Introduction:  A plethora of geophysical, geo-chemical, and geodynamical observations indicate that the terrestrial planets have differentiated into silicate crusts and mantles that surround a dense core. The latter consists primarily of Fe and some lighter alloying elements (e.g., S, Si, C, O, and H). There is strong evidence from measurements of the tidal deformation of the planet that the core of Mars is presently liquid.

The InSight mission aims at constraining these numbers via the RISE radio tracking experiment, and the SEIS seismic package. We used data recorded by SEIS for high SNR marsquakes between March 2019 and July 2020. The InSight Marsquake Service located these events in the distance range 27-40 degrees, based on identification of P- and S-body waves. Later studies identified a number of secondary, surface-reflected phases, which were used to constrain the upper mantle. We build upon the velocity models derived from these phase picks to constrain the time window in which to look for shear waves reflected from the core mantle boundary. Since shear waves cannot propagate in a fluid medium, the core mantle boundary (CMB) acts as a polarization filter, which fully reflects horizontally polarized shear waves back into the mantle. Shear waves reflected from the CMB, called ScS, are therefore expected to have a predominantly horizontal polarization at the receiver, with an azimuth orthogonal to the source direction. In this distance range, ScS is separated in time from any other body wave phase and therefore well-observable.

Methods: We follow a two-step approach: 1. Confirm seismic arrivals as ScS, based on existing mantle velocity models. 2. Pick precise arrival times and invert those for mantle profiles and core size, constrained by mineralogy, moment of inertia and average density of the planet.

Results: The inversion of travel times constrains the core radius to the upper end of pre-mission geophysics-based estimates. This value is compatible with estimates from the geodetic experiment RISE onboard and implies that a lower mantle is unlikely to be present. Moreover, a large core has important implications for core composition. Average retrieved core density is 6 g/cm^3, which implies that for a (Fe-Ni)-S composition, a sulfur content in excess of 18% is required. This is above the eutectic composition observed experimentally with potentially profound implications for the future crystallization of the Martian core, subject to further laboratory research of Fe-S data under core conditions.

All ScS candidate phases that were observed show significant seismic energy and a relatively flat spectrum above 0.1 Hz, which implies a low seismic attenuation throughout the mantle. The spectral character of direct S-phases for the distant-most events is consistent with that of the ScS-phases for more nearby events, which supports the identification of the arrivals as core-reflected.

How to cite: Stähler, S. C., Khan, A., Ceylan, S., Duran, A. C., Garcia, R., Giardini, D., Huang, Q., Kim, D., Lognonné, P., Maguire, R., Marusiak, A., Samuel, H., Schmerr, N., Schimmel, M., Sollberger, D., Stutzmann, E., and Banerdt, W. B. and the InSight Core Collaboration: Seismic detection of the Martian core by InSight, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13310, https://doi.org/10.5194/egusphere-egu21-13310, 2021.

The InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) lander successfully delivered a geophysical instrument package to the Martian surface on November 26, 2018, including a broadband seismometer called SEIS (Seismic Experiment for Interior Structure). After two years of recording, seismic body waves phases of a small number of high-quality marsquakes have been clearly identified. In this work, we will present how we estimate the body waves arrival times, and how we handle them to constrain the locations of the marsquakes and the interior structure. The inverse problem relies on a Bayesian approach, to investigate a large range of possible locations and interior models. Due to the small number of data, the advantage of using such a method is to provide a quantitative measure of the uncertainties and the non-uniqueness. In order to take into account the strong variations of the crustal thickness due to the crustal dichotomy, and thus consider the seismic lateral variations, which could cause significant misinterpretations, arrival times corrections are added using crustal thickness maps obtained from gravity and topography data.

How to cite: Drilleau, M., Garcia, R., Samuel, H., Rivoldini, A., Wieczorek, M., Lognonné, P., Panning, M., Perrin, C., Ceylan, S., Schmerr, N., Khan, A., Lekic, V., Stähler, S., Giardini, D., Kim, D., Huang, Q., Clinton, J., Kawamura, T., Scholz, J.-R., and Davis, P. and the InSight Science Team: Estimation of the marsquakes’ location and the interior structure of Mars using InSight data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14998, https://doi.org/10.5194/egusphere-egu21-14998, 2021.

The InSight seismometer SEIS recorded tens of high-frequency (1.5-5Hz; HF) and Very-high frequency (1.5-15Hz, VF) Martian events. They are characterized by two temporally separated arrivals with a gradual beginning, a broad maximum and a very long decay. This observation is consistent with a long-range propagation of seismic P and S waves in a heterogeneous crust (Van Driel et al., accepted). To examine this hypothesis, first, we employ basic multiple-scattering concepts on the two groups of events. Then, we propose a full envelope modeling based on elastic radiative transport in a half-space. The model parametrization and the radiative transfer equations are presented in (Lognonné, P., et al. (2020) and Margerin, L., (2017)). We find that both HF and VF signals are depolarized and verify Gaussian statistics, at the exception of the ballistic primary and secondary arrivals. These properties agree with a multiple-scattering origin. For VF events, the energy partitioning ratio V²/H² between horizontal and vertical components is frequency dependent. We observe that V²/H² is maximum at the so-called ‘2.4Hz resonance’ (~2) and decreases rapidly at frequencies higher than 5Hz (~0.1) then i remains relatively low up to frequencies of 15Hz at least. HF events do not exhibit a decrease of V²/H² at high frequencies however further analysis reveals a strong correlation between energy partitioning and signal-to-noise (S/N) ratio for HF events. This observation suggests that a part of the difference between the HF and VF events can to some extent be explained by noise contamination. The generally low V²/H² ratio of VF events is reminiscent of the response of unconsolidated layers, as observed at Pinyon Flats Observatory on Earth (Margerin, L., et al. (2009)). Unlike earthquakes and moonquakes observed in the same frequency band, the delay time measured from onset to peak of the secondary arrival of HF and VF events is frequency-independent. This suggests that the spectrum of heterogeneity of the Martian crust is smooth. We observe that, for HF and VF events, the delay time is weakly dependent on hypocentral distance. This observation cannot be reconciled with the predictions of multiple-scattering theories in a statistically homogeneous medium however it suggests a stratification of heterogeneity in the Martian lithosphere. The coda quality factor Q_c of VF events is high and shows a linear increase with frequency. Q_c of HF events is higher but it may be overestimated due to the noise contamination. The linear frequency dependence of Q_c is strongly reminiscent of the leakage effect in a crustal scattering waveguide and suggests that part of the observed coda attenuation may be of structural origin. The full envelope modeling of the S0334a VF event results shows that the estimated value of the diffusivity (≃ 619 km²/s) is almost 6 times greater than for the S0128a VF event (≃ 90 km²/s). This observation again suggests a stratification of heterogeneity. In future works, we will perform the full envelope modeling of all the VF selected events at different frequencies to constrain a 1D attenuation and diffusion model of the Martian crust.

How to cite: Menina, S., Margerin, L., Kawamura, T., Lognonné, P., Marti, J., Drilleau, M., Calvet, M., Schmerr, N., van Driel, M., and Karakostas, F.: Energetic characteristics of High Frequency (HF) and Very High Frequency (VF) Martian events, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14609, https://doi.org/10.5194/egusphere-egu21-14609, 2021.

Since InSight (the Interior Exploration using Geodesy and Heat Transport) landed 26 months ago and deployed an ultra sensitive broadband seismometer(SEIS) on the surface of Mars, around 500 seismic events of diverse variety have been detected, making it possible to directly analyze the subsurface properties of Mars for the very first time. One of the primary goals of the mission is to retrieve the crustal structure below the landing site. Current estimates differ by more than 100% for the average crustal thickness. Since data from orbital gravity measurementsprovide information on relative variations of crustal thickness but not absolute values, this landing site measurement could serve as a tie point to retrieve global crustal structure models. To do so, we propose using a joint inversion of receiver functions and apparent incidence angles, which contain information on absolute S-wave velocities of the subsurface. Since receiver function inversions suffer from a velocity depth trade-off, we in addition exploit a simple relation which defines apparent S-wave velocity as a function of observed apparent P-wave incidence angles to constrain the parameter space. Finally we use the Neighbourhood Algorithm for the inversion of a suitable joint objective function. The resulting ensemble of models is then used to derive the full uncertainty estimates for each model parameter. Before its application on data from InSight mission, we successfully tested the method on Mars synthetics and terrestrial data from various geological settings using both single and multiple events. Using the same method, we have previously been able to constrain the S-wave velocity and depth for the first inter-crustal layer of Mars between 1.7 to 2.1 km/s and 8 to 11 km, respectively. Here we present the results of applying this technique on our selected data set from the InSight mission. Results show that the data can be explained equally well by models with 2 or 3 crustal layers with constant velocities. Due to the limited data set it is difficult to resolve the ambiguity of this bi-modal solution. We therefore investigate information theoretic statistical tests as a model selection criteria and discuss their relevance and implications in seismological framework.

How to cite: Joshi, R., Knapmeyer-Endrun, B., Mosegaard, K., Bissig, F., Khan, A., Panning, M., Staehler, S., Tauzin, B., Lekic, V., Scholz, J.-R., Davis, P., Widmer-Schnidrig, R., Garcia, R., Pinot, B., Lognonné, P., and Christensen, U.: Joint inversion of receiver functions and apparent incidence angles to investigate the crustal structure of Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9470, https://doi.org/10.5194/egusphere-egu21-9470, 2021.

Historical dike intrusions in the vicinity of volcanic edifices on Earth are known to produce swarms of seismic activity with cumulative seismic moments between 1·10¹² and 1·10²⁰ Nm, equivalent to moment magnitudes between 2 and 7. On Mars, long linear graben systems are likely to host giant dike complexes at depth, which possibly produced significant seismicity during their intrusion. Not only this, but dike intrusions are also candidates to produce crustal seismicity at present day, which may be detected during the lifespan of the InSight mission. In this work we infer the possible geometry of dikes underneath Cerberus Fossae, and make estimations of the energy released during their intrusion.

We used cross section area balancing on topographic profiles orthogonal to several of the Cerberus Fossae graben to estimate proxies for the geometry of the underlying dikes (aperture, height, depth, etc.). This technique has already been used to approximate dike properties at the nearby Elysium Fossae, with successful results. At Cerberus Fossae, the obtained dike aspect ratios are consistent with sublinear scaling, which is characteristic of fluid-induced fractures (as expected for dikes). These results support the presence of giant dikes underneath Cerberus, which may be up to 700 m thick, 140 km long, and have heights of up to 20 km.

Additionally, we used the inferred geometries and assumptions about the host rock mechanical properties to estimate various energy quantities related to dike intrusion, and compared them with the energy releases in terrestrial diking episodes. Two calculations are of special interest; M_d, the energy associated to dike inflation, and M_s, an approximation to the cumulative seismic moment release. The obtained M_d values are between 3.1·10²⁰ and 5.0·10²¹ Nm, and are 1 to 2 orders of magnitude larger than the equivalent moments in terrestrial events. M_s was calculated from M_d with two key assumptions; 1) that all aseismic energy was released by the dike, and 2) values of seismic efficiency (the percentage of seismic relative to the total energy released) based on terrestrial examples. The obtained M_s are between 6.3·10¹⁹ and 2.2·10²¹ Nm, which are equivalent to moment magnitudes of 6.5 and 7.9. These are comparable to, albeit slightly larger than, the cumulative moments of some of the largest terrestrial diking events, such as the first episode in the Manda-Hararo sequence (Ethiopia, 2005, M_s = 6.2) or the Miyake-jima event (Japan, 2000, M_s = 6.8).

The Elysium volcanic province is thought to have been active until very recent times, and possibly even at present day. If this is the case, then intrusions in the lower size of the spectrum investigated at Cerberus, and smaller-sized events, may be detected by InSight as a series of crustal seismic events with cumulative moment magnitudes <6. Further research is needed to fully assess the validity of the comparisons between terrestrial and Martian events, and the possible energy releases of dike-induced marsquakes.

How to cite: Rivas-Dorado, S., Ruiz, J., and Romeo, I.: First approximations to the energy release of giant dikes at Cerberus Fossae, Mars , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13008, https://doi.org/10.5194/egusphere-egu21-13008, 2021.

On the first hundreds of sols in which the InSight lander operated on the surface of Mars, its instrumentation has proven to be particularly suitable to unveil and understand atmospheric variability at all temporal scales, from the synoptic scale (baroclinic waves) to the sub-hour scale (gravity waves, bores) down to the turbulent scale (vortices, gusts, infrasounds). Recently, the InSight lander achieved a complete Martian year of observations of the atmosphere of Mars -- allowing for the seasonal variability of the Martian atmosphere and its phenomena at all scales to be monitored almost continuously, including during several large dust storms episodes. In this presentation, based on this Martian year of InSight observations, we will review the annual CO2 sublimation / condensation cycle, the variability of large-scale meteorology, the statistics of a year of wind observations -- and insightful comparisons with global climate models, the strong seasonal variability of gravity wave and turbulent activity, including a burst of activity of convective vortices in Mars' southern summer. We will also discuss how the atmosphere influences seismic and magnetic signals captured by InSight -- and the search for Martian infrasound.

How to cite: Spiga, A., Banfield, D., Newman, C., Murdoch, N., Lorenz, R., Garcia, R. F., Viúdez‐Moreiras, D., Pla-Garcia, J., Forget, F., Charalambous, C., Baker, M., Martire, L., Perrin, C., Lemmon, M., Stutzmann, É., Mittelholz, A., Stott, A., Mueller, N., Horleston, A., and Ceylan, S. and the InSight & TWINS & SEIS teams: A complete Martian year of atmospheric observations with InSight instruments, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-4967, https://doi.org/10.5194/egusphere-egu21-4967, 2021.

HEND (High Energy Neutron Detector) onboard NASA’s Mars Odyssey spacecraft performs measurements of neutron emission of Martian surface 2002. HEND uses ³He counters for detection of epithermal neutrons generated by Galaсtic Cosmic Rays interaction with surface and atmosphere of Mars.

Weak Martian atmosphere emits, absorbs and scatters neutrons slightly, and outgoing neutron flux on the orbit is changing depending on atmospheric density along the Martian seasons. We have analyzed the HEND data for seasonal variations of outgoing neutron flux above several areas of Mars for nine Martian annual cycles. Measured seasonal variations, presented as Ls profiles for individual years, are compared with numerically predicted profiles according to the model of Martian atmosphere.

How to cite: Golovin, D., Mitrofanov, I., Litvak, M., Sanin, A., and Malakhov, A.: Annual variations of Mars atmosphere, as seen by HEND data since 2002, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11879, https://doi.org/10.5194/egusphere-egu21-11879, 2021.

The ubiquitous dust aerosol particles in the atmosphere of Mars play a main role on the behaviour and evolution of its climate. By absorbing and scattering the incoming solar radiation, they modify the atmospheric thermal structure and dynamics. Dust radiative forcing calculations are of high relevance to understand Mars' overall atmospheric dynamics. The accuracy in determining internal radiation fields and the resulting atmospheric heating/cooling rates contribute to the uncertainties in these calculations.

Radiative transfer schemes using 2-stream approximations are widely implemented in multiple Mars’ dynamical models and Global Circulation Models (GCMs). The uncertainties associated to this approximation are related to neglecting details of dust particles’ scattering phase function: the higher the number of streams considered, the better the accuracy of the scheme, although there is a persistent trade-off between accuracy and computational cost. The objective of this work is to evaluate the accuracy of dust aerosol radiative forcing estimations in the Martian atmosphere by multiple-stream schemes.

Several scenarios covering the different atmospheric conditions during the Martian Year were simulated with different radiative transfer models, as well as other high-opacity dust storm scenarios. The atmosphere was discretised into 50 levels from 0 to 100 km, with atmospheric variables loaded from LMD’s Mars Climate Database (MCD). The visible and infrared spectral regions were divided into 12 bands, covering from 0.24 to 1,000 μm. Gaseous opacities were calculated with the correlated-k method, with absorption data retrieved from HITRAN. Dust aerosol radiative properties were derived using the wavelength-dependent properties reported by Wolff et al. (2006, 2009), with vertical distributions following a Conrath profile, and assuming a well-mixed dust scenario. Particle size (effective radius) and column dust opacity were given values to characterise every scenario. Finally, the calculated internal radiation fields and heating/cooling rates with the two-stream approximation code were compared with 4, 8, 16 and 32-stream solutions using the discrete ordinates method (DISORT).

The comparison of the results with respect to the 32-stream model shows heating rate underestimations with average differences of about 2.7, 0.3, 0.1, and 0.1 K/sol for the 2-, 4-, 8-, and 16-stream models, respectively. Such differences tend to be larger when there is more dust is loaded into the atmosphere. On the other hand, the average computational times for 1 sol using the 4-, 8-, 16-, and 32-stream schemes are about 15, 25, 40 and 135 times longer than the 2-stream scheme, respectively.

Future research prospects include the implementation of multiple-stream DISORT codes in Mars’ mesoscale dynamical models to investigate the accuracy of simulations of the atmospheric effects generated by local and regional dust storms.

How to cite: Chen-Chen, H., Pérez-Hoyos, S., and Sánchez-Lavega, A.: Comparison of radiative transfer schemes for the calculation of heating rates in the atmosphere of Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12590, https://doi.org/10.5194/egusphere-egu21-12590, 2021.

The electron density (N_e) profiles over the northern high-latitude region measured with Radio Occultation Science Experiments (ROSE) onboard the Mars Atmosphere and Volatile Evolution (MAVEN) have indicated more complicated ionospheric structure of Mars than previously thought.  Some of the profiles have shown wide and narrow shapes of the main N_e peaks, while others show anomalous characteristics of the topside plasma distribution.  Large variations in the topside N_e scale heights are observed presumably in response to the outward flow of ionospheric plasma or changes in plasma temperatures.   We use our 1-D chemical diffusive model coupled with the Mars - Global Ionosphere Thermosphere Model (M-GITM) to interpret these N_e profiles.  Our model is a coupled finite difference primitive equation model which solves for plasma densities and vertical ion fluxes.  The photochemical equilibrium in the model for each ion is assumed at the lower boundary, while the flux boundary condition is assumed at the upper boundary to simulate plasma loss from the Martian ionosphere.  The crustal magnetic field at the measured N_e locations is weak and mainly horizontal and does not allow plasma to move vertically.   Thus, the primary plasma loss from the topside ionosphere at these locations is most likely caused by diverging horizontal fluxes of ions, indicating that the dynamics of the upper ionosphere of Mars is controlled by the solar wind.  The primary source of ionization in the model is due to solar EUV radiation.  We find that the variation in the topside N_e scale heights is sensitive to magnitudes of upward ion fluxes derived from ion velocities that we impose at the upper boundary to explain the topside ionospheric structure.  The model requires upward velocities ranging from 60 ms^-1 to 80 ms^-1 for all ions to ensure an agreement with the measured N_e profiles. The corresponding outward fluxes in the range 1.6 x 10⁶ – 3.8 x 10⁶ cm^-2 s^-1 are calculated for O₂⁺ compared to those for O⁺ in the range 4 x 105 – 6 x 105 cm^-2 s^-1.  The model results for the northern N_e profiles will be presented in comparison with the measured N_e profiles.  This work is supported by Mohammed Bin Rashid Space Centre (MBRSC), Dubai, UAE, under Grant ID number 201604.MA.AUS.

How to cite: Majeed, T., Al-Mutawa, S., and Bougher, S.: A Model Analysis of the MAVEN/ROSE Electron Density Profiles at Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6555, https://doi.org/10.5194/egusphere-egu21-6555, 2021.

We investigate a range of atmospheric phenomena concerning their potential to address the Martian methane lifetime discrepancy. This refers to the over-estimate of the modelled lifetimes compared to observations by a factor of up to six hundred. We apply a newly developed atmospheric photochemical model where we vary in a Monte Carlo approach the chemical rate and Eddy mixing coefficients within their current uncertainties. We also investigate the effect of air shower events due to galactic cosmic rays and solar cosmic rays. Our results suggest that the current uncertainty in chemical rates and transport together with seasonal changes in the water column can likely account for up to a factor of about thirty in the Mars methane lifetime discrepancy whereas the air shower effects are likely to be of secondary importance.

How to cite: Grenfell, J. L., Wunderlich, F., Sinnhuber, M., Herbst, K., Scheucher, M., Gebauer, S., and Rauer, H.: Atmospheric phenomena affecting the methane lifetime on Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15442, https://doi.org/10.5194/egusphere-egu21-15442, 2021.

Several detections of methane in the Martian atmosphere have been reported from Earth-based and Mars orbit instruments with abundances ranging up to tens of ppbv, while in-situ measurements performed by the MSL rover at Gale crater showed some peaks up to 7 ppbv. A variety of methane formation mechanisms occurring in the subsurface have been proposed such as abiotic synthesis through Fischer-Tropsch Type (FTT) reactions. After its generation at depth, Martian methane can migrate upwards and be either directly released at the surface or trapped in subsurface reservoirs, such as clathrate hydrates, where it could accumulate over long time before being episodically liberated during destabilizing events. When ascending through stratigraphic layers, methane can move via one or several transport mechanisms. Seepage can occur through advection, the main CH₄ transport process on Earth, driven by pressure gradients and permeability and generally associated to fracture networks. Another transport mechanism is diffusion, which is mainly controlled by concentration gradient. This process is not efficient on short timescales and short-lived methane plumes related to diffusion should therefore originate from very shallow depths.

In this work, we model the subsurface transport of methane on Mars and its subsequent trapping in clathrate hydrates. For the latter, the effect of the clathrate formation pressure is especially examined, while methane subsurface transport is studied considering adsorption onto, advection and diffusion through the regolith.

How to cite: Gloesener, E., Karatekin, Ö., and Dehant, V.: Migration and storage of methane in the Martian crust , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15495, https://doi.org/10.5194/egusphere-egu21-15495, 2021.

Photoanalytical segmentation of individual soil grains and granulometry in high-resolution surface images are key in understanding sedimentation processes of planetary bodies before samples return to Earth. Here we present a Mathematica-based semi-automated image segmenting software tool that allows fast segmentation and granulometry analysis of Martian (soil) images based on the algorithm of Karunatillake et al. (2013, 2014), with a graphical user interface (GUI) to increase the software accessibility.

Our software has been adapted to Martian in-situ observation images including the Mars Hand Lens Imager (MAHLI) and Microscopic Imager (MI), providing segmenting and granulometry measurement through steps below: (1) Image imported: all common raster images are supported, as well as the IMG formatted MAHLI and MI images. While the MI image possesses a constant pixel size of 31 μm/pixel, for MAHLI images with various focal lengths, a focus motor count is required to calculate pixel size. The imported images are processed with gamma correction, contrast adjustment, background sharpen, and are visually decided whether there is a distinct foreground before going to the second step: (2) Image segmented: two independent modules are designed for segmenting the foreground and background with separate parameters, the coarser-grained foreground was masked before the finer-grained background is segmented. The GUI allows dynamic visualization of how the segmenting result changes with each parameter, facilitating the setting of parameters. (3) Granulometry: the grain size is calculated from the focal length and Wentworth classification of detected grains is established, highlighting the dominant class of grain size. The probability density and cumulative distribution of grain size can also be plotted. The granulometry results and parameters used are supported to export.

To check the performance of our software, we qualitatively tested our software with 57 MAHLI and MI images with or without foreground, with comparison to region based segmentation method such as BASEGRAIN, edge detection based method such as ENVI Classification tools and Feature Extraction tools, and supervised segmentation methods such as ENVI supervised classification tools and ImageJ Trainable Weka Segmentation tool. Our software shows better results in generating grains with closed boundaries and distinguishing adjacent grains with similar colors, with the fastest speed and less workload. Factors that may influence the accuracy of segmenting include image resolution, camera angle, inter-grain brightness/color contrast and shadow coverage.

In future work, a particle morphometry measuring function will be added so that statistics of grain roundness, sphericity, and angularity could be obtained. High-resolution images from the Moon and the asteroids will also be used in software testing to expand the range of its applicability to other planetary bodies. We will also consider its application on terrestrial cases, such as images of terrestrial sediments or petrological thin sections, which will need further improvement of the software concerning the increased compositional and optical complexity of terrestrial grains.

How to cite: Shi, Y., Zhao, S., Karunatillake, S., and Xiao, L.: Semi-automated Image Segmenting Software for Martian Soil Granulometry, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7872, https://doi.org/10.5194/egusphere-egu21-7872, 2021.

On Earth, jarosite is a weathering product forming in acidic-oxidative environments from the alteration of iron-bearing minerals in presence of liquid water. Typical settings where this iron-potassium hydrated sulphate is found, are weathering zones of pyrite-rich deposits, evaporative basins and fumaroles. Jarosite is not only known on Earth, it also occurs on Mars, where it was firstly identified by the Opportunity rover. The mineral was in fact recognized in the finely layered formations outcropping at Meridiani Planum and that were accurately investigated by the rover (Klingelhöfer et al. 2004). Since jarosite requires liquid water to form, its occurrence on Mars has been regarded as an evidence for the presence of liquid water in the geologic past of Mars (Elwood-Madden et al., 2004). Since then, many models have been proposed to describe the environments where the precipitation of Martian jarosite took place. The most accepted ones deal with evaporative basins similar to Earth’s playas, others concern volcanic activity and hydrothermal processes. An alternative proposal predicted that jarosite may have formed as a consequence of weathering of mineral dust trapped in massive ice deposits, i.e. the ice-weathering model (Niles & Michalsky, 2009). The hypothesis that jarosite formed on Mars because of low-temperature, acidic and water limited weathering, is not new (Burns, 1987), but until now no direct evidences were available to support it.

A potential Earth analogue to investigate such processes is deep Antarctic ice. We present a first investigation of deep ice samples from the Talos Dome ice core (East Antarctica) aimed at the identification of englacial jarosite, so as to support the ice-weathering model. Evidences gathered through independent techniques showed that jarosite is actually present in deep Antarctic ice and results from the weathering of dust trapped into ice. The process is controlled by the re-crystallization of ice grains and the concurrent re-location of impurities at grain-junctions, which both depend on ice depth. This study demonstrates that the deep englacial environment is suitable for jarosite precipitation. Our findings support the hypothesis that, as originally predicted by the ice-weathering model, paleo ice-related processes have been important in the geologic and geochemical history of Mars.

References

Burns, R. Ferric sulfates on Mars. J. Geophys. Res. 92, E570-E574 (1987).

Elwood-Madden et al., 2004. Jarosite as an indicator of water-limited chemical weathering on Mars. Nature 431, 821-823 (2004).

Klingelhöfer, G. et al. Jarosite and Hematite at Meridiani Planum from Opportunity's Mössbauer Spectrometer. Science 306, 1740-1745 (2004).

Niles, P. B. & Michalski, J. M. Meridiani Planum sediments on Mars formed through weathering in massive ice deposits. Nat. Geosci. 2, 215-220 (2009).

How to cite: Baccolo, G., Delmonte, B., Niles, P., Cibin, G., Di Stefano, E., Hampai, D., Keller, L., Maggi, V., Marcelli, A., Michalski, J., Snead, C., and Frezzotti, M.: Jarosite in Antarctic deep ice supports the ice-weathering model for jarosite formation on Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6279, https://doi.org/10.5194/egusphere-egu21-6279, 2021.

Recent modelling efforts based on MAVEN measurements suggest that the Martian Moon Phobos is affected by a unique space weathering scenario [1]. On rocky bodies in the solar system, mostly solar wind ions cause ion-induced space weathering of their surfaces. Space weathering is an important driver for the alteration of planetary surfaces [2], as well as for the creation of exospheres on, for example, the Moon or Mercury [3, 4]. As a consequence, most analog experiments aim to investigate effects by the impact of solar wind ions [5, 6].

Phobos is not only exposed to the solar wind, but also significantly sputtered by planetary oxygen ions originating from the Martian atmosphere due to its proximity to Mars [7]. O ions at energies of several 100s to several 1000s eV are responsible for the dominant erosion process on the surface of Phobos in the Martian magnetotail [1]. However, there still remain uncertainties as the sputtering by planetary O ions has not yet been investigated experimentally.

Here we present experiments on the sputtering of Phobos analog materials by O⁺ and O₂⁺ ions at different energies [8]. As analog material, thin films of augite (Ca,Mg,Fe)₂Si₂O₆ on a quartz crystal microbalance (QCM) are used. The QCM allows in-situ real-time sputtering experiments by measuring the sample’s mass change [9]. Experimental sputtering yields are compared to simulations with the SRIM package and SDTrimSP [10, 11]. The latter has shown better accuracy for reproducing sputtering yields [6, 12], which is also found in the presented studies [8].

Oxygen ion irradiations of Phobos analog materials show fluence-dependent mass changes, indicating that both sputtering and O ion implantation in the near-surface region occur at the same time. The measurements can be consistently reproduced by dynamic SDTrimSP simulations that include O implantation up to local concentrations of 67%. The new experimental findings show that sputtering by O ions is about 50% lower than previously assumed. However, our measurements still support the importance of sputtering by planetary ions in the Martian tail, where it will dominate over solar wind sputtering by up to a factor of 10 [8].

References

 [1]         Q. Nenon, et al., J. Geophys. Res.: Planets 124 (2019), 3385

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

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

[4]          R.M. Killen, et al., Space Sci. Rev. 132 (2007), 509

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

[6]          P.S. Szabo, et al., Astrophys. J. 891 (2020), 100

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[8]          P.S. Szabo, et al., J. Geophys. Res.: Planets 125 (2020), e2020JE006583

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

[10]        J. Ziegler, et al., NIMB, 268 (2010), 1818

[11]        A. Mutzke, IPP-Report 2019-02 (2019)

[12]        M. Schaible, et al., J. Geophys. Res.: Planets 122 (2017), 1968

How to cite: Szabo, P. S., Biber, H., Jäggi, N., Wappl, M., Stadlmayr, R., Primetzhofer, D., Nenning, A., Mutzke, A., Fleig, J., Mezger, K., Lammer, H., Galli, A., Wurz, P., and Aumayr, F.: Quantifying Space Weathering of Phobos by Martian Planetary Oxygen Ions, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1813, https://doi.org/10.5194/egusphere-egu21-1813, 2021.

This work presents the latest results on the estimations of Water Equivalent Hydrogen (WEH) gathered in martian areas Vera Rubin ridge (VRR) and Glen Torridon (GT) by the Dynamic Albedo of Neutron (DAN) instrument installed onboard NASA’s Curiosity rover. The main science objective of DAN is to study bound water content in shallow layer of martian subsurface down to 0.6 m [1].

Extensive scientific campaign on Vera Rubin ridge was started in the middle of 2017 and lasted until the beginning of 2019 when the rover reached another region – Glen Torridon. VRR is mostly related to hematite minerals that might be formed in the presence of liquid water. On the other hand, GT region is thought to be associated with clay minerals, according to CRISM observations [2].

We will present the latest results on DAN passive observations in these Mars areas. Data are referred to the period of more than 3 years of observations or MSL traverse segment from 17 km to 23 km. The main result is the notable increase of WEH in GT in comparison with VRR, as well as in comparison with the whole Curiosity traverse. Possibly, the increase may indicate on the qualitative difference in neutron-absorption elements that are forming the soil of the GT region.

References:

[1] Mitrofanov, I. G., et al., (2014). Water and chlorine content in the Martian soil along the first 1900 m of the Curiosity rover traverse as estimated by the DAN instrument. J. Geophys. Res., 119(7), 1579–1596. doi:10.1002/2013JE004553.

[2] Murchie, S. L., et al. (2009), Compact Reconnaissance Imaging Spectrometer for Mars investigation and data set from the Mars Reconnaissance Orbiter's primary science phase, J. Geophys. Res., 114, E00D07, doi:10.1029/2009JE003344.

How to cite: Nikiforov, S., Djachkova, M., Mitrofanov, I., Litvak, M., Lisov, D., and Sanin, A.: Estimation of Water Content in Vera Rubin Ridge and Glen Torridon areas Based on Measurements of the MSL/DAN Instrument in Gale crater, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11196, https://doi.org/10.5194/egusphere-egu21-11196, 2021.

Current knowledge of the clay unit at Oxia Planum, the Rosalind Franklin rovers landing site, is based in large part on spectroscopy data from the OMEGA and CRISM instruments. While these instruments have proved useful for creating a broad map of this unit, along with identifying candidates for the clay making up the unit, their usefulness is limited by their spatial resolution. Mapping at Oxia has primarily been carried out using 1200-300m/pixel OMEGA or 200-100m/pixel CRISM data and, even accounting for the intermittent 18m/pixel CRISM hyperspectral data available, existing clay maps are insufficient for the purposes of rover traverse planning.

Images from the Colour and Stereo Surface Imaging System¹ (CaSSIS), which has a resolution of 4m/pixel, can improve upon this. Work done by members of the CaSSIS science team identified certain CaSSIS band ratios which can aid in identifying the presence of ferric/ferrous minerals². In a more recent study CRISM, HiRISE colour and CaSSIS data were used to identify that at least two spectrally and morphologically distinct subunits make up the Oxia clay unit³. These sub units are divided into a lower and upper member. The lower member appears orange in CaSSIS/HiRISE VNIR images, shows extensive metre-scale fracturing and possesses CRISM spectral signatures consistent with the presence of a Fe/Mg-rich clay mineral. The upper member, blue in CaSSIS/HiRISE VNIR images, shows metre-decametre scale fracturing along with CRISM spectral signatures consistent with a mix of a Fe/Mg-rich clay mineral and olivine.

This work demonstrates that ferric detections within CaSSIS band ratios correlate well with CRISM, and that the lower clay member appears to have a higher ferric content than the upper member. Given this a new, higher resolution clay map is being created using CaSSIS band ratios in conjunction with HiRISE greyscale imagery to observe fracture size. This map, currently being constructed over the 1-sigma landing ellipses, delineates between the two subunits well in addition to revealing those areas where the two subunits are too intermixed to reliably differentiate at CaSSIS’s resolution. Given that CaSSIS has higher resolution in comparison to the CRISM/OMEGA instruments, that it can differentiate between the clay sub-units, and that it provides higher landing site coverage compared to CRISM hyperspectral data, means this map will provide a significant improvement over what is currently available for the sites clay unit.

References; 1; Thomas N. et al. (2017). "The Colour and Stereo Surface Imaging System (CaSSIS) for the ExoMars Trace Gas Orbiter." Space Science Reviews 212(3-4): 1897-1944. 2; Tornabene L. L. et al. (2017). "Image Simulation and Assessment of the Colour and Spatial Capabilities of the Colour and Stereo Surface Imaging System (CaSSIS) on the ExoMars Trace Gas Orbiter." Space Science Reviews 214(1). 3; Mandon L. et al. (in review). "Spectral Diversity and Stratigraphy of the Clay-Bearing Unit at the Exomars 2020 Landing Site Oxia Planum." Astrobiology

Acknowledgement; CaSSIS is a project of the University of Bern, with instrument hardware development supported by INAF/Astronomical Observatory of Padova (ASI-INAF agreement n.2020-17-HH.0), and the Space Research Center (CBK) in Warsaw.

How to cite: Parkes Bowen, A., Mandon, L., Bridges, J., Quantin-Nataf, C., Tornabene, L., Briggs, J., Thomas, N., and Cremonese, G.: Mapping and characterisation of the Oxia Planum clay-bearing unit using CaSSIS imagery, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13356, https://doi.org/10.5194/egusphere-egu21-13356, 2021.

Pit craters are enigmatic sub-circular depressions observed on rocky and icy planetary bodies across the Solar System. These craters do not primarily form during catastrophic impact or the forcible eruption of subsurface materials, but likely due to collapse of subsurface cavities following fluid (e.g., magma) movement and/or extensional tectonics. Pit craters thus provide important surficial records of otherwise inaccessible subsurface processes. However, unlocking these pit crater archives is difficult because we do not know how their surface expression relates to their subsurface structure or driving mechanisms. As such, there is a variety of hypotheses concerning pit crater formation, which variously relate cavity collapse to: (i) opening of dilatational jogs during faulting; (ii) tensile fracturing; (iii) karst development; (iv) permafrost melting; (v) lava tube evacuation; (vi) volatile release from dyke tip process zones; (vii) pressure waning behind a propagating dike tip; (viii) migration of magma away from a reservoir; and/or (ix) hydrothermal fluid movement inducing host rock porosity collapse. Validating whether these proposed mechanisms can drive pit crater formation and, if so, identifying how the physical characteristics of pits can be used to infer their driving mechanisms, is critical to probing subsurface processes on Earth and other planetary bodies.

Here we use seismic reflection data from the North Carnarvon Basin offshore NW Australia, which provides ultra-sound like images of Earth’s subsurface, to characterize the subsurface structure of natural pit craters. We extracted geometrical data for 61 pits, and find that they are broadly cylindrical, with some displaying an inverted conical (trumpet-like) morphology at their tops. Fifty-six pit craters, which are sub-circular and have widths of ~150–740 m, extend down ~500 m to and are aligned in chains above the upper tips of dikes; crater depths are  ~12–225 m. These dike-related pit craters occur within long, linear graben interpreted to be bound by dyke-induced normal faults. Five pit craters, which are ~140–740 m wide and ~32–107 m deep, formed independent of dykes and are associated only with tectonic normal faults. Our preliminary data reveal a moderate, positive correlation between crater width and depth but there is no distinction between the depth and width trends of pit craters associated with dikes and those with tectonic normal faults. To test whether our quantitative data can be used to inform interpretation of pit craters observed on other planetary bodies, we compare their morphology to those imaged in Noctis Labyrinthus on Mars; there are >200 pit craters here, most of which occur in chains, with widths ranging from 369–11743 m and depths from 1–1858 m.

Overall, we show reflection seismology is a powerful tool for studying the three-dimensional geometry of pit craters, with which we can test pit crater formation mechanisms. We anticipate future seismic-based studies will improve our understanding of how the surface expressions of pit craters (either in subaerial or submarine settings) can be used to reconstruct subsurface structures and processes on other planetary bodies, where such subsurface information is not currently available.

How to cite: Magee, C., Jackson, C. A.-L., Kling, C. L., and Byrne, P. K.: Imaging the subsurface structure of pit craters, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5067, https://doi.org/10.5194/egusphere-egu21-5067, 2021.

The North Polar Layered Deposits (NPLD), which consist of dusty water ice layers, have recorded the climatic variations of Mars. We use High Resolution Imaging Science Experiment (HiRISE) data (ground pixel size of up to ~0.25m/pixel) to study the morphology and current erosional processes at the NPLD scarps. Fanara et al. (1,2) have performed automated detection of the fallen ice blocks at the foot of scarps. Our aim is to search for their possible source areas.

We apply change detection techniques to multi-temporal images. The images are ortho-rectified using HiRISE Digital Terrain Model (DTM) and then co-registered to ensure subpixel alignment accuracy. Due to the low-sun conditions in Martian polar areas, the surface morphology can be revealed from cast shadows. In addition, HiRISE operates on a nearly sun-synchronous orbit, which means the images are taken at the same local time of day, providing good conditions for automatically detecting changes in shadow patterns of the ice-fragments.

The areas with changed shadows illustrate the spatial distribution of mass wasting activities. Our results show that most of the detached ice-fragments originate from the lower parts of the scarp, which are heavily affected by fracturing. Based on the detected changes, we will further investigate the characteristics of mass wasting and estimate the volume of the detached ice-fragments. The temporal and spatial distribution of detached ice fragments at different NPLD scarps can provide insights into the ice behavior and thus support modelling studies of viscous flow velocities (3), thermoelastic stresses (4) and climate variations of Mars. Ultimately, we intend to explore the evolution of the NPLD scarps by correlating long-term mass wasting characteristics with seasonal and morphological parameters.

References

[1] Fanara et al.,2020. Planetary and Space Science. 180, p.104733.

[2] Fanara et al.,2020. Icarus. 342, p.113434.

[3] Sori et al., 2016. Geophysical Research Letters, 43(2), pp.541-549.

[4] Byrne et al., 2017. EPSC, Vol. 11.

How to cite: Su, S., Fanara, L., Zhang, X., Gwinner, K., Hauber, E., and Oberst, J.: Sources of ice block falls at the Martian north polar scarps: detection from multi-temporal HiRISE image sets, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7489, https://doi.org/10.5194/egusphere-egu21-7489, 2021.

Most Noachian-aged craters on Mars have distinctive morphologic characteristics that suggest they were modified by runoff from rainfall in a predominantly warm and wet early Mars climate. However, melting and runoff of frozen water ice (snowmelt) represents a plausible alternative for fluvial erosion in the Noachian. In recent work, we described a "closed-source drainage basin" (CSDB) crater in Terra Sabaea that contained inverted fluvial channel networks and lacustrine deposits. The crater is not breached by fluvial channels and lacks depositional morphologies such as fans or deltas, which sets it apart from previously described open- and closed-basin lakes on Mars that are hydrologically connected to their surroundings. The lack of hydrologic connectivity, along with additional evidence of remnant cold-based glacial morphologies within the crater, led us to hypothesize top-down melting of a cold-based crater wall glacier as the source of runoff and sediment for the fluvial and lacustrine deposits, which produced one or more proglacial lakes within the crater.

Here, we describe the results of a follow-on survey of the region within 500 km of the first CSDB crater. We searched for examples of features that could be interpreted as inverted fluvial channels regardless of their location. Of the 42 inverted channel networks we identified, 19 are located within unbreached craters; 17 are within breached craters with at least one inlet but no outlets; and 6 are located in the intercrater plains. The features are not randomly distributed; rather, they form two distinct groupings, one in the southwest of the study area and another in the east, with very few in the north or west. All but one occurs within an elevation range of 0 to +3 km. There are several previously identified closed-basin lakes within the study area, but none contained inverted channels.

The 42 inverted channel systems represent a wide variety of geologic and hydrologic settings. The region has distinctly low valley network density, and the few mapped valley networks in the region are clustered around +2 km elevation. If the fluvial regime were controlled primarily by elevation, and assuming no significant sequestration, lower elevations should have greater overall runoff production due to the accumulation of flow from upslope. The difference between breached and unbreached craters could therefore represent glacial melting occurring within craters (higher elevation) as opposed to significantly upslope of them (lower elevation), which would instead promote runoff and breaching of craters by valley networks.

We previously described a single CSDB crater that showed evidence for cold-based crater wall glaciation, sedimentation and proglacial lake formation, but this new work adds a significant body of evidence that such processes were operating at much greater regional scales. While runoff from rainfall is usually considered the most likely mechanism of fluvial erosion in the Noachian, the possibility remains that fluvial erosion could have occurred via snowmelt in a subfreezing ambient climate. We have provided compelling evidence that fluvial and lacustrine features could have formed in such a climate and that Noachian Mars may have been colder than previously believed.

How to cite: Boatwright, B., Head, J., and Palumbo, A.: Inverted Fluvial Channels in Terra Sabaea, Mars: Geomorphic Evidence for Proglacial Lakes and Widespread Highlands Glaciation in the Late Noachian, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8504, https://doi.org/10.5194/egusphere-egu21-8504, 2021.

We continue the analysis of HiRISE high resolution images of Mars to understand properties of dust covering the surface. The data on dust devils observed with Mars landers and surface traces of dust devils could be expanded with elongated albedo features imaged near “new” impact sites (“new” means that we have orbital images before and after the meteoroid impact, which give us an estimate of the impact date and the age of a feature). The age of these features is from 0.5 to 12 terrestrial years. From geometric reasons we could assume that the most possible mechanism of this elongated albedo details is the “footprint” of two or more colliding air shock waves, generated at the impact site. Of ~1200 “new” impacts known today, in 18 cases crater pairs or clusters, created with fragments of the same “parent” meteoroid, we recognize 24 thin “parabolas” with a width of 1 to 10 m (0.2 to 10 main crater diameters, D), extended to 100 – 400 m (3 to 100 D) from the impact site. In ~30 cases near a single crater we observe a curved albedo feature nick-named “scimitar”. These features have width, growing with a distance from the impact point. The length varies from 10 to 100 D, the width varies from 1 to 10 D. Our working hypothesis is that “scimitars” are footprints of ballistic and spherical air shock wave collision at the surface. Both “parabolas” and “scimitars” have an exact bilateral symmetry, which allows us to reconstruct the flight direction of projectiles.

We estimate the equivalent energy of spherical air blasts with two different assumptions for “parabolas” and “scimitars” formation. For parabolas we assume a mechanism, similar to dust devil track formation – the negative pressure excurse uplifts the upper fine dust layer. The main assumption is that the dark parabolic strip width corresponds the wave length of the negative pressure phase in the air shock wave. It gives us the minimum energy estimate as in reality the negative phase could be longer. The negative pressures here along the parabola length decay from about 10 to 5 Pa with the phase duration of a few milliseconds. Such a suction pulse is able to mobilize dust particles 50 to 100 microns in size.

For scimitars, which in contrast to “dark” parabolas are typically “brighter” than surrounding area, we have no a good mechanical explanation of origin. However, with limits of our current model, the spherical “explosion” air blast should be enough energetic, to overrun the ballistic shock wave. From non-linear motion of the shock wave front we can estimate the fraction of meteoroid’s kinetic energy, converted to the air blast energy. The model is able to reproduce approximately the scimitar’s curvature.

How to cite: Ivanov, B.: Mars surface dust activation at small meteoroid’s impacts, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10018, https://doi.org/10.5194/egusphere-egu21-10018, 2021.

       There are thousands of small cones on Isidis Planitia on Mars. The cones have diameters of 300–500 m and heights of ~30 m. Many cones form subparallel chains several kilometers in length. Their origin is discussed in many papers [1,2,3,4] however, the mechanism of their formation is not explained, nor the reason for their arrangement in subparallel chains. The cones may be: rootless cones, cinder cones, tuff cones, pingos, mud volcanoes etc. [4]. Some of chains have a characteristic furrow suggesting possibility of fissure volcanism.

       The prevalence of these chains indicates that large-scale processes are responsible for their formation. Their proper classification can help identify their origin and explain other large-scale processes on Isidis Planitia. There are a few works about statistics of cones  on Isidis Planitia e.g. [1,2,5]. However, we approached the problem in a different way. 

        Our analysis indicates that the cones can be grouped in larger systems. We divided Isidis Planitia into several characteristic regions. There may be several types of cones in one of the distinguished regions. Our division is based on the following structures:

1.Chains of separate cones,

2.Chains of cones connected with each other,

3a. Chains of cones connected to the furrow through the center,

3b. Chains of cones connected to the furrow through the center with elongated, elliptical cones,

4. Chains of cones with the traces of flows,

5. Chains of irregular cones without calderas with a depression around the cones,

6a. Ridge arches without cones,

6b. Chains of cones on the ridges. 

        We also paid attention to the orientation of the chains of cones. In most of our regions there are also groups of cones that do not form linear chains. Such group are named as "field of cones''

         Our current Isidis Planitia division includes 36 regions. We distinguished 11 regions with the predominant arrangement of arcs in the directions between ENE and ESE, 5 regions with the directions between WNW and WSW, 2 regions with the directions between NNE and NNW and 15 areas with the directions between SSE and SSW, 3 areas where the arcs of the cones form circles. In the rest of our regions there are no chains of cones.  

       We marked also sinuous ridges, cracks and serial depressions, occurring near craters, fields with polygonally cracked surface and quasi-circular depressions sQCDs - ghost craters [4].

Plan of future research: The next stage of our research is to explain the origin of the formation of each type of cone and their chains on Isidis Planitia.

References:

[1] Guidat, T., et al., (2015) Earth and Planet. Sci. Let . 411, 253-267. [2] Souček, O., et al., (2015) Earth and Planet. Sci. Let 426, 176-190.  [3] Gallinger, C.L. and Ghent, R. R., (2016) 40th Lunar and Planet. Sci. Conf. 1953. [4] Ghent, R. R., et al., (2012) Icarus 217, 1169-183. [5] Hiesinger H., et al., (2009)  47th Lunar and Planet. Sci. Conf. 2767.

How to cite: Zalewska, N., Czechowski, L., Ciążela, J., and Kuzaj, M.: Regional morphological division on Isidis Planitia on Mars, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13700, https://doi.org/10.5194/egusphere-egu21-13700, 2021.

Dynamic changes of Martian north polar scarps present a valuable insight into the planet's natural climate cycles (Byrne, 2009; Head et al., 2003)^1,2. Annual avalanches and block falls are amongst the most noticeable surface processes that can be directly linked with the extent of the latter dynamics (Fanara et al, 2020)³. New remote sensing approaches based on machine learning allow us to make precise records of the aforementioned mass wasting activity by automatically extracting and analyzing bulk information obtained from satellite imagery.  Previous studies have concluded that a Support Vector Machine (SVM) classifier trained using Histograms of Oriented Gradients (HOG) can be used to efficiently detect block falls, even against backgrounds with increased complexity (Fanara et al., 2020)⁴. We hypothesise that this pretrained model can now be utilized to generate an extended dataset of labelled image data, sufficient in size to opt for a deep learning approach. On top of improving the detection model we also attempt to address the image co-registration protocol. Prior research has suggested this to be a substantial bottleneck, which reduces the amounts of suitable images. We plan to overcome these limitations either by extending our model to include multi-sensor data, or by deploying improved methods designed for exclusively optical data (e.g.  COSI-CORR software (Ayoub, Leprince and Avouac, 2017)⁵).  The resulting algorithm should be a robust solution capable of improving on the already established baselines of 75.1% and 8.5% for TPR and FDR respectively (Fanara et al., 2020)4. The NPLD is our primary area of interest due to it’s high levels of activity and good satellite image density, yet we also plan to apply our pipeline to different surface changes and Martian regions as well as on other celestial objects.

1. Head, J.W., Mustard, J.F., Kreslavsky, M.A., Milliken, R.E., Marchant, D.R., 2003. Recent ice ages on Mars. Nature 426, 797–802

2. Byrne, S., 2009. The polar deposits of Mars. Annu. Rev. Earth Planet. Sci. 37, 535–560.

3. Fanara, K. Gwinner, E. Hauber, J. Oberst, Present-day erosion rate of north polar scarps on Mars due to active mass wasting; Icarus,Volume 342, 2020; 113434, ISSN 0019-1035.

4. Fanara, K. Gwinner, E. Hauber, J. Oberst, Automated detection of block falls in the north polar region of Mars; Planetary and Space Science, Volume 180, 2020; 104733, ISSN 0032-0633.

5. Ayoub, F.; Leprince, S.; Avouac, J.-P. User’s Guide to COSI-CORR Co-registration of Optically Sensed Images and Correlation; California Institute of Technology: Pasadena, CA, USA, 2009; pp. 1–49.

How to cite: Martynchuk, O., Fanara, L., Hauber, E., Oberst, J., and Gwinner, K.: Computer vision model for detecting block falls at the martian north polar region., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15776, https://doi.org/10.5194/egusphere-egu21-15776, 2021.

Seeking signs of past life in the geological record of Mars is one of the four primary goals of the NASA Mars 2020 mission. However, scant attention has been paid to the fossilized products of life-substrate interactions (ichnofossils), which are one of the most abundant and reliable biosignatures on Earth. This lack of attention is surprising because the ichnofossil heritage does not include only metazoan tracks, but also macroscopic burrows produced by bacteria, microborings ascribed to the activity of bacteria and fungi, and biostratification structures produced by archaea, cyanobacteria and euglenozoans. In light of this gap, the goal of the present study is evaluating the suitability of the Mars 2020 Landing Site for ichnofossils. To this goal, this work applies palaeontological predictive modelling, a technique used to predict the location of fossil sites in uninvestigated areas on Earth. Accordingly, a GIS of the landing site is developed. Each layer of the GIS maps the suitability for one or more ichnofossil types (bioturbation, bioerosion, biostratification structure) based on an assessment of a single attribute (suitability factor) of the Martian environment. Suitability criteria have been selected among the environmental attributes that control ichnofossil abundance, preservation, and accessibility in W Liguria (Italy), Naturtejo UNESCO Geopark (Portugal), and Ômnôgov district (Mongolia). The goal of this research will be delivered through a predictive map showing which areas of the Mars 2020 landing site are more likely to preserve ichnofossils. This map can be used to guide future efforts to the regions of the Mars 2020 Landing Site with the highest ichnological potential, realizing benefits in life-search efficiency and cost‐reduction.

How to cite: Baucon, A., Neto De Carvalho, C., Briguglio, A., Felletti, F., and Piazza, M.: An ichnological predictive map of the Jezero Crater, Mars: searching for potential traces of life-substrate interactions based on terrestrial analogues (Liguria, Italy; Naturtejo UNESCO Geopark, Portugal; Ômnôgov, Mongolia), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9051, https://doi.org/10.5194/egusphere-egu21-9051, 2021.

In 2022, ESA/ROSCOSMOS will launch the ExoMars2022 rover mission to Mars. The selected landing site for the mission is Oxia Planum, a wide, Noachian-age, phyllosilicate-bearing plain located on the SE border of Chryse Planitia. The Fe,Mg-rich clay mineral deposits at Oxia Planum are one of the largest exposures of this type on Mars, with a thickness of more than 10 m. They clearly record complex water-rock interactions and as such are a promising target to answer scientific questions posed by the ExoMars 2022 mission pertaining to the history of water and the geochemical environment in the shallow Martian subsurface, and the ancient and present habitability of the planet.

From the spectral analysis by CRISM and OMEGA, bedrock deposits at Oxia appear to contain vermiculite, a hydrous 2:1 phyllosilicate. But the exact mineralogy of the deposits and their origin is not yet fully understood. To fill this gap, and to better prepare for in-situ analyses by the ExoMars2022 rover, we performed a survey of potential terrestrial analog rocks by determining their mineralogy and NIR spectra for comparison with CRISM and OMEGA spectra of bedrock deposits at Oxia. The study focused on Fe-rich, trioctahedral vermiculite.

Two terrestrial sites were identified and studied: Otago, New Zealand with vermiculitized chlorite-schists that underwent alteration without significant oxidation; and Granby, Massachusetts with basaltic tuffs containing Fe-rich clays of apparent hydrothermal origin filling amygdales. Both analogues have been added to a newly built Planetary Terrestrial Analogue Library (PTAL) collection. The PTAL collection aims to provide the scientific community with analogue rocks to help characterize and define the mineralogy and geochemistry of landing sites on Mars chosen for in-situ analyses (www.ptal.eu).

The analogue comparisons reveal that Oxia bedrock deposits consist of Fe-rich, trioctahedral vermiculite, which is well crystallized and probably mixed with minor saponite. Additionally, NIR data analysis suggests that the deposits were not oxidized, nor illitized after formation. Based on this study, Oxia’s bedrock deposits may have formed from: (1) hydrothermal or magma fractionation-related origin of phyllosilicates and formation as an ash-fall deposits or (2) chlorite-rich sediment transported to a basin where chlorite was subsequently altered to vermiculite under anoxic, reducing conditions. The detailed characterization of the analogues and discussion of processes inferred for the evolution of Oxia Planum will be presented during the meeting.

Vermiculite, with its high surface area and exchange capacity, has great potential to store organic compounds. The mineralogy of the bedrock deposits at Oxia, along with the anoxic, reducing conditions that might have been prevalent during Noachian time would be advantageous for retaining and preserving organic matter and make it a promising site for future analysis.

How to cite: Krzesinska, A., Bultel, B., Loizeau, D., Craw, D., April, R., Poulet, F., and Werner, S.: Mineralogy, aqueous history and biosignature preservation potential of bedrock deposits at Oxia Planum, ExoMars 2022 landing site - Spectral characterization of terrestrial analogues., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-841, https://doi.org/10.5194/egusphere-egu21-841, 2021.

Serpentinization and carbonation have affected ultramafic rocks on Noachian Mars in several places. Among the most prominent systems revealing mineral assemblages characteristic of serpentinization/carbonation is the Nili Fossae region [1]. Jezero crater – the target of the Mars 2020 rover –hosted a paleolake which constitutes a sink for sediments from Nili Fossae [1]. Thanks to the near infrared spectrometer onboard Mars2020 [2], the mission has the potential to offer ground truth measurement for other putative serpentinization/carbonation system documented on Mars. Several important aspects that may be addressed are: Do carbonates result from primary alteration of olivine-rich lithologies or are they derived by reprocessing of previous alteration minerals [3]? What is the composition? and nature of the protolith, which appear to be constituted of considerable amounts of olivine [4]? To reveal critical information regarding the conditions of serpentinization/carbonation, accessory minerals need detailed studies [1; 5]. In case of Jezero Crater, and serpentinization on Mars in general, the main alteration minerals are identified, but little is known about the accessory minerals.

The Nili Fossae-Jezero system has potential analogues in terrestrial serpentinized and carbonated rocks, such as the Leka Ophiolite Complex, Norway (PTAL collection, https://www.ptal.eu). Here, distinct mineral assemblages record different stages of hydration and carbonation of ultramafic rocks [6].

We perform petrological and mineralogical analyses on thin sections to characterize the major and trace minerals and combine with Near Infrared (NIR) spectroscopy measurements. We study the significance of the mineralogical assemblages including solid solution composition and nature of accessory minerals. Effect of the presence of accessory minerals on the NIR signal is investigated and their potential incidence on the amount of H₂/CH₄ production in mafic or ultramafic system is discussed [5; 8]. This could improve our understanding of serpentinization and carbonation processes on Mars, which can guide future in-situ operations and also help for a better interpretation of the remote sensing data acquired on other possible serpentinization/carbonation systems.

 References:

1. Brown, A. J., et al. EPSL297.1-2 (2010): 174-182.

2. Wiens, R.C., et al.  Space Sci Rev217, 4 (2021).

3. Horgan, B., et al. Second International Mars Sample Return. Vol. 2071. 2018.

4. Ody, A., et al. JGR: Planets118.2 (2013): 234-262.

5. Klein, F., et al. Lithos178 (2013): 55-69.

6. Bjerga, A., et al. Lithos227 (2015): 21-36.

7. Bultel, B. (Doctoral dissertation, Lyon). (2016).

How to cite: Bultel, B., Krzesinska, A., Loizeau, D., Poulet, F., Astrheim, H. O., Bjerga, A., 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 2021, online, 19–30 Apr 2021, EGU21-12057, https://doi.org/10.5194/egusphere-egu21-12057, 2021.

The Mars organic molecular analyzer (MOMA) of the Rosalind Franklin rover (ExoMars project) will combine laser desorption-ionization mass spectrometry (LDI-MS) and gas-chromatography mass spectrometry (GC-MS) to assess the origin of organic matter on planet Mars. In order to further assess the type of molecular information that can be retrieved with the former technique, we applied high-resolution laser two-step mass spectrometry (L2MS) to fossil organic matter of sedimentary rock from the Jurassic deposit of Orbagnoux, France. Abundant sulfur-rich microbial organic matter has been thoroughly documented in this deposit [1]. This sample has been chosen following the detection of thiophenes at Gale Crater on Mars by the Sample analysis at Mars (SAM) instrument [2]. In our L2MS instrument [3], the samples are irradiated with a pulsed desorption laser (532 or 266 nm), which generates a plume of chemical species that can be further ionized with a second orthogonal laser beam (266 nm). A radiofrequency ion guide is used to carry the ions to an orthogonal time-of-flight mass spectrometer (oToF-MS system by Fasmatech), yielding high-resolution mass spectra (m/Δm ~10000 at 128 m/z). Focusing of the desorption laser using a reflective objective and automated micro-positioning of the sample were used to generate hyperspectral raster mappings. Subsamples included solvent-extracted molecules (bitumen and maltene fractions), insoluble macromolecular organic matter (kerogen), rock powder and a polished slice. Our analyses showed that we can extract chemical information with LDI-MS from both soluble and insoluble organic fractions of the Orbagnoux samples and that various chemical families can be distinguished even in mineralized samples. Carbon clusters, including sulfurated and hydrogenated species could be detected in all subsamples. With the exception of the rock slice, polyaromatic hydrocarbons could be detected in all samples. Oxygenated molecules and alkylbenzenes could only be detected in extracts, which generated rich and intense mass spectra. Various inorganic ions were also generated in all sample fractions. Using focused desorption beams, carbon clusters (including sulfurated clusters) and inorganic species could be detected and mapped in the polished slice with <50 µm lateral resolution. L2MS thus shows great promise for fast screening of organic/inorganic species on Mars, and for microanalyses applied to paleontological questions.

[1] Mongenot, T., Derenne, S., Largeau, C., Tribovillard, N.P., Lallier-Vergès, E., Dessort, D., Connan, J., 1999. Spectroscopic, kinetic and pyrolytic studies of kerogen from the dark parallel laminae facies of the sulphur-rich Orbagnoux deposit (Upper Kimmeridgian, Jura). Org. Geochem. 30, 39–56. 

[2] Eigenbrode, J.L., Summons, R.E., Steele, A., Freissinet, C., Millan, M., Navarro-González, R., Sutter, B., McAdam, A.C., Franz, H.B., Glavin, D.P., Archer, P.D., Mahaffy, P.R., Conrad, P.G., Hurowitz, J.A., Grotzinger, J.P., Gupta, S., Ming, D.W., Sumner, D.Y., Szopa, C., Malespin, C., Buch, A., Coll, P., 2018. Organic matter preserved in 3-billion-year-old mudstones at Gale crater, Mars. Science (80-. ). 360, 1096–1101. 

[3] A. Faccinetto, P. Desgroux, M. Ziskind, E. Therssen, C. Focsa, High-sensitivitydetection of polycyclic aromatic hydrocarbons adsorbed onto soot particles using laser desorption/laser ionization/time-of-flight mass spectrometry: An approach to studying the soot inception process in low-pressure flames, Combustion and Flame 158 (2011) 227–239. 

How to cite: Thlaijeh, S., Lepot, K., Carpentier, Y., Duca, D., Egorov, D., Riboulleau, A., Tribovillard, N., and Focsa, C.: Multiscale analysis of Jurassic rocks with sulfur-rich organic matter using laser desorption/ionization mass spectrometry, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16158, https://doi.org/10.5194/egusphere-egu21-16158, 2021.

After 17 years in orbit Mars Express remains one of ESA’s most scientifically productive Solar System missions which publication record exceeds 1300 papers. Characterization of the surface geology 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 characterized the geology of Jezero crater in great detail and provided Digital Elevation Model (DEM) of several equatorial regions at 50 m/px resolution. New maps and catalogues of surface minerals with 200 m/px resolution were released. MARSIS radar published new observations and analysis of the multiple subglacial water bodies underneath the Southern polar cap. Modelling suggested that the “ponds” can be composed of hypersaline perchlorate brines.

Spectrometers and imagers SPICAM, PFS, OMEGA, HRSC and VMC continued amending the longest record of atmospheric parameters such as temperature, dust loading, water vapor and ozone abundance, water ice and CO₂ clouds distribution and observing transient phenomena. More than 27,000 ozone profiles derived from SPICAM UV spectra obtained in MY#26 through MY#28 were assimilated in the OpenMARS database. A new “scan” mode of the spacecraft was designed and implemented to investigate diurnal variations of the atmospheric parameters. Observations of Tharsis region and Hellas basin contribute to mesoscale meteorology.

ASPERA measurements together with MAVEN “deep dip” data enabled assessment of the conditions that lead to the formation of the dayside ionopause in the regions with and without strong crustal magnetic fields suggesting that the ionopause occurs where the total ionospheric pressure (magnetic + thermal) equals the upstream solar wind dynamic pressure.

In 2020 Mars Express successfully performed two types of novel observations. In egress-only radio-occultations a two-way radio link was locked at a tangent altitude of about 50 km. This is well below the ionospheric peak and would allow perfect sounding of the entire ionosphere thus doubling the number of ionospheric soundings. MEX and TGO performed several test UHF occultations. The dual-spacecraft radio-occultation technique would significantly enhance the missions’ capabilities in atmospheric sounding.  

Mars Express is extended till the end of 2022. A science case for the mission extension till the end of 2025 will be developed and submitted by summer 2021. 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., Carter, J., Duxbury, T., Forget, F., Giuranna, M., González-Galindo, F., Holmström, M., Jaumann, R., Määttänen, A., Martin, P., Montmessin, F., Orosei, R., Pätzold, M., Plaut, J., and Team, M. S.: Mars Express science highlights and future plans, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-12956, https://doi.org/10.5194/egusphere-egu21-12956, 2021.

The wide field of view of the Visual Monitoring Camera (VMC) onboard Mars Express, together with the polar orbit of the spacecraft, make VMC very suitable to monitor polar phenomena on Mars¹. During Martian Years 34 and 35, Martian polar regions were imaged regularly by VMC, and in this work we use this set of images to analyze the evolution of both north and south polar ice caps. We determine the limits of the ice cap at different longitudes and the total area covered by ice as the season evolves, and we analyze the possible influence of the Global Dust Storm in the evolution of the ice caps regression curves. Finally, we describe a number of mid-scale atmospheric features that develop at the edge of the polar caps.

¹ Hernandez-Bernal et al. ”The 2018 Martian Global Dust Storm Over the South Polar Region Studied With MEx/VMC” Geophys. Res. Lett. 46, pp 10330-10337 (2019)

How to cite: del Río-Gaztelurrutia, T., Sánchez-Lavega, A., Hernández-Bernal, J., Angulo, A., Hueso, R., Cardesín-Moinelo, A., Martin, P., Wood, S., and Titov, D.: Analysis of the evolution of Martian polar caps during Martian Years 34-35 from Mars Express Visual Monitoring Camera, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-7787, https://doi.org/10.5194/egusphere-egu21-7787, 2021.

Introduction: The European Space Agency’s (ESA) Mars Express (MEX) mission to Mars has been returning valuable scientific data for ~17 years.  This data is available to the public for free via the Planetary Science Archive (PSA), which houses the raw, calibrated, and higher-level data returned by the ESA’s planetary missions, including data provided by the various MEX instrument teams.  The Visual Monitoring Camera (VMC) was originally used to monitor the deployment of the Beagle 2 lander.  In recent years, these images have been worked on by a science team from Bilbao for scientific research.  These raw and processed images of this new ‘8th instrument’ have been included in the PSA, including observations of an elongated cloud near Arsia Mons that garnered considerable public attention [1].  In this presentation we will show how to use the PSA user interface to find this data.

The PSA user interfaces: The ESA’s PSA uses the Planetary Data System (PDS) format developed by NASA to store the data from its various planetary missions.  In the case of MEX, the data is stored in the PDS3 format, which primarily uses ASCII files to store and describe the data.  There are two primary ways in which to find the data.  One is the FTP area, which houses all the public data in the PSA.  Here, there are no advanced search capabilities, but it does provide access to all the supporting files and documentation for the various datasets.  When first searching for new data, users would benefit from using the web-based search interfaces [2].  Here the user can search using various parameters, such as mission name, target (e.g. Mars), instrument name, processing level, observation times, etc.  The development of the PSA’s search capabilities continues, thus more search parameters continue to be added.  The Image View interface is particularly helpful when looking through browse images provided by the instrument teams.  Recently, a prototype of a new Map View has been made public, in which most of the MEX data can be seen.  These various search methods rely on the metadata provided by the instrument teams in the labels associated with each of the data products.

Access and Feedback: All this data can be freely accessed at the ESA’s PSA, at https://archives.esac.esa.int/psa/.  There are multiple ways of browsing the data.  The development of the PSA’s user interface is an ongoing project, and we welcome feedback from the community for suggestions on new ways to search this wealth of data.  Feedback and suggestions can be sent to psahelp@cosmos.esa.int.

References: 
[1] Bauer M. (2018, October 25) ESA Science & Exploration. Mars Express keeps an eye on curious cloud. Retrieved from http://www.esa.int/Science_Exploration/Space_Science/Mars_Express/Mars_Express_keeps_an_eye_on_curious_cloud
[2] Besse S., Vallat C., Barthelemy M., Coia D., Costa M., De Marchi G., Fraga D., Grotheer E., Heather D., Lim T., Martinez S., Arviset C., Barbarisi I., Docosal R., Macfarlane A., Rios C., Saiz J., and Vallejo F. (2018) Planetary and Space Science, Vol. 150, pp. 131-140.

How to cite: Grotheer, E. and the Mars Express Science Ground Segment, Planetary Science Archive team, and the MEX-VMC instrument team: Using the ESA’s Planetary Science Archive to Search for Mars Express VMC Data of an Elongated Cloud near Arsia Mons, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3374, https://doi.org/10.5194/egusphere-egu21-3374, 2021.

The Trace Gas Orbiter, TGO, is now well into its second Martian year of operations. The first year has been a highly successful Martian 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 dynamic behaviour as a consequence of the dust storm. A significant observations is the strong upward transport of water vapour that has been found during the dust storm. HCl has been detected for the first time in the Martian atmosphere, and characterisations of the other minor species and trace gasses are continuing. A large numbers of profiles are being produced on a daily basis. The dedicated search of methane is continuing and still shows that there is no methane above an altitude of a few km, with an upper limit established at about 20 pptv (2∙10^-11).

We now have a full Martian year of observations after the Global dust storm, and seasonal effects can now be studied under normal conditions. Climatological studies, benefitting from the 400km, 74 degrees inclination non-solar synchronous orbit, have been initiated, 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 to do. 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 well above 15,000 of images over a large variety of targets, including the landing sites of the 2020 NASA and 2022 ESA rovers, Jezero Crater and Oxia Planum. Stereo imaging has enabled topographic information and precise 3-D landscape synthesis.

This presentation will summarise the highlights and recent results 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 2022 mission, to be launched in September 2022, carrying a Rover and a surface science platform to the surface of Mars.

How to cite: Svedhem, H., Vandaele, A., Korablev, O., Mitrofanov, I., and Thomas, N.: The ExoMars Trace Gas Orbiter – Progress and future studies, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16216, https://doi.org/10.5194/egusphere-egu21-16216, 2021.

The molecular oxygen (O2) and carbon oxide (CO) are minor constituents of the Martian atmosphere with the annual mean mixing ratio of (1560 ± 60 ppm) and (673 ± 2.6 ppm), respectively (Krasnopolsky, 2017). Both are non-condensable species and their latitudinal variations are induced by condensation and sublimation of CO₂ from the polar caps that result in enrichment and depletion and seasonal variations are following the total CO₂ amount in the atmosphere.

The Atmospheric Chemistry Suite (ACS) is a set of three spectrometers (-NIR, -MIR, and -TIRVIM) intended to observe Mars atmosphere onboard the ESA-Roscosmos ExoMars 2016 Trace Gas Orbiter (TGO) mission (Korablev et al., 2018). The near infrared channel (NIR) is a compact spectrometer operating in the range of 0.7–1.7 µm with a resolving power of λ/Δλ ~ 25,000. It is designed to operate in nadir and in solar occultation modes. The simultaneous vertical profiling of the O₂ and CO density at altitudes of 10-60 km based on 0.76 µm and 1.57 µm bands, respectively, is a unique feature of the ACS NIR science in occultation. In this work we present the seasonal and latitudional distribution of the O₂ and CO mixing ratios obtained for period of 2018-2020 (MY34 and35) and the comparison with the LMD General Circulation model. We report the averaged mixing ratio for CO of ~950 ppm and for O2 of~1800 ppm at low altitudes (~20 km). Also, we detected extremely enriched CO layer at 10-15 km in the southern polar region at Ls=100-200° both for MY34 and MY35.

How to cite: Fedorova, A., Lefèvre, F., Trokhimovskiy, A., Korablev, O., Montmessin, F., Forget, F., Olsen, K., Luginin, M., Lomakin, A., Ignatiev, N., Belyaev, D., Patrakeev, A., and Alday, J.: CO and O2 in the Martian atmosphere with ACS NIR onboard TGO., EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14406, https://doi.org/10.5194/egusphere-egu21-14406, 2021.

This work takes advantage of the NOMAD spectrometer observations, on board the 2016 ExoMars Trace Gas Orbiter. ExoMars is an ESA-Roscosmos joint mission consisting of a rover and an orbiter (Trace Gas Orbiter - TGO). The Nadir and Occultation for Mars Discovery (NOMAD) is one of the four instruments on board TGO. The instrument is a suite of three spectrometers designed to observe the atmosphere and the surface of Mars in the UV, visible and IR. For this study, the Limb, Nadir and Occultation (LNO) channel, operating in the IR, is selected [1][2].  We focus on specific signatures in the [2.3 - 3.8 μm] range of NOMAD-LNO in order to study the possible detection of clouds at these wavelengths in the infrared.

For this study, we have selected the order 169 ([2611.8 nm - 2632.7 nm]) located in the vicinity of 2.7 µm CO₂/H₂O ices absorption band. We search for the presence of ice clouds in MY 34 (L_S = 150° - 360°) and MY 35 for observations with a solar zenith angle below 80 degrees.  The detection method is adapted from Bellucci et al., 2019 [3] and L. Ruiz Lozano et al., 2020 [4].  The initial results indicate a number of detections in the Tharsis region consistent with the known ‘W’ clouds [6][7].  Finally, these results will be compared with the NOMAD-UVIS observations ([230 nm - 310 nm]) obtained at the same TGO orbits.

Acknowledgements

The NOMAD experiment is led by the Royal Belgian Institute for Space Aeronomy (IASB-BIRA), assisted by Co-PI teams from Spain (IAA-CSIC), Italy (INAF-IAPS), and the United Kingdom (Open University). This project acknowledges funding by the Belgian Science Policy Office (BELSPO), the Belgian Fonds de la Recherche Scientifique – FNRS under grant number 30442502 (ET_HOME) and the FRIA, with the financial and contractual coordination by the ESA Prodex Office (PEA 4000103401, 4000121493), by Spanish Ministry of Science and Innovation (MCIU) and by European funds under grants PGC2018-101836-B-I00 and ESP2017-87143-R (MINECO/FEDER), as well as by UK Space Agency through grants ST/R005761/1, ST/P001262/1, ST/R001405/1 and ST/R001405/1 and Italian Space Agency through grant 2018-2-HH.0.

References
[1] A.C. Vandaele et al., 2015. Optical and radiometric models of the NOMAD instrument part I: the UVIS channel. Optics Express, 23(23):30028–30042.
[2] E. Neefs et al., 2015. NOMAD spectrometer on the ExoMars trace gas orbiter mission: part 1—design, manufacturing and testing of the infrared channels. Applied optics, 54(28):8494–8520.
[3] G. Bellucci et al., 2019. TGO/NOMAD Nadir observations during the 2018 global dust storm event, EPSC-DPS 2019
[4] L. Ruiz Lozano et al., 2020. Use of TGO-NOMAD nadir observations for ice detection, EPSC Abstracts, Vol. 14, Virtual EPSC 2020, EPSC2020-748.
[5] M. Vincendon, et al., 2011. New near‐IR observations of mesospheric CO2 and H2O clouds on Mars, J. Geophys. Res., 116, E00J02, doi:10.1029/2011JE003827.
[6] J. L. Benson, et al., 2003. The seasonal behavior of water ice clouds in the Tharsis and Valles Marineris regions of Mars: Mars Orbiter Camera Observations, Icarus, Volume 165, Issue 1, 2003, Pages 34-52, ISSN 0019-1035, https://doi.org/10.1016/S0019-1035(03)00175-1.

How to cite: Ruiz Lozano, L., Karatekin, Ö., Dehant, V., Bellucci, G., Oliva, F., Altieri, F., Carrozzo, F. G., D'Aversa, E., Daerden, F., Thomas, I., Ristic, B., Willame, Y., Depiesse, C., Mason, J., Patel, M., López Moreno, J. J., and Vandaele, A. C.: Ice clouds detection with NOMAD-LNO onboard ExoMars Trace Gas Orbiter, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14775, https://doi.org/10.5194/egusphere-egu21-14775, 2021.

The NOMAD instrument currently in orbit around Mars on board ESA's ExoMars Trace Gas Orbiter (TGO) includes UVIS, a UV-visible spectrograph covering the spectral range 200-700 nm. This instrument has two channels, one for solar occultation and a nadir channel essentially designed to analyse solar backscattered radiation. Since April 2019, the TGO spacecraft is occasionally tilted so that the nadir channel is pointed toward the Martian limb to observe the planetary airglow. A first success was the discovery of the forbidden oxygen green line at 557.7 nm that is ubiquitous in all UVIS limb dayside observations. This emission gives its characteristic colour to the terrestrial polar aurora but had was never been observed before in the airglow of other planetary atmospheres. This emission is excited by the interaction between solar radiation and CO₂ and shows a mean intensity peak near 80 km. More recently, the much weaker OI 630-nm emission has been detected following co-addition of several hundreds of UVIS spectra. It is much weaker than the green line, as a consequence of collisional deactivation of the long-lived O(¹D) excited state. Both oxygen dayglow emissions have been successfully modelled. Molecular transitions are also identified in the UVIS ultraviolet spectrum, including the CO Cameron bands, the CO₂⁺ ultraviolet doublet at 298-299 nm and the Fox-Duffendack-Baker (FDB) bands. They originate from the lower thermosphere near 120 km.

The seasonal-latitudinal evolution of the 557.7-nm emission will be described and compared with model simulations for the conditions of the observations. Simultaneous observations of dayglow emissions originating from different altitude will be available over a full Martian year. Coupled with model simulations, they provide constraints on the changing structure and composition of the Martian lower thermosphere, a region difficult to probe otherwise.

How to cite: Gérard, J.-C., Aoki, S., Leonardos, G., Lauriane, S., Yannick, W., Ian, T., Cédric, D., Bojan, R., Ann Carine, V., Frank, D., Manish, P., Jose, L.-M., Giancarlo, B., and Jon, M.: Multispectral analysis of the Martian dayglow from UVIS-NOMAD on board TGO, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-5164, https://doi.org/10.5194/egusphere-egu21-5164, 2021.

We will present the vertical distribution of ozone obtained from NOMAD-UVIS solar occultations and we will compare the results of three retrieval schemes.

NOMAD (Nadir and Occultation for MArs Discovery) 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 [1,2].

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 [3].

Since the beginning of operations, on 21 April 2018, NOMAD UVIS acquired more than 4000 solar occultations with an almost complete coverage of the planet.

NOMAD-UVIS spectra are simulated using three different retrieval scheme:

1) An onion peeling approach based on [4,5] deriving slant columns at the different altitudes sounded, from which local densities are obtained;

2) The line-by-line radiative transfer code ASIMUT-ALVL developed at IASB-BIRA [6] using the Optimal Estimation Method to derive the local density profile in one go (on all transmittances of one occultation observation);

3) A direct onion peeling method deriving sequentially from top to bottom the local densities in the different layers probed.

We will compare results obtained from the different retrieval methods as well as their uncertainties and we will discuss the advantages and difficulties of each method.

References

[1] Vandaele, A.C., et al., Planetary and Space Science, Vol. 119, pp. 233–249, 2015.

[2] Neefs, E., et al., Applied Optics, Vol. 54 (28), pp. 8494-8520, 2015.

[3] M.R. Patel et al., In: Appl. Opt. 56.10 (2017), pp. 2771–2782. DOI: 10.1364/AO.56.002771.

[4] Quémerais, E.,et al. J.Geophys. Res. (Planets)111, 9, 2006.

[5] Piccialli, A. et al., Planetary and Space Science, 113-114(2015) 321–335

[6] Vandaele, A.C., et al., JGR, 2008. 113 doi:10.1029/2008JE003140.

How to cite: Piccialli, A., Vandaele, A. C., Willame, Y., Aoki, S., Depiesse, C., Trompet, L., Neary, L., Viscardy, S., Daerden, F., Erwin, J., Thomas, I. R., Ristic, B., Mason, J., Patel, M., Khayat, A., Wolff, M., Bellucci, G., and Lopez Moreno, J. J.: Ozone vertical profiles from TGO/NOMAD-UVIS: an inter-comparison of three retrieval schemes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10062, https://doi.org/10.5194/egusphere-egu21-10062, 2021.

FREND is a neutron telescope installed onboard Russian-European ExoMars mission Trace Gas Orbiter. Neutron measurements from orbit are a good characteristic of water content in the subsurface of Mars down to 1 meter in depth. The instrument’s major characteristic is its neutron collimator that narrows significantly the field of view allowing for mapping with high spatial resolution of 60-200 km.

Previous missions (e.g. HEND experiment on NASA’s Mars Odyssey) showed that water content is enhanced mainly in Martian polar regions and at Arabia area, however spatial resolution of these instruments only allowed to map the surface with a resolution of several hundreds of kilometers. A study performed on FREND data accumulated during its science mission between May 2018 and January 2021 was targeted on equatorial band of ±40° latitude. We identified several local areas with enhanced mass fraction of water and performed a thorough analysis of each of them to identify the water content and estimate statistical significance of such wet spots.

The locations found are associated with major Martian relief formations, e.g. Olympus Mons, Ascraeus Mons, Xanthe Terra, Valles Marineris and others, each showing water content of tens of weight percent (wt%), with good statistical certainty above 3σ relative to the immediate dry surroundings.

In this talk we will present the areas identified as well as explain the search algorithm and water content estimation techniques.

How to cite: Malakhov, A., Mitrofanov, I., Litvak, M., Sanin, A., Golovin, D., Djachkova, M., Nikiforov, S., Anikin, A., Lisov, D., Lukyanov, N., and Mokrousov, M.: High Water Content Areas Identified In Equatorial Band of Mars by FREND Neutron Telescope Onboard ExoMars TGO, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8797, https://doi.org/10.5194/egusphere-egu21-8797, 2021.

Radiation environment in the interplanetary space and Mars orbit during the declining phase of 24th solar cycle and transition to 25th cycle according measurements aboard ExoMars TGO

Jordanka Semkova1, Rositza Koleva1, Victor Benghin3, Krasimir Krastev1, Tsvetan Dachev1, Yuri Matviichuk1, Borislav Tomov1, Stephan Maltchev1, Plamen Dimitrov1, Nikolay Bankov1, Igor Mitrofanov2, Alexey Malakhov2, Dmitry Golovin2, Maxim Mokrousov2, Anton Sanin2, Maxim Litvak2, Maya Djachkova2, Sergey Nikiforov2, Denis Lisov2, Artem Anikin2, Vyacheslav Shurshakov³, Sergey Drobyshev³

¹Space Research and Technology Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria, jsemkova@stil.bas.bg

²Space Research Institute, Russian Academy of Sciences, Moscow, Russia, mitrofanov@np.cosmos.ru

³State Scientific Center of Russian Federation, Institute of Biomedical Problems, Russian Academy of Sciences, Moscow, Russia, v_benghin@mail.ru

The dosimetric telescope Liulin-MO for measuring the radiation environment is a module of the Fine Resolution Epithermal Neutron Detector (FREND) onboard the ExoMars TGO.

Here we present results from measurements of the charged particle fluxes, dose rates and estimation of radiation quality factors and dose equivalent rates at ExoMars TGO science orbit (circular orbit with 400 km altitude, 74⁰ inclination, 2 hours orbit period), provided by Liulin-MO from May 01, 2018 to January 10, 2021.

The obtained data show that: an increase of the dose rates and fluxes is observed from May 2018 to February 2020 which corresponds to the increase of galactic cosmic rays (GCR) intensity during the declining of the solar activity in 24th solar cycle; From March to August 2020 the measured radiation values are practically equal, corresponding to the minimum of 24th cycle and transition to 25th cycle. The highest values of the dose rate (15.5/16.2 µGy h-1 at two perpendicular directions) and particle flux (3.24/3.33 cm-2s-1 at two perpendicular directions) are registered in this period; Since September 2020 a decrease of the dose rates and fluxes is observed, corresponding to the decrease of GCR intensity during the inclination phase of the 25th cycle.

The cosmic ray fluxes and doses measured in Mars orbit are recalculated into values meaningful for the deep interplanetary space at about 1.5 AU. The flux in the free space is at least 3.68 cm-2s-1 and the dose rate is 18.9 µGy h-1 in August 2020. The results demonstrate that the radiation conditions in the interplanetary space worsen in the minimum of the solar activity in 24th cycle compared to the previous solar minimum.

Liulin-MO charged particles measurements are compared for completeness to similar measurements performed by FREND neutron detectors: the instrument’s 3He neutron detectors are also a source of charged particles flux signal that can be used for correlation.

The results are of importance for benchmarking of the space radiation environment models and for assessment of the radiation risk to future manned missions to Mars.

Acknowledgements

The work in Bulgaria is supported by Project No 129 (KP-06 Russia 24) for bilateral projects of the National Science Fund of Bulgaria and Russian Foundation for Basic Research. The work in Russia is supported by Grant 19-52-18009 for bilateral projects of the National Science Fund of Bulgaria and Russian Foundation for Basic Research.

How to cite: Semkova, J. and the FREND Liulin-MO team: Radiation environment in the interplanetary space and Mars orbit during the declining phase of 24th solar cycle and transition to 25th cycle according measurements aboard ExoMars TGO, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-2925, https://doi.org/10.5194/egusphere-egu21-2925, 2021.

The Emirates Mars Mission (EMM) is the United Arab Emirates’ (UAE) first mission to Mars and is the first Arab mission to another planet. It launched an unmanned observatory called “Hope” into an elliptical orbit around Mars on July 20, 2020  carrying three scientific instruments to study the Martian atmosphere in visible, ultraviolet, and infrared wavelengths. EMM will be the first mission to provide the first truly global picture of the Martian atmosphere, revealing important information about how atmospheric processes drive diurnal variations for a period of one Martian year. This will provide scientists with valuable understanding of the changes to the Martian atmosphere today through the achievement of three scientific objectives:

• Characterize the state of the Martian lower atmosphere on global scales and its geographic, diurnal and seasonal variability.
• Correlate rates of thermal and photochemical atmospheric escape with conditions in the collisional Martian atmosphere.
• Characterize the spatial structure and variability of key constituents in the Martian exosphere.

The mission is led by Emiratis from Mohammed Bin Rashid Space Centre (MBRSC) and is expanding the nation’s human capital through knowledge transfer programs set with international partners from the University of Colorado Laboratory for Atmospheric and Space Physics (LASP), Arizona State University (ASU) School of Earth and Space Exploration, and University of California Berkeley Space Sciences Laboratory (SSL). The presentation will review the status of the mission up to and beyond a successful Mars Orbit Insertion on Feb 9, 2021, including activities from Mars orbit in preparation for the start of mission science in May 2021.

How to cite: Sharaf, O., Amiri, S., Almatroushi, H., AlRais, A., Wali, M., AlShamsi, Z., AlTeneiji, N., McGrath, M., Withnell, P., Brain, D., Ferrington, N., Reed, H., Landin, B., Ryan, S., Pramann, B., Holsclaw, G., Edwards, C., and Wolff, M. and the EMM Team: Emirates Mars Mission (EMM) 2020 Overview and Status, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1906, https://doi.org/10.5194/egusphere-egu21-1906, 2021.

The Mars 2020 Mission was designed  to address four overarching goals [1]: i) investigate the mineralogy and geology of the Jezero crater as representative of the ancient Martian environment, ii) assess the habitability of this ancient environment, iii) identify and cache samples with a high potential of preserving biosignatures, iv) study the current environmental Martian conditions in preparation for human exploration.The SuperCam Instrumental Suite was designed as the primary tool to remotely investigate elemental composition and mineralogy of rock and soil targets. It will also provide sub-mm context color imaging of outcrop textures, search for organics and volatiles, perform atmospheric characterization, and record sounds [2], [3]. To achieve these objectives, SuperCam implements four nested and co-aligned spectroscopic techniques: laser induced breakdown spectroscopy (LIBS), Raman spectroscopy, time-resolved fluorescence spectroscopy, and passive VISIR spectroscopy. Laser-induced breakdown spectroscopy (LIBS) obtains emission spectra of materials ablated from the samples in electronically excited states. The Supercam LIBS instrument comprises three spectrometers covering the UV (245 – 340 nm), the violet (385 – 465 nm), and the visible and near-infrared (VNIR, 536 – 853 nm) ranges encompassing spectral lines of the majority of the elements of interest.  Using a dedicated LIBS database, it is possible to retrieve the composition of the ablated targets. For ChemCam, the first planetary LIBS device on board the Curiosity rover on Mars, this was achieved using multivariate techniques [4] for the major elements and univariate techniques for some minors and traces [5].  A similar procedure has been applied on SuperCam: LIBS measurements of a suite of more than 300 samples covering a wide range of compositions for the major elements has been acquired at a distance of 3m with a representative model of the instrument. The database includes a set of the calibration targets (SCCT) similar to those that are mounted on the Perseverance rover. Measurements of the SCCT were also acquired a 1.5m and 4.2m. Some SCCTs were also analysed using the Flight Model during System Thermal Test (STT). Several steps in the quantification procedure are achieved. i) Identification and removal of outliers ii) Definition of representative five-fold cross-validation for model evaluation. iii) definition of the train set and test set.  iv) training of various multivariate regression methods among them Partial Least Squares (PLS), linear methods (Lasso, Elastic Net, Blended Lasso [6]) or ensemble methods (Random Forest, Gradient Boosting) v) prediction of the test set and SCCT at various distances and on the STT targets. The performances of the methods are evaluated using statistical for both the Cross Validation and Prediction) vi) Selection of the best model for a given element. A specialized pipeline is designed to produce the quantified results at tactical timescales.

[1] Farley et al. (2020), Space Sci. Rev. 216, 142.  [2] Wiens et al. (2020) Space Sci. Rev. 216, in press [3] Maurice et al. (2020) Space Sci. Rev. 216, in press [4] Clegg et al. (2017), SCAB, 129, 64. [5] Payré et al. (2017) JGR, 122, 650. [6] Anderson et al. (2017), SCAB, 129, 49.

How to cite: Forni, O., Anderson, R. B., Cousin, A., Clegg, S. M., Frydenvang, J., Pilleri, P., Legett, C., Wiens, R. C., and Maurice, S.: Supercam Laser Induced Breakdown Spectroscopy Calibration, Data Processing, and First Results, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1081, https://doi.org/10.5194/egusphere-egu21-1081, 2021.

Starting in February 2021, the Perseverance rover will characterize a new landing site, the Jezero crater on Mars, and assemble a returnable cache of samples [1]. Among the remote sensing instruments, SuperCam combines chemical, mineralogical and organic spectroscopy, sound recording and imaging [2, 3, 4]. SuperCam’s RMI (Remote Micro-Imager) provides pictures for local context and site imaging at high-resolution.

The 110-mm SuperCam telescope with a focal length of 563 mm allows to take color images of 2048x2048 pixels with a CMOS camera on a bandwidth from ~375 to ~655 nm. The images will be divided by a reference flat-field to correct the attenuation factor of ~5 due to vignetting. The diameter of the circular field-of-view is ~18.8 mrad. The angular size of the RMI pixels is slightly less than 10 microrads, and the effective image resolution is better than 80 microrads, which represents 0.24 mm at 3 m.

Images will be taken at the start and end of the SuperCam raster observations [3] and assembled into annotated mosaics, which will provide information on the nature of the targets at the scale of the SuperCam investigation. Images will also be taken to study remote outcrops. At the time of the conference, Perseverance will have been on Mars for 2 months. Although the first images of the RMI will be used to check the health of the instrument, we also hope to have a first view of the landing site by then.

References: [1] Farley K.A. et al. (2020) SSR, 216, 142. [2] Maurice S. et al. (in revision) SSR. [3] Wiens R.C. et al. (2021) SSR, 217, 4. [4] Maurice S. et al. (this issue). 

How to cite: Gasnault, O., Virmontois, C., Maurice, S., Wiens, R. C., Le Mouelic, S., Bernardi, P., Forni, O., Pilleri, P., Daydou, Y., Rapin, W., and Cais, P.: A first look at the SuperCam RMI images aboard Perseverance , EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16461, https://doi.org/10.5194/egusphere-egu21-16461, 2021.

The NASA Perseverance rover will land on Mars in February 2021, bringing with it a new suite of analytical instruments with which to explore its landing site in Jezero crater. The primary goal of this new mission is to assess the geology and past habitability in order to identify and cache samples with a high likelihood of preserving biosignatures, in preparation for a future sample return mission [1]. As part of its instrument payload, Perseverance will carry the SuperCam instrument [2-3]. SuperCam combines a number of analytical techniques, notably a laser-induced breakdown spectroscopy (LIBS) instrument for chemical analysis that is coupled with a microphone for acoustic studies. The SuperCam microphone is a commercial of-the-shelf electret (based on Knowles EK-23132) and is designed to record sounds in the audible range, from 100 Hz to 10 kHz, during the surface mission. There are three main science investigations of interest for the SuperCam microphone: 1) Analysis of the LIBS acoustic signal; 2) study of atmospheric phenomena; and 3) examination of rover mechanical sounds. Since the atmosphere will be the source of acoustic signals, the microphone may be used to better understand the nature of the atmosphere and related phenomena such as thermal gradient and convective behavior in the rover’s vicinity [4], the behavior of dust devils [5], and to refine current atmospheric attenuation models for Mars [6]. Under atmosphere, LIBS analysis produces an acoustic signal due to the creation of a shock wave during laser ablation of a target. This acoustic signal can provide critical information about a target’s hardness and ablation depth [7-8] and whether there are coatings or thin layers present [9]. Mechanisms on the rover itself will also provide a source of acoustic signal that may be examined by the SuperCam microphone, notably sounds produced by the Mars Oxygen ISRU Experiment (MOXIE, [10]) instrument pumps during oxygen production. By the time of the conference, the SuperCam microphone should have acquired the first sounds on Mars; we will report on these exciting initial results and compare them to our prelanding expectations.

[1] Farley K.A. et al. (2020) SSR 216, 142. [2] Wiens R.C. et al. (2021) SSR 217(4). [3] Maurice, S. et al. (in revision) SSR. [4] Chide, B. et al. (2020) 52^nd LPSC. [5] Murdoch, N. et al. (2021) 52^nd LPSC. [6] Chide, B. et al. (2020) AGU Fall meeting, S007-02. [7] Chide, B. et al. (2019) SAB 153, 50-60. [8] Chide, B. et al. (2020) SAB 174, 106000. [9] Lanza, N.L. et al (2020) 51^st LPSC, no. 2807. [10] Hecht, M. H. et al. (2015) 46^th LPSC, no. 2774.

How to cite: Lanza, N., Chide, B., Mimoun, D., Alvarez, C., Angel, S., Bernardi, P., Beyssac, O., Bousquet, B., Cadu, A., Clave, E., Forni, O., Fouchet, T., Gasnault, O., Jacob, X., Lacombe, G., Laserna, J., Lasue, J., Lorenz, R., Meslin, P.-Y., and Montmessin, F. and the SuperCam Acoustics Working Group: Expected first results from the SuperCam microphone onboard the NASA Perseverance rover, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8505, https://doi.org/10.5194/egusphere-egu21-8505, 2021.

The SuperCam Instrument Suite [1-4], a US-French-Spanish-Danish collaboration, consists of three separate units: the Body Unit (BU) within the Rover [2], the Mast Unit (MU) at the top of the Perseverance Remote Sensing Mast [3], and Calibration Targets [4] located on the rover deck. SuperCam includes a passive visible/near-infrared (VISIR) spectroscopy system that will identify minerals near the rover (mm-scale) to distant outcrops (m-scale) over an extended wavelength range (0.385-0.465 µm, 0.536-0.853 µm, 1.3-2.6 µm) that is diagnostic for most mineral classes.

The infrared spectrometer (IRS) in the MU [5] uses an acousto-optic tunable filter (AOTF) excited by a RF signal to successively diffract up to 256 different wavelengths ranging between 1.3 and 2.6 µm on one of two available photodiodes to produce a single spectrum in about 80 seconds at a spectral resolution of 5-20 nm. The field-of-view (FOV) of the IRS is 1.15 mrad and is co-aligned with the RMI boresight. The visible (VIS) system in the BU comprises three spectrometers covering the UV (245 – 340 nm), violet (385 – 465 nm), and visible and near-infrared (VNIR, 536–853 nm). The spectrometers are fed by light collected by the telescope in the MU through an optical fiber connecting the MU and BU. The violet spectrometer has a spectral resolution of 0.12 nm, and the VNIR transmission spectrometer has a spectral resolution of 0.35 – 0.70 nm. The VIS FOV is 0.74 mrad and co-aligned with the IR FOV.

Several SuperCam calibration targets (SCCT) are dedicated to VISIR spectroscopy, including an AluWhite white target, an Aeroglaze Z307 black target, and red, cyan, and green color targets [4]. Several of the other targets whose primary purpose is for other techniques exhibit useful VISIR spectral features and will be observed [5].

Raw data will be converted to radiance (W/m2/sr/µm) with calibrated wavelengths using the instrument transfer function [6-7]. Relative reflectance spectra will be generated by dividing the calibrated radiance spectrum by either (1) a Mars atmospheric transmission spectrum and then by a modeled solar irradiance spectrum; or (2) a radiance spectrum of the white SCCT taken close in time to the surface observation, as is done with Mastcam-Z calibration [8].

This poster will show initial VISIR data acquired on Mars, compared with test and performance data obtained at Paris Observatory, LANL, and JPL. As of this writing, the planned observations during the first ~30 sols include spectra of the white and black SCCTs, and at least one Mars target spectrum.

[1] Farley et al. (2020), Space Sci. Rev. 216, 142. [2] Wiens et al. (2020) Space Sci. Rev. 216, in press, [3] Maurice et al. (2020) Space Sci. Rev. 216,in press, [4] Manrique et al. (2020) Space Sci. Rev. 216, 8, 1-27; [5] Cousin et al. (2021) this meeting [6] Fouchet et al. (2021) Icarus, in prep. [7] Royer et al. (2020) Rev. Scient. Instrum. 91, 063105. [8] Bell, J.F. et al. (2021), Space Sci. Rev, in press.

How to cite: Johnson, J., Fouchet, T., Forni, O., Reess, J.-M., Bernardi, P., Newell, R., Ollila, A., Legett, C., Beck, P., Cousin, A., Royer, C., Pilorget, C., Poulet, F., Cloutis, E., McConnochie, T., Wiens, R. C., and Maurice, S.: Initial SuperCam Visible/Near-Infrared Spectra from the Mars 2020 Perseverance Rover, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-986, https://doi.org/10.5194/egusphere-egu21-986, 2021.

The Mars 2020 “Perseverance” rover’s SuperCam instrument suite [1,2,3] provides a wide variety of active and passive remote sensing techniques [4, 5, 6, 7] including passive visible & near-infrared (“VISIR”) spectroscopy [8]. Here we present our plans to use the VISIR technique for atmospheric science by observing solar radiation scattered by the Martian sky, similar to the “passive sky” technique demonstrated with ChemCam on the Mars Science Laboratory (MSL) rover [9]. Our presentation will focus on the objectives and techniques of SuperCam VISIR atmospheric science, but we will also present initial atmospheric science results or relevant instrument performance validation results to the extent that such are available at the time of the conference.

The objectives of VISIR atmospheric science are O₂, CO, and H₂O vapor column abundances, and aerosol particle sizes and composition. These objectives are motivated by unexpected seasonal and interannual variability in the O₂mixing ratio that is argued to be so large as to require O₂ sources and sinks in surface soils [10], by evidence of surface-atmosphere exchange of H₂O [11], by the potential significance of O₂ and H₂O volatiles as field context for returned samples due to their active exchanges with surface materials, and by the Mars 2020 mission [12] objectives of characterizing dust and validating global atmospheric models to prepare for human exploration

The SuperCam spectrometers used for VISIR mode are a ChemCam-heritage reflection spectrometer covering 385–465 nm with < 0.2 nm res. [2], an intensified transmission spectrometer covering 536–853 nm with 0.3–0.7 nm res. [2], and an acousto-optic-tunable-filter (AOTF) -based IR spectrometer covering 1300–2600 nm with 20–30 cm^-1 res. [1, 8]. Our primary observing strategy is the same approach used for MSL ChemCam “passive sky” observations [9]: ratioing instrument signals from the two pointing positions with different elevation angles eliminates solar spectrum and instrument response uncertainties that are ~100x and ~10x larger than signals of interest for the transmission and AOTF IR spectrometers, respectively. We will also make use of single pointings directed at the white SuperCam calibration target for less-resource-intensive water vapor and aerosol monitoring, and of multiple-pointing lower-signal-to-noise sky scans to better constrain aerosol size and shape. Sky radiance is fit with a discrete ordinates multiple scattering radiative transfer model identical to that of [9]. As in [9] gas abundances are made robust to aerosol scattering uncertainties by fitting CO₂ absorption bands with an aerosol vertical profile parameter.

References: [1] Maurice S. et al. (2020) SSR, in press. [2] Wiens R.C. et al. (2021) SSR 217, 4. [3] Manrique J.-A. et al. (2020) SSR 216, 138. [4] Ollila A.M. et al. (2021), this meeting. [5] Ollila A.M. et al. (2018) LPSC 49, 2786. [6] Forni O. et al. (2021), this meeting. [7] Lanza N. L. et al. (2021), this meeting. [8] Johnson J.R et al. (2021), this meeting. [9] McConnochie T.H et al. (2018), Icarus 307, 294. [10] Trainer M.G. et al. (2019), JGR 124, 3000. [11] Savijärvi H. et al. (2016), Icarus 265, 63. [12] Farley K.A. et al. (2020), SSR 216, 142.

How to cite: McConnochie, T., Fouchet, T., Montmessin, F., Beck, P., Chide, B., Francis, R., Gasnault, O., Lasue, J., Legett, C., Lemmon, M., Maurice, S., Newell, R., Newmann, C., Venhaus, D., Wiens, R., and Wolff, M.: Atmospheric Science with Visible/Near-Infrared Spectra from the Mars 2020 Perseverance Rover, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-1986, https://doi.org/10.5194/egusphere-egu21-1986, 2021.