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We reassessed several orbital topographic data sets for the Perseverance rover landing site at Jezero Crater, Mars to better understand its floor units. Tens‐of‐meters deep topographic anomalies occur in the volcanic floor of Jezero crater and are not a result of impact cratering. Eight km‐scale steep escarpment‐bounded depressions may be locations of paleotopographic highs that were embayed by the volcanic floor lava flows, forming inverted topography from either contemporaneous upward inflation of embaying lavas or later deep scour due to differential erosion over 107−9 years. Five multi km‐scale shallow‐sloped depressions linked by channel‐like forms may record locations of buried paleolakes and channels that predate the volcanic floor units or a drained magma system. These results indicate Jezero experienced multiple closed‐basin or dry phases, allowing erosion of the crater floor and creation of topography, which provides new geologic context for the samples gathered by Perseverance. Plain Language Summary The Perseverance rover has been on Mars in Jezero Crater for over 2 years collecting rock samples. We reexamined elevation data to better understand the volcanic lava unit on the floor of the crater. We found that the floor is slightly tilted south‐southeast, possibly due to sediment, sourced from the north, beneath the volcanic floor. In the floor we found eight depressions bounded by cliffs, possibly formed by past lava flows around hills of weaker rocks that are now eroded away or by the lavas rising upward around the hills of rock. We also found five large, shallow depressions connected by channels. These might indicate old locations of lakes and rivers before the more recent volcanic activity or a drained magma system. This suggests Jezero Crater experienced alternating phases of being dry and being filled with water, providing key information to help interpret the collected samples. Key Points Tens‐of‐meters deep topographic anomalies occur in the volcanic floor of Jezero Crater Several multi‐km2 scale shallow‐sloped depressions and channels may record lower lake levels or a drained magma system Eight escarpment‐bounded depressions formed by lava embayment of preexisting topography followed by lava inflation or differential erosion

Precipitated minerals, including salts, are primary tracers of atmospheric conditions and water chemistry in lake basins. Ongoing in situ exploration by the Curiosity rover of Hesperian (around 3.3–3.7 Gyr old) sedimentary rocks within Gale crater on Mars has revealed clay-bearing fluvio-lacustrine deposits with sporadic occurrences of sulfate minerals, primarily as late-stage diagenetic veins and concretions. Here we report bulk enrichments, disseminated in the bedrock, of 30–50 wt% calcium sulfate intermittently over about 150 m of stratigraphy, and of 26–36 wt% hydrated magnesium sulfate within a thinner section of strata. We use geochemical analysis, primarily from the ChemCam laser-induced breakdown spectrometer, combined with results from other rover instruments, to characterize the enrichments and their lithology. The deposits are consistent with early diagenetic, pre-compaction salt precipitation from brines concentrated by evaporation, including magnesium sulfate-rich brines from extreme evaporative concentration. This saline interval represents a substantial hydrological perturbation of the lake basin, which may reflect variations in Mars’ obliquity and orbital parameters. Our findings support stepwise changes in Martian climate during the Hesperian, leading to more arid and sulfate-dominated environments as previously inferred from orbital observations.

Mastcam-Z is a multispectral, stereoscopic imaging investigation on the Mars 2020 mission’s Perseverance rover. Mastcam-Z consists of a pair of focusable, 4:1 zoomable cameras that provide broadband red/green/blue and narrowband 400-1000 nm color imaging with fields of view from 25.6° × 19.2° (26 mm focal length at 283 μrad/pixel) to 6.2° × 4.6° (110 mm focal length at 67.4 μrad/pixel). The cameras can resolve (≥ 5 pixels) ∼0.7 mm features at 2 m and ∼3.3 cm features at 100 m distance. Mastcam-Z shares significant heritage with the Mastcam instruments on the Mars Science Laboratory Curiosity rover. Each Mastcam-Z camera consists of zoom, focus, and filter wheel mechanisms and a 1648 × 1214 pixel charge-coupled device detector and electronics. The two Mastcam-Z cameras are mounted with a 24.4 cm stereo baseline and 2.3° total toe-in on a camera plate ∼2 m above the surface on the rover’s Remote Sensing Mast, which provides azimuth and elevation actuation. A separate digital electronics assembly inside the rover provides power, data processing and storage, and the interface to the rover computer. Primary and secondary Mastcam-Z calibration targets mounted on the rover top deck enable tactical reflectance calibration. Mastcam-Z multispectral, stereo, and panoramic images will be used to provide detailed morphology, topography, and geologic context along the rover’s traverse; constrain mineralogic, photometric, and physical properties of surface materials; monitor and characterize atmospheric and astronomical phenomena; and document the rover’s sample extraction and caching locations. Mastcam-Z images will also provide key engineering information to support sample selection and other rover driving and tool/instrument operations decisions.

The surface elemental composition of dwarf planet Ceres constrains its regolith ice content, aqueous alteration processes, and interior evolution. Using nuclear spectroscopy data acquired by NASA’s Dawn mission, we determined the concentrations of elemental hydrogen, iron, and potassium on Ceres. The data show that surface materials were processed by the action of water within the interior. The non-icy portion of Ceres’ carbon-bearing regolith contains similar amounts of hydrogen to those present in aqueously altered carbonaceous chondrites; however, the concentration of iron on Ceres is lower than in the aforementioned chondrites. This allows for the possibility that Ceres experienced modest ice-rock fractionation, resulting in differences between surface and bulk composition. At mid-to-high latitudes, the regolith contains high concentrations of hydrogen, consistent with broad expanses of water ice, confirming theoretical predictions that ice can survive for billions of years just beneath the surface.

Serpentine, recently discovered on Mars using Mars Reconnaissance Orbiter data, is uncommon but found in three geologic settings: (1) in mélange terrains at the Claritas Rise and the Nili Fossae, (2) associated with a few southern highlands impact craters, and (3) associated with a regional olivine‐rich stratigraphic unit near the Isidis basin. Any presently active serpentinization processes would be occurring beneath the surface and mineral products would not be apparent with surface and orbital data; however, finding serpentine in several Noachian terrains indicates active serpentinization processes in Mars' past. Important implications are the past production of magnetite, which may contribute to chemical remnant magnetization of Mars' crust, and production of H2, which is a suitable energy source for chemosynthetic microbial life.

The Mars Reconnaissance Orbiter and its Context Camera (CTX) have acquired more than 100,000 separate panchromatic images that capture nearly the entire surface of Mars at ∼5–6 m/pixel. This paper describes a data processing workflow used to generate the first contiguous global mosaic of CTX data, which represents a large improvement in spatial resolution over existing 100 m/pixel contiguous global mosaics. We describe the overarching strategy for the mosaic's construction, which was to maximize the scientific utility of a continuous mosaic that is 5.7 trillion pixels in size. The pipeline used for data processing prioritized traceability and reproducibility of the final mosaic, such that the provenance of all pixels is reported, equipping scientists with information to differentiate mosaic artifacts from surface landforms and to incorporate critical image metadata into their analyses. The CTX data set synthesized into a global CTX mosaic facilitates ready analysis and provides a new capability in transitioning global studies of Mars from high‐resolution investigations of individual images to systematic studies of the entire Martian surface at outcrop‐resolving quality without regard to image boundaries. Plain Language Summary We generated a global mosaic of Mars using Context Camera satellite imagery at 5.0 m/pixel, a substantial improvement in spatial resolution over the previous global mosaic at 100 m/pixel. This paper describes a new technique for merging overlapping images together in a way that preserves all information from each component image and produces a map of all image boundaries that is included with the mosaic. This makes scientific analyses that are facilitated by the mosaic fully traceable and reproducible. With this mosaic, scientists can now readily analyze landforms without the overhead of downloading individual images and perform complete global analyses of Mars at a resolution capable of seeing rock outcrops on the surface. Key Points A global mosaic of Mars at 5.0 m/pixel has been created from 86,571 Context Camera images that are co‐registered to each other and seam‐corrected Non‐destructive image processing was used to preserve all image metadata and map seams The new mosaic will facilitate systematic studies of Mars at 5.0 m/pixel spatial resolution

The dwarf planet Ceres is known to host phyllosilicate minerals at its surface, but their distribution and origin have not previously been determined. We used the spectrometer onboard the Dawn spacecraft to map their spatial distribution on the basis of diagnostic absorption features in the visible and near-infrared spectral range (0.25 to 5.0 micrometers). We found that magnesium- and ammonium-bearing minerals are ubiquitous across the surface. Variations in the strength of the absorption features are spatially correlated and indicate considerable variability in the relative abundance of the phyllosilicates, although their composition is fairly uniform. These data, along with the distinctive spectral properties of Ceres relative to other asteroids and carbonaceous meteorites, indicate that the phyllosilicates were formed endogenously by a globally widespread and extensive alteration process.

Definitive exposures of pristine, ancient crust on Mars are rare, and the finding that much of the ancient Noachian terrain on Mars exhibits evidence of phyllosilicate alteration adds further complexity. We have analyzed high‐resolution data from the Mars Reconnaissance Orbiter in the well‐exposed Noachian crust surrounding the Isidis basin. We focus on data from the Compact Reconnaissance Imaging Spectrometer for Mars as well as imaging data sets from High Resolution Imagine Science Experiment and Context Imager. These data show the lowermost unit of Noachian crust in this region is a complex, brecciated unit of diverse compositions. Breccia blocks consisting of unaltered mafic rocks together with rocks showing signatures of Fe/Mg‐phyllosilicates are commonly observed. In regions of good exposure, layered or banded phyllosilicate‐bearing breccia rocks are observed suggestive of pre‐Isidis sedimentary deposits. In places, the phyllosilicate‐bearing material appears as a matrix surrounding mafic blocks, and the mafic rocks show evidence of complex folded relationships possibly formed in the turbulent flow during emplacement of basin‐scale ejecta. These materials likely include both pre‐Isidis basement rocks as well as the brecciated products of the Isidis basin–forming event at 3.9 Ga. A banded olivine unit capped by a mafic unit covers a large topographic and geographic range from northwest of Nili Fossae to the southern edge of the Isidis basin. This olivine‐mafic cap combination superimposes the phyllosilicate‐bearing basement rocks and distinctly conforms to the underlying basement topography. This may be due to draping of the topography by a fluid or tectonic deformation of a previously flatter lying morphology. We interpret the draping, superposed olivine‐mafic cap combination to be impact melt from the Isidis basin–forming event. While some distinct post‐Isidis alteration is evident (carbonate, kaolinite, and serpentine), the persistence of olivine from the time of Isidis basin suggests that large‐scale aqueous alteration processes had ceased by the time this unit was emplaced.

The history of water in Mars The Mars Phoenix mission has sent back images of what — before it melted away — looked like water ice. Meanwhile our knowledge of the planet's distant watery past is being refined by the instruments on-board Mars Reconnaissance Orbiter. The presence of interlayered hydrated silicate (phyllosilicate) minerals on Mars preserves a record of past interactions between liquid water and rocks. The phyllosilicates are restricted to ancient terrains dating from the earliest geologic era of Mars, the Noachian, and previous data suggested that phyllosilicates existed within a relatively narrow range of mineralogy. The latest spectromety data from the Reconnaissance Orbiter are consistent with an ancient Noachian origin for the phyllosilicates — but point to a much more varied mineralogy indicative of active, pervasive hydrologic processes throughout the crust of early Mars, including the surface. Results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions are reported. It is discovered that stratigraphic relationships show olivine-rich materials overlying phyllosilicate-bearing units, indicating cessation of aqueous alteration before emplacement of the olivine-bearing unit. It is also found phyllosilicates in sedimentary deposits clearly laid by water, pointing to a rich diversity of Noachian environments conducive to habitability. Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L’Eau, les Glaces et l’Activitié) instrument 1 , 2 , preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity 3 ) were specific to surface environments during the earliest era of Mars’s history 4 . Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) 4 of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

Columbus crater in the Terra Sirenum region of the Martian southern highlands contains light‐toned layered deposits with interbedded sulfate and phyllosilicate minerals, a rare occurrence on Mars. Here we investigate in detail the morphology, thermophysical properties, mineralogy, and stratigraphy of these deposits; explore their regional context; and interpret the crater's aqueous history. Hydrated mineral‐bearing deposits occupy a discrete ring around the walls of Columbus crater and are also exposed beneath younger materials, possibly lava flows, on its floor. Widespread minerals identified in the crater include gypsum, polyhydrated and monohydrated Mg/Fe‐sulfates, and kaolinite; localized deposits consistent with montmorillonite, Fe/Mg‐phyllosilicates, jarosite, alunite, and crystalline ferric oxide or hydroxide are also detected. Thermal emission spectra suggest abundances of these minerals in the tens of percent range. Other craters in northwest Terra Sirenum also contain layered deposits and Al/Fe/Mg‐phyllosilicates, but sulfates have so far been found only in Columbus and Cross craters. The region's intercrater plains contain scattered exposures of Al‐phyllosilicates and one isolated mound with opaline silica, in addition to more common Fe/Mg‐phyllosilicates with chlorides. A Late Noachian age is estimated for the aqueous deposits in Columbus, coinciding with a period of inferred groundwater upwelling and evaporation, which (according to model results reported here) could have formed evaporites in Columbus and other craters in Terra Sirenum. Hypotheses for the origin of these deposits include groundwater cementation of crater‐filling sediments and/or direct precipitation from subaerial springs or in a deep (∼900 m) paleolake. Especially under the deep lake scenario, which we prefer, chemical gradients in Columbus crater may have created a habitable environment at this location on early Mars.