target>

        <quadsys></quadsys>

        <quadname></quadname>

        <rada></rada>

        <radb></radb>

        <radc></radc>

        <lattype></lattype>

        <londom></londom>

        <londir></londir>

        <ctrlnet></ctrlnet>

    </body>

    <footprin>

        <maxlat></maxlat>

        <minlat></minlat>

        <maxlon></maxlon>

        <minlon></minlon>

    </footprin>

    <feature>

        <featkey></featkey>

    </feature>

    <litho>

        <lithokey></lithokey>

    </litho>

    <tempo>

        <tempokey></tempokey>

    </tempo>

    <mission>

        <missikey></missikey>

    </mission>

    <instr>

        <instrkey></instrkey>

    </instr>

    <pdsstat></pdsstat>

    <pdsarch></pdsarch>

    <rover>

        <sol></sol>

        <featname></featname>

        <feattarg></feattarg>

    </rover>

    <sample>

        <strdepth></strdepth>

        <endepth></endepth>

    </sample>

    <bittype></bittype>

    <scale></scale>

    <bands></bands>

    <wkt></wkt>

</solarsys>

How to cite: Hunter, M., Bailen, M., and Hare, T.: A Proposed Planetary Extension for FGDC Geospatial Metadata, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-11206, https://doi.org/10.5194/egusphere-egu2020-11206, 2020.

 

Channel morphologies are sinuous, negative-relief linear forms that form by a current of water or lava. They may be fluvial or volcanic in origin. Channels are exclusively volcanic on Venus, volcanic or fluvial on Mars and fluvial on Titan. On Venus and Mars, channels are all paleoforms while on Titan (and Earth) they are actively forming. Channels may be hosted by valleys, that represent the cumulative erosional history of the embedded channel. They may be singular or may form braided pattern separated by streamlined island forms (e.g., Kasei Valles); a channel floor may host interior channels (e.g., Navua Valles), and channels may disappear gradually into flat plains (e.g., Simud Vallis). These are just a few of their characteristics that make their cartographic representation a complex issue.

In this work we analyzed and compared the symbology of channel forms in planetary geologic maps. An ongoing work on planetary geologic symbology identified 95 maps containing channel symbols in a total of 154 map (Nass et al. 2017b). Symbology is important for several reasons (Nass et al. 2011, Nass et al. 2017a). Although each map is complete on its own, standardized symbology enables direct comparison between maps. Maps are used for measurements: channel morphometry measurements across different quadrangles become problematic if symbols are used and defined differently.

Planetary geologic maps use three classes of symbols for representing channel forms: polygons as geologic units, polygons as surficial units laid over a geologic unit and line symbols for smaller channels. Line symbols often transform to geologic units when they reach a cutoff size for the used map scale. Line symbols do not continue over the unit symbols. This way drainage networks are split into two, incompatible symbol types. The cutoff size is often not reported in the legend that use the vague "narrow channels" designation for the line symbols. Sometimes line symbols are used only for "small distributary channels" or "small valleys".

Named channel units may be grouped geographically (e.g., Ares Vallis), by age (e.g., Hesperian channels), by morphology (steep walled channels), process (outflow channels) or as true geologic units (vallis floor sediments). These categories may be even mixed within one map.

The line symbols are typically solid blue (cyan) lines. This is in accordance with FGDC standards (FGDC 2006).

Different problems arise with drainage databases (Hynek et al. 2010, Alemanno et al. 2018). They typically uniformly trace dendritic valley networks, but they also contain singular and other channel forms, whereas "outflow channels" and lava channels are missing from these databases. The global map of Tanaka et al. (2014) uses two different blue line symbols for "channel axis" (i.e., valley network and some outflow-like channels) and "outflow channels".

It is needed to redefine channel form classification in the planetary domain and symbology (from Venus to Mars to Titan) and make it clear for mappers if different symbols should be used for different sizes, origins, and morphologies and how different symbols may be combined in one map.

 

How to cite: Hargitai, H.: Cartographic Representation of Channel Forms on Planetary Geologic Maps, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20298, https://doi.org/10.5194/egusphere-egu2020-20298, 2020.

EGU2020-22625 | Displays | PS6.3

gsymblib: Geologic symbols library and development for QGIS

Alessandro Frigeri

The gsymblib brings symbols and patterns useful in the earth and planetary geological mapping into QGIS, the desktop GIS application from the OSGeo geospatial software stack. Styling for points, lines, fill patterns and gradients are included.   Apart from the symbols' library,  gsymblib offers a build mechanism that allows to incrementally add and update symbols of the library.  This way, even small contributions will enhance the size and quality of the library.  The project is currently hosted and developed on Github at https://github.com/afrigeri/geologic-symbols-qgis, where the uses can choose to download only the symbols' library or the entire development environment to implement new symbols and contribute back to the project.  Currently, the library includes more than 100 user-contributed symbols and patterns defined by the Federal Geographic Data Committee (FGDC) for planetary geologic mapping, but others from different mapping authorities/institutions can be added. 

How to cite: Frigeri, A.: gsymblib: Geologic symbols library and development for QGIS, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-22625, https://doi.org/10.5194/egusphere-egu2020-22625, 2020.

This session will focus on Indexed 3D Scene Layers (I3S) and its evolution, as an OGC (Open Geospatial Consortium) community Standard. I3S enables the storage and streaming of massive amounts of heterogeneously distributed geospatial content, in the form of millions of discrete 3D objects with attributes, integrated surface meshes and point cloud data covering vast geographic areas, to web browsers, mobile apps and desktop.

Ability to stream millions of triangles and billions of point cloud, regardless of platform constraints, has opened a new 3D graphics and visual computing front in the geospatial world, where there is an increasing demand for high quality 3D application.

In this session, we will describe principles and concepts for organizing geospatial data based on bounding volume hierarchy (BVH), various spatial subdivision algorithms, efficient mesh representation, as well as exploring point cloud, mesh and texture compression/decompression techniques, while keeping the content friendly to GPUs. We will also demonstrate various examples of the different layer types and profiles that are supported in I3S and how the data structure and organization help to efficiently store segmentation/classification information as well as triangle/point level attribution.

Technological advancements in 3D graphics, data structuring, mesh and texture compression, efficient client-side filtering and so forth have significantly contributed to a paradigm shift in how geospatial content is created and disseminated, regardless of size and scale. Formats such as I3S now allow 3d content to be authored/created once and be efficiently consumed in various platforms including desktop, web and mobile for both offline and online access. This phenomenon – create once and consume everywhere model, has encouraged the dissemination and sharing of geospatial content for both planetary (whole earth) and planar 3D visualization experiences.

The session will show case numerous examples (for desktop, web and mobile experience) illustrating the many advancements made in geospatial technologies that are ripe to be embraced in various geoscience disciplines.

The I3S specification was released as a free and open standard by Esri and has been adopted as an OGC community standard for the past 2 and half years and is evolving vastly with many use cases.

How to cite: Belayneh, T.: I3S - an open standard for 3D GIS visualization on Web, Desktop and Mobile Platforms, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13542, https://doi.org/10.5194/egusphere-egu2020-13542, 2020.

EGU2020-20093 | Displays | PS6.3

New search capabilities based on observational geometry for Mars Express data in the ESA’s Planetary Science Archive

Emmanuel Grotheer and Nicolas Manaud and the ESA PSA and MEX SGS teams
The European Space Agency’s (ESA) Mars Express (MEX) mission to Mars has been returning valuable scientific data for ~16 years.  This data is available to the public for free via the Planetary Science Archive (PSA), which houses the raw, calibrated, and higher-level data returned by the ESA’s planetary missions, including data provided by the various MEX instrument teams.  Besides an FTP server, there is also a user interface with different search views available for the public to search for archived data.  Development of a map-based search interface is underway.  As a first step towards this, the geometrical parameters of all the data products from a wide variety of instruments had to be computed in a unified manner.  These values will be used to enable searches based on observational geometry via the Table View, and other views as well.   
1. The PSA user interfaces
The ESA’s PSA uses the Planetary Data System (PDS) format developed by NASA to store the data from its various planetary missions.  In the case of MEX, the data is stored in the PDS3 format, which primarily uses ASCII files to store and describe the data.  When first searching for new data, users would benefit from using the Table View search interface [1].  Here the user can search using various parameters, such as mission name, target (e.g. Mars), instrument name, processing level, observation times, etc.  The development of the PSA’s search capabilities continues, thus more search parameters will be added over time.  In particular, this presentation will focus on the development of new filter menus within the Table View to allow for searches based on the observational geometry of the data products. 
Also available in the Table View interface is a section for “Free Search”, allowing one to use Contextual Query Language (CQL) to search over additional parameters.  These various search methods rely mainly on the metadata provided by the instrument teams in the labels associated with each of the data products.  In the case of the observational geometry searches, in order to provide a uniform search capability, the GEOGEN tool was developed by SpaceFrog Design to provide the tables of relevant parameters to be queried.
 
2. Summary and Conclusions
Thanks to the efforts of the MEX instrument teams, the MEX Science Ground Segment team, and the PSA Archive Scientists and Engineers, over 16 years worth of observational data from Mars orbit are available to the public.  This data can be freely accessed at the ESA’s PSA, at .  There are multiple ways of browsing the archived data, including those from other planetary missions, though in this presentation we will focus on the new observational geometry search capability that will become available soon. 
The development of the PSA’s user interface is an ongoing project, and we welcome feedback from the community for suggestions on new ways to search this wealth of data.  Feedback and suggestions can be sent to .

How to cite: Grotheer, E. and Manaud, N. and the ESA PSA and MEX SGS teams: New search capabilities based on observational geometry for Mars Express data in the ESA’s Planetary Science Archive, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-20093, https://doi.org/10.5194/egusphere-egu2020-20093, 2020.

EGU2020-19961 | Displays | PS6.3 | Highlight

Planetary GIS – Review and the Road ahead

Stephan van Gasselt and Andrea Nass

Since the mid 1990s, off-the-shelf Geographic Information Systems (GIS) have been increasingly accepted as essential tools for data management, data analysis and visualization in the planetary sciences, in particular in planetary surface studies.

With that advance, small homebrew and niche solutions have been slowly abandoned in favor of commercial off-the-shelf (COTS) and established free and open-source software (FOSS) which are capable of providing a wide range of generic analyses tools.

This transition has likely been facilitated by three contemporaneous developments:

  1. the integrability and provision of planetary spheroid specifications with arbitrary radii definitions,
  2. the possibility to ingest planetary data in their native formats or to be able to use tools exporting data into common formats,
  3. the need to be able to ingest and co-register data at medium low (>200 m) as well as highest resolution (<5 m) at the same time as well as the need to make extensive use of digital terrain model analyses. These needs resulted from the release of data with varying spatial and temporal resolution initiated in the course of the Mars Global Surveyor mission.

To no surprise, user demands have been increasing over the last two decades due to high data-volume returns from Mars, the Moon and from Saturn’s satellites.

This particular development as well as an education which has been increasingly centered on spatial awareness helped shaping the landscape of spatial data management, data analysis and visualization supported by GIS technology. New challenges in these fields currently arise while other challenges just became more apparent and have been ghosting around for over 30 years without being solved thus far. Some of the new challenges evolve around the obvious need to be able to integrate large amounts of variable data, not only in terms of storing and managing, but also with respect to extracting meaningful information with purposeful tools as well as with respect to visualization. While the exponential data growth and the need for more sophisticated tools did certainly not come as a surprise, innovation and solutions to cope with such a demand lag far behind.

Open standards and stable interfaces allowing to extend functionalities have been demanded and discussed as essential challenge in GIS development for more than 30 years, and yet, “open data” has seemingly only recently become a market “vision”, and the future will show if interoperability will become bidirectional at the end. The relatively small planetary sciences community will need to come up (and has come up) with their own tools to extend GIS functionalities although that experience might be hampered by ever-changing interface specifications with new GIS releases rendering updates unsustainable on the long run. Other challenges, e.g., cartography of irregular bodies, cannot be addressed using additional tools as they target the very core of contemporary GIS tools.

In this presentation we will summarize and discuss recent challenges in Planetary GIS and focus on perspectives within a currently changing GIS landscape and try to address potential solutions and bypasses.

How to cite: van Gasselt, S. and Nass, A.: Planetary GIS – Review and the Road ahead, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-19961, https://doi.org/10.5194/egusphere-egu2020-19961, 2020.

CC BY 4.0