Oxia Planum Research Articles

Targeting Shallow Subsurface Sampling for Mars at Oxia Planum Using Fluvial Erosion–Deposition Modeling

A model-based surface fluvial erosion and deposition approach was adapted to Martian conditions to forecast the potential locations for shallow subsurface sampling by the Rosalind Franklin ExoMars rover at Oxia Planum. While remote and on-site images show only the surface visible features, former fluvial-related accumulation sites might be hidden. During the fluvial activity, most accumulation-related areas are interesting with regard to clay-like sediments, which could adsorb organics effectively—such sites could be identified by modeling. By applying the SIMWE fluvial erosion/deposition model, substantial variability in accumulation and deposition-dominated areas with their specific pattern and spatial distribution could be outlined, indicating that sophisticated targeting of future sampling could use such a model-based approach. At the main valley-like feature, former water flow tracks were identified, as well as deposition-dominated locations, which are the best targets for shallow subsurface sampling. Joint evaluation of safety aspects like slope angle and loose sand dunes with scientific aspects provide the best sampling locations. Such model-based targeting is important as by using only orbital images, these locations could not be identified.

Clay mineralogy in west Chryse Planitia, Mars: Comparison with present and future landing sites

On Mars, the well-known crustal dichotomy marks the boundary between the old southern highlands and the younger northern lowlands. Among these lowlands, Chryse Planitia resembles a quasi-circular basin surrounded by several highlands, and blends into Acidalia Planitia, another flat lowland located farther north. The transition area between these highlands and the Chryse basin is often designated as “circum-Chryse Planitia”, and is the terminus for many outflow channels. Infrared datasets display several sites therein with extensive clay-bearing outcrops, further testifying for aqueous activity on early Mars – notably around Mawrth Vallis, Oxia Planum and Xanthe Terra. In this study, we investigate clay-bearing outcrops identified along the western margins of circum-Chryse basin, often overlooked in the Martian literature. We also compare them with outcrops found in other regions along the crustal dichotomy and relevant in the Martian literature, such as Oxia Planum, Mawrth Vallis and Nili Fossae. Investigating such deposits is crucial for astrobiological perspectives, as they are appealing targets to search for organic compounds possibly stored throughout the rocks and soils. Fe,Mg-rich clays generally result from the interaction of liquid water with rocks under low temperatures, moderate pH levels and neutral to reducing conditions, factors favorable for life. Here, the clay minerals detected in west Chryse Planitia are consistent with either ferrosaponites or vermiculites associated with hydrobiotite, as recently inferred in Oxia Planum and north Xanthe Terra. Diverse alteration pathways might be involved based on either of these clay species. The clay-bearing rocks crop out in isolated hills in Lunae Planum, and along inverted channels and small craters in Tempe Terra. Further geologic investigations in circum-Chryse Planitia should certainly provide new clues on their origin and weathering conditions, while supporting the upcoming ExoMars rover mission and other future explorations.

The high-resolution map of Oxia Planum, Mars; the landing site of the ExoMars Rosalind Franklin rover mission

ABSTRACT This 1:30,000 scale geological map describes Oxia Planum, Mars, the landing site for the ExoMars Rosalind Franklin rover mission. The map represents our current understanding of bedrock units and their relationships prior to Rosalind Franklin’s exploration of this location. The map details 15 bedrock units organised into 6 groups and 7 textural and surficial units. The bedrock units were identified using visible and near-infrared remote sensing datasets. The objectives of this map are (i) to identify where the most astrobiologically relevant rocks are likely to be found, (ii) to show where hypotheses about their geological context (within Oxia Planum and in the wider geological history of Mars) can be tested, (iii) to inform both the long-term (hundreds of metres to ∼1 km) and the short-term (tens of metres) activity planning for rover exploration, and (iv) to allow the samples analysed by the rover to be interpreted within their regional geological context.

Periodic Bedrock Ridges at Oxia Planum and Chryse Planitia, Mars: Evidence for widespread aeolian erosion of an ancient surface by regional paleowinds

Periodic Bedrock Ridges (PBRs) are repeating, symmetrical, wind-transverse, bedrock-abraded linear ridges that occur on Mars as parallel sets. Here, we extend our previous survey of PBRs at Oxia Planum – the landing site of ESA's ExoMars Rosalind Franklin rover – to include three additional sites along the margins of the circum-Chryse basin to understand patterns in PBR orientation and occurrence. We analyzed PBR crestline orientation at each study site and found them to be consistent across this large region, but their orientations do not align with global circulation model winds, suggesting contemporary winds are not responsible for PBR development. Furthermore, we used observations of landscape-level stratigraphic relationships at Oxia Planum to constrain the formation age of PBRs to be late Noachian to early Amazonian. Their consistent orientations and age suggest that the Chryse-margin PBRs formed concurrently and represent modification of an ancient palaeosurface. In addition, we find a tendency for PBRs to preferentially occur in regions where Fe/Mg-rich phyllosilicate minerals were detected in hyperspectral remote sensing data. We conclude that regional scale aeolian processes formed the circum-Chryse PBRs, and that exposed bedrock with Fe/Mg-rich phyllosilicate detections were either more susceptible to PBR formation, or better preserve PBRs than other regional lithologies.

Evaluation of the interference of Tenax®TA adsorbent with dimethylformamide dimethyl acetal reagent for gas chromatography-Dragonfly mass spectrometry and future gas chromatography-mass spectrometry in situ analysis

Among future space missions, national aeronautics and space administration (NASA) selected two of them to analyze the diversity in organic content within Martian and Titan soil samples using a gas chromatograph – mass spectrometer (GC–MS) instrument. The Dragonfly space mission is planned to be launched in 2027 to Titan's surface and explore the Shangri-La surface region for years. One of the main goals of this mission is to understand the past and actual abundant prebiotic chemistry on Titan, which is not well characterized yet. The ExoMars space mission is planned to be launched in 2028 to Mars’ surface and explore the Oxia Planum and Mawrth Vallis region for years. The main objectives focus on the exploration of the subsurface soil samples, potentially richer in organics, that might be relevant for the search of past life traces on Mars where irradiation does not impact the matrices and organics. One recently used sample pre-treatment for gas chromatography – mass spectrometry analysis is planned on both space missions to detect refractory organic molecules of interest for astrobiology. This pre-treatment is called derivatization and uses a chemical reagent – called dimethylformamide dimethyl acetal (DMF-DMA) – to sublimate organic compounds keeping them safe from thermal degradation and conserving the chirality of the molecules extracted from Titan or Mars’ matrices. Indeed, the detection of building blocks of life or enantiomeric excess of some organics (e.g. amino acids) after DMF-DMA pre-treatment and GC–MS analyses would be both bioindicators. The main results highlighted by our work on DMF-DMA and Tenax®TA interaction and efficiency to detect organic compounds at ppb levels in a fast and single preparation are first that Tenax®TA did not show the onset of degradation until after 150 experiments – a 120 h at 300 °C experiment – which greatly exceeds the experimental lifetimes for the DraMS and GC-space in situ investigations. Tenax®TA polymer and DMF-DMA produce many by-products (about 70 and 46, respectively, depending on the activation temperature). Further, the interaction between the two leads to the production of 22 additional by-products from DMF-DMA degradation, but these listed by-products do not prevent the detection of trace-level organic molecules after their efficient derivatization and volatilization by DMF-DMA in the oven ahead the GC–MS trap and column.

Mapping the mineralogy in the Oxia Planum and Mawrth Vallis ExoMars landing sites – implications for aqueous alteration and paleoenvironmental evolution

Mineralogical studies constitute one of the main tools to investigate geological processes on Mars. Here, the mineralogy of the ExoMars landing sites Oxia Planum and Mawrth Vallis is analyzed based on multispectral datasets of the CRISM Compact Reconnaissance Imaging Spectrometer for Mars of Mars Reconnaissance Orbiter, TES Thermal Emission Spectrometer of Mars Global Surveyor and OMEGA Visible and Infrared Mineralogical Mapping Spectrometer of Mars Express are integrated and interpreted. Primary and secondary minerals of carbonates, oxides, silicates and sulphates mineral groups are characterized, with most minerals produced by aqueous alteration, with 35 mineral species identified, amongst which phyllosilicates are the dominant group. Coexisting mineral types point to distinct hydrothermal and alteration stages. Our investigation supports that water must have been present on early Mars on superficial and endogenous processes, causing direct precipitation and transformations of secondary minerals, with some not usually formed simultaneously. Hence, it is likely that species may have arisen at different times, due to changes of Martian climate. Some minerals may have formed in the subsurface. The Martian palaeoenvironments might include subaerial, underwater, and shallow subsurface hydrothermal systems, cold springs, alkaline lakes, sabkhas, and playas. Our results contribute to our understanding of the planned landing sites to prepare for what the ExoMars rover mission may encounter, highlighting the impact that water may have had on the mineral genesis, alteration processes and their astrobiological potential.

Combination of MRO SHARAD and deep-learning-based DTM to search for subsurface features in Oxia Planum, Mars

Context. Oxia Planum is a mid-latitude region on Mars that attracts a great amount of interest worldwide. An orbiting radar provides an effective way to probe the Martian subsurface and detect buried layers or geomorphological features. The Shallow radar orbital radar system on board the NASA Mars reconnaissance orbiter transmits pulsed signals towards the nadir and receives returned echoes from dielectric boundaries. However, radar clutter can be induced by a higher topography of the off-nadir region than that at the nadir, which is then manifested as subsurface reflectors in the radar image. Aims. This study combines radar observations, terrain models, and surface images to investigate the subsurface features of the ExoMars landing site in Oxia Planum. Methods. Possible subsurface features are observed in radargrams. Radar clutter is simulated using the terrain models, and these are then compared to radar observations to exclude clutter and identify possible subsurface return echoes. Finally, the dielectric constant is estimated with measurements in both radargrams and surface imagery. Results. The resolution and quality of the terrain models greatly influence the clutter simulations. Higher resolution can produce finer cluttergrams, which assists in identifying possible subsurface features. One possible subsurface layering sequence is identified in one radargram. Conclusions. A combination of radar observations, terrain models, and surface images reveals the dielectric constant of the surface deposit in Oxia Planum to be 4.9–8.8, indicating that the surface-covering material is made up of clay-bearing units in this region.

Raman analyses of Al and Fe/Mg‐rich clays: Challenges and possibilities for planetary missions

AbstractClays are fine‐grained rocks that form in the presence of water. Their occurrence typically depends on a combination of geological setting and geochemical conditions. The widespread and diverse clay deposits identified on Mars indicate that the planet experienced multiple episodes of water activity, especially in the early period. The characterisation of Martian clays will reveal key information on geological history, the past climatic conditions and the overall habitability of Mars. Among the analytical techniques typically utilised for such mineralogical characterisation, Raman spectroscopy will be applied for the first time during several robotic exploration missions of Mars in the 2020s. In this study, various clay‐rich samples from Westerwald, Germany were analysed to help inform mission operations and interpretation of data returned by the miniaturised Raman instruments. The samples, as verified by infrared spectroscopy, constitute kaolinites, Al‐rich smectites and Fe/Mg‐rich smectites, which are relevant to the clay mineralogy expected at Martian landing sites (Jezero crater and Oxia Planum). Despite the levels of fluorescence experienced during Raman measurements of the clay‐rich powder samples when using a 532 nm laser, the Raman signatures of phyllosilicates were identified for kaolinite and several different types of smectite (e.g. montmorillonite, nontronite, saponite) in these complex dispersions. Following these measurements, identification of various accessory minerals disseminated in the clay matrix was also achieved using the micro‐Raman system. Finally, a brief discussion concerning the analytical strategies for successful clay analyses using miniaturised Raman instruments is provided.

Thermal Modeling of Oxia Planum: Thermophysical Characterization of the Dark Resistant Unit (DRU) in the Germania Lacus

The aim of this work is to characterize, from a thermophysical perspective, the dark resistant unit (DRU) characterizing Germania Lacus in the Oxia Planum Region, providing new insights to constrain the nature of the materials which compose this unit. We investigated the temperature distribution of the DRU by adopting common values of the thermophysical parameters of the basalt and by exploring several values of porosity. As an additional case, we also explore a composition made of pebbles. The numerical model developed here represents a follow-up of the work recently published by Formisano et al. 2021, and it takes into account a large-scale topography of the site and assumes a diurnal temperature profile for the atmosphere rather than a constant value (unlike Formisano et al. 2021). Comparisons with Mars Pathfinder and Viking data as well as numerical models are also reported. The methodology described here could be useful to characterize as well other sites on Mars’ surface with available small-scale topographic data.

SOPHIA: A mineralogical simulant for phyllosilicate terrains at the Rosalind Franklin landing site, Oxia Planum, Mars

The phyllosilicate-bearing martian plain, Oxia Planum, is the proposed landing site for the Rosalind Franklin rover mission, scheduled to launch in 2028. Rosalind Franklin which will search for signs of past or present life on Mars. Terrestrial analogue sites and simulants can be used to test instruments analogous to those on Rosalind Franklin, however no simulant for Oxia Planum currently exists. In anticipation of this mission, a simulant - SOPHIA (Simulant for Oxia Planum: Hydrated, Igneous, and Amorphous) - representative of the local mineralogy at Oxia Planum has been developed for biosignature and mineralogy experiments, which will assist in interpreting data returned by the rover. The simulant is derived from orbital observations of Oxia Planum and its catchment area. As no in situ data is available for Oxia Planum, mineralogy from other comparable sites on Mars was used to design the simulant including orbital data from Arabia Terra and Mawrth Vallis and in situ data collected from Gale crater. The mineralogy, chemistry and physical properties of the simulant were characterised using standard laboratory techniques (SEM-EDS, XRF, XRD).Techniques analogous to rover instruments (Raman spectroscopy, Near-IR spectroscopy analogous to the Raman laser spectrometer and ISEM and MicrOmega instruments) were also used. The simulant is rich in Fe/Mg phyllosilicates with additional primary igneous and other alteration minerals and is an appropriate spectral and mineralogical analogue for Oxia Planum.

Spectral Analysis of Clay-bearing Outcrops in Northern Xanthe Terra, Mars: Comparison with Oxia Planum, the Landing Site for the ExoMars Rover Mission

Clay minerals detected on Mars are valuable targets to seek traces of life on the planet, where biosignatures might be preserved. Here, we report an in-depth spectral analysis of clay-rich outcrops identified in northern Xanthe Terra (300°–320° E, 10°–20° N). We focused particularly on the absorptions centered in the 1.0–2.6 μm spectral range to (1) constrain the mineralogy of the clay outcrops, (2) map their strength and distribution throughout the region, and thus (3) develop a better understanding of the geologic environment at circum–Chryse Planitia. We then compared the infrared signatures in Xanthe Terra and Oxia Planum. Like in Oxia Planum, Xanthe’s clays are consistent with either Fe-bearing saponites or vermiculites. However, the spectral signatures in Xanthe are weaker relative to Oxia Planum, perhaps due to significant dust cover in the region. Besides the spectral signatures, northern Xanthe Terra displays several morphological features similar to Oxia Planum, indicating long-lasting aqueous activity (fluvial channels and fan deltas). Clays found at the fan deltas could be detrital (fluvial transport) or authigenic (lacustrine or deltaic sedimentation), while the origin of clays seen elsewhere on the surrounding plateaus remains undetermined. Oxia Planum has been selected as the landing site for ESA’s ExoMars “Rosalind Franklin” rover, where its instruments will search for signs of life and constrain the nature and origin of the clays. This exploration will indubitably provide new clues on the clays found in the circum-Chryse basin.

Investigating the Oxia Planum subsurface with the ExoMars rover and drill

To search for possible signs of life on Mars (past and present), it is necessary to investigate the subsurface. The thin martian atmosphere allows UV and ionizing radiation to damage potential chemical biosignatures at or below the surface. This effect, however, decreases with depth. Thus, organic molecules and potential biomarkers can be better preserved in the subsurface. The ExoMars Rosalind Franklin rover is equipped with a drill able to collect samples from a maximum depth of 2 m for the first time on Mars. In this study we describe how we will use the drill telemetry information in combination with the rover subsurface instruments’ data to better assess the stratification, compositional variations and connection with surface morphology. Understanding the subsurface sample environment is crucial to inform the investigations to be conducted on samples within the rover’s Analytical Laboratory Drawer (ALD). Moreover, the synergic use of drill telemetry and the rover subsurface instruments’ outcomes will inform planning of drilling activities and improve the selection of drilling sites.

Ancient alluvial plains at Oxia Planum, Mars

The geologic origin of the ancient, phyllosilicate-bearing bedrock at Oxia Planum, Mars, the ExoMars rover landing site, is unknown. The phyllosilicates record ancient aqueous processes, but the processes that formed the host bedrock remain elusive. Here, we use high-resolution orbital and topographic datasets from the HiRISE, CaSSIS and CTX instruments to investigate and characterize fluvial sinuous ridges (FSRs), found across the Oxia Planum region. The FSRs form segments up to 70 km long, are 20-600 m wide, and up to 9 m in height, with sub-horizontal layering common in ridge margins. Some FSRs comprise multi-story ridge systems; many are embedded within the phyllosilicate-bearing bedrock. We interpret the FSRs at Oxia Planum as deposits of ancient, episodically active, alluvial river systems (channel-belt and overbank deposits). Thus, at least some of the phyllosilicate-bearing bedrock was formed by ancient alluvial rivers, active across the wider region, though we do not exclude other processes from contributing to its formation as well. The presence of alluvial floodplains at Oxia Planum increases the chances of the ExoMars rover detecting signs of ancient life. Future exploration by the ExoMars rover can verify the alluvial interpretation and provides an opportunity to investigate some of the oldest river deposits in the Solar System.

Mounds in Oxia Planum: The Burial and Exhumation of the ExoMars Rover Landing Site

AbstractOxia Planum, the planned landing site of the ExoMars “Rosalind Franklin” rover, is a low relief clay‐bearing plain, of which approximately 1% is covered by 396 upstanding isolated landforms (“mounds”). The mounds are continuous with a circum‐Chryse mound population representing the remnants of a regionally significant Noachian‐aged deposit. This detailed study suggests that the Oxia Planum mounds are also erosional remnants of this deposit, with little evidence to suggest they are constructional landforms such as sedimentary volcanoes. We calculate that up to 130 m of mound‐forming material has been removed from the landing site through erosion. The mound‐forming layer lies unconformably on the clay‐bearing plains with the upper surface severely truncated by significant erosion resulting in the topography we see today. The mounds themselves comprise at least three members, distinct in color and texture, separated stratigraphically by further unconformities. Calculated minimum erosion/deposition rates of the removed mound material are comparable to previous Noachian estimates, suggesting a more erosive (and probably therefore warmer and/or wetter) environment than today. The clay‐bearing materials which remain buried directly under the mounds have been continually protected from the Martian environment since the Noachian, and are likely to represent some of the most pristine clay‐rich materials in the landing site. By inference, the plains directly adjacent to the mounds are most likely to have been exposed for less time than areas further from the mounds. These are therefore amongst the most likely locations where Rosalind Franklin could sample recently exposed materials and hence detect biosignatures.

Digital elevation model workflow improvements for the MarsSI platform and resulting orthorectified mosaic of Oxia Planum, the landing site of the ExoMars 2022 rover

In this publication, we explore the options to improve the quality and speed of DEM generation procedures from stereo-photogrammetry pipeline of the MarsSI online service. We study available algorithms, options and workflows. Taking inspiration on earth-based work, we propose a new workflow relying on the semi-global matching algorithms and a two steps approach with the result of artifacts/noise reduction in the products, and improved co-registration of the outputs. We use this new workflow in the production of mosaic of ground models and orthorectified images. We illustrate the pipeline with the example of the othorectified HiRISE images mosaic that has been used in the framework of Exomars project to perform a join mapping of Oxia Planum, the landing site of Exomars rover. • Describes the new DEM workflow of the MarsSI platform. • Noise and artifact levels were improved. • Alignment to MOLA was improved, enough to consider automated CTX mosaics. • ESA ExoMars 2022 landing site covering DEM and orthorectified image datasets.

Investigation of Absorption Bands around 3.3 μm in CRISM Data

Absorptions in the range 3.1 μm to 3.6 μm are under the spotlight in the context of planetary research, because hydrocarbon molecules show absorption bands in this range. Consequently, even knowing that the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) was designed for the detection of mineralogical features on Mars’s surface, we exploited CRISM data in the range 3.2 μm to 3.4 μm to search for potential hydrocarbon compounds. To date, methane has been the only hydrocarbon detected on Mars. Therefore, we began our investigation into CRISM data in locations in which methane had been detected and where it could form due to the mineralogy of the specific site. The datasets chosen for this study included observation sites in the Oxia Planum, the Gale Crater, and Nili Fossae areas. We mapped the modified Gaussian model (MGM) to fit the CRISM data in order to extract the band parameters of the absorptions in the 3.3 μm spectral region. As a result, we found clusters of pixels with spectra that exhibited band centers between approximately 3.28 and 3.35 μm. The hydrocarbons showing absorptions in this range included polycyclic aromatic compounds as well as methane, ethane, and aliphatic compounds. We speculated that some absorptions of approximately 3.3 μm could be related to methane, so we calculated a theoretical lower limit of detection for each observation in the selected CRISM datasets. This was performed by simulating the CRISM spectra for the different sites, with diverse concentrations of CH4, using NASA’s Planetary Spectrum Generator online tool. These simulations established the relationship between the concentration and methane band depths, as detected by the CRISM. Methane band depths exceeding the thresholds varied from one observation to another, in the range of 0.0136 to 0.0237, which corresponded to a range of theoretically lower limits of concentration between 180 and 600 ppbv. Although we could not confirm or deny the occurrences of methane seepages or hydrocarbons in the investigated datasets, we demonstrated a possible method for searching for hydrocarbons in other CRISM data and for assessing a confidence limit in the detection of the methane band in CRISM data.

An Adversarial Generative Network Designed for High-Resolution Monocular Depth Estimation from 2D HiRISE Images of Mars

In computer vision, stereoscopy allows the three-dimensional reconstruction of a scene using two 2D images taken from two slightly different points of view, to extract spatial information on the depth of the scene in the form of a map of disparities. In stereophotogrammetry, the disparity map is essential in extracting the digital terrain model (DTM) and thus obtaining a 3D spatial mapping, which is necessary for a better analysis of planetary surfaces. However, the entire reconstruction process performed with the stereo-matching algorithm can be time consuming and can generate many artifacts. Coupled with the lack of adequate stereo coverage, it can pose a significant obstacle to 3D planetary mapping. Recently, many deep learning architectures have been proposed for monocular depth estimation, which aspires to predict the third dimension given a single 2D image, with considerable advantages thanks to the simplification of the reconstruction problem, leading to a significant increase in interest in deep models for the generation of super-resolution images and DTM estimation. In this paper, we combine these last two concepts into a single end-to-end model and introduce a new generative adversarial network solution that estimates the DTM at 4× resolution from a single monocular image, called SRDiNet (super-resolution depth image network). Furthermore, we introduce a sub-network able to apply a refinement using interpolated input images to better enhance the fine details of the final product, and we demonstrate the effectiveness of its benefits through three different versions of the proposal: SRDiNet with GAN approach, SRDiNet without adversarial network, and SRDiNet without the refinement learned network plus GAN approach. The results of Oxia Planum (the landing site of the European Space Agency’s Rosalind Franklin ExoMars rover 2023) are reported, applying the best model along all Oxia Planum tiles and releasing a 3D product enhanced by 4×.

Oxia Planum, Mars, classified using the NOAH-H deep-learning terrain classification system

ABSTRACT We present a map of Oxia Planum, Mars, the landing site for the ExoMars Rover. This shows surface texture and aeolian bedform distribution, classified using a deep learning (DL) system. A hierarchical classification scheme was developed, categorising the surface textures observed at the site. This was then used to train a DL network, the ‘Novelty or Anomaly Hunter – HiRISE’ (NOAH-H). The DL applied the classification scheme across a wider area than could have been mapped manually. The result showed strong agreement with human-mapped areas reserved for validation. The resulting product is presented in two ways, representing the two principle levels of the classification scheme. ‘Descriptive classes’ are purely textural in nature, making them compatible with a machine learning approach. These are then combined into ‘interpretive groups’, broader thematic classes, which provide an interpretation of the landscape. This step allows for a more intuitive analysis of the results by human users.

Jezero crater, Mars: application of the deep learning NOAH-H terrain classification system

ABSTRACT We applied a deep learning terrain classification system, the ‘Novelty or Anomaly Hunter – HiRISE’ (NOAH-H), originally developed for the ExoMars landing sites in Oxia Planum and Mawrth Vallis, to the Mars 2020 Perseverance rover landing site in Jezero crater. NOAH-H successfully classified the terrain in four HiRISE images of Jezero even though the landforms in the Jezero study area were slightly different from those in the training dataset. We mosaicked the NOAH-H classified rasters and compared them with a manually generated photogeological map, and with Perseverance rover and Ingenuity helicopter images. We find that grouped NOAH-H classes correspond well with the humanmade map and that individual classes are corroborated by the available ground-truth images. We conclude that our NOAH-H products can be refined for feeding into traversability analysis of the ExoMars Rosalind Franklin rover landing site at Oxia Planum and that they can also be used to aid the photogeological mapping process.

Constraining the spectral behavior of the clay-bearing outcrops in Oxia Planum, the landing site for ExoMars “Rosalind Franklin” rover

Oxia Planum (335.5°E, 18.2°N) is selected as the landing site for ExoMars rover mission (ESA/Roscosmos), where the “Rosalind Franklin” rover is scheduled to land in the decade. The region reveals several extensive clay-bearing outcrops recently exhumed, where biosignatures are possibly preserved. The objectives of the mission are to search for organics and investigate traces of past or extant life on Mars. Preliminary surveys of these outcrops show infrared absorptions typical of Fe,Mg-rich clays in the 1.0–2.6 μm range (1.4, 1.9, 2.3 and 2.4 μm) and an additional absorption at 2.5 μm implying a possible mixture with other mineral phase(s). Here we provide a detailed description of absorptions of the clay-rich materials detected in Oxia Planum, and map their strength and distribution throughout the region using hyperspectral data gathered by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) onboard NASA's Mars Reconnaissance Orbiter (MRO) mission. Our analysis suggests that the Fe,Mg-rich clays identified in Oxia Planum mainly correspond to either Fe-bearing saponites (e.g., Griffithite) or vermiculite ores (i.e., vermiculite associated with a hydrobiotite component). Conversely, large clay-bearing outcrops found in the catchment area (337°E, 16.7°N) are rather consistent with nontronites in association with Al-rich clays and kaolins, in agreement with previous identification in the Mawrth Vallis – west Arabia Terra province. Presence of Fe,Ca-rich carbonates is recognized with the absorption near 2.53 μm and the observation of a broad peak in the 3–4 μm range, supporting their co-occurrence with the clays in Oxia Planum and its catchment area. Although we favor a pedogenesis alteration for the clays found in the catchment area, the origin of those studied in Oxia's basin remains enigmatic, where alternative scenarios could be either lacustrine and deltaic sedimentation, groundwater circulation, or even hydrothermal fluid circulation. Future in-situ measurements by “Rosalind Franklin” rover will indubitably provide new insights on the mineralogical diversity seen in the region and their origins.