Displays

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 24^o 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.

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.

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.

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.

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.

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.

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.

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.

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.

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 H_D=(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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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 82^oS and 108^oE, where the crustal field is strong with a radial component ~30^o 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.

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.

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.

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.

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.

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.

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.

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.

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.