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The behavior and the rheology of mud during the emplacement of terrestrial sedimentary volcanism has been extensively investigated (e.g., [1,2]). In contrast, this is not the case for Mars and other planetary bodies within the Solar System for which sedimentary volcanism has been proposed [e.g., 3]. The propagation behavior of low viscosity mud in a low-pressure chamber, that partly simulated the environment of Mars, was firstly experimentally studied by [4,5]. Their work revealed that bentonite-based mud could flow in a completely different manner in such conditions. On Mars, mud flowing over cold surfaces would rapidly freeze due to evaporative cooling [6] forming an icy-crust leading to the behavior of some of the mud flows in a similar manner to pahoehoe lava on Earth [4]. However, we lack the knowledge how variations of salt types and their content would affect the flow style and finite pattern of such mudflows as a presence of various salts can be natural on Mars as well (e.g., [7,8]). Therefore increased content of salts can strongly affect the P-T-t dependent cooling and at the same time the rheology of mud which can lead to significantly different propagation potential and finite geometry. In a set of experiments, performed in the Mars Simulation Chamber (Open University, UK), we tested several selected salts relevant for the Mars environment (namely NaCl, MgSO4, Na2SO4 and CaSO4) and various salinities of these salts (0.5-15 wt%). These experiments were performed in metallic trays infilled with dry and precooled sand to -25 °C (to simulate the martian surface) and which were inclined to 5°. A container filled with 500 ml mud was positioned above the tray. Then we decreased the pressure to 4.5-6 mbar and released mud. Experiments were documented by a system of video cameras situated around the model box. At the same time, referential cooling experiments of binary solutions (water-salt) were performed. Results revealed contrasting scenarios of mud propagation which result in a wide range of shapes. We also found several transitional regimes in behavior between current concentrations and various salts. It was confirmed that the high content of salt in a mud or mud composed by different salts can undergo slightly to significantly different cooling according to thermodynamic equilibria which shifts both freezing and boiling point. Thus, the resultant style of flow process and finite morphology of such mudflows can be highly variable. For example, high content of MgSO4 (typically 5-10 wt%) leads to development of long and narrow streams and with increasing content also develops a “ropy pattern” structure, whereas the same behavior occurs for 2.5 wt% of the NaCl. References: [1] O’Brien and Julien (1988), Journal of Hydraulic Engineering 114 [2] Laigle and Coussot (1997), J. Hydraul. Eng., 123 [3] Ruesch et al. (2019) Nature Geoscience 12 [4] Brož et al. (2020), Nature Geoscience [5] Brož et al. (2020), EPSL 545 [6] Bargery et al. (2010), Icarus 210(1), Chevrier et al. (2020), The planetary science journal, 1(3) [8] Nuding, et al. (2014), Icarus, 243.

Analysis of data from the seismometer SEIS on NASA’s InSight mission has by now provided a wealth of information on the crustal structure of Mars, both beneath the lander and at other locations on the planet. Here, we collect the P- and S-wave velocity information for kilometer-scale crustal layers available up to now and compare it to predictions by rock physics models to guide the interpretation in terms of crustal lithology.Modeling is performed based on the Hertz-Mindlin model for un- or poorly consolidated sediments, Dvorkin and Nur’s cemented-sand model for consolidated sediments and Berryman’s self-consistent approximation to simulate cracked rocks. Considered lithologies include basalt, andesite, dacite, kaolinite, and plagioclase, and cementation due to calcite, gypsum, halite and ice. We use Gassmann fluid substitution to study the effect of liquid water instead of atmosphere filling the pores or cracks.Below the lander, available constraints are based on Ps-receiver functions and vertical component autocorrelations for SV- and P-wave velocities, whereas SH-reflections and SsPp phases provide additional information on SH- and P-wave velocities in the uppermost 8-10 km, respectively. SS and PP precursors at the bouncing point of the most distant marsquake contain information on crustal velocities at a near-equatorial location far from InSight. Surface wave observations from two large impacts as well as the largest marsquake recorded by InSight provide average crustal velocities along their raypaths, which are distinct from the body wave results.The subsurface structure beneath the lander can be explained by 2 km of either unconsolidated basaltic sands, clay with a low amount (2%) of cementation, or cracked rocks (e.g. basalts with at least 12% porosity). Within the range of lithologies considered, the seismic velocities can neither be explained by intact rocks, nor rocks with completely filled pores, e.g. by ice, nor by fluid-saturated rocks. Below, down to a depth of about 10 km beneath InSight, both P- and SV-wave velocities are consistent with fractured basaltic rocks or plagioclase of at least 5% porosity, depending on crack aspect ratios. About 10% of that porosity needs to have a preferred orientation to explain the observed anisotropy. For porosities exceeding 12%, the measured velocities would also be consistent with water-saturated rocks. The transition to higher velocities at about 10 km depth beneath InSight can be modeled by more intact material, i.e. a porosity reduction by 50% compared to the layer above, which can be achieved by either cementation or a lower initial porosity.The SV-velocities derived by surface waves down to 25-30 km depth, averaging over a large part of Mars, are consistent with basalts of a porosity of less than 5% or nearly intact plagioclase. They could also be explained by rocks with a higher porosity if pores are filled by ice, but that is unlikely for the whole depth range considered. The velocities at larger depth, i.e. below about 20 km beneath InSight and 25-30 km along the surface wave paths, are consistent with intact basalt.

The majority of Tharsis is covered by relatively young and low-viscous widespread lava plains, being of basaltic composition. They likely buried older volcanic landforms which could have provided important data about ancient eruptive style and magma composition. However, several fractured regions forming topographic raises survived regional resurfacing, and they are providing an insight into the volcanic history of the planet. To date, these Noachian/Hesperian-aged fractured terrains revealed the presence of putative scoria cones in Ulysses (Brož and Hauber, 2012) and Noctis Fossaes (Pieterek et al., 2022) supporting a hypothesis that the volcanic activity differed in the past from waste eruptions of young low-viscous lavas. Here, we present results of mapping that focused on the edifices superimposed on the Noachian-age fractured crust within the Claritas Fossae region. The aim was to decipher their origin and provide additional constraints on the volcanism emplaced on the ancient terrains.In the studied region, we mapped 39 topographically positive edifices of constructional character. They are spread on the ancient crust showing NW-SE trending alignment over an area of 170 x 500 km. Based on the CTX observations, we noted that their majority is characterized by elongated (WNW-trending) to irregular or circular outlines and relatively steep-appearing flanks without associated flow-like units. Among these edifices, one circular-shaped edifice located in the easternmost part of the studied area is associated with short-distance flow-like units and rimmed by a caldera-like structure. We also determined the mineralogical composition for several edifices with available CRISM spectral data. This showed that edifices are spatially associated with high concentrations of igneous-origin low-calcium pyroxenes (LCP). Based on the relative stratigraphy, we showed that volcanic activity postdates the fracturing, the age of which has been estimated to space between ~3.4 to ~2.6 Ga and likely predates the formation of Thaumasia graben (Late Hesperian/Early Amazonian).The shapes, sizes, distribution pattern, and mineralogical composition of the mapped edifices are consistent with putative volcanic origin. Therefore, we argue that Claritas Fossae’s field mainly experienced effusive eruptions characterized by highly viscous, volatile-poor magma(s). Such composition limited the ability of the effused lavas to spread from the site into the surroundings. The elongation and spatial distribution of the edifices together with their LCP-rich composition indicate volcanic eruptions might be controlled by the migration of subsurface dike(s) from the shallow magma chamber(s). Altogether the comprehensive study of the volcanic evolution of the Thaumasia region showed that the studied edifices might express the late-stage dike migration of LCP-rich magmas that used the reactivated WNW-ESE tectonic pathways.Besides the effusive-origin edifices, the area might contain one of the best-preserved kilometer-sized, explosive-type volcanic edifice emplaced within the putative caldera-like rim known from Mars.This research was funded by the “GEO-INTER-APLIKACJE” project no. POWR.03.02.00-00-I027/17.ReferencesBrož, P., Hauber, E., 2012. A unique volcanic field in Tharsis, Mars: Pyroclastic cones as evidence for explosive eruptions. Icarus 218, 88–99. https://doi.org/10.1016/j.icarus.2011.11.030Pieterek, B., Laban, M., Ciążela, J., Muszyński, A., 2022. Explosive volcanism in Noctis Fossae on Mars. Icarus 375, 114851. https://doi.org/doi.org/10.1016/j.icarus.2021.11485

Extensive fields of sub-kilometre-to kilometre-scale mounds, cones, domes, shields, and flow-like edifices cover large parts of the martian lowlands. These features have been compared to structures on Earth produced by sedimentary volcanism – a process that involves subsurface sediment/fluid mobilization and commonly releases methane to the atmosphere. It was proposed that such process might help to explain the presence of methane in martian atmosphere and also may have additionally produced habitable, subsurface settings of potential astrobiological relevance. However, it remains unclear whether sedimentary volcanism on Earth and Mars share genetic similarities; hence whether methane, or other gases were released on Mars during this process. The aim of this review is to summarize the current knowledge about mud-volcano-like structures on Mars, address the critical aspects of this process, identify key open questions, and point to areas where further research is needed to understand this phenomenon and its importance for the red planet’s geological evolution. We show here that after several decades of exploration, the amount of evidence supporting a martian sedimentary volcanism scenario has increased significantly, but as critical ground truth is still lacking, alternative explanations cannot always be ruled out. We also highlight that the lower gravity and temperatures on Mars compared to Earth control the dynamics of clastic eruptions as well as surface emplacement and resulting morphologies of erupted material. This implies that shapes and triggering mechanisms of mud-volcano-like structures may be different from those observed on Earth. Therefore comparative studies should be done with caution. To provide a better understanding of the significance of these abundant features on Mars, we argue for follow-up studies targeting putative sedimentary volcanic features identified on the planet’s surface and, if possible, for in situ investigations by landed missions such as that currently in progress by the Zhurong rover.

With MaQuIs we propose a mission to investigate the gravitational field of Mars. Observing the gravitational field over time yields information about the planets tectonic lithoshphere, mass distribution, and composition. Consequently, this mission allows to study static and dynamic processes on and under the surface of Mars, including phenomena such as melting cycles and tectonic activity.MaQuIs will deploy quantum mechanical means to measure Mars gravitational field with the highest precision yet. In addition, the nature of the proposed instrumentation achieves high sensitivities without needing more complex satellite constellations. As such, MaQuIs follows successful missions for the Earth and Moon, extending the technology to Mars.In this presentation we will outline the expected scientific merit and explain the underlying technology and planned configuration of the mission.

The evolution of the Ladon basin has been marked by intense geological activity and the discharge of huge volumes of water from the Martian highlands to the lowlands in the late Noachian and Hesperian. We explore the potential of the ExoMars Trace Gas Orbiter/Color and Stereo Surface Imaging System color image data set for geological interpretation and show that it is particularly effective for geologic mapping in combination with other data sets such as HiRISE, Context, and Compact Reconnaissance Imaging Spectrometer for Mars. The study area displays dark lobate flows of upper Hesperian to early Amazonian age, which were likely extruded from a regional extensional fault network. Spectral analysis suggests that these flows and the underlying rocks are ultramafic. Two distinct altered levels are observed below the lobate flows. The upper, yellow-orange level shows hundreds of structurally controlled narrow ridges reminiscent of ridges of listwanite, a suite of silicified, fracture-controlled silica-carbonate rocks derived from an ultramafic source and from serpentine. In addition to serpentinite, the detected mineral assemblages may include chlorite, carbonates, and talc. Kaolin minerals are detected in the lower, white level, which could have formed by groundwater alteration of plagioclase in the volcanic pile. Volcanism, tectonics, hydrothermal activity, and kaolinization are interpreted to be coeval, with hydrothermal activity and kaolinization controlled by the interactions between the aquifer and the hot, ultramafic lobate flows. Following our interpretations, East Ladon may host the first listwanite ridges described on Mars, involving a hydrothermal system rooted in a Hesperian aquifer and affecting ultramafic rocks from a magmatic source yet to be identified.

Summary Fault population studies are essential to investigate lithospheric strength and stress conditions [1]. Understanding the displacement-length relationship of faults helps us to understand the lithosphere and stress states, and may inform on the stratigraphy of crustal rocks [2]. However, the number of slip events, linkage, and reactivation may affect the Dmax/L ratios [3]. The investigation of current seismicity on Mars is the motivation for a renewed and detailed analysis of the fault systems of Mars. Using Digital Elevation Models (DEM) and corresponding orthoimages derived from High Resolution Stereo Camera (HRSC) data, we obtained information on the displacement distribution on fault traces as well as the maximum displacement. The Dmax/L ratio is calculated as ~0.007, consistent with previous measurements of martian faults (0.006; [4]). Based on these analyses, we discuss the implications of fault segmentation and linkage for further interpretation. Introduction Detailed investigation on geometric fault properties can provide insights into the mechanical and temporal evolution of fault systems [5,6], and the past and future potential for seismic energy release [7]. In planetary science, where a lack of seismometers is unfortunately the rule rather than the exception, the analysis of faults with remote sensing data typically provides the only direct observational evidence to constrain the tectonic history of a planet [1]. Since the seismic moment released during the growth of a fault is strongly connected to the fault geometry, the study of fault populations can also help to estimate the current seismicity level [2,8]. Until today, only a few data on the relationships between fault displacement and length have been collected for extraterrestrial bodies [9], partly due to the limited number of reliable topographic datasets. The InSight mission put a lander in the Elysium region of Mars in 2018. It is equipped with a seismometer [10] that has recorded several marsquakes for which the locations could be determined [11]. As a starting point for our analysis of fault geometries, we selected the Memnonia Fossae fracture system, one of the closest fracture sets to the InSight landing site, which radiates outward from the Tharsis region in a southwesterly direction. Data and Methods All topographic measurements in this study are based on Digital Elevation Models (DEM) based on HRSC data (High Resolution Stereo Camera; [10]). As HRSC is a push-broom scanning instrument with nine CCD line detectors mounted in parallel on a focal plane, its unique feature is the ability to obtain imaging data at high resolution, with along-track triple stereo, four colors and five different phase angles. The spatial scale of HRSC is 10 m/pixel at the nominal periapsis altitude of 250 km, with an image swath of 53 km. Figure 1: Images show faults from Memnonia Fossae region with three different image system: a. Orthoimage from HRSC, b. DEM derived from HRSC data, c. CTX image. We use DEM and orthoimages from HRSC [10] to obtain information on the displacement distribution along fault traces. This also enabled determining the maximum displacement. We compare our results to previous measurements of faults on Mars, Earth, and beyond. Based on these analyses, we discuss the implications of fault segmentation and linkage for further interpretation. HRSC data offer high-resolution topography and spatially contiguous coverage, which are required to analyze detailed topographic characteristics of large fault systems. For structural interpretation of key locations (e.g., relay ramps), CTX images (~5-6 m px-1) have been inspected. Fault length was digitized along the fault line, and multiple topographic cross-sections across the fault were drawn with a spacing of ~1 km. Fault throw (a proxy for true displacement) was visually determined in the digitized cross-sections. Results At the time of writing, 16 images out of 75 available images/DEM from the Memnonia Fossae region exhibiting normal faults have been investigated. In this preliminary stage, a total number of 83 faults in Memnonia Fossae were studied. We find an average Dmax/L ratio of 0.007, consistent with our previous findings for other regions on Mars, where this ratio had an average value of 0.006 [4]. References [1] Schultz, R.A. et al. (2010) J. Struct. Geol., 32, 855-875. [2] Golombek, M.P. et al. (1992) Science 258, 979-981. [3] ] Kim, Y., Sanderson, D. J. (2005) Earth Sci. Reviews, 68, 317-334. [4] Hauber, E. et al. (2014) Lunar Planet. Sci. Conf. 45, #1981. [5] Cartwright, J. A., et al., J. Struct. Geol. 17, 1319-1326, 1995. [6] Cowie, P.A. and Scholz, C.H., J. Struct. Geol. 14, 1133-1148, 1992. [7] Wells, D.L. and Coppersmith, K.J. (1994) Bull. Seismol. Soc. Amer., 84, 974-1002. [8] Knapmeyer, M. et al. (2006) J. Geophys. Res., 111, E11006. [9] Schultz, R.A. et al. (2006) J. Struct. Geol., 28, 2182-2193. [10] Lognonné, P., et al., (2019) Space Science Reviews, 215(1), 1-70. [11] Drilleau, M., et al., (2021) EGU General Assembly. Conf. 14998. [12] Gwinner et al., Planetary and Space Science 126 (2016) 93–138.

Introduction: The behavior and the rheology of mud during the emplacement of terrestrial sedimentary volcanism has been previously investigated (e.g., [1,2]). In contrast, this is not the case for Mars nor for other planetary bodies within the Solar System for which sedimentary volcanism has been proposed [e.g., 3]. The propagation behavior of low viscosity mud in a low-pressure chamber that partly simulated the surface environment of Mars was experimentally studied for the first time by [4,5]. Their work revealed that low viscosity mud flows could propagate over cold (273 K) surfaces at martian atmospheric pressure, however, the mechanism of such propagation is different to that observed on Earth. On Mars, mud propagating over cold surfaces should rapidly freeze due to evaporative cooling [6] forming an icy-crust leading to propagation in a similar manner to pahoehoe lava flows on Earth [4]. In contrast, mud propagating over a warm surface boils and levitates above the surface. The viscosity of ascending mud varies depending on its water content, and the behavior of high viscosity mud under martian atmospheric pressure remains unexplored. Experimental setup: We used the Mars Simulation Chamber at the Open University (UK) into which we inserted a 0.9 × 0.4 m plastic box filled with a ~10 cm thick layer of natural sand (ø ~200 µm) mixed with water to limit the infiltration of mud into the sand and to better maintain the temperature below 0°C. Inside was placed a container to accommodate 600 ml of mud (Fig. 1). The infilled box was cooled to a temperature of ~-20°C. The temperature of the mud when inserted into the container was 1-3°C and 20-22°C respectively. Two different viscosities were tested – the first mix contained 50 wt% clay (a bentonite composed of 76% montmorillonite, 23% illite and 1% kaolinite) and water (1:1 mix). The other was prepared by mixing 75 wt% clay with 25 wt% water (3:1). The pressure was gradually reduced from 1 bar to 6 mbar within a timeframe of minutes (rapid) or in >hour (slow). Each experimental run was triplicated to confirm reproducibility. Observations: With the 1:1 mixture, once the atmospheric pressure was reduced, the mud started to boil (Figure 2). In the case of mud at room temperature and a rapid pressure drop, significant boiling caused an ejection of muddy droplets from the container into the surroundings. Such behavior was not observed for other experiments and mud was extruded due to the volumetric increase. Once the pressure dropped below 7 mbar, freezing occurred leading to the formation of an icy-muddy crust. Once this crust covered the entire mud surface, additional boiling and volumetric increase was limited. However, when the crust broke up, gasses were capable to escape and the deflation was observed. For the 3:1 mixture vigorous boiling was not observed during the pressure drop. Instead, as the pressure decreased, the mud volume increased and sets of cracks developed on the surface. Regardless of the tested parameters, the volumetric increase was observed during all experiments as bubbles within the mud developed and increased their volume. In the case of 1:1 and 3:1 mixture the mud inflation reached up to ~15% and ~28% respectively (the observed volumetric changes were quantified by semi-manual processing of selected images using the PIV [Particle Image Velocimetry] and photogrammetry methods). In addition, we also observed a partial collapse of the newly formed foamy edifice as the gas trapped inside the mud escaped. This inflation and deflation of the mud often repeated and the magnitude of volumetric change leads to different morphologies (Figure 3). Discussion and conclusion: The volumetric increase is caused by the formation of small water vapor bubbles which are trapped within the mud (Figure 4). The buoyancy of the bubbles is not sufficient to overcome the drag force within the viscous material and rise to the surface. Hence, these bubbles remain trapped and gradually grow up to centimeter scale sizes. During their growth they push the mud out of the container resulting in horizontal and vertical inflation of the mud surface over cm- scales (e.g., see outlines in Figure 2). This behavior is not observed at terrestrial mud flows. Our experimental approach hence shows that viscous mud exposed to reduced atmospheric pressure behaves differently when compared to conditions on Earth. Acknowledgments: The access to the Large Mars Chamber at the Open University was provided by Europlanet 2024 RI which has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No 871149. References: [1] O’Brien and Julien (1988), Journal of Hydraulic Engineering 114 [2] Laigle and Coussot (1997), J. Hydraul. Eng., 123 [3] Ruesch et al. (2019) Nature Geoscience 12 [4] Brož et al. (2020), Nature Geoscience [5] Brož et al. (2020), EPSL 545 [6] Bargery et al. (2010), Icarus 210(1). Fig. 1: Experimental setup. Figure 2: A sequence of images capturing the volumetric change of 1:1 mud (T=1°C) depending on the pressure value. The simplified sketch shows the extent of such changes indicated with different colors. Figure 3: Examples of morphologies resulting from inflation of the mud induced by low pressure conditions. The blue and red boxes mark different temperatures of the mud. Morphologies of 3:1 mud are relatively uniform, in contrast a wider variety exists for less viscous 1:1 mud. The white dashed lines mark the position of the 9 cm large container. Figure 4: Simplified concept of mud inflation due to the pressure drop. Behaviour of 1:3 mud based on work of [4].

Introduction Antoniadi basin is a 330 km diameter Noachian basin localized in the eastern Arabia Terra that contains a network of dendritic ridges. Branched, dendritic ridges, such as these can form by a variety of processes including the inversion of fluvial deposits, thus potentially highlighting aqueous processes of interest for understanding Mars’ climate evolution. Here, we test this hypothesis by analyzing in details data from Colour and Stereo Surface Imaging System (CaSSIS), High Resolution Imaging Science Experiment (HiRISE) and High Resolution Stereo Camera (HRSC). Age of landforms Antoniadi’s interior plains are filled by deposits interpreted to be Hesperian or younger and volcanic in origin, possibly coeval with the volcanic episodes of the nearby Syrtis Major Planum [1]. The dendritic ridges lie on these volcanic plains to the south of a 28 km-diameter well-preserved crater (Fig. 1). Although this crater predates the branched ridges it is devoid of any fluvial erosion and appears mostly similar to many fresh, Amazonian age craters. While some erosion has affected the ridges, there is no indication of exhumation of these ridges from putative layers above the current plains surface. The crater size frequency distribution of the volcanic plains gives a model age of 2.5±0.5 Gy, using diameters of 200 m to 2 km. Thus, the branched ridges are Early Amazonian or younger. Figure. 1: Four Cassis images projected on CTX mosaic. The fresh crater to the north has been covered by fresh lava flows which themselves have been covered by the dendritic features. Morphometry and topography Individual ridges are easily recognizable with their dark tone in visible images compared to surrounding plains (Fig. 2), which display a slightly lighter tone. The ridges are organized as a dendritic network reaching a Strahler order of 4, i.e. the degree of hierarchy from the primary branches counting the number of junctions. Assuming tributary flows, this organization indicates a northward flow direction. However, the local slope is of 0.2° toward South, and thus contrary to the apparent network organization (assuming tributary flows). The branched ridges are also present on some of the lowest areas of these plains, but there is no evidence of terminal fans nor of erosional features affecting the plains in their more elevated areas. The texture of ridges at HiRISE scale (25cm/pixel) is rubbly with the occurrence of blocks up to ~1 m in size and a complete lack of layering in all HiRISE images where they are present unlike sedimentary strata usually observed within inverted channels on Mars. A HiRISE elevation model shows that branched ridges are between 1-5 m high, although erosion can explain some variations in height among the ridges. Ridges are up to 10 km long and 10-200 m wide without any obvious trends in width, i.e. ridges are not wider with increasing Strahler order. The order 1 branches are also peculiar in plan-view shape. They frequently display lobate shapes and are up to 100 m wide, which is wider than the ridge measured after the junction with several order 1 branches. North of the main pattern, a 500 m wide sinuous ridge present in the middle of the plain displays the same internal texture (rubbly) suggesting that it formed by the same process (white arrow at the top of Fig. 1). Figure 2: Close-up on the dendritic network with CaSSIS images. Conclusion Previous assessments of these landforms favored an origin as inverted channels [2]. Yet, our observations show many inconsistencies with this interpretation: (i) The rubbly texture lacks any layering at meter scale, a typical feature of inverted channels observed elsewhere on Mars [e.g., 3, 4]. (ii) The order 1 branches display a lobate shape and a larger width than higher order branches unlike river flows as observed on Earth. (iii) There is no increase in width from degree 1 branches of the network towards the north as would be expected for channels with increasing discharge rates downstream. (iv) The slope towards the south is contrary to the inferred flow direction to the north assuming a tributary network. Wrinkle ridges may be evidence for post-depositional changes in topography, but these uplifts appear localized (Fig. 1). Thus, the detailed analysis of these branched ridges shows characteristics difficult to reconcile with inverted fluvial channels. Subglacial drainages are known to locally flow against topography, but rarely display a dendritic pattern [5]. Assuming that deposition occurred along the current slope from north to south, the organization of the network requires a control by distributary channels rather than tributary channels. Distributary fluvial channels are possible for fluvial flows, but generally limited to braiding regimes or deltaic deposits, of which no further evidence is observed here. The lobate digitate shapes of the degree 1 branches are actually more in line with deposits of viscous flows, thus as terminal branches (Fig. 3). Such an interpretation is consistent with lava flows or mudflows that formed along the current topography. This conclusion would explain the presence of these landforms in an Early Amazonian plain lacking any evidence of fluvial activity, including the fresh crater that is stratigraphically older than the landforms studied. Acknowledgments: French authors are supported by the CNES. The authors wish to thank the spacecraft and instrument engineering teams. CaSSIS is a project of the University of Bern and funded through the Swiss Space Office via ESA’s PRODEX. The instrument hardware development was also supported by the Italian Space Agency (ASI) (agreement no. I/018/12/0), INAF/Astronomical Observatory of Padova, and the Space Research Center (CBK) in Warsaw. Support from SGF (Budapest), the Univ. of Arizona (Lunar and Planet. Lab.) and NASA are gratefully acknowledged. References : [1] Tanaka K. L. et al. (2014) USGS map 3292. [2] Zaki et al. (2019) EPSC-DPS2019-244-1. [3] Burr et al. (2010) JGR-Planets, 115, E07011. [4] Mangold et al. (2008) JGR-Planets, 113, E08009. [5] Menzies, J (2002), Modern and Past Glacial Environments, Oxford.

Orbital missions have shown that some regions of the ancient Martian crust contain hundreds of discrete terrains covered by chloride evaporites. In terrestrial evaporitic systems, aqueous precipitation typically begins with the deposition of carbonates, followed by sulfates, and finally chlorides, a depositional sequence that has not yet been found on Mars. Instead, sulfide deposits are always separated spatially from chlorides and appear younger. This temporal and spatial separation suggests two different depositional regimes. Here, we present a model driven by the Martian chlorine geochemical cycle that allows the formation of chlorides whilst simultaneously inhibiting sulfate and carbonate precipitation. In this model, the chlorides are formed under reducing and acidic conditions in two contrasting settings the hydrothermal alteration of the Martian crust associated with the formation of faults: by direct evaporation of water bodies fed by meteoric solutions (type 1) and by precipitation from ascending saline solutions along the tectonic conduits (type 2). Such processes were sustained under a relatively thick and reducing atmosphere (1-0.1 bar) similar to the predicted conditions for the early Earth. The crustal circulation of chloride-precipitating fluids may have been driven by tectonic suction and pumping processes.

Imaging the environment is an essential method in spatial science when studying the Earth or any other planet. Thus, this method is also a crucial component in the exploration of the ocean floor but also of planetary surfaces. In both domains, this is applied at various scales – from microscopy through ambient imaging to remote sensing – and provides rich information for science.Due to recent the increasing number data acquisition technologies, advances in imaging capabilities, and number of platforms that provide imagery and related research data, data volume in nature science, and thus also for ocean and planetary research, is further increasing at an exponential rate. Although many datasets have already been collected and analyzed, the systematic, comparable, and transferable description of research data through metadata is still a big challenge in and for both fields. However, these descriptive elements are crucial, to enable efficient (re)use of valuable research data, prepare the scientific domains e.g. for data analytical tasks such as machine learning, big data analytics, but also to improve interdisciplinary science by other research groups not involved directly with the data collection.In order to achieve more effectiveness and efficiency in managing, interpreting, reusing and publishing imaging data, we here present a project to develop interoperable metadata recommendations in the form of FAIR [1] digital objects (FDOs) [2] for 5D (i.e. x, y, z, time, spatial reference) imagery of Earth and other planet(s). An FDO is a human and machine-readable file format for an entire image set, although it does not contain the actual image data, only references to it through persistent identifiers (FAIR marine images [3]). Thus, the FDOs for spatial sciences are characterized at their core by 5D navigation data mentioned above which discriminates them from imagery of other domains (e.g., medical). In addition to these core metadata, further descriptive elements are required to describe and quantify the semantic content of imaging research data. Such semantic FDOs are similarly domain-specific but again synergies are expected between Earth and planetary research. Subsequent, by developing ontology concepts for these two imaging domains, scientific analogies and causal connections between the two research domains can be illuminated.The main benefit expected by this project is to (1) improve the quality and reusability of future research data, (2) support a sustainable research data environment by closing the life cycle of the research data, (3) increase the inter- and transdisciplinary comparability of data sets, and (4) enable further scientific communities in transference of their own vocabularies, and in the use of the ontology concepts within other natural science applications.We here present the current status of the project, with the specific tasks on joint metadata description of planetary and oceanic data outlined. In particular we show how we intend to implement metadata for valuable research data in both domains in the future, and demonstrate where these developments should be adopted.[1] Wilkinson, M., Dumontier, M., Aalbersberg, I. et al. The FAIR Guiding Principles for scientific data management and stewardship. Sci Data 3, 160018 (2016), doi:10.1038/sdata.2016.18.[2] https://fairdigitalobjectframework.org/[3] https://marine-imaging.com/fair/ifdos/iFDO-overview/

The formation of Ganymede’s light or bright tectonically resurfaced terrain and its possible interaction with a subsurface ocean has been made one of the top goals of the upcoming JUICE mission [1]. We therefore investigate the currently available Voyager and Galileo imaging data covering Ganymede’s light terrain with sufficient spatial resolution. Our focus lies on (1) the definition and characterization of the tectonic subunits/cells of the light terrain including its contact to the neighboring dark terrain and (2) their stratigraphic relationship to each other. Our goal is to study the local formation processes, to identify any changes in tectonic style through time across Ganymede, and also to compare possible differences and similarities of light terrain at different locations. We specifically focus on Mummu and Sippar Sulci which complement our studies of 1) Byblus and Nippur Sulcus (39°N/160°E and 49°N/157°E), 2) Arbela Sulcus (15°S/13°E), 3) Harpagia Sulcus (16°S/50°E) as presented in [2]. We use the geologic mapping procedure defined in previous studies [3, 4] and crater counting techniques for relative geologic age estimation [5,6]. Based on the principle of cross-cutting relationships, the light terrain units (light grooved terrain, light subdued terrain, light irregular terrain and an undivided region) are classified into 3 main categories: (i) Category 1 (lg1, ls1 and li1) contains light terrain units, which are crosscut by all other light terrain units, (ii) Category 2 (lg2, ls2 and li2) contains those light terrain units, which crosscut the Category 1 terrain units and are crosscut by Category 3 units, (iii) Category 3 (lg3, ls3 and li3) contains those light terrain units, which crosscut all adjacent light terrains. The narrow NE-SW striking band that bifurcates in the western part (ls3) crosscuts all other geological units and is consequently mapped as the youngest terrain followed by pateras, which are being crosscut by ls3. This, however, contradicts the theory that the light subdued terrains were formed in the early stage of the light terrain formation [3, 4]. On the contrary, according to our crater counting results, ls3 shows an age similar or slightly older than the adjacent crosscutting terrains like lg2(3) and lg1. The effects of secondary impacts, size and geographic location of the study area onto the crater density results are still under evaluation. REFERENCES: [1] Stephan, K. et al. (2021) PSS. 208, 105324. [2] Baby, N. R. et al. (2021) EPSC abstracts, #EPSC2021-352. [3] Patterson, W. et al. (2010) Icarus, 848. [4] Collins, G. C. et al. (2013) USGS Sci. Inv. Map #3237. [5] Michael, G.G. et al. (2010) Earth and Planetary Science Letters, 294 (3-4), 223-229. [6] Wagner, R. J. et al. (2018) EPSC abstracts, #EPSC2018-855.

The behavior and the rheology of mud during the emplacement of terrestrial sedimentary volcanism has been previously investigated (e.g., [1,2]). In contrast, this is not the case for Mars nor for other planetary bodies within the Solar System for which sedimentary volcanism has been proposed [e.g., 3]. The propagation behavior of low viscosity mud in a low-pressure chamber that partly simulated the environment of Mars was firstly experimentally studied by [4,5]. Their work revealed that low viscosity mud could flow over cold (273 K) surfaces at martian atmospheric pressure, however, the mechanism of such propagation would be very different from that observed on Earth. On Mars, mud flowing over cold surfaces would rapidly freeze due to evaporative cooling [6] forming an icy-crust leading to the behavior of some of the mud flows in a similar manner to pahoehoe lava on Earth [4]. In contrast, the mud propagating over the warm surface boils and levitates above the surface. However, as the viscosity of ascending mud can vary, depending on water content, it remains unclear how this affects the mud behavior.To investigate the behavior of muds more viscous than that studied by [4,5] in low pressure conditions, we used the Mars Simulation Chamber at the Open University (UK). In a set of experiments, we tested how the volume of mud (water-bentonite mixture) changed depending on different depressurization rates, mud initial viscosity and initial temperature. These experiments were performed in plastic boxes infilled with frozen (wet) sand (to simulate the martian surface). In the center of these boxes we placed a container filled with a mud volume, then we decreased the pressure to 7 mbar. Experiments were documented by system of video cameras situated around the model box. Quantification of the volumetric changes used semi-manual and automatized image analyses using the PIV (Particle Image Velocimetry) and photogrammetry methods.Results revealed a significant volume increase during the experiments with slow depressurization, higher mud viscosity and low initial mud temperature. The volumetric change occurs due to the formation of water vapor bubbles, which are temporarily trapped within the mud. This phenomenon occurs since the bubble buoyancy is insufficient to overcome the drag force within the viscous material. Hence, these bubbles remain trapped in the mud allowing their gradual growth up to centimeter-scale sizes. During their volume increase, they push the mud out from the container resulting in horizontal and vertical propagation of the mud over cm-scales. In those experiments where the mud bulge freezes due to the evaporative cooling, the internal structure is kept in (or beneath) the icy crust. Our experimental approach hence shows that when mud with identical characteristics is extruded on Earth and Mars, different morphologies would result. References: [1] O’Brien and Julien (1988), Journal of Hydraulic Engineering 114 [2] Laigle and Coussot (1997), J. Hydraul. Eng., 123 [3] Ruesch et al. (2019) Nature Geoscience 12 [4] Brož et al. (2020), Nature Geoscience [5] Brož et al. (2020), EPSL 545 [6] Bargery et al. (2010), Icarus 210(1).

Landforms with specific flow-like morphology are characteristic for the area of Adamas Labyrinthus in the southwestern part of Utopia Planitia. These landforms have been previously described as degraded mud flows originating from a partly frozen muddy ocean. However, such interpretation remained ambiguous as lava flows observed elsewhere on Mars look quite similar. We mapped and investigated over 300 features spread across a 500 × 1300 km large area in order to reveal whether they were formed by the movement of mud or lava. Based on our systematic examination of their shapes, their spatial distribution as well as geological context we conclude that they were formed due to the ejection of mud from a gradually freezing muddy body. Once exposed to the surface, the mud spread by flowing over the surface, while freezing at the same time. This limited its ability to flow and caused the resulting outflows to have an appearance similar to terrestrial lava flows. Emergent landforms differentiated based on the effusion rates and overall volumes of the source material and subsequently degraded over time as the liquid part of the compound sublimed away. These processes eventually lead to the characteristic morphology of hills, ridges, plateaus, and complexly layered units which we observe today. We propose that all the >300 studied features were formed by subsurface sediment mobilization and that the material likely originated from the same source.

Here we present the results of our mapping of a large field of landforms characterized by flow-like morphology in the southwestern part of Utopia Planitia. They have been previously interpreted as mud flows associated with a partly frozen muddy ocean [1,2]. We find that these features can be grouped into four separate classes with distinct shapes and sizes and a clear evolutionary sequence among them. This suggests that all 205 studied features spread across the 500 × 1300 km large area were formed by the same basic process and that the material likely originated from the same source. Introduction The deepest parts of Utopia Planitia served as depocenters or sinks since early in the Martian history [2,3] and would be the final destination for any material released during Hesperian catastrophic floods [4]. Consequently, it was proposed that a large body of water might once or repetitively have been present there [1,5]. However, such hypothesis is still controversial due to the lack of unambiguous morphological evidence [6]. A promising area to search for such evidence is Adamas Labyrinthus, where the presence of putative mud flows has been previously reported [2,5]. Data and Methods Our mapping is based on the global CTX Mosaic (5m/pixel) [7] which served as the base map for delineation of the observed features. The features were marked as point, linear, and polygonal features in a QGIS environment. HiRISE (0.3 m/pixel) and CTX stereo pairs were processed using the MarsSI service [8] to produce digital elevation models (DEM) for some studied landforms. This enabled us to calculate their basic morphometric characteristics, height and volume, but also to reveal the relative stratigraphy among them and their surroundings. Results We found and mapped 205 features with positive topography characterized by flow-like appearance (Fig. 1). We classified them into four groups based on their extent, shape, and morphological properties (e.g., surface roughness). The resulting classes are ‘hills’ (Fig. 2a), ‘ridges’ (Fig. 2b), ‘plateaus’ (Fig. 2c), and ‘complexly layered units’ (CLUs, Fig. 2d), but we note that landforms commonly show transitional stages, hence share characteristics of multiple classes (such as in Fig. 2b). Hills are the smallest studied features. They are characterized by circular plan-map appearance. Their surface texture can be either smooth or rough with flow-like structures extending beyond their bases (Fig. 2a). Hills can be solitary features or be associated with fractures, in which case they form hill chains. Ridges are elongated features with rough surface. They vary in width from narrow sub-kilometer stretches to wide and elevated smooth plateau-like features (see Fig. 2b) surrounded by hummocky rims. Plateaus (referred to in [2] as “etched flows”) are kilometer-sized features characterized by a smooth central uplifted unit usually surrounded by a rough boundary (Fig. 2c). The smooth unit often contains rimless pits. Plateaus sometimes superpose the polygonal throughs typical for Adamas Labyrinthus. The final type are CLUs represented by extensive and often chaotic combination of overlapping landforms mentioned above (Fig. 2d). Their relative stratigraphy is decipherable only with the use of DEMs. Discussion Previously, many flow-like features have been described elsewhere on Mars as lava flows [9,10]. At the first glance this might seem like a plausible scenario even here as the studied features bear many morphological similarities with terrestrial and martian lava flows. However, our survey did not reveal signs of subsidence or explosive excavation associated with studied features, which are commonly accompanying volcanic eruptions [e.g. 9,10]. We also did not find evidence of lava-water interactions (e.g., rootless cones) which would have favorable conditions to occur at this location as the studied features are superposed on terrain enriched in volatiles as documented by polygonal troughs, ghost craters and pedestal craters [2]. Instead, the morphological characteristics of the mapped features, transitions between their categories and the spatial context of the study suggest that the landforms are of sedimentary (mud) volcanic origin. Recently, Brož et al. [11] showed experimentally that low viscosity mud effusively emplaced onto the cold martian surface under the low atmospheric pressure of 7 mbar would behave similar to pahoehoe lava, and resulting landforms might have similar appearance. This is because the evaporative cooling of water would cause the formation of an icy crust on the surface of the mud flow, analogous to a solidified lava crust. This process might explain the observed shapes of the studied features. Conclusions We propose that the studied features were formed due to the expulsion of mud from a gradually freezing muddy body. Because of the climatic conditions on Mars such body would be freezing from the top down, causing an increase in the internal pressure of the still liquid mixture underneath. This would trigger the ascent of the mud towards the surface via cracks in the frozen crust and subsequent effusive eruptions. Once the mud would be exposed to the surface, it would spread by flowing over the surface, while freezing at the same time. This would limit its ability to flow but cause the resulting outflow to have an appearance similar to terrestrial lava flows. This process gave rise to the observed hills, ridges, plateaus and complexly layered units. Emergent landforms degraded over time as the volatile part of the compound sublimed away eventually leading to the characteristic morphology we observe today. Acknowledgements: VC, PB & YM were supported by Czech Science Foundation (#20-27624Y). References: [1] Jöns (1985), Lunar Planet. Sci. 16, 414–415; [2] Ivanov et al. (2014), Icarus 228, 121-140; [3] Frey et al. (2002), Geophysical Research Letters 29, no. 10, 22-1-22-4; [4] Carr (1996), Planetary and Space Science 44, 1411-1423; [5] Ivanov et al. (2015), Icarus 248, 383-391; [6] Sholes et al. (2021), Journal of Geophysical Research: Planets 126, no. 5; [7] Dickson et al. (2018), 49th Lunar and Planetary Science Conference 2018, LPI Contrib. No. 2083 ; [8] Quantin-Nataf et al. (2018), Planetary and Space Science 150, 157-170; [9] Hodges & Moore (1994), Atlas of volcanic features on Mars; [10] Hauber et al. (2009), JVGR 185, 69-95; [11] Brož et al. (2020), Nat. Geo. 13, 403-407

The mid-latitudes of Mars host a large amount of buried ice deposits [1], which bear a record on the very Late Amazonian climate evolution (~107 to 108 yr.) [2] and are a possible resource for future exploration [3]. The reconstruction of the history of these ice reservoirs and the characterization of their current state is critical to enable putting constraints on the interplay between climate change, volatile migration and landform evolution. Examination of terrestrial analogs can help to identify similarities and – equally important – differences between the response of buried ice on Mars and Earth to changing environmental parameters. Here we report on our long-term investigations of an ice-cored moraine on Svalbard, a proxy for mid-latitude debris-covered glacier on Mars [4]. Our study area is an ice-cored lateral moraine of Kongsvegen glacier on the southern shore of Kongsforden in NW Spitsbergen (Svalbard). This site is subject to rapid degradation by melting and redistribution of surficial sediment, e.g., by thaw slumps and debris flows [5]. We couple multi-year fieldwork with repeat remote-sensing observations. Fieldwork includes DGPS-supported monitoring of surface changes by several imaging methods comparisons to environmental data (e.g., [6]). In 2008, a flight campaign with HRSC-AX (an airborne version of DLR’s High Resolution Stereo Camera on Mars Express) provided orthoimages (20 cm/px) and a Digital Elevation Model (DEM; 50 cm ground sampling distance, GSD) [7]. In 2020 a repeat campaign with DLR’s MACS (Modular Airborne Camera System) achieved ground pixel sizes between 5 cm and 10 cm for RGB images, and 10 cm to 15 cm for NIR images. The associated DEM has the same resolution [8]. MACS also acquires TIR data,which we use to identify regions with anomalous temperatures (e.g., exposed ice). We use for detailed mapping of ice-rich viscous flow features on Mars [9]. This study focuses on the Nereidum Montes area in the northern part of the Argyre basin. Image analysis, mapping of landforms and documentation of results were carried out using the QGIS software. A difference DEM was generated to determine the elevation differences (i.e. volume changes) on the ice-cored moraine between 2008 and 2020. Hillshade layers were created for each dataset to facilitate quick visual identification of morphological changes. Slump scars were digitized in 2008 and 2020 on orthoimages and hillshade views, and prominent slumps of 2020 (most recent, visible and best preserved) have been geomorphologically mapped with a focus on buried dead ice, collapsed sediment, and the relative activity of mud flows. Image analysis and mapping of Martian landforms is currently ongoing. There are 4 areas of major activity within the ice-cored moraine (Fig.1.a) highlighted by the four red boxes b, c, d and e, with more than 10m of elevation losses. There are many areas showing a neutral balance in terms of topographic evolution (white pixels). Hillshade layers from 2008 (Fig.1.f) and 2020 (Fig.1.g) correspond to the area of box d and show that significant changes have occurred in 12 years, indicating a massive degradation of ice-cored moraine in the last decade. This also demonstrates that the general trend is towards a heterogenous loss of material. The slump scars appear to be concentrated in the same areas described above. In 2008, 85 scars were counted against 157 scars in 2020, i.e. almost twice as many. It also appears that the 2020 scars are following the outlines of high activity areas while the 2008 scars are within these areas. Regarding the detailed mapping of slumps, the area corresponding to the buried dead ice, mapped with the TIR channel, can vary in shape and size depending on the shape of headscarp and the other units, i.e. the collapsed sediments and the mudflows (Fig.2.b,d). The collapsed sediments are washed away by the mudflows. The mudflow seems more active near the previously exposed dead ice. Therefore, the degradation of ice-cored moraines takes place mainly through the melting of the ice, which leads to mass wasting and rapid degradation. As Mars does not have the same climatic conditions, it is interesting to see whether the same landforms can be found on it at a very local scale. The Mars case study displays gullies, arcuate ridges with small gullies superposed on their slopes, flow features and also possible sublimation features such as pitted terrain, broad pits, and lineated patterned ground (Fig.3.b). The area is also filled with washboard terrain which is only found at steep slopes, above the lobate flow feature. It is marked by a close alternation of closely-spaced scarps which are parallel to the contour lines (possible evidence for paraglacial sacking [10]). Tension cracks are also found at the ridges and parallel to gully headscarps indicating recent activity. These tension cracks may be similar to headscarp retreats on backwasting processes on ice-cored moraines (Fig.3.d). The ice-cored ridge or arcuate ridge may still undergo degradation. The first results show that the degradation processes are rather related to potential ice sublimation and that signs of melting ice, if they exist on Mars, are not strongly encountered, which is consistent with the studies on very Late Amazonian climate evolution. References [1] Levy, J. S. et al. (2014), J. Geophys. Res. Planets, 119, 2188– 2196. [2] Bramson, A. et al. (2021), Bull. Amer. Astron. Soc., 53(4), e-id. 115. [3] Putzig, N. et al. (2022) LPSC 53, #2443. [4] Petersen,E. et al. (2017) LPSC 48, #2966. [5] Bennett, M. et al. (2000) Geomorphology, 35, 21-40. [6] Boike, J. et al. (2018), Earth Syst. Sci. Data, 10, 355–390. [7] Hauber, E. et al. (2011), Geological Society of America, 483, 177–201. [8] DLR - Institut für Optische - Sensorsysteme, (2020). [9] Souness, C. and Hubbard, B. (2012), Progress in Phys. Geog. 36(2), 238-261. [10] Jawin, E. R. et al. (2018), Icarus, 309, 187-206.

Introduction The formation of Ganymede’s light terrain and its possible interaction with a subsurface ocean, have made its investigation one of the top goals of the upcoming JUICE mission [1, 2]. In this study we present a detailed stratigraphic analysis of areas that were observed by the Galileo SSI camera at highest possible spatial resolution (scales of ~11 m/pxl) in order to see what information of the light terrain’s stratigraphic position in Ganymede’s surface evolution can be gained from mapping and crater counting results and to identify what still has to be done in order to prepare for the upcoming JUICE mission. Study areas Based on the available data set, we selected four major regions (Region A, B, C and D) that are covered by more than one high-resolution SSI image for our study (Fig. 1): Region A and D from the anti-Jovian hemisphere and Region B and C from sub-Jovian hemisphere. Region A comprises of Byblus Sulcus (G2GSGRVLNS01), Nippur and Philus Sulcus (G2GSNIPPUR01) and the Transitional region (G2GSTRANST01) with the context info provided by the SSI observation G8GSREGCON01. Region B is dominated by Arbela Sulcus (28GSARBELA01+02/ G7GSNICHOL01), Region C is the Harpagia Sulcus region (28GSBRTDRK02, 28GSCALDRA02 and 28GSSMOOTH02) and Region D comprises Erech Sulcus (G8GSERECH01), Mummu and Sippar Sulci (G8GSCALDRA01). Mapping results Geologic maps are prepared for the four regions using ArcGIS. The naming/categorization of geological units follows from [4, 5] but are refined and modified wherever necessary (Fig. 2). Among the light terrain units, ls and lg are the most commonly occurring than li. Stratigraphic correlation: On the whole, the relative ages from crater density measurements (Fig. 5) follow the mapping results. In brief, in Byblus Sulcus the two light terrain units are of similar age from crater counts while lg3 is younger than lg2 from crosscutting relationships. (Fig. 2). In case of Region B (Arbela Sulcus), we could find that the age relationship of the two light terrain units and two dark terrain units agree with the relative age inferred from crosscutting relationship (Fig. 3a) In more extensively resurfaced areas of the light terrain the situation appears to be more complex. In Region C, the terrain units ls also have comparatively higher age than lg terrain units (Fig. 3b-3d). In Region D the terrain units (Fig. 4) are highly interrupted by the secondary craters formed during the Osiris and Melkart impact events [6]. Discussion We used two most favored chronology models LDM (Lunar Derived Model by [7]) and JCM (Jupiter Comets Model by [8]) (Fig.6). In general, based on the LDM ages the crater densities point to a relatively high age of the light terrain units not much younger that the ancient dark terrain and could imply a relatively short time period of formation for most of our mapped light terrain units. This relatively high age fits into the theory that the light terrain could have formed as a direct result of internal differentiation followed by a global expansion [9]. On the contrary, the JCM derived ages point to a longer formation period of light terrain units around 2 Ga [9]. While the impact chronology in the Jovian system and of its satellites is still not fully solved, newest results infer that the craters on these bodies were created from members of a collisionally evolved impactor family, similar to those in the inner solar system [10]. This does not straightforwardly support the lunar-derived chronology model (LDM) by [7] but allows to derive a Ganymede-specific crater production function empirically from the lunar one. We used this production function to fit our crater distributions and to derive absolute model ages for both model chronologies [7][8]. Figure 1: Regions of Interest in this study with the available Galileo SSI coverage indicated. Figure 2: Geologic mapping results for Region A: a) Byblus Sulcus (G2GSGRVLNS01), b) Nippur and Philus Sulcus (G2GSNIPPUR01) and c) the Transitional region (G2TRANST01). The legend applies also to Figures 3 and 4. Figure 3: Geologic mapping results for Region B dominated by Arbela Sulcus (28GSARBELA01+02/ G7GSNICHOL01) and Region C by Harpagia Sulcus (b) 28GSBRTDRK02, c) 28GSCALDRA02 and d) 28GSSMOOTH02). Figure 4: Geologic mapping results for Region D comprises of a) Erech (G8GSERECH01) and b) Mummu and Sippar Sulci (G8GSCALDRA01). Figure 5: Comparison of relative ages of different terrain units from a) Region A (Byblus Sulcus), b) Region B (Arbela Sulcus), c) Region C (Harpagia Sulcus - 28GSBRTDRK02) and d) Region D (Erech Sulcus) based on crater size frequency distributions. Figure 6: Stratigraphic correlation of Region a) A, b) B, c) C and d) D in which relative ages are determined by plotting the N(10) values with respect to each terrain units and corresponding ages based on LDM [7] and JCM [8]models. Please note that ages of fresh impact craters such as Nergal (N), Kittu (K), Enkidu (E), Melkart (M) and Osiris (O) have been added as additional stratigraphic markers. Since terrain types often appear more than one time in a geologic map the different facies are indicated by different colors. References: [1] Grasset, O., et al.: Planetary and Space Science, 78, 1-21, 2013. [2] Stephan, K., et al.: Planetary and space science, 208, 105324, 2021. [3] Pappalardo, R. T., et al.: Jupiter: The Planet, Satellites and Magnetosphere, 363-396, 2004. [4] Collins, G.C., et al.: Global geologic map of Ganymede (p. 3237), US Geological Survey, 2013. [5] Patterson, G. W. et al.: Icarus, 207, 845-867, 2010. [6] Baby, N. R., et al.: LPI Contributions, 2678, abstr. #1350, 2022. [7] Neukum, G., et al.: LPSC XXIX, abstr. #1742, 1998. [8] Zahnle, K., et al.: Icarus 163, 263-289, 2003. [9] Bland, M. T. et al. : Icarus 200, 207- 221, 2009. [10] Bottke et al.: LPSC, #2638, 2022.

The Mars Sample Return (MSR) Campaign must meet a series of scientific and technical achievements to be successful. While the respective engineering responsibilities to retrieve the samples have been formalized through a Memorandum of Understanding between ESA and NASA, the roles and responsibilities of the scientific elements have yet to be fully defined. In April 2020, ESA and NASA jointly chartered the MSR Science Planning Group 2 (MSPG2) to build upon previous planning efforts in defining 1) an end-to-end MSR Science Program and 2) needed functionalities and design requirements for an MSR Sample Receiving Facility (SRF). The challenges for the first samples brought from another planet include not only maintaining and providing samples in pristine condition for study, but also maintaining biological containment until the samples meet sample safety criteria for distribution outside of biocontainment. The MSPG2 produced six reports outlining 66 findings. Abbreviated versions of the five additional high-level MSPG2 summary findings are: Summary-1. A long-term NASA/ESA MSR Science Program, along with the necessary funding and human resources, will be required to accomplish the end-to-end scientific objectives of MSR. Summary-2. MSR curation would need to be done concurrently with Biosafety Level-4 containment. This would lead to complex first-of-a-kind curation implementations and require further technology development. Summary-3. Most aspects of MSR sample science could, and should, be performed on samples deemed safe in laboratories outside of the SRF. However, other aspects of MSR sample science are both time-sensitive and sterilization-sensitive and would need to be carried out in the SRF. Summary-4. To meet the unique science, curation, and planetary protection needs of MSR, substantial analytical and sample management capabilities would be required in an SRF. Summary-5. Because of the long lead-time for SRF design, construction, and certification, it is important that preparations begin immediately, even if there is delay in the return of samples.

Rocks around the InSight lander were measured in lander orthoimages of the near field (

Slope streaks are albedo features that form frequently on equatorial Martian slopes. Most slope streaks are dark relative to surrounding terrains, a minor fraction is bright, and there are rare transitioning streaks that exhibit a contrast reversal partway downslope. Their formation mechanisms and physical surface properties are not well understood. New observations acquired by the Colour and Stereo Surface Imaging System (CaSSIS) on board ESA's ExoMars Trace Gas Orbiter (TGO) provide insights into slope streaks' surface microstructure, roughness and particle size ranges. Using multiple phase angle observations, we show that dark slope streaks are substantially rougher and possibly more porous than their bright counterparts, which are likely composed of more compact regolith. Color data acquired in the four wavelength bands suggest that dark streaks are spectrally similar to bright streaks but are composed of larger particles. The comparison of our orbital results to the laboratory measurements of Martian regolith analogs indicates that particles within dark slope streaks may be up to a factor of four larger than the granular material of the surrounding terrains. At one study site in Arabia Terra, using complementary imagery from other orbiters, we identify a case where dark slope streaks turned fully bright in a twenty-year period. These and CaSSIS observations suggest that bright slope streaks are old dark slope streaks, likely formed by deposition of dust or decomposition of surface aggregates into smaller particles.

During an extensive grid-mapping campaign on Mars' southern hemisphere, we have detected so-called sheet flow deposits, which are defined by distinctive lobate fronts, thin and mostly planar layers, and faint sub-parallel surface lineations. They originate from the high plains of Dryas Mons, a large massif of impact and tectonic origin, and follow the topographic gradient down into the adjacent basins. Their sources often coincide with steep and multi-layered outcrops. This work addresses the formation of these deposits, and if they are related to the unique tectonic and endogenic environment of Dryas Mons. We applied photogeological mapping, age determinations by crater counts, as well as topographic and heat flow measurements in order to reconstruct the evolution of these landforms. The calculated ages (mid to late Amazonian), their location in the mid-latitudes, as well as some specific morphologies like lobate flow fronts are typical for standard viscous-flow features on Mars. In contrast to such viscous-flow features, the sheet flow deposits occur isolated in the Dryas Mons region. Aside from that, major other landforms, typical for viscous-flow features are lacking, like sublimation pits, brain terrain or arcuate deformations. Considering these similarities and differences, we suggest that both landforms viscous-flow features and the sheet flow deposits of Dryas Mons were formed by the involvement of volatiles; however, at varying amounts and by different emplacement processes. As the formation of the sheet flow deposits is located in an area with one of the highest heat flow values planet-wide, we calculated if the heat flow could be a potential trigger for the release of outcropping volatile-rich layers. However, our calculations have shown that the heat flow is still insufficient to enable near-surface melting. Instead, we suggest that the volatiles originate from deep layers affected by magmatic and/or intrusive activities in a tectonically active environment. These conditions led to melting and mobilisation of the volatiles by advective hydrothermal processes. Thus, the volatiles migrated upward along hypothesized deep-seated fault systems, formed by Noachian/Hesperian impacts and tectonic activities, until they reached conductive layers outcropping at Dryas Mons, enabling them to drain. After their release to the cold Amazonian atmosphere, this mixture of volatiles and solids partially froze, resulting in a comparatively high viscosity, and hence, a slow and laminar (non-turbulent) movement. This flow behaviour might have led to the formation of the lineations at their surface along shear zones. Hence, we suggest that the sheet flow deposits may have originally formed as slowly moving icy debris flows during the mid- to late Amazonian. This work has been funded by the Research Fellowship Program through the European Space Agency. J. Ruiz contribution was supported by the project PGC2018-095340-B-I00 from the Spanish Ministry of Science, Innovation and Universities.

International audience; Introduction: High-resolution images show the presence of kilometer-sized flows (KSFs) on Mars. Most of KSFs are associated with well-known volcanic centers, hence they have been interpreted as lava flows [1,2]. However, some KSFs occur in regions where such link is not obvious and processes related to sedimentary volcanism have been proposed as an alternative [3-7]. A remarkable example of such KSF was reported by Komatsu et al. [6,8] at the southern margin of Chryse Planitia (19.16°N; 322.71°E). Later thirty-five similar KSFs (e.g., Fig. 1a) have been observed in the region [7]. KSFs typically feature three morphological elements: a) a central depression from which channel(s) originate(s), b) leveed channel(s), c) a distal portion of the fading channel where the material is deposited forming terminal lobes.Brož et al. [7] proposed that the KSFs resulted from low viscosity mud extrusions that propagate through extensive networks of channels that gradually lose their transport energy. As initial studies were based on Context Camera (CTX) images (~5-6 m/px, [9]) and HiRISE images (~30 cm/px; [10]), they lacked topographic resolution to support these hypotheses. Currently, six KSFs are covered by HiRISE stereo pairs. Using established methods [11], we generated seven Digital Elevation Models (DEMs) with a ground sampling of 1-2 m/px to obtain additional insights about their origin.Observations: Studied KSFs show a topographically well-defined “source” area displaying circular, semicircular or elongated map-view outline (Figs. 1, 2a). Three source areas are situated on relatively flat plains and are surrounded by ~hundred(s) of meter-wide elevated rims (Fig. 2a). The other source areas are superposed on higher elevation/inclined pre-existing surfaces with laterally less extensive rims (Fig. 1). The elevation difference between source area floors and the rims ranges from 10 to 20 m. The elevation of the source area floors is the same as that of the flat plains beyond the elevated margins on which KSFs are superposed. The margins of all studied source areas are breached, enabling any extruded fluid to flow out. The presence of elevated mounds (

Gorgonum Chaos is part of the Eridania paleolake in Terra Sirenum and displays a number of prominent light‐toned morphological features that bear a record of the regional climatic conditions throughout most of Martian history. Based on an intergrated analysis of orbital data, we mapped a 1,500 km2 area in the southeast of Gorgonum Chaos. Morphologic, spectroscopic, and stratigraphic analyses were used to determine age and composition of the main geological units in the area. We identified four major geological units with decreasing content of hydrated minerals from the oldest to the youngest units, which were completely free of hydrated minerals. In the study area, phyllosilicate‐rich Noachian units compose the majority of the basin floor. Deposits enriched with evaporites were formed around the Noachian/Hesperian transition and erosion created prominent inverted morphologies. Loess‐like material without significant amounts of hydrated minerals was deposited until the late Hesperian. The youngest unit is an Amazonian layer free of hydrated minerals that originated from volcanic activities. This succession of minerals reflects the transition from more humid climatic conditions with the ability to sustain liquid water on the planet's surface during the Noachian to the hyper‐arid Amazonian environment we observe currently on Mars., Plain Language Summary: Gorgonum Chaos is part of the Eridania basin, which is a former lake system located at the southern hemisphere of Mars. The landforms observed in this area and their variable brightness suggest dramatically changing climatic conditions during the history of Mars. In an area of 1,500 km2 in size, we analyzed different landforms, their spectral characteristics, and their temporal sequences to determine the age and composition of the geological units. We found four major geologic units whose content of hydrated minerals decreased dramatically from oldest to youngest. The oldest unit with a high content of clay minerals is about 3.7 billion years old and formed the former lake bottom. This is followed by a younger unit with a mineral composition that indicates desiccation of the lake and erosion by wind. These, in turn, were largely covered by materials deposited by wind, which show very little evidence of liquid water. The last and youngest unit is volcanic in origin and completely devoid of minerals indicative of water. This succession of minerals reflects the evolution of the Martian surface, which was capable to sustain liquid water in the early stages of the planet and lost this ability during a drastic climate change., Key Points: We produced a geological map of southeastern Gorgonum Chaos. We find a succession from phyllosilicates to olivine in aeolian deposits. The presence of water decreases over time.

The presence of delta deposits on Mars has been thoroughly demonstrated for decades and large scale mapping [1,2] highlighted the presence of several delta fans mainly located on the dichotomy boundary. While a previous delta inventory was compiled by Morgan et al. [3], we aim to update and finalize a complete mapping of delta deposits in order to allow the examination of the evolution and distribution of standing bodies of water on Mars. The objective of our project focuses on the production of a global catalogue of water-related features at the Martian surface, which are commonly studied separately or at smaller scales.Globally, we located around 150 deltas among which many were not previously included in published literature [e.g. 1,2,4]. We then examined the deltas based on two main traits. Firstly, we measured the length of the feeding channels since it may be (i) a proxy for the duration of the aqueous activity in the channel-delta system, and (ii) proportional to the age of the delta [2]. The latter relationship links older deltas near Chryse Planitia (>3 Ga) to longer valleys, while younger deltas are usually fed by shorter valleys [2]. Secondly, we measured the elevation of the delta population and compared the obtained dataset with the hypothesized sea level elevation of -2540 ± 177 m firstly suggested by Di Achille and Hynek [1] for a northern ocean through the analysis of deltas.We observed that, if the relationship between feeding channel length and delta age found for a sub-group of the population [2] is applicable as a rule of thumb to all deltas, many of the deposits have the potential to be Hesperian or Amazonian in age. They would thus be younger than the ocean that might have occupied the northern lowlands during the Noachian-Hesperian boundary period [1] and thus be unrelated to a global sea level range. In fact, less than half of the delta population is related to medium/long feeding channels (>30 km). Abundant pristine morphologies, both related to channels and deltas, also supports the hypothesis that part of the population is younger than Noachian. Additionally, the large variety of elevations where the deltaic deposits can be found and the very small amount of deltas included in the sea level elevation range proposed by Di Achille and Hynek [1] raise questions about the generation and environmental implications of these features, especially when seen at global scale. [1] Di Achille, G. & Hynek, B. M., Nat. Geosci. 3, 459–463 (2010).[2] Hauber, E. et al., J. Geophys. Res. E Planets 118, 1529–1544 (2013).[3] Morgan, A. M., et al., Lunar Planet. Sci. Conf. (2018).[4] Ori, G.G. et al., J. Geophys. Res. E Planets 105, 17629–17641 (2000).

Introduction: ESA’s ExoMars rover will land in the Oxia Planum (OP) region [1,2], which was chosen for its ancient age, evidence for the sustained presence of water, the presence of layered deposits, and the potential for biosignature preservation [2]. While some of the geological characteristics have been studied in detail [3-5], other aspects are less well understood. In particular, it is unclear if the situation in OP is a unique one, or if the geologic setting is representative for Mars on a regional, or even a global scale. Specifically, the stratigraphic relationship of the geologic units in OP to the nearby ancient impact basin, Chryse Planitia, requires further study. For example, a »bathtub«-like ring of Fe/Mg-rich phyllosilicates around Chryse [6] may indicate that the phyllosilicates at OP reflect aqueous processes that operated in a specific context at basin-scale. To test the hypothesis that OP is representative for a circum-Chryse geologic setting, we selected a site in northern Xanthe Terra (XT) (~9-13.5°N/315-318.5°E; Fig. 1) to investigate key geologic features and compare them to OP. This site displays several characteristics similar to OP, making it a suitable reference site: The presence of phyllosilicates [7], the proximity to fluvial features [8-10], and the abundance of remnant buttes that are indicative of widespread erosional processes [11]. Here we present preliminary results of our mapping and geologic analysis. Preliminary Results and Discussion: The study area is approximately 225 × 190 km in size. The general elevation increases in height from north to south from approximately -2,960 m to -1,800 m. Both at OP and XT, the lowland-highland boundary is expressed as a gradual slope rather than a sharp topographic step. Figure 1: (A) THEMIS nighttime IR and (B) HRSC image mosaics of the study site in Xanthe Terra. In the northwestern study area, the Hypanis fan represents the arguably largest sedimentary fan deposit on Mars [8-10]. These deposits are finely layered and appear dark in THEMIS nighttime IR images (Fig. 1). Sedimentary fan deposits, while having a smaller extent, are also present in OP at the termination of the Coogoon Valles fluvial system [5,12,13]. Both the sedimentary deposits in XT [8-10] and OP [13] are thought to have a fluvial origin. Phyllosilicates are widespread in OP [4-6] and are the main target of the ExoMars rover. Apart from their spectral signature, they are also characterized by a bright THEMIS nighttime IR signature and a polygonised texture at HiRISE scale. A global-scale search for chemical alteration signatures revealed the presence of Fe/Mg phyllosilicates in northern XT, marginal to Chryse [4]. As in OP, the phyllosilicate-bearing plains appear bright in THEMIS nighttime IR images (Fig. 1). At least two different units are present in this region. The most widespread is a light and layered unit, which is partly eroded, exposing a darker material underneath (Fig. 2). NW – SE orientated small dunes and periodic bedrock ridges, a type of aeolian erosional landforms which is ubiquitous in the clay-bearing plains of OP [14], are present on top of the darker unit. HiRISE coverage of both units shows distinct polygonised textures. Several inverted craters are present within this two units. The material of these inverted craters differs from both units, and, therefore, represents the remnants of at least one further eroded unit. The phyllosilicate-bearing plains are overlain by a widespread unit, which seems to be present in most of the northern study area. Figure 2: (A) HRSC mosaic of the phyllosilicate-bearing plains. The erosional contact is shown in (B). (C) and (D) are HiRISE images of the lighter and darker unit, respectively. The rims of ancient filled craters are outlined by rings of mounds. The diameters of these mounds range from tens of meters to several kilometers. Their appearance is variable and resembles mesas, rounded knobs/buttes, and “bread-crust-like features” (Fig. 3). These mounds are increasing in height and abundance towards north, i.e. towards Chryse. A similar trend of height and abundance was also observed in OP [15]. However, the height of these mounds varies individually. Rounded buttes, for example, can be higher than mesas in their immediate neighborhood. Some mounds show a fine layering, and, in some cases, mounds stand on top of a finely layered basis. The mounds appear dark in THEMIS nighttime infrared images (Fig. 1). Similar mounds are present along the eastern highland boundary of Chryse [11]. The composition of the mounds and their erosional history are not yet clear. The low thermal inertia and the fine layering of some of the mounds, however, favor a sedimentary material. The timing of mound formation relative to other geological units is also still unknown since stratigraphic relationships between these units still seem conflicting. Figure 3: (A) Mapped mounds in the study area. Rounded buttes are shown in green and mesas in orange. (B) CTX and HiRISE images of the remnant mound types. Preliminary Conclusions: Northern XT and OP share various geological characteristics (e.g., sedimentary fans, phyllosilicates, remnant mounds) and a comparable location at the lowland-highland boundary at Chryse Planitia. These similarities enable a comparison between both sites and a testing of hypotheses related to the ExoMars rover landing site. References: [1] Vago, J. L. et al. (2015) Sol. Syst. Res., 49, 538–542. [2] Bridges, J. C. et al. (2018), LPS XLIX, Abstract #2177. [3] Vago, J. L. et al. (2017) Astrobiol., 17, 471–510. [4] Carter, J. et al., (2013) J. Geophys. Res., 118, 831–858. [5] Quantin-Nataf, C. et al. (2021) Astrobiol., 21, 994-1013. [6] Mandon, L. et al. (2021) Astrobiol., 21, 464-480. [7] Carter, J. et al. (2019) Ninth Int. Conf. Mars, Abstract #6175. [8] Hauber, E. et al. (2009) Planet. Space Sci., 57, 944–957. [9] Fawdon et al. (2018) EPSL, 500, 225–241. [10] Adler, J. B. et al. (2019) Icarus, 319, 885–908. [11] McNeil, J. et al. (2021) LPSC, 52, Abstract #2548. [12] Ivanov, M. A. et al. (2020) Sol. Syst. Res., 54, 1-14. [13] Molina, A. et al. (2017) Icarus, 293, 27-44. [14] Silvestro, S. et al. (2021) GRL), doi: 10.1029/2020GL091651. [15] McNeil, J. D. et al. (2020) LPSC, 51, Abstract #1948.

1. Introduction The north polar region of Mars is one of the most active places of the planet with avalanches[1] and ice block falls[2] being observed every year on High Resolution Imaging Science Experiment (HiRISE) data. Both phenomena originate at the steep icy scarps surrounding the north polar plateau, Planum Boreum. The exposed layers of ice and dust contain important information about the climate cycles of the planet[3]. We are interested in monitoring how the current scarp erosion rate (quantified through analysing block falls) is linked to these periodic changes in temperature. The large scale of the region of interest, combined with a growing amount of available satellite data makes automation key for this project. Our goal is to monitor robustly the whole north polar region for ice block falls throughout the entire Mars Reconnaissance Orbiter (MRO) mission. The active scarps of the north polar region contain two main geological units, the older and darker Planum Boreum Cavi unit, also called Basal Unit (BU) and the younger and brighter Planum Boreum 1 unit, which is a part of the so called North Polar Layered Deposits (NPLD)[4]. These geologic units are mapped by Tanaka et al. (2012), however the scale of this map is not sufficient for our work, as it is based on coarse resolution data. For our project it is important to segment the HiRISE images of the steep scarps in NPLD and BU regions with high precision, both to restrict the area where the algorithm will look for fallen blocks and to differentiate between the activity originating in the NPLD[5] from that originating in the BU. Here we present our algorithm for automated scarp mapping – the first completed step towards a fully streamlined monitoring pipeline. 2. Methods and Results First the original high-resolution images have to be downscaled by 90% in both dimensions. Given the initial 0.3 m/pixel precision, this procedure increases the delineation error margin to about 3 meters. This tradeoff is required to achieve greater computational efficiency during the subsequent pre-processing steps. OpenCV canny edge detection (CED) algorithm can then be applied to the downscaled result, yielding a binary contour map (Fig.1). Two parameters have to be specified when running edge detection, namely: min and max thresholding values. These are used by the algorithm to decide whether an edge is to be kept or to be discarded. We propose a fully automated method for choosing the optimal constraints. Our approach relies on the fact that the exposed scarp produces a spike in the histogram of pixel brightness values. We utilize kernel density estimation (KDE) to fit a gaussian distribution to this area of the histogram and then select its 5th percentile and mode as minVal and maxVal respectively (Fig.2). The CED output contains both the scarp trace and the noise resulting from numerous other objects present in the FOV (Fig.3 bottom left). To filter out the unnecessary detail, we roll a sliding window across the image, tracking areas containing many pixels with high edge responses. The y-coordinate of every new box in a sequence is adjusted to follow the underlying bright pixels as tightly as possible. The longest of the sequences is expected to contain the scarp and therefore only its content is retrieved (Fig.3 top). Since CED struggles to connect all the separate edges at such a large scale, the boundary of the scarp is delineated by a collection of disjointed lines (Fig.3 bottom left). Before we can derive a continuous polynomial that can bridge the gaps in between these lines, an even more rigorous de-noising is required. We propose a two-stage procedure based on density clustering[6]. The whole length of the scarp is first divided into overlapping segments. HDBCSAN is then applied to each segment independently, yielding numerous clusters of varying size (Fig.3 bottom right). We proceed by linking these clusters through sets of shared points located in the overlap areas. As a result, the scarp trace is represented by the largest grouping of pixel co-ordinates and all the smaller clusters are discarded. Upon tightening the parameters of HDBSCAN to filter out the finer noise ignored by the previous crude sweep, we obtain the final scarp outline. This preprocessed contour map is then subjected to a custom data boundary fitting algorithm, which uses cubic splines to connect the adjacent edges[7] (Fig.4). Since the resolution, sliding window sizes and scarp segmentation schemes are kept constant between the images, most of the internal parameters can be set to sensible defaults, thus minimizing the user input. 3. Conclusions and future projects Our first step towards fully monitoring the activity of the north polar region resulted in a detailed and automatically produced map of the boundary between BU and the NPLD based on the significant difference in intensity between them. Fanara et al. (2020a) already used traditional machine learning techniques to detect newly appeared ice blocks, achieving a good performance and estimating the current erosion rate of a steep scarp[8]. We are now planning to complement this study with our scarp mapping algorithm. This should allow to further extend the training dataset, hopefully generating enough input for a computer vision model based on convolutional neural networks. The NPLD remains our primary area of interest due to its high levels of activity and good image density, yet we also plan to apply our pipeline to different surface changes and Martian regions as well as other celestial objects. References 1. Russell P., Thomas, N. Byrne, S. Herkenhoff, K. Fishbaugh, K. Bridges, N. Okubo, C. Milazzo, M. Daubar, I. Hansen. Seasonally active frost-dust avalanches on a north polar scarp of Mars captured by HiRISE, Geophys. Res. Lett. 35, L23204, 2008. 2. L. 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. 3. Smith I.B., Putzig N.E., Holt J.W. and Phillips R.J. An ice age recorded in the polar deposits of Mars, Science, 352, 1075–1078, 2016. 4. Tanaka, K.L., and Fortezzo, C.M., 2012, Geologic map of the north polar region of Mars: U.S. Geological Survey Scientific Investigations Map 3177, pamphlet 11 p., 1 sheet, scale 1:2,000,000. 5. 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. 6. Leland McInnes1, John Healy1, and Steve Astels2. HDBSCAN: Hierarchical density-based clustering. (1) Tutte Institute for Mathematics and Computing, (2) Shopify. 7. N. Cardiel. Data boundary fitting using a generalized least-squares method; Mon. Not. R. Astron. Soc. 396, 2009, ISSN 680–695. 8. L. 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.

We present a study of the morphology, patterns, and dynamics of dust storms on Mars observed at the edge of the North Polar cap during the Northern Hemisphere Spring Equinox from May to June 2019 (MY35) [1] and of the onset of the Global Dust Storm in May to June 2018 (MY34) [2]. The analysis is based on images obtained by the Visual Monitoring Camera (VMC) [3] and the High Resolution Stereo Camera (HRSC) [4] onboard Mars Express, and MARCI camera onboard Mars Reconnaissance Orbiter (MRO) [5-6]. VMC images were analyzed with tools described in previous works [7-8], HRSC images were analyzed from map-projections, and MARCI were processed and projected using the Integrated Software for Imagers and Spectrometers (ISIS) of the USGS [9]. The dust activity at the edge on the North Polar cap in MY35 (Ls = 28°-35°) took place around latitude 60°N in the longitude range 140°E -240°E (along Acidalia, Arcadia and Amazonis planitias). These features exhibited a rich phenomenology typical of this season with different morphologies in form of filaments and fronts, flushing storms (large arc-shaped features), compact textured storms and well developed spiral systems, sometimes mixed with water-ice clouds [1]. Here we concentrate in these last two types of features. The textured and spiral storms are of local type (areas < 1.6x106 km2) and contained cellular patterns suggestive of organized active updrafts within the storms. The cells varied in size from one storm to other: 50x20 km, 135x60 km and 70x40 km. In all cases, the cell texture is anisotropic in the horizontal size (length/width, l/w~ 2) with values well above the atmospheric scale height (H ~ 8 km). Measured local winds reached velocities from 20 to 45 ms-1. The presence of storms with such different overall structure, for example in the form of compact areas on the one hand and spiral systems on the other, indicates that the underlying mechanisms are different but that above a threshold velocity, all of them generate the dust storms. We explore the action of dry convection in the formation of these patterns driven by buoyancy generated by the radiative heating of atmospheric dust. The onset of the last Global Dust Storm (GDS 2018) took place on 30 May 2018 (Ls = 182°) at latitude ~ 33°N and longitude 342°E, following a precursor storm on 26-27 May 2018 at latitude ~ 58°N and longitude 325°E [2]. The MARCI high-resolution images reveal again the presence of cellular patterns at different scales (typically 40x20 km) with a well defined frontal line marking the storm advance. The storm morphology rapidly evolved in one day showing patterns of long wave trains with wavelengths ranging from 10 to 20 km. We interpret these as gravity waves formed by intense winds flowing over craters and other topographic structures. References: [1] Sánchez-Lavega A. et al., Patterns in textured dust storms in Mars North Pole, Europlanet Science Congress 2020, EPSC Abstracts Vol., EPSC2020-141 (2020) [2] Sánchez-Lavega A., T. del Río-Gaztelurrutia, J. Hernández-Bernal, M. Delcroix, The onset and growth of the 2018 Martian Global Dust Storm, Geophys. Res. Lett., 46, 6101-6108 (2019). doi.org/10.1029/2019GL083207. [3] Ormston, T., Denis, M., Scuka, D., & Griebel, H., An ordinary camera in an extraordinary location: Outreach with the Mars Webcam. Acta Astronautica, 69, 703-713 (2011) [4] Jaumann, R., Neukum, G., Behnke, T., Duxbury, T. C., Eichentopf, K., Flohrer, et al., The high-resolution stereo camera (HRSC) experiment on Mars Express: Instrument aspects and experiment conduct from interplanetary cruise through the nominal mission. Planetary and Space Science, 55, 928-952 (2007) [5] Malin, M.C., Bell, J.F., Calvin, W., Clancy, R.T., Haberle, R.M., James, P.B., Lee, S.W., Thomas, P.C., Caplinger, M.A., Mars Color Imager (MARCI) on the Mars Climate Orbiter. J. Geophys. Res. 106 (E8), 17651–17672 (2001) [6] Bell, J.F., et al., Mars Reconnaissance Orbiter Mars Color Imager (MARCI): instrument, description, calibration, and performance. J. Geophys. Res. E 114 (8), E08S92 (2009). https://doi.org/10.1029/2008JE003315. [7] Sánchez-Lavega, A., Chen-Chen, H., Ordonez-Etxeberria, I., Hueso, R., del Rio-Gaztelurrutia, T., Garro, A., & Wood, S., Limb clouds and dust on Mars from images obtained by the Visual Monitoring Camera (VMC) onboard Mars Express. Icarus, 299, 194-205 (2018) [8] Hernández‐Bernal, J., Sánchez‐Lavega, A., del Río‐Gaztelurrutia, T., Hueso, R., Cardesín‐Moinelo, A., Ravanis, E. M., Tivov, D., & Wood, S., The 2018 Martian Global Dust Storm over the South Polar Region studied with MEx/VMC. Geophys. Research Lett., 46, 10330-10337 (2019) [9] ISIS. Integrated Software for Imagers and Spectrometers (accessed 2021). https://isis.astrogeology.usgs.gov/

International audience; On February 18, 2021 NASA's Perseverance rover landed in Jezero crater, located at the northwestern edge of the Isidis basin on Mars. The uppermost surface of the present-day crater floor is dominated by a distinct geologic assemblage previously referred to as the dark-toned floor. It consists of a smooth, dark-toned unit overlying and variably covering light-toned, roughly eroded deposits showing evidence of discrete layers. In this study, we investigated the stratigraphic relations between materials that comprise this assemblage, the main western delta deposit, as well as isolated mesas located east of the main delta body that potentially represent delta remnants. A more detailed classification and differentiation of crater floor units in Jezero and determination of their relative ages is vital for the understanding of the geologic evolution of the crater system, and determination of the potential timeline and environments of habitability. We have investigated unit contacts using topographic profiles and DEMs as well as the distribution of small craters and fractures on the youngest portions of the crater floor. Our results indicate that at least some of the deltaic deposition in Jezero postdates emplacement of the uppermost surface of the crater floor assemblage. The inferred age of the floor assemblage can therefore help to constrain the timing of the Jezero fluviolacustrine system, wherein at least some lake activity postdates the age of the uppermost crater floor. We present hypotheses that can be tested by Perseverance and can be used to advance our knowledge of the geologic evolution of the area.

International audience; We report the aeolian changes observed in situ by NASA's InSight lander during the first 400 sols of operations: Granule creep, saltation, dust removal, and the formation of dark surface tracks. Aeolian changes are infrequent and sporadic. However, on sols, when they do occur, they consistently appear between noon to 3 p.m., and are associated with the passage of convective vortices during periods of high vortex activity. Aeolian changes are more frequent at elevated locations, such as the top surfaces of rocks and lander footpads. InSight observed these changes using, for the first time, simultaneous insitu and orbital imaging and high-frequency meteorological, seismological, and magnetic measurements. Seismometer measurements of ground acceleration constrain the timing and trajectory of convective vortex encounters, linking surface changes to source vortices. Magnetometer measurements show perturbations in magnetic field strength during the passage of convective vortices consistent with chargedparticle motion. Detachment of sand-scale particles occurs when high background winds and vortexinduced turbulence provide a peak surface friction wind speed above the classic saltation fluid threshold. However, detachment of dust-and granule-scale particles also occurred when the surface friction wind speed remained below this threshold. This may be explained by local enhancement of the surface roughness and other effects described here and further studied in Part 2 (Baker et al., 2021). The lack of saltation and bright dust-coated surfaces at the InSight landing site implies surface stability and the onset of particle motion may be suppressed by dust "cushioning." This differentiates the InSight landing site from other areas on Mars that exhibit more aeolian activity. Plain Language Summary Aeolian activity, the movement of dust and sand by the wind, is common on Earth and has been observed on other planets, including Mars. A new Mars lander, InSight, has for the first time monitored aeolian changes by combining imaging with weather, seismic and CHARALAMBOUS ET AL.

Mars Polar Science is an integrated, compelling system that serves as a nearby analogue to numerous other planets, supports human exploration, and habitability. Mars possesses the closest and most easily accessible layered ice deposits outside of Earth, and accessing those layers to read the climate record would be a triumph for planetary science.

This paper emphasizes the importance of using terrestrial analogues to improve our understanding of the role of ice on Mars through its associated landforms. We discuss terrestrial regions and techniques that can help understand Martian icy environments, and highlight the necessity to explore the Martian cryosphere as the next natural step.

We report a previously unnoticed annually repeating phenomenon consisting of the daily formation of an extremely elongated cloud extending as far as 1,800 km westward from Arsia Mons. It takes place in the solar longitude (Ls) range of ∼220°-320°, around the Southern solstice. We study this Arsia Mons Elongated Cloud (AMEC) using images from different orbiters, including ESA Mars Express, NASA MAVEN, Viking 2, MRO, and ISRO Mars Orbiter Mission (MOM). We study the AMEC in detail in Martian year (MY) 34 in terms of local time and Ls and find that it exhibits a very rapid daily cycle: the cloud growth starts before sunrise on the western slope of the volcano, followed by a westward expansion that lasts 2.5 h with a velocity of around 170 m/s in the mesosphere (∼45 km over the areoid). The cloud formation then ceases, detaches from its formation point, and continues moving westward until it evaporates before the afternoon, when most sun synchronous orbiters make observations. Moreover, we comparatively study observations from different years (i.e., MYs 29-34) in search of interannual variations and find that in MY33 the cloud exhibits lower activity, while in MY34 the beginning of its formation was delayed compared with other years, most likely due to the Global Dust Storm. This phenomenon takes place in a season known for the general lack of clouds on Mars. In this paper we focus on observations, and a theoretical interpretation will be the subject of a separate paper.

Polygonal patterned ground is ubiquitous in the martian mid-latitudes and in the polar regions of Earth. The latitude dependence of martian patterned ground and its morphological similarity to terrestrial patterned ground suggests that thermal contraction cracking may have been the leading formation mechanism for those polygons. Due to a lack of ground truthing on martian patterned ground, the role of liquid water in its formation and weather freeze-thaw processes lead to their origin is still debated. This study uses a quantitative approach, based on geomorphometrical and soil characteristics of patterned ground in continental Antarctica and glacial deposits with low inclination of Terra Nova Bay as terrestrial analogues, to understand polygon formation in martian hyper-arid conditions. We investigated polygons in ice-free parts of the mountain range of Helliwell Hills (~71°43S / 161°2E) in continental Antarctica and the Northern Foothills in the coastal Terra Nova Bay area (74°45S / 164°E).Field observations were made during the austral summer on the GANOVEX XI and GANOVEX XIII expeditions in Dec-Jan 2015/2016 and Oct-Nov 2018, respectively. The polygonal troughs have been mapped and digitized in ArcGIS based on high resolution satellite images. For Helliwell Hills we used World View 2 images with a pixel size of 50 cm. For Terra Nova Bay, Quickbird satellite imagery has been used with a pixel size of 60 cm. Based on these datasets, parameters such as area, perimeter, length, and width have been measured, and size, circularity, orientation, and aspect ratio of each polygon were derived from these measurements. Additionally, we used a DTM derived from World View 2 stereo imagery (ground sampling distance: 8 m) to calculate the average slope, aspect, and solar irradiation of each polygon. The quantitative analysis shows that the geomorphometric characteristics of polygons in the Helliwell Hills differ significantly from those in Terra Nova Bay. Polygons in the Helliwell Hills are significantly smaller than in Terra Nova Bay and are organized as orthogonal, random-orthogonal and hexagonal polygon networks, while all polygons in Terra Nova Bay form hexagonal polygon-net geometries. The correlation of polygon-net geometries and the slope gradient shows that hexagonal polygon-net geometries dominate in flat terrains, while orthogonal geometries have developed on steeper slopes or in the immediate proximity of sharp terrain margins such as topographic slopes. The polygons in Helliwell Hills do not display significant local relief, but overall, the polygon centres are slightly higher than the bounding cracks (i.e. high-centered polygons). In Terra Nova Bay the appearance of high centred polygons and a deeper trough is even more developed and well distinguishable on satellite images.During the fieldwork in Helliwell Hills, excavations were made in the center of polygons and across the bounding cracks. Typically, the uppermost ∼40 cm of regolith are dry and unconsolidated. Below that, there is commonly a sharp transition to ice-cemented material or very clear ice with no bubbles. The grain size analysis indicated no significant trend of sorting. We will present the results of our analysis and compare them with selected polygon sites on Mars.

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.

Oxia Planum (OP), located at the transition between the ancient terrain of Arabia Terra and the low lying basin of Chryse Planitia, will be the landing site for the ESA-Roscosmos ExoMars Programme’s 2022 mission [1]. The descent module and landing platform, Kazachock, will transport the Rosalind Franklin Rover to search for signs of past and present life on Mars, and investigate the geochemical environment in the shallow subsurface over a 211-sol nominal mission.OP forms a shallow basin, open to the north, characterized by clay-bearing bedrock, and episodic geological activity spans from the ~mid-Noachian to ~early Amazonian in age [2,3,4]. Building a thorough understanding of Oxia Planum prior to operations will provide testable hypotheses that facilitate interpretation of results, and hence provide an effective approach to address the mission’s science objectives. To this end, we have run a detailed group mapping campaign at HiRISE-scale using the Multi-Mission Geographic Information System (MMGIS) [5], co-registered HRSC [6], CaSSIS and HiRISE mosaics [7], and 116 1km2 quads covering the 1-sigma landing ellipse envelope. Complementary CTX-scale mapping covers the wider area around the landing site and is described elsewhere [8].Throughout 2020, 84 mapping volunteers associated with the mission’s Rover Science Operations Working Group followed a pre-formulated programme of training, familiarisation and mapping. With the mapping phase complete, a small sub-team are focused on map reconciliation phase, comprising data cleaning and science decision making. The process will culminate in map finalisation and submission for publication, and use in activities to plan rover science activities.This campaign yields important advances for overall science readiness of the ExoMars 2022 mission:Team experience working, communicating and learning together, valuable for operations. Building team knowledge of the landing site, and the main scientific interpretations. Curated datasets and software available for team use in ongoing planning. High-resolution map data representing our geologic understanding of Oxia Planum. This is an input to ongoing RSOWG work to construct the mission strategic plan, which provides science traceability from mission objectives to rover activities.Acknowledgments: We thank Fred Calef and Tariq Soliman at JPL for their support regarding MMGIS.References: [1] Vago, J. L. et al., (2017) Astrobiology 17 (6–7), 471–510. [2] Carter, J. et al., (2013) J. Geophys. Res. 118 (4), 831–858. [3] Quantin-Nataf, C. et al., (2021) Astrobiol. 21 (3), doi:10.1089/ast.2019.2191. [4] Fawdon P. et al., (2019) LPSC50 #2132. [5] Calef, F. J. et al., (2019) in 4th Planet. Data Work., Vol. 2151. [6] Gwinner, K. et al., (2016) Planet. Space Sci. 126, 93–138. [7] Volat, M. et al., (2020), EPSC, #564. [8] Hauber, E. et al. (2021), LPSC52.

The ExoMars mission will deploy a stationary surface platform and a rover in Oxia Planum (OP), a region at the transition between the heavily cratered highlands of Mars and the ancient and filled impact basin, Chryse Planitia. While the fundamental geologic characteristics of the area have been investigated during the landing site selection process, detailed geologic or morpho-stratigraphic mapping is still missing. To fill this knowledge gap, two complementary mapping approaches were initiated by the ExoMars RSOWG: (1) Local HiRISE-scale mapping of the landing ellipse(s) area (reported elsewhere: Sefton-Nash et al., LPSC 2020). (2) Regional mapping at ~CTX-scale [this study] will provide a more synoptic view of the wider landing site within OP, enabling the contextualization of the units within the stratigraphy of western Arabia Terra and Chryse Planitia, and a comparison to other sites with similar key geologic and physiographic characteristics. It is also expected that this map will serve as a geologic reference throughout the mission and subsequent data analysis. The study area is located between 16.5°N and 19.5°N, and 334°E to 338°E. The data sets used for mapping include HRSC, THEMIS IR (day and night), CTX, and CaSSIS. Mapping scale in a GIS environment is 1:100,000, which will result in a final printable map at a scale of 1:1M. Mapping started in mid-October 2019. Overall, the identified map units are very similar to those described by Quantin et al. (Astrobiology, submitted): The spatially most widespread units are the phyllosilicate-bearing unit that is the prime ExoMars target (with distinctly enhanced THEMIS nighttime temperatures when compared to its surroundings), a dark resistant unit of possibly volcanic or sedimentary origin, and a mantling unit that was likely emplaced by eolian processes. Multiple channels of various morphology and degradation state as well as sedimentary fan-shaped deposits (with low nighttime temperatures) imply a diverse and possibly long-lived history of surface runoff, perhaps accompanied or replaced by groundwater processes such as sapping. Inverted landforms (channels, impact craters) are the result of intense erosion. Additional mapped features include tectonic structures such as wrinkle ridges and lobate scarps (delineating a basin-like depression in the central mapping area), remnant erosional buttes in the northwestern portion of the mapping area (i.e. towards Chryse Planitia), craters and their ejecta blankets, and fields of eolian bedforms and secondary craters. At the time of writing, the mapping is incomplete (partly cecause of the impact of the covid-19 crisis on the coordination of the joint mapping), and only initial and limited conclusions can be drawn. Overall, the mapping confirms previous geologic analyses. However, some features (e.g., contractional structures, channels, possible sapping landforms) need further attention as the may provide important constraints on the tectonic and aqueous evolution of the ExoMars landing area. A comparison to a distant, but geologically very similar site in Xanthe Terra, southeast of the Hypanis fan-shaped deposits, may enable testing of hypotheses raised by the geologic mapping of Oxia Planum.

Antoniadi basin is a 330 km diameter Noachian basin localized in the East of Arabia Terra that contains a network of ridges with a tree-like organization. Branched ridges, such as these can form by a variety of processes including the inversion of fluvial deposits, thus potentially highlighting aqueous processes of interest for understanding Mars’ climate evolution. Here, we test this hypothesis by analyzing in details data from Colour and Stereo Surface Imaging System (CaSSIS), High Resolution Imaging Science Experiment (HiRISE) and High Resolution Stereo Camera (HRSC).Branched ridges are up to 10 km long and from 10 to 200 m wide without obvious organization in width. The branched ridges texture is rubbly with the occurrence of blocks up to ~1 m in size and a complete lack of layering. A HiRISE elevation model shows the local slope is of 0.2° toward South, and thus contrary to the apparent network organization (assuming tributary flows). There is no indication of exhumation of these ridges from layers below the current plains surface. Our observations are not consistent with the interpretation of digitate landforms such as inverted channels: (i) The rubbly texture lacking any layering at meter scale is distinct from inverted channels as observed elsewhere on Mars. (ii) Heads of presumed inverted channels display a lobate shape unlike river springs. (iii) There is no increase in width from small branches toward North as expected for channels with increasing discharge rates downstream. (iv) The slope toward South is contrary to the inferred flow direction to the North. The detailed analysis of these branched ridges shows many characteristics difficult to reconcile with inverted channels formed by fluvial channels flowing northward. Subglacial drainages are known to locally flow against topography, but they are rarely dendritic. Assuming that deposition occurred along the current slope, thus from North to South, the organization of the network requires a control by distributary channels rather than tributary ones. Distributary channels are possible for fluvial flows, but generally limited to braiding regimes or deltaic deposits, of which no further evidence is observed here. The lobate digitate shapes of the degree 1 branches are actually more in line with deposits of viscous flows, thus as terminal branches. Such an interpretation is consistent with lava or mudflows that formed along the current topography. The next step in this study will be to determine more precisely the rheology of these unusual flows.Acknowledgments: French authors are supported by the CNES. The authors wish to thank the spacecraft and instrument engineering teams. CaSSIS is a project of the University of Bern and funded through the Swiss Space Office via ESA’s PRODEX. The instrument hardware development was also supported by the Italian Space Agency (ASI) (agreement no. I/018/12/0), INAF/Astronomical Observatory of Padova, and the Space Research Center (CBK) in Warsaw. Support from SGF (Budapest), the Univ. of Arizona (Lunar and Planet. Lab.) and NASA are gratefully acknowledged.

The Danakil depression in Ethiopia, at the end of the southern Red Sea, has been the locus of volcanic crises in 2004-10, with emplacement of 15 dykes: one, non-emergent, in Lake Asale next to Blac...

We present the geography of Oxia Planum, the landing site for the ExoMars 2022 mission. This map provides the planetary science community with a framework to understand this, until recently, unexplored area. The map comprises (1) a mosaic of the panchromatic Context Camera (CTX) Digital Elevation Models (DEM) and Ortho Rectified Images (ORI) controlled to the High Resolution Stereo Camera (HRSC) multiorbit Digital Elevation Models (DEM) and (2) a mosaic of Colour and Stereo Surface Imaging System (CaSSIS) synthetic colour data products, registered to the CTX ORI mosaic. We define a grid of exploration quadrangles (quads) and an informal group of geographic regions to describe Oxia Planum. These regions bridge the scale gap between features observed on large areas (���100s km2) and the local geography (10s km2) relevant to the Rosalind Franklin rover���s operations in Oxia Planum.

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, 797–8022. 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.