Monica Rasmussen

Rock fractures on planetary bodies provide critical insights into composition and geologic history. On Earth, fracture mapping is performed manually on-site or remotely through drone, aircraft, or orbital photography. On other planets, fracture mapping mainly relies on orbital data, with on-the-ground confirmation only possible in very limited areas. To date, a repeatable and clearly defined workflow for fracture mapping from orbital data has not been presented. Here, we present a workflow protocol for producing comparable and consistent fracture data using orbital imaging. We present a case study of Oxia Planum, Mars, the landing site for the European Space Agency's ExoMars Rosalind Franklin Rover mission. On Mars, the High Resolution Imaging Science Experiment (HiRISE) provides over 100,000 0.25-0.50 m/px orbital images, equivalent to very-high resolution orbital imagery of Earth. Existing fracture mapping products around Mars are not directly comparable due to the interpretive nature of fracture mapping and a bias which leads to characterizing the most clearly visible fractures. This study leverages field fracture mapping expertise to present an unbiased, reproducible approach, and provides recommendations for basic statistical assessment of fracture data. We found that fracture density is reproduced to ±5%, and minimum visual resolvability of fracture lengths is 0.5 cm on screen. Comparison of fracture data with bedrock characteristics confirms the general unit descriptions for the area, where visually bright, clay-rich rocks are more fractured than other units, with significantly higher numbers of fractures and sum fracture lengths (387% and 360%, respectively).

IntroductionOxia Planum (Fig. 1) is a region of Mars located on the margin between the old, heavily cratered highlands of Arabia Terra (Noachian-aged) and the younger, smoother lowlands of Chryse Planitia (Hesperian-aged). From orbit it shows several geomorphological records of past widespread water–rock interactions, including fractured, layered, clay-bearing deposits with high astrobiological potential [1, 2, 3]. For this reason, Oxia Planum has been selected as the landing site for the ESA Rosalind Franklin Mission (RFM). The main goal of the RFM is to search for past (and/or present) traces of life, particularly in the Martian shallow subsurface where material of astrobiological interest is better preserved. To achieve this, the RFM rover is equipped with a drill capable of collecting, for the first time for a mission on Mars, samples down to a depth of 2 meters, and with a suite of instruments designed to discriminate biosignatures in the samples, gathering supporting geological context information [4]. Figure 1: Oxia Planum, Mars with CTX basemap colored by elevation. The white ellipses represent the current landing ellipses, and the orange polygon in center represents the outline of the geologic map of the region [5], with the map’s cross-section added in orange. Note that two cubes selected for study overlap with the geologic map while one cube for study is towards the delta and outside the previously mapped area.Here, we focus on selected regions of interest (ROIs) within the Oxia Planum landing area (Fig. 2) to investigate how clay distribution relates to other geologic features. We incorporate an Oxia Planum survey of fractures mapped at 1:1250 scale in spaced windows (e.g., blue squares in Fig. 2) which provides the general fracture characteristics of multiple units. Within ROIs, we repeat this fracture mapping to connect the geomorphological and spectral analysis with bedrock fracture behavior to more fully characterize the rocks, and contribute to strategies for guiding the selection of drilling sites.Figure 2: CRISM spectral maps of the 2.3 micron band depth [3] where yellow tones represent high Fe,Mg-phyllosilicate signatures, with CTX basemap as background and the geologic cross-section [5] overlain in orange. The ROIs are shown and labeled in white. Dark blue squares represent areas where regional fracture analysis has been performed to aid in extending the geologic mapping to unmapped areas. Inset of ROI 10 shows the fractures which have been mapped (blue) on HiRISE imagery (shown), and exhibit a strong correlation with clay-rich areas. Data and MethodsROIs were chosen based on (1) mapped contacts between bedrock units [5], (2) stratigraphic exposures within mounds and/or crater walls, (3) association with the geologic cross-section [5], and/or (4) high likelihood of encountering phyllosilicates (Fe,Mg-rich clays), based on CRISM cube analysis [3]. The southernmost CRISM cube of interest, FRT09A16 (Fig. 1), is located near the delta containing sediments derived from the highlands, thus providing a key insight into the stratigraphic relationships and depositional modes of the units farther downslope. Within ROIs, we created meter-scale resolution digital terrain models (DTMs) using the NASA Ames Stereo Pipeline and HiRISE stereopairs, tied to MOLA elevations.Fracture mapping was performed on HiRISE images which were manually georeferenced to improve their correlation with CRISM data. Mapping at 1:2000 scale (minimum resolvable fracture size approximately 10m) provides comparable data to the fracture survey, providing a dataset that aids in expanding geologic units beyond the current bounds of the map [5]. Detailed mapping at 1:1000 scale, following [8], has sufficient detail to analyze fracture topology, improving unit characterization and providing insight into fracture formation mechanisms [e.g., 9].Preliminary results and Discussion Figure 3 compares the DTM created from HiRISE using the NASA Ames Stereo Pipeline [6] with the MADNET DTM [7] created through machine learning, both of which are based on HiRISE images. The example shows the subdued elevation changes of the MADNET DTM, where the elevation decrease from west to east is partially inherited within the crater rim elevations. The Ames Stereo Pipeline DTM shows a more accurate crater depth-to-width ratio of approximately 0.1, with the crater rim maintaining a realistic cross-sectional shape and the elevation change mostly impacting the surrounding landforms.Figure 3: Example DTM quality comparison at a crater near transect 9 (Fig. 2), with the MADNET DTM [7] shown in red and the DTM from Ames Stereo Pipeline [6] shown in purple (this work).Fracture mapping performed across the broader area shows that the phyllosilicate clays exhibit a higher number (fracture density) and sum length (fracture intensity) of fractures per area, relative to low-clay areas that are also mapped as bedrock units. Preliminary results suggest that this trend is consistent within the ROIs. In the southernmost ROIs which the geologic map does not cover, CTX brightness and CRISM clay signatures are used to identify the clay-rich bedrock groups. We then manually assign unit designations based on comparison with the stratigraphic relationships, fracture characteristics, and geomorphological behavior of the units in mapped regions, leveraging the fracture survey to inform unit extents.By combining multiple datasets (CTX, CRISM, HiRISE) with different scientific approaches (spectral, fracture, and geomorphological analysis) we provide further context for RFM. Although orbital data only provides information on the surface and limited subsurface exposures, using a combination of geologic approaches allows us to propose realistic subsurface scenarios, critical for mission success in drilling the near subsurface. Acknowledgements: This work is supported by the ASI-INAF Mars Exploration agreement 2023-3-HH 0 and the European Space...

Carbonates on Mars provide key evidence of past environmental conditions because they can form through alteration of ultramafic rocks by liquid water in a dense CO2–rich atmosphere. We searched for carbonates by examining the 2.3, 2.5, and 3.5 µm absorption bands in 540 CRISM near-infrared hyperspectral cubes. The detected carbonates are best described as Fe–Mg solid solutions within the siderite–magnesite series, likely formed under reducing conditions and preserved despite later acidic, oxidizing environments. We identify new carbonate-rich deposits associated with clay-bearing terrains, revealing a more widespread co-occurrence of carbonates and clays than previously recognized, partly because carbonates can be spectrally masked by clays. Their association suggests formation in neutral to mildly alkaline waters early in Mars’ history, implying prolonged aqueous alteration, sustained liquid water, and environments potentially favorable for microbial life. These findings expand the known distribution of carbonates and highlight promising targets for future biosignature exploration.

Studying the geomorphology of crater ejecta at Martian mid- to high-latitudes is essential for understanding how impact-generated flows and debris patterns indicate subsurface ice or water at the time of impact. By analyzing ejecta morphologies, such as rampart structures, lobate flows, and layered deposits, we can reconstruct the distribution and abundance of volatiles in the Martian subsurface. These morphological observations provide the basis for stratigraphic correlations and spectroscopic analyses, enabling more precise quantification of past and present water-ice concentrations in the upper crust. Our study focuses on a fresh crater (43.81N, 301.53E) located roughly 225km NE of Timoshenko crater, in Tempe Terra. By using Digital Terrain Models (DTMs) at different scales (CTX at 6m ppx and HiRISE at 0.3m ppx) we map the different ejecta blankets that comprise this crater and classify it based on their topography and shape. We created DTMs using the Ames Stereo Pipeline (ASP, [1]) and two stereopairs per instrument (CTX J14_050126_2236_XN_43N058W and P12_005807_2238_XI_43N058W, HiRISE ESP_059370_22401 and ESP_077029_2240), aligned to overlying MOLA data from PDS ([2]), and then projected within a GIS software (QGIS, v3.40.5), which helps in DTM manipulation, visualization, and topographic studies of the ejecta layers and their subsequent plotting, while using different data formats. From CTX imagery, we recognize 2 ejecta layers: one proximal to the crater (500m from crater rim), with a slope of 20˚ and smoother topography, which ends in a small (~10m) edge step; and a second more distal, showing a radial lobate pattern exuding from the crater, composed of rougher materials, with little to no slope (~3˚).Following [3]’s classification, we classify this as a type 2 (double ejecta facies) or type 3 (multiple facies) crater. This uncertainty is related to the resolution limits of CTX; it is difficult to determine whether the second ejecta layer is further subdivided into more layers, as the contacts become diffuse, and the more distal parts of it appear as isolated ejecta clusters, disconnected from the main facies, especially in the NW and SE margins. Our multi-scale morphological analysis of the crater will place it into context with its surroundings [4] and prepare for specific studies, such as the spectroscopic analysis of specific areas [5]. Using CTX DTMs as a basemap will provide a robust and smooth topography, which can be better interpreted and used for mapping; HiRISE will offer very high resolution, allowing a more robust identification of smaller features. The accurate development of DTMs at appropriate resolution is key and we will concentrate efforts on uncertainty analyses of these higher-level data products. We are applying these techniques into operational mission-driven scenarios like the Oxia Planum landing site of the ESA/ExoMars Rosalind Franklin Rover [5].This work is funded by the Italian Space Agency (ASI) [Grant ASI-INAF n. 2023–3–HH.0].References: [1] Beyer et al. (2018) ESS 5(9), 537-548; [2] Smith et al. (2001) JGR Journal of Geophysical Research: Planets 106.(E10); 2156-2202. [3] Mouginis-Mark (1979) JGR Solid Earth 84(B14), 8011-8022. [4] Rasmussen et al., (2025) GSA A&Ps 57(6), p. 4976. [5] Altieri et al. (2026), this conference.

The European Space Agency (ESA) Rosalind Franklin rover Mission (RFM) is expected to land at Oxia Planum, Mars in 2030. Orbital spectral data and imagery reveal layered, clay-rich sedimentary deposits, often overlain by or interbedded with a dark, more resistant rock rich in mafic minerals [e.g., 1, 2]. The 1:30k scale geologic map of the landing site [1] associates two geologic units to their VNIR color and fracture spacing; Apuzzo et al. [3] studied directional statistics of fractures in selected regions of interest. However, complete quantitative fracture metrics over the RFM landing area are not yet available. Since at least 35% of the landing site is covered by fractures [3], a comprehensive study of fractures, and the composition of their hosting bedrock, is critical for elucidating whether formation mechanism, alteration history, and/or mineralogy vary across the Oxia Planum site.Here, we present fracture density (number of fractures/m^2) and topological connectivity of fractures within an unbiased collection of 33 approximately 500x500 m square windows spaced along transects over the center of the predicted landing footprint of the RFM. Multiple windows overlap with Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral cubes for which Fe,Mg-clay abundance has been qualitatively estimated [2]. Fractures are mapped manually as linear segments in QGIS software, using visual interpretation of High Resolution Imaging Science Experiment (HiRISE) images (0.3 m/px) in the red spectral range. We map at 1:1250 scale resulting in a minimum resolvable fracture length of about five pixels, or 1.5 m. The NetworkGT QGIS software plugin [4] is used to extract node connectivity, fracture orientations, and fracture lengths.Topological analysis of node types and fracture-bounded polygon shapes is then leveraged to aid in interpreting (1) changes in fracture behavior across previously mapped unit boundaries, and (2) formation mechanisms of the fracture networks, following [5]. We also compare fracture mapping within and outside specific clay-rich areas of interest [2, 6] to determine if they have unique mechanical or formation characteristics. Preliminary analysisindicates that fracture density is often higher within more clay-rich areas, and that the majority of mapped fractures are “I-node”, meaning they terminate without connecting to another fracture. Where fractures do connect, three- and four-sided polygon shapes dominate. We compare these findings with previous topological network characterization [e.g., 5] to enhance our interpretation of the possible scenarios of formation and current unit composition at Oxia Planum, considering topological characteristics will better constrain our understanding of past aqueous activity. Our results will support the better selection of analog materials for terrestrial drill testing before mission launch, and help inform drill site selection when the rover reaches Mars’ surface.References: [1] Fawdon et al. (2024) Journal of Maps 20, 2302361. [2] Brossier et al. (2022) Icarus 386, 115114. [3] Apuzzo et al. (2025) PSS 267, 106169. [4] Nyberg et al. (2018) Geosphere 14(4) 10.1130/GES01595.1. [5] Silver et al. (2025) PNAS 22 (10) e2411738122. [6] Altieri et al. (2026), this conference.Acknowledgements: This work is funded by the Italian Space Agency (ASI) [Grant ASI-INAF n. 2023–3–HH.0].

Oxia Planum, the landing site of the Rosalind Franklin Mission (RFM), is located between the ancient highlands of Arabia Terra and the younger plains of Chryse Planitia [1]. The region preserves clear evidence of past water-rock interactions, particularly layered clay-rich deposits that are considered prime targets for astrobiological investigation [2, 3]. This study focuses on a selection of Regions of Interest (ROIs), areas with the highest concentrations of ferromagnesian clays as identified through remote sensing analyses. We derive local digital terrain models from stereo photogrammetry and quantify horizontal and vertical accuracy [4], a key requirement for interpreting water-related processes and stratigraphic relationships in the low-relief Oxia Planum. Our objective is to examine how clay distribution relates to other geologic elements, in particular fractures [5, 6], to better constrain their geologic interpretation and stratigraphic context [7], contributing to strategies for guiding the selection of drilling sites once the rover arrives on Mars. This work is funded by the Italian Space Agency (ASI) [Grant ASI-INAF n. 2023–3–HH.0]. References: [1] Quantin-Nataf et al. (2021) Astrobiology 21, 345–366. [2] Mandon et al. (2021) Astrobiology 21, 464–480. [3] Brossier et al. (2022) Icarus 386, 115114. [4] Trisic Ponce et al. (2026), this conference. [5] Apuzzo et al. (2025) PSS 267, 106169. [6] Rasmussen et al. (2026), this conference. [7] Fawdon et al. (2024) Journal of Maps 20, 2302361.

Rock fracturing regulates the topography, carbon cycle, geologic hazards, and infrastructure degradation of the Earth. Yet, there remains a paucity of constraints on long‐term fracturing behavior. Here we use field measurements of 2221 clasts across a range of environments and rock types to show that the number and total length of fractures in natural surface rocks increase rapidly within the first ∼10 kyr of exposure, and then the rate of fracture growth slows exponentially over geologic time up to ∼150 ka. Similar rock breakdown deceleration trends were independently documented using a novel application of infrared photoluminescence (IRPL) dating for a visibly fractured boulder at one site. Previous work shows that increasing microcrack intensity correlates with enhanced compliance in the bulk rock over the same timescales that our bulk macroscale fracturing rates decrease. We hypothesize that enhanced compliance contributes significantly to the observed decrease in fracturing rates via increased material toughness. Our results contrast with current landscape‐scale conceptual models that assume bulk fracturing rates and characteristics are invariant over time and are controlled by short term rock strength and external stress magnitudes alone. Instead, our findings indicate that, over geologic time, fracturing of rocks increases its effective toughness.

Extensive research over the past two decades has shown that early Mars likely had a warmer, wetter climate with widespread water activity. Ferromagnesian (Fe,Mg‐rich) clay deposits are compelling markers of these ancient environments, helping reconstruct Mars' hydrologic evolution, assess past habitability, and guide future exploration. This study analyzes hyperspectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) aboard NASA's Mars Reconnaissance Orbiter , focusing on regions along the Martian crustal dichotomy—where clay deposits occur at the boundary between the ancient southern highlands and the younger northern lowlands. We systematically surveyed ∼1500 CRISM targeted observations (1–2.6 μm) to identify ferromagnesian clays, distinguish them from other hydrated minerals, and characterize compositional differences between Fe‐ and Mg‐rich species using diagnostic absorptions around 1.4, 2.3, and 2.4 μm. Results reveal spatial variations in clay mineralogy: Fe‐rich nontronites are prevalent around Mawrth Vallis, while Mg‐rich saponites are more locally distributed in Nili Fossae and Libya Montes. Oxia Planum—the Rosalind Franklin rover landing site—exhibits more compositionally intermediate clays such as vermiculites and ferrosaponites. These differences may reflect variations in the iron and magnesium abundance or in the iron oxidation state. Moreover, a recurring absorption near 2.5 μm suggests co‐occurring carbonates like magnesite and siderite, increasing the potential for biosignature preservation. These findings refine our understanding of Mars' aqueous history and offer an important mineralogical context for future rover and sample return missions. They also emphasize the need for a next‐generation orbital imaging spectrometer to succeed CRISM and extend its legacy.

Over nearly two decades numerous studies have revealed evidence for widespread aqueous activities on Mars’ surface, likely occurring from Noachian to Hesperian epochs [1,2]. Clay-bearing deposits are valuable targets to constrain the water history on early Mars and consequently search for signs of life [3]. The possible co-occurrence of carbonates throughout these deposits may also suggest a high potential for biosignature preservation. Nevertheless, the definitive characterization of these deposits remains a challenging task. This study builds upon our previous works [4–6] by focusing on hyperspectral data gathered by the CRISM instrument onboard NASA’s Mars Reconnaissance Orbiter mission [7] to analyze the spectral signatures of clay deposits in the 1–4 µm range, and their potential mixtures with carbonates. We collected data along the Martian crustal dichotomy (Figure 1) – the boundary between the ancient, cratered highlands and the northern lowlands – where extensive clay deposits are exposed, selecting several regions of interest (ROIs). For all ROIs we conducted a spectral survey to determine the exact positions of the band centers for key clay absorptions around 1.4, 2.3, and 2.4 µm, and after applying a continuum removal to emphasize the absorptions. Band centers observed for the clay deposits show some variations from one region to another, as expected from ferromagnesian (Fe,Mg-rich) clays on Mars.Figure 1 – Global map of Mars with colorized topography (MOLA). We investigated more than 600 CRISM cubes along the crustal dichotomy (color-coded circles). We found ferromagnesian clays in around 400 cubes, mostly concentrated in the vicinity of Mawrth Vallis, Nili Fossae, Libya Montes. Other mineral phases are also detected, such as sulfates in Aram Chaos and Meridiani Planum, or even chlorites in Lyot crater. Nontronites (Fe-rich) are extensively detected around Mawrth Vallis, whereas saponites (Mg-rich) are more locally distributed across Nili Fossae and Lybia Montes. Oxia Planum – ESA’s ExoMars rover landing site – exhibits more “intermediate” clays such as vermiculites or even ferrosaponites. These variations may depend on the relative abundance of iron and magnesium in the clay structure, or even the oxidation state of iron [8]. Additionally, clay deposits often display a shallow absorption near 2.50–2.53 µm, suggesting the presence of carbonates intermixed with the clays. Overall, the carbonates possibly found in these deposits appear to have variable compositions, spanning within the siderite (Fe-rich) and magnesite (Mg-rich) series. This may indicate the presence of carbonates as siderite/magnesite solid solutions, likely reflecting multiple alteration events [9].This work follows previous in-situ and orbital measurements and prepares for upcoming missions and campaigns on Mars (e.g., ExoMars rover mission, Mars Sample Return, etc.), by offering a more comprehensive understanding of clay mineralogies to inform the search for biomarkers.Fundings: This work is supported by the Italian Space Agency (ASI) [ASI-INAF n.23-3-HH.0]References: [1] Carter et al. (2013) JGR Planets 118: 831–858. [2] Ehlmann and Edwards (2014) Ann. Rev. Earth Planet. Sci. 42:291–315. [3] Vago et al. (2017) Astrobiology 17: 471–510. [4] Brossier et al. (2022) Icarus 386: 115114. [5] Brossier et al. (2023) PSJ 4:27. [6] Brossier et al. (2024) PSS 247: 115924. [7] Murchie et al. (2007) JGR Planets 112: E05S03. [8] Michalski et al. (2015) EPSL 427: 215–225. [9] Beck et al. (2024) Earth and Space Science 11: e2024EA003666

We present our work on developing the 1:1M scale geologic map of a quadrangle of Mars in the Northeastern Tempe Terra region, next to the transition between Martian highlands and lowlands. The MTM 45302 quadrangle covers an area of about 200 by 300 kilometers, centered at 302.5°E, 42.5°N. We based our mapping on data from NASA’s Mars Global Surveyor, Mars Odyssey, Mars Reconnaissance Orbiter, the ESA’s Mars Express, and CNSA’s Tianwen-1.The regional topography in the area dips towards the northeast, with a total elevation decrease of about 2000 meters. We defined three plateau units in the area, with morphologies of wide, gently-dipping flat surfaces bounded by cliffs. Moderate resolution imagery shows spots with evidence of layering within the plateaus units. Crater size frequency distribution indicates ages of 3.9 to 3.4 Ga for the plateau units. The three mapped units are separated stratigraphically by erosional unconformities, cross-cutting craters, and linear features. The middle and most extensive plateau unit is cut by parallel elongated valleys oriented NNE-SSW, exposing mounds, pitted terrain, fan deltas, and inverted channels in the lower plateau unit. The mapped channel axes are often associated with the trend of the valleys formed by the erosion of plateaus. Wrinkle ridges are present on each plateau unit, and their tectonic expression is confined to each relative unit. In the south portion of the quadrangle, ENE-WSW trending linear tectonic features of the Tempe Terra system cut through all the units. Craters in the MTM exhibit pedestal, radial, single- and multi-layer ejecta morphologies, and different infill styles. Several crater floors contain curvilinear ridges and troughs. We are currently reviewing the interpretation of the mapped features, their stratigraphic relationship and building hypotheses on the geologic evolution of the area, preparing the final geologic mapping product.Besides the purpose of describing the evolution in space and time of the area, our mapping project serves as a context for a companion study about the presence of ice in the shallow Martian crust, observed from imaging spectroscopy at a spatial resolution of about 20 meters per pixel. The area of our map also contains six ~0.5 - 2 km diameter, relatively recent impact craters with similar thermal inertia and crater morphology characteristics, including radial ejecta which exhibit unusually bright thermal inertia at night. Furnari et al. (2024) studied one of these craters using spectral analysis, highlighting an anomalously large abundance of seasonal water ice on the ejecta, offering new insights on ice variation in the Martian ground. Additionally, crater analysis by Gou et al. (2024) in the lowlands Chryse Planitia region to the southeast of our study area posits that craters with multi-layer ejecta at this latitude indicate the presence of subsurface volatiles. The stratigraphic and structural relations of the geologic features mapped in this work provide the key to reconstruct the geologic evolution of processes that occurred on Mars in an area where the southern highlands are transitioning to the northern lowlands. Evidences for ice-related processes in the geologic history, combined with the instrumental record of ice in relatively recent craters, suggests that this region likely hosted ice in the past and potentially in the present. Acknowledgements: This work is supported by the ASI-INAF Mars Exploration agreement 2023-3-HH 0.References: Furnari et al., 2024, Study of the seasonal water ice in the ejecta of a small crater on Mars. Congresso di Scienze Planetarie, Bormio, Italy, 5-9 Febbraio 2024; Gou et al., 2024, Paleoenvironment implications of layered ejecta craters in the Chryse Planitia, Mars, Icarus, Volume 410, 115918.