Abstract The outer slopes of the western Jezero crater rim are hypothesized to expose sections of Early‐ to Pre‐Noachian crust uplifted by the Jezero impact, providing an excellent opportunity to investigate the earliest geologic processes active on terrestrial planets. Here, we analyze a ∼75‐m‐thick layered bedrock succession explored by the Perseverance rover on the outer Jezero crater rim, informally named the Broom Point member of the Witch Hazel Hill formation, to reconstruct its emplacement processes. Layering is steeply inclined and offset by rim‐transverse faults, consistent with uplifted pre‐impact target rock of Noachian age. Lithofacies include clast‐ and matrix‐supported melt‐bearing breccias, a planar‐laminated to potentially cross‐stratified facies containing candidate accretionary lapilli, and an unstratified to weakly laminated facies, with angular silt‐sized grains. These lithofacies are interpreted as the products of concentrated, ground‐hugging density flows, dilute surges and fall produced by explosive volcanism or impacts. However, millimeter‐ to sub‐millimeter‐diameter glassy spherules with vesicular, fluidal and agglutinated morphologies are also present throughout the section, including as a ∼20‐cm‐thick framework‐supported layer. Their morphologies, compositions and distributions appear inconsistent with diagenetic or volcanic spherules, and instead resemble spherules produced by impacts, suggesting that the lithofacies of the Broom Point member were predominantly emplaced as impactites. Geological cross sections and stratigraphic columns were constructed through the unit, and allowed us to reconstruct the depositional evolution of these deposits. The section preserves repeated phases of flow and fall, and intercalated proximal and distal ejecta, suggesting that Mars' ancient stratified crust preserves evidence for repeated impacts early in its history.

Martian fluvial valleys provide evidence for the surface flow of liquid water, making them a key target for rover-based investigations of ancient habitability. The Mars 2020 Perseverance rover spent similar to 85 sols exploring the Bright Angel formation, exposed across the floor of Neretva Vallis: the western inlet channel of Jezero crater. This study documents the sedimentology and stratigraphy of the Bright Angel formation to reconstruct its depositional setting. The unit preserves a concave-up bedding structure consistent with a young channel-fill deposit, rather than an older unit exposed by incision of Neretva Vallis. The lower stratigraphy displays a fining-up sequence from coarse-grained sediments up to pebble-conglomerates (the Tuff Cliff member) into a >= 10-m-thick succession of laminated mudstone (the Walhalla Glades member), interpreted as a transgressive sequence recording the onset of lacustrine conditions in Neretva Vallis. Lenses of matrix-supported granule-conglomerate adjacent to the valley wall (the Fern Glen Rapids member) may preserve locally derived debris flows entering the lake. These are overlain by a polymict, matrix-supported, boulder-conglomerate (the Mount Spoonhead member), interpreted as a high-energy debrite derived from the watershed. The sequence is capped by cross-stratified sediments (the Serpentine Rapids member), preserving lake margin deposits. The Bright Angel lacustrine sequence occurs similar to 10-50 m higher in elevation than the lake level anticipated for the Jezero western delta, requiring an additional period of lacustrine activity. The structure and spatial distribution of the unit leads us to propose that a late-stage blockage of Neretva Vallis may have facilitated the formation of a perched, valley-confined lake upstream.

Multiple orbital studies have highlighted the importance of Fe/Mg phyllosilicate minerals on Mars, especially in Noachian terrains (e.g. Poulet et al., 2006; Mangold et al., 2007;), even showing that they are the dominant hydrous mineral family on Mars (Carter et al., 2013). Although widespread in exposures of the oldest terrains on Mars, it is hard to constrain either their composition or formation process based on orbital data only (Ehlmann et al., 2011; Carter et al., 2015). The best matches for the orbital spectra were proposed to be smectite (nontronite, saponite) and/or vermiculite (Carter et al., 2013). In the Nili Fossae region specifically, the Noachian basement was shown to be bear widespread signatures of Fe/Mg smectites (Goudge et al., 2015).After exploring diverse geological units inside Jezero Crater (Nili Fossae, Mars), and going over the rim of the crater, the Perseverance rover has reached a unit informally called Krokodillen, at the base of the outer part of the rim. It is thought to be part of the Noachian crust that was locally uplifted by the emplacement of Jezero Crater (Sun & Stack et al., 2020). Dark looking from orbit, it is surrounded on the North, West and South by ridges and an exposure of the regional olivine-rich unit, understood to be younger.We will present the data acquired on rocks of the Krokodillen area with the SuperCam instrument (ref Maurice et al., SSR 2021; Wiens et al., SSR 2021). Overall structureless, the rocks of Krokodillen are generally fine grained, with locally some millimetric granules. The chemical composition characterized with LIBS shows a relatively homogeneous composition intermediate between the average basaltic crust of Mars and orthopyroxene. This is likely an average, close to the bulk composition, due to the mixing of multiple fine-grain mineral phases within the footprint of the LIBS analysis. Visible and near infrared (VISIR) reflectance spectroscopy data show strong and ubiquitous signatures of Fe-Mg phyllosilicates, closely matching those observed from orbit in the broader Nili Fossae region.We propose that the rocks of Krokodillen are representative of the Noachian clay-bearing rocks characterized from orbit, specifically the (ridged) Altered Basement mapped by Goudge et al., (2015) in the Jezero watershed. In that case, the in situ measurements from the Mars 2020 mission provide the first in situ constraints on the composition, aqueous alteration and emplacement mechanism of these rocks.

Abstract. In August 2024, MAJIS, the visible and infrared mapping spectrometer onboard the ESA-Juice spacecraft, collected its first observations of resolved targets during Lunar and Earth Gravity Assist maneuver (LEGA). One month before, during payload checkout 2 (PC2), MAJIS performed two starfield observations to evaluate its post-launch geometric performances that can be compared with the LEGA data. This work presents an overview of the spatial distribution of the MAJIS signal collected at different scan angles and their position in MAJIS field of view. In PC2 starfields, 14 stars were identified, allowing us to derive a new in-flight alignment with an accuracy of 0.7 ± 0.4 MAJIS instantaneous field of view (IFOV). The offset between the nominal boresight of Juice remote sensing platform (+Z) and MAJIS boresight was evaluated to be 27 samples (along-slit) and 31 lines (cross-slit). With this new alignment, MAJIS observations on the Moon are co-aligned with JANUS camera with an accuracy of 2.2 ± 0.9 IFOV which could be improved to 1.1 ± 0.6 IFOV with bundle adjustment. A comparison of MAJIS Earth observations with simultaneous weather satellites observations confirmed that the MAJIS alignment is accurate for the full close Earth flyby. Residual misalignments with JANUS and NavCam remain visible in the Earth dataset but they can be easily corrected using small timing and scan angle adjustments (<10 IFOV). The instrument and frame kernels for MAJIS will be updated on the basis of these results. The improved co-alignment between MAJIS, JANUS and NavCam ensures strong synergy between the remote sensing instruments during the nominal scientific phase when they operate at the same time.

Investigating sedimentary carbonate phases in situ is a primary objective of Mars exploration. Such mineral phases commonly precipitate from surficial waters or near-surface diagenetic fluids, and therefore their presence can constrain past aqueous conditions, have the potential to preserve biosignatures, and may be a mineralogical record of the ancient CO2-rich atmosphere. Jezero crater, the field site for NASA's Mars 2020 Perseverance rover, has experienced multiple periods of aqueous activity and has crater-rim-margin carbonate mineralization evident in orbital spectral data. Here, we report on two new carbonate-bearing sedimentary rocks identified in data collected by the Perseverance rover in the lower portion of the Jezero western sedimentary fan. This study integrates multiple image datasets at these previously unrecognized carbonate localities, Rockytop and Jenkins Gap, to investigate their depositional setting. Differences in their sedimentary attributes and geologic context indicate distinct conditions of carbonate formation that are likely linked to the former lake in Jezero crater. We find that the Rockytop outcrop, comprised of alternating fine gravel and medium sandstone couplets, has carbonate present in detrital grains as well as in the matrix. We interpret these couplets as event beds formed via sedimentary gravity flows. In contrast, the second site has carbonate-encrusted gravels in an unsorted conglomerate that are texturally similar to carbonate cementation in near-shore lacustrine settings (‘tufas’). Both carbonate rocks were apparently deposited during the lacustrine period in Jezero crater, but may not be contemporaneous. We also present an alternate model with the sediment in upper Rockytop deposited in an alluvial/fluvial setting with ambiguous timing. Plain language summary Instruments on spacecraft orbiting or roving Mars can detect rock compositions that are linked to past environmental conditions. Carbonate minerals, in particular, commonly form in near-surface environments and can preserve biosignatures, if present. One of the main reasons the Jezero crater is the field site for NASA's Mars 2020 rover mission is because carbonate mineral signatures defined from orbit are correlated with the hypothesized ancient lake shoreline. Rover observations discovered carbonate mineral phases at two sites in the lower Jezero sedimentary fan that are not detectable in orbital spectral data. At these sites, we found evidence that carbonate is linked to the former lake in Jezero crater. Carbonate precipitation occurred in lake and/or river settings. This study confirms additional habitable settings with biosignature preservation potential for samples collected by the Perseverance rover.

The Curiosity rover continues its exploration of Mount Sharp, Gale crater’s ~5000 m-high sedimentary pile, and has been traversing for the past three years the Layered Sulfate unit (LSu), an interval initially characterized from orbit and thought to have recorded a global climatic transition toward the more arid conditions we observe nowadays on Mars. This unit, also informally known as the Mirador formation, is rich in sulfates and record mostly aeolian settings. Unexpectedly, the rover has also encountered numerous strata arguing for a recurring aqueous activity punctuating the overall arid, aeolian depositional environment.Lately, Curiosity explored the “boxwork” unit, a high-interest region named after the orbital observation of “box-forming”, (deca-)meter-scale rectilinear features cropping out of the ground. Diagenetically-altered, fine-grained rocks making the most of the boxwork unit are probably of lacustrine origin, stressing out the importance of these aqueous conditions in the midst of the LSu. But when looking at the walls of this valley, made up of the Texoli, Mishe Mokwa and Cordillera buttes, we notably observe coarser-grained, erosion-resistant beds displaying a wealth of multi-scale sedimentary structures.Among them are several occurrences of clinoform geometries that we sorted into three classes. Type 1 are characterized by inclined, sigmoidal to poorly cross-bedded strata, filling meter-scale, individualized lens-shaped bodies. Type 2 are characterized by inclined strata, sigmoidal but more cross-bedded strata. They are also observed filling lens-shaped bodies, but contrary to Type 1, these lenses are laterally stacked and cross-cutting each other’s immediate neighbor. Finally, Type 3 clinoforms occur in unconfined packages evidencing clearly sigmoidal, steeply-dipping (15-20°) and non-cross-bedded strata. While they are conformable with lower sub-horizontal layers pertaining to the bedrock, their top is mostly truncated by unconformable sub-horizontal layers. At the outcrop, the steeply dipping, sigmoidal strata also define a conspicuous lobate shape.We interpret Types 1 and 2 clinoforms as the record of fluvial channels, with Type 1 a record of braided rivers and Type 2 a record of laterally migrating bars of a meandering river. Type 3 marks a conspicuous change and we interpret the vertical tripartite stratal pattern as bottomsets, foresets and topsets of a Gilbert-deltaic suite. These strata reflect fluvial to deltaic depositional settings with decreasing levels of energy from strictly fluvial, individual channels (Type 1), meandering channels (Type 2) and finally within a delta (Type 3).These settings are in line with the quieter, presumably lacustrine, environment the boxwork unit’s strata likely origin from, and could represent the local sedimentary input. They contrast with the overall arid, aeolian structures observed to make most of the surrounding buttes and overall LSu. They nevertheless highlight a recurrence of humid episodes throughout the LSu. These events illustrate a more complex and unpredictable climatic pattern as Mars became colder and more arid.

We present a global survey of 232 ice-exposing scarps incised into the Latitude Dependent Mantle (LDM) on Mars and analyze their morphology, spatial distribution, and geomorphological context. These features are confined to 40-60 degrees latitude due to the latitudinal dependence of sublimation-driven scarp formation and the equatorward extent of excess subsurface ice. Scarps are predominantly located on the lower, concave parts of leeward hillslopes, suggesting these areas represent zones of preferential snow accumulation and preservation. Using high-resolution digital terrain models, we estimated the local thickness of the Latitude-Dependent Mantle (LDM) from the depth of scarp depressions. Values range from 40 to over 190 meters, with thicker mantle observed downslope and on leeward slopes. The morphology and internal stratigraphy of the exposed layers reveal variable geometries, including fine, dipping layering interpreted as wind-blown snow mixed with dust and sand, similar to terrestrial niveo-aeolian deposits. These results support the hypothesis that the LDM formed through atmospheric processes, with wind and topography jointly controlling the distribution, structure, and thickness of ice-rich deposits. This has implications for Amazonian climate interpretations, as the LDM may not preserve a continuous climate record, and for future in situ resource utilization (ISRU), where ice accessibility is likely to vary greatly at small scales depending on local terrain and past depositional conditions.

The Lunar-Earth Gravitational Assist (LEGA) of 19-20 August 2024 marked the first in-flight opportunity beyond functional checks to perform MAJIS (Moons and Jupiter Imaging Spectrometer) observations on-board the ESA's Jupiter Icy Moons Explorer (JUICE) spacecraft. This unique double flyby involved sequential close approaches to the Moon and Earth, offering an unprecedented configuration to evaluate MAJIS under high radiance, rapidly changing geometric, and operationally constrained conditions. A total of 24 hyperspectral image cubes were acquired (5 targeting the Moon and 19 the Earth) providing a dataset of approximately 7.5 Gbit. This work presents the primary goal of this observation campaign, which was to verify key aspects of MAJIS performance, including radiometric and spectral calibration, straylight behavior, geometric alignment, the use of onboard browse products, and interference tests with other JUICE instruments. This event also enabled assessment of thermal behavior and susceptibility to electromagnetic interference, and provided a first operational benchmark for MAJIS and a basis for refining future observation strategies and data analyses during JUICE's cruise and science phases. In addition, despite limited spatial and temporal coverage of the observations, the analyses presented here and in a series of companion papers of the special issue "The first-ever lunar-Earth flyby: a unique test environment for JUICE" demonstrated the instrument's ability to characterize mineralogical features on the Moon and atmospheric constituents on Earth. Observations include detection of mafic minerals (some associated to fresh excavated materials), thermal emission, and emissivity variations on the Moon at spatial scale of 100-200 m. Characterization of atmospheric absorption features, thermal brightness, icy cloud properties are captured for the Earth at km-scale and briefly discussed in the framework of the atmospheric biosignatures relevant to exoplanet habitability studies. Near-coincident acquisitions with other JUICE instruments and Earth-orbiting spectrometers provided valuable inter-calibration and cross-validation opportunities.

Tyrrhena Terra, a region located in the cratered highlands between Hellas and Isidis Planitia on Mars, is distinguished by its extensive presence of hydrated minerals. Using 542 hyperspectral images from the Compact Reconnaissance Imaging Spectrometer for Mars, we detected 252 exposures of hydrated minerals. This region is characterized by a widespread distribution of Fe/Mg-smectites/vermiculites and chlorite, with additional detections of Al-phyllosilicates, zeolites, prehnite, hydrated silica, and carbonates. We classified the mineralogical detections in classes of impact crater diameters, locations in craters, and for those > 20 km, their relative degradation stages. We found that craters < 10 km display a lower mineral diversity than larger ones. In contrast, craters > 20 km display a high mineral diversity, especially in central peaks, suggesting a strong influence of hydrothermal processes and deep excavation. Among this diameter range, fresh, young craters exhibit a much higher mineral diversity than degraded, old craters. Fe/Mg-phyllosilicates are dominant in the latter, as well as in sedimentary units of topographically low areas. These results indicate a long-term alteration cycle in the most ancient period, where the initial, diverse hydrated minerals-formed through exhumation and/or hydrothermal circulation within large impacts-were subsequently transformed by surface weathering and/or buried, dissolved, or eroded away by other post-impact processes, then transported and deposited in lowlands by fluvial erosion. Although Tyrrhena Terra is dominated by impact-related hydrated mineral detections, our study shows that the overprint of Noachian age weathering is visible within these detections.

In Jezero crater, Mars, the Perseverance rover has explored the western fan and encountered loose pieces of rock separated from outcrops or “float” rocks. Comparing float rocks to in‐place outcrops can provide key insights into the crater's erosional history and the diversity of units in the Jezero watershed that Perseverance cannot visit in situ. Here, we used multispectral observations from Perseverance's Mastcam‐Z instrument to investigate the lithology and origin of float rocks found on the western Jezero fan front (sols 415–707). We identified four textural classes of float rocks (conglomerates, layered, massive, and light‐toned) and investigated their physical characteristics, spectral properties, and distribution to interpret their source and mode of transport. Likely derived from local sedimentary fan outcrops, conglomerate and layered float rocks are highly spectrally variable and altered with differing ferric and ferrous signatures. Massive float rocks are the least altered with ferrous signatures and likely derived from local outcrop sources or more distal sources (∼50–250 km) in the Jezero watershed. Massive float rocks separate into two subclasses: massive olivine and massive pyroxene, which are likely derived from the regional olivine‐carbonate‐bearing watershed unit and the crustal Noachian basement unit, respectively. The unique light‐toned float rocks have variable hydration and low Fe‐abundance, but there is no local outcrop equivalent of these rocks on the crater floor or fan front, suggesting transport into the basin from a source region outside Jezero. Perseverance found no meteorites at the western fan, implying that fan sediments may be in the youngest ages estimated from crater counts (Hesperian).

The Mars 2020 Perseverance rover landing site is located within Jezero crater, a  $\sim50~\mbox{km}$ diameter impact crater interpreted to be a Noachian-aged lake basin inside the western edge of the Isidis impact structure. Jezero hosts remnants of a fluvial delta, inlet and outlet valleys, and infill deposits containing diverse carbonate, mafic, and hydrated minerals. Prior to the launch of the Mars 2020 mission, members of the Science Team collaborated to produce a photogeologic map of the Perseverance landing site in Jezero crater. Mapping was performed at a 1:5000 digital map scale using a 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) orthoimage mosaic base map and a 1 m/pixel HiRISE stereo digital terrain model. Mapped bedrock and surficial units were distinguished by differences in relative brightness, tone, topography, surface texture, and apparent roughness. Mapped bedrock units are generally consistent with those identified in previously published mapping efforts, but this study’s map includes the distribution of surficial deposits and sub-units of the Jezero delta at a higher level of detail than previous studies. This study considers four possible unit correlations to explain the relative age relationships of major units within the map area. Unit correlations include previously published interpretations as well as those that consider more complex interfingering relationships and alternative relative age relationships. The photogeologic map presented here is the foundation for scientific hypothesis development and strategic planning for Perseverance’s exploration of Jezero crater.

In 2023, the Mars 2020 Perseverance rover investigated the Skrinkle Haven member of the Tenby formation in the > 3.5-billion-year Jezero Crater western fan. This unit was interpreted from orbiter data as bank attached, lateral-accretion bars in a sinuous river on a muddy delta plain. To test that hypothesis, this study applies facies and stratigraphic analyses of both rover and orbiter data. Rover images show that the Skrinkle Haven member is composed of two lithofacies: a fine-grained sandstone and a pebble conglomerate. Both lithofacies are composed of structureless, ungraded, planar-parallel beds that have sharp, nongradational contacts and depositional angles up to similar to 30 degrees. These characteristics indicate that grain flow was the main depositional process and that the sedimentary bodies were built through downstream accretion. Architectural analysis suggests that the Skrinkle Haven member was deposited primarily as delta foresets and mouth bars, with limited river bar deposition. The sequence stratigraphic analysis identified five maximum-flooding surfaces associated with relative-lake-level increases ranging from 5 to 25 m. In the sequences, deltaic strata prograded during normal and forced regressions. Some sequences have evidence for compensational stacking. Lake levels decreased through time both within sequences and throughout the duration of the Skrinkle Haven member deposition, from at least -2415 m in the oldest sequence to at most -2455 m in the youngest. The elevation range of the Skrinkle Haven member is below the modern Jezero Crater outlet breach, suggesting that the Jezero Crater lake basin was closed at that time. Overall, the Skrinkle Haven member records the deposition of a sandy to conglomeratic deltaic system that prograded into a closed lake basin during both forced and normal regressions. This type of fluvial-deltaic system is significantly different from the muddy delta topsets originally interpreted from orbiter data, because of the different implications for biosignature preservation and the paleohydrology of the Jezero Crater.

Abstract Iron oxide-hydroxide minerals in Martian dust provide crucial insights into Mars’ past climate and habitability. Previous studies attributed Mars’ red color to anhydrous hematite formed through recent weathering. Here, we show that poorly crystalline ferrihydrite (Fe5O8H · nH2O) is the dominant iron oxide-bearing phase in Martian dust, based on combined analyses of orbital, in-situ, and laboratory visible near-infrared spectra. Spectroscopic analyses indicate that a hyperfine mixture of ferrihydrite, basalt and sulfate best matches Martian dust observations. Through laboratory experiments and kinetic calculations, we demonstrate that ferrihydrite remains stable under present-day Martian conditions, preserving its poorly crystalline structure. The persistence of ferrihydrite suggests it formed during a cold, wet period on early Mars under oxidative conditions, followed by a transition to the current hyper-arid environment. This finding challenges previous models of continuous dry oxidation and indicates that ancient Mars experienced aqueous alteration before transitioning to its current desert state.

The experiments of aeolian impact ripples are carried out in a wind tunnel at atmospheric pressure and temperature. A spatial and temporal study of wavelength, flux and friction velocity correlated with the appearance and development of aeolian impact ripples has been studied using photogrammetry. Digital Elevation Models have been generated, providing a wealth of information such as spatial evolution, temporal evolution, wavelength, erosion rate, migration speed and mass flow rate. In particular, we seek to relate ripple migration velocities to the mass flow rate of the system and the retroactive effect of aeolian impact ripples on the mass flow rate for different flow velocities.This experimental study focuses on morphological changes of aeolian impact ripples and their migration velocity at different evolution stages for grain size ~310 µm in order to investigate if there is a difference in wavelength between initial formation and full development time. We also investigate aeolian impact ripples development conditions according to saturated and unsaturated flux.

The modern surface of Mars does not sustain liquid water, however relict landforms observed on orbital images provide strong evidence of past aqueous activity. Nevertheless on-the-ground analysis of sedimentary strata are required to robustly characterise the specific nature of early Mars palaeoenvironments. The Mars 2020 Perseverance rover is exploring a prominent sedimentary fan deposit at the western margin of Jezero crater – the Western fan – which has been interpreted to be an river delta that prograded into an ancient lake basin during the Late Noachian-Early Hesperian epochs on Mars (~3.6-3.8 Ga). Perseverance’s traverse across the fan in 2022-2023 provides a remarkable window into a fossilised sediment routing system on Mars with potential to understand how water and sediment were distributed across a Martian landscape under a markedly different climate to present day. Here we use the rover’s Mastcam-Z cameras to characterise sedimentary geometries in a distal to proximal transect across the western fan and reconstruct sediment dynamics on the Western fan and infer past environmental change. The distal reaches of the preserved fan show a sedimentary succession that records a transition from distal alluvial fan into lacustrine and subsequently foreset delta deposits. This succession records the initiation of a martian lake system and lake level rise, though the delta stratal geometries suggest deposition during episodes of lake level fall. In the medial sector of the upper exhumed portion of the fan, complex stratal geometries are observed with a variety of scenarios for palaeoenvironmental interactions possible. In particular, the presence of large-scale foreset units preserved in this ‘mid-fan’ sector possibly suggests complex deltaic interfingering with fluvial strata during lake level fluctuations. In more proximal and stratigraphically higher (and hence younger) sectors of the fan, we observe strata deposited by progradation of fluvial systems culminating in a sequence of rounded boulder-containing deposits that signal transition to a routing system characterised by high discharges. Misquoting Shakira “the sediments don’t lie”; they record a history of sustained water transport and habitability on early Mars.