Microbial communities living on and in rocks operate at the microscale, where interactions with minerals fundamentally shape community structure and function. Yet the relationship between micron scale mineralogical configurations and microbial distributions remains poorly understood. We tested the hypothesis that microbial biomass spatially correlates with areas of heightened mineralogical heterogeneity by applying Raman microspectroscopy to rock samples from three geologically distinct substrates: authigenic carbonates from a marine methane seep, volcanic basalt from Iceland, and polymetallic nodules from the abyssal seafloor. Using spectral decomposition and multiple complementary metrics of compositional heterogeneity, we evaluated intra-pixel and inter-pixel heterogeneity patterns in relation to biomass distribution. Our analyses reveal three patterns across all sample types. 1) When spectra are deconstructed into their constituent components, biomass zones are disproportionately dominated by the biomass spectral component compared with primary mineral components in zones of different minerals. 2) Biomass spectra have more homogeneous compositional profiles than mineral spectra. 3) Biomass is surrounded by more heterogeneous microhabitats than mineral pixels. These findings demonstrate that biomass exerts a distinctive and consistent influence on Raman spectral signatures, both within and between pixels, in ways that mineral components do not. Our results establish generalizable principles linking microscale mineralogical properties to microbial biogeography; these properties could be used as a potential biosignature and may provide a standardized workflow applicable to diverse rock systems and astrobiological exploration strategies.

Serpentinization is one of the major processes of silicate alteration in the solar system. Associated reactions are drivers for redox disequilibria and sources of H2, which are favorable to habitability. Minerals formed are responsible for crustal density and magnetization changes, and a significant amount of water can be sequestered. Released gases are expected to affect climate and have been proposed as potentially responsible for warming early Mars [1]. However, depending on protolith and geochemical conditions, a diversity of mineral assemblages exist, and the full spectrum of serpentinization is not well understood. In addition, some products are not well characterized, reducing our ability to assess serpentinization in the solar system. The Oman Drilling Project [2] is a multi-national collaboration to characterize the Samail ophiolite in Oman, which consists of altered oceanic crust. About 3.2 km of core were recovered and characterized with bulk rock and vein description, thin section photos, rock chemistry and mineralogy, microbial cell abundance, and borehole water properties, performed at regular intervals [2]. In addition, rock cores were analyzed using a hyperspectral imager covering the 0.4–2.6 µm range at a submillimeter spatial resolution (Fig. 1; [2]), allowing fine-scale characterization of the whole cores (as opposed to specific depth intervals), with tracking of most minerals of interest, hydration and Fe redox – of particular interest in understanding the fate of Fe in serpentinized systems and production of H2. This spectroscopy technique is also widely used in planetary exploration to assess composition of surfaces (e.g., [3]); collection of spectra of materials present in the cores will aid in the detection and characterization of serpentinization on Earth, Mars, asteroids and ocean worlds. Our ongoing study builds on previous hyperspectral analysis of the gabbroic section [4, 5], and focuses on the mantle section, some of which may be actively weathering. We will present our approach to automatically map minerals, hydration and serpentine redox on ~1 km of core from three boreholes, allowing us to investigate how these parameters vary with depth (e.g., what is the extent of carbonation and hydration in the oceanic crust/mantle?) and with variables that influence serpentinization processes (e.g., rock chemistry, faults, biology or fluid chemistry). This approach allows us to better understand serpentinization processes and products and their impacts on planetary crusts. Figure 1. Spectral mapping of a portion of the Oman mantle core at a depth of 370 m (left: color composite from data in the visible; right: classification based on SWIR data). [1] Ramirez et al. (2014), Nat. Geo. 7(1) [2] Kelemen et al. (2020), Proceedings of the Oman Drilling Project [3] Carter et al. (2023), Icarus 389 [4] Greenberger et al. (2021), JGR: Solid Earth 126(8) [5] Crotteau et al. (2021), JGR: Solid Earth 126(11)

The NASA Mars 2020 Perseverance Rover Mission has collected samples of rock, regolith, and atmosphere within the Noachian-aged Jezero Crater, once the site of a delta-lake system with a high potential for habitability and biosignature preservation. Between sols 109 and 1,088 of the mission, 27 sample tubes have been sealed, including witness tubes. Each sealed sample tube has been collected along with detailed documentation provided by the Perseverance instrument payload, preserving geological and environmental context. Samples representative of the stratigraphy within each of four campaigns have been collected: samples from the Crater Floor Campaign represent a suite of potentially petrogenetically related igneous rocks displaying variable degrees of aqueous alteration; samples from the Fan Front record fluvial to deltaic sediments formed by the transport and deposition of materials from the Jezero watershed; regolith samples from the Fan Front preserve material possibly representative of global dust as well as diverse, locally derived clasts; Upper Fan samples record the latest stages of aqueous activity within Jezero; and samples from the Margin Campaign preserve lacustrine, littoral, or possibly igneous processes that may have occurred early in the history of the crater. Along with anticipated samples from the older rocks within the rim of Jezero Crater, Perseverance promises to deliver a suite of samples preserving a diversity of formation environments and ages. Upon return to Earth and analysis in terrestrial laboratories, these samples would address longstanding questions pertaining to the geologic evolution of Mars, its habitability, and the potential for life outside the Earth.

The Mars Sample Return (MSR) Campaign aims to retrieve a set of carefully selected and documented samples collected by NASA's Perseverance rover in and around Jezero Crater on Mars and deliver this set to Earth for comprehensive laboratory analyses. To emphasize the immense scientific return of this unique collection, this work presents a Sample Science Traceability Matrix (SSTM), a systematic framework that aligns each sample with the MSR campaign's defined science objectives, subobjectives, and critical research questions. The SSTM explicitly connects prioritized goals-including geologic history, astrobiology, planetary evolution, and human exploration science-to each of the individual samples gathered in and around Jezero Crater on Mars. This matrix offers a structured, quantitative method to assess each sample's capacity to address key scientific questions, while highlighting synergies across the sample suite and showcasing the overall value of the collection. The SSTM provides a valuable tool for guiding future sample analyses and identifying the most impactful samples that could be collected in the future to complete the set collected by the Mars 2020 mission. It also supports the next phase of Mars sample science and informs strategies for future Mars exploration missions. Key Words: Mars Sample Return-Perseverance-Jezero Crater-Laboratory-Sample collection-Science goals. Astrobiology 25, 725-741.

The Perseverance rover has sampled mm-size lithic fragments containing olivine likely from at least two source regions from the surface of an inactive megaripple surface, and fine-grained material from the surface and to a depth of similar to 4-6 cm. Some of the mm-size grains lack a coherent diffraction pattern measured by PIXL, consistent with the presence of poorly ordered secondary phases that have been altered. Analysis of these materials on Earth will allow examination of materials that have experienced aqueous, potentially habitable environments that could contain biosignatures. Fluorescence of three different patterns was detected, consistent with inorganic emissions from silica defects or rare earth elements in certain mineral phases, although organic origin cannot be excluded. Analysis of Autofocus Context Imager and Wide Angle Topographic Sensor for Operations and eNgineering images of the subsurface material and MEDA thermal inertia measurements indicate average grain sizes of similar to 125 and similar to 150 mu m, respectively, for the bulk material within the megaripple. The fine-grained material in the sampling location indicates chemical compositions similar to previously proposed global components as well as airfall dust. In situ and associated atmospheric measurements provide evidence of recent processes likely including water vapor in soil crust formation. The sampled material will therefore help elucidate the formation of Martian soils; current surface-atmosphere interactions; the composition, shape, and size distribution of dust grains valuable for studies of past and present Martian climate and for assessing potential health and other risks to human missions; and ancient, aqueously altered environments that could have been habitable, and, if Mars contained life, possibly contain biosignatures.

Abstract The Perseverance rover has collected seven oriented samples of sedimentary rocks, all likely older than the oldest signs of widespread life on Earth, at the exposed base of the western fan in Jezero crater, Mars. The samples include a sulfate‐ and clay‐bearing mudstone and sandstone, a fluvial sandstone from a stratigraphically low position at the fan front, and a carbonate‐bearing sandstone deposited above the sulfate‐bearing strata. All samples contain aqueously precipitated materials and most or all were aqueously deposited. Although the rover instruments have not confidently detected organic matter in the rocks from the fan front, the much more sensitive terrestrial instruments will still be able to search for remnants of prebiotic chemistries and past life, and study Mars's past habitability in the samples returned to Earth. The hydrated, sulfate‐bearing mudstone has the highest potential to preserve organic matter and biosignatures, whereas the carbonate‐bearing sandstones can be used to constrain when and for how long Jezero crater contained liquid water. Returned sample science analyses of sulfate, carbonate, clay, phosphate and igneous minerals as well as trace metals and volatiles that are present in the samples acquired at the fan front would provide transformative insights into past habitable environments on Mars, the evolution of its magnetic field, atmosphere and climate and the past and present cycling of atmospheric and crustal water, sulfur and carbon.

Perseverance roverMars 2020 Perseverance rover is currently exploring Jezero Crater on Mars, which contains an ancient lake-delta fan system with a high potential for past habitability. One of Perseverance’s primary science goals is to collect a set of scientifically return-worthy samples for return to Earth (Mars Sample Return; MSR) [1]. Between February 2021 and May 2024, Perseverance has sealed 24 tubes containing 21 rock cores, 2 regolith samples and one atmosphere sample. Of the 17 rock cores and regolith samples, 8 were collected on the crater floor, 9 at the fan front, 3 at fan top and 3 at the Margin. Additionally, 3 witness tube assemblies (WTAs), which will serve as blanks for contamination control, have been sealed. A total of ten tubes have been deposited in a depot in the Three Forks area. All rock and regolith samples are accompanied by a set of observations (Sample Threshold Observation Protocol, the STOP List) performed on abrasion patches or regolith near each sample collection site. These observations are documented in the Initial Reports and the Sample Dossier which are available through the Geosciences Node of the Planetary Data System (https://pds-geosciences.wustl.edu). Samples The eight rock cores collected on the crater floor include samples of the two major rock units of the crater floor, the Máaz formation (basaltic to basaltic-andesite) and the Séitah formation (olivine-cumulate). In addition to the primary igneous mineralogy such as olivine, pyroxene and feldspar, these samples contain alteration minerals such as sulfates, carbonates and perchlorates indicating interaction with liquid water in the past [2]. These samples will be important for understanding Mars igneous history and providing constraints on the timing of Jezero crater and the fan units. The alteration phases in the rocks will enable studies of water-rock interaction within Jezero crater.The seven rock cores collected from the Shenandoah formation at the fan front are all fine-grained sedimentary rocks that were likely deposited in a lacustrine environment [3]. If returned to Earth, these rocks would be the first sedimentary rocks from Mars to be studied in terrestrial laboratories. Three cores (Hazeltop, Bearwallow and Kukaklek) were collected at the layered outcrops Wildcat Ridge and the stratigraphically equivalent Hidden Harbor. These samples are fine-grained sandstones to siltstones and are mainly composed of sulfates and phyllosilicates. They also contain various diagenetic features such as calcium sulfate veins/veinlets (typically anhydrite) and putative concretions. Two cores (Swift Run and Skyland) were collected at the layered outcrop Skinner Ridge. They are medium- to coarse- grained sandstones containing pyroxene, feldspar, carbonates and serpentine. Finally, two cores (Shuyak and Mageik) were collected at the layered outcrop Amalik. They are fine-grained sandstones and mainly composed of olivine grains that have been altered to phyllosilicates, most likely a serpentine phase. There are also carbonates associated with these cores. The phyllosilicates, sulfates and other alteration phases present in the fan front rock cores could potentially have trapped organic matter and other biosignatures originating from the ancient lake or from the Jezero watershed. Thus, these samples will be exceptionally valuable for astrobiological investigations upon return from Mars.The two regolith samples (Atmo mountain and Crosswind) were collected at a megaripple, Observation Mountain, near Amalik at the delta front [4]. The samples consist of different-sized grains of varying compositions including olivine, altered olivine, feldspar, carbonates, sulfates and phosphates. These samples will enable studies of the regolith and dust of Mars.Three cores were collected at the fan top, Melyn, Otis Peak and Pilot Mountain [5]. They are all poorly sorted medium sandstone with clasts ranging up to pebble sizes and believed to be part of the Tenby formation, which likely represents a fluvial environment and overlies the fan front. They contain olivine, feldspar, pyroxene and alteration phases such as Mg-Fe carbonates, Mg-sulfates, Ca-sulfates, phyllosilicates and chlorinated phases. These samples represent some of the coarsest sedimentary material yet sampled by the rover. Their detrital clasts have diverse lithologies likely sourced from the Nili Planum region outside Jezero crater that contains some of the oldest known rocks on Mars (>~4 billion years old). Therefore, laboratory investigations of these samples will enable the study of a source-to-sink sedimentary system on Mars that will inform how surface environments, aqueous processes, and habitability evolved through time, both within the catchment and the fan. Finally, three cores were collected in the Margin unit with two cores collected in the eastern Margin (Pelican Point and Lefroy Bay) and one core in the western Margin (Comet Geyser) [6]. They are all medium to coarse sandstones expect Comet Geyser which could be either a coarse sandstone or aqueously altered igneous rock. The rocks contain a high portion of carbonates with silica as a likely cement. Also present are olivine, pyroxene, minor feldspar, altered silicates and phyllosilicates. The Margin unit has a high astrobiological interest due to its high carbonate signal as observed from space and in-situ and its potential as a shoreline deposit. Parts of carbonates and silica are microcrystalline which make them excellent for biosignature preservation.Perseverance is currently continuing its exploration of the Margin unit with the possible collection of one more sample. After finishing the Margin campaign, the next step is to explore the crater rim which will include some of the oldest rocks on Mars (>~4 billion years old).[1] Farley K.A. et al. Space Science Reviews, 216 (2020), [2] Farley, K.A. et al. Science, 377 (2022), [3] Bosak et al. Lunar Planetary and Science Conference (2024), [4] Hausrath, E.M et al. Lunar Planetary and Science Conference (2023), [5] Weiss B. et al. Lunar Planetary and Science Conference (2024), [6] Siljeström et al. Lunar Planetary and Science Conference (2024)

The Mars Sample Return mission intends to retrieve a sealed collection of rocks, regolith, and atmosphere sampled from Jezero Crater, Mars, by the NASA Perseverance rover mission. For all life-related research, it is necessary to evaluate water availability in the samples and on Mars. Within the first Martian year, Perseverance has acquired an estimated total mass of 355 g of rocks and regolith, and 38 μmoles of Martian atmospheric gas. Using in-situ observations acquired by the Perseverance rover, we show that the present-day environmental conditions at Jezero allow for the hydration of sulfates, chlorides, and perchlorates and the occasional formation of frost as well as a diurnal atmospheric-surface water exchange of 0.5–10 g water per m2 (assuming a well-mixed atmosphere). At night, when the temperature drops below 190 K, the surface water activity can exceed 0.5, the lowest limit for cell reproduction. During the day, when the temperature is above the cell replication limit of 245 K, water activity is less than 0.02. The environmental conditions at the surface of Jezero Crater, where these samples were acquired, are incompatible with the cell replication limits currently known on Earth.

The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here, we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the mission on the crater floor, using the visible and near-infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine-bearing rocks at the bottom of the stratigraphy and high-Ca pyroxene-bearing rocks at the top. This is distinct from the overall low-Ca pyroxene-bearing composition of the watershed of Jezero and points toward an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.

The first samples collected by the Mars 2020 mission represent units exposed on the Jezero Crater floor, from the potentially oldest Séítah formation outcrops to the potentially youngest rocks of the heavily cratered Máaz formation. Surface investigations reveal landscape‐to‐microscopic textural, mineralogical, and geochemical evidence for igneous lithologies, some possibly emplaced as lava flows. The samples contain major rock‐forming minerals such as pyroxene, olivine, and feldspar, accessory minerals including oxides and phosphates, and evidence for various degrees of aqueous activity in the form of water‐soluble salt, carbonate, sulfate, iron oxide, and iron silicate minerals. Following sample return, the compositions and ages of these variably altered igneous rocks are expected to reveal the geophysical and geochemical nature of the planet's interior at the time of emplacement, characterize martian magmatism, and place timing constraints on geologic processes, both in Jezero Crater and more widely on Mars. Petrographic observations and geochemical analyses, coupled with geochronology of secondary minerals, can also reveal the timing of aqueous activity as well as constrain the chemical and physical conditions of the environments in which these minerals precipitated, and the nature and composition of organic compounds preserved in association with these phases. Returned samples from these units will help constrain the crater chronology of Mars and the global evolution of the planet's interior, for understanding the processes that formed Jezero Crater floor units, and for constraining the style and duration of aqueous activity in Jezero Crater, past habitability, and cycling of organic elements in Jezero Crater.

The Perseverance rover landed in Jezero crater, Mars, to investigate ancient lake and river deposits. We report observations of the crater floor, below the crater’s sedimentary delta, finding that the floor consists of igneous rocks altered by water. The lowest exposed unit, informally named Séítah, is a coarsely crystalline olivine-rich rock, which accumulated at the base of a magma body. Magnesium-iron carbonates along grain boundaries indicate reactions with carbon dioxide–rich water under water-poor conditions. Overlying Séítah is a unit informally named Máaz, which we interpret as lava flows or the chemical complement to Séítah in a layered igneous body. Voids in these rocks contain sulfates and perchlorates, likely introduced by later near-surface brine evaporation. Core samples of these rocks have been stored aboard Perseverance for potential return to Earth.

We examine the observed properties of the Nili Fossae olivine-clay-carbonate lithology from orbital data and in situ by the Mars 2020 rover at the S\'e\'itah unit in Jezero crater, including: 1) composition (Liu, 2022) 2) grain size (Tice, 2022) 3) inferred viscosity (calculated based on geochemistry collected by SuperCam (Wiens, 2022)). Based on the low viscosity and distribution of the unit we postulate a flood lava origin for the olivine-clay-carbonate at S\'e\'itah. We include a new CRISM map of the clay 2.38 {\mu}m band and use in situ data to show that the clay in the olivine cumulate in the S\'e\'itah formation is consistent with talc or serpentine from Mars 2020 SuperCam LIBS and VISIR and MastCam-Z observations. We discuss two intertwining aspects of the history of the lithology: 1) the emplacement and properties of the cumulate layer within a lava lake, based on terrestrial analogs in the Pilbara, Western Australia, and using previously published models of flood lavas and lava lakes, and 2) the limited extent of post emplacement alteration, including clay and carbonate alteration (Clave, 2022; Mandon, 2022).

The NASA Mars 2020 Perseverance rover mission will collect a suite of scientifically compelling samples for return to Earth. On the basis of orbital data, the Mars 2020 science team* identified two notional sample caches to study (1) the geology of Jezero crater, collected during the prime mission and (2) the ancient crust outside of Jezero crater, collected during a possible extended mission. Jezero crater geology consists of well-preserved, Early Hesperian to Late Noachian deltaic and lacustrine deposits sourced from a river system that drained Noachian terrain. The crater floor comprises at least two distinct units of sedimentary or volcanic origin whose relationship to the deltaic deposits is presently unclear. Remotely-sensed data reveal signatures of carbonate+olivine and clay minerals within crater floor and crater margin units. Samples from within Jezero that comprise the prime mission notional sample collection thus include: crater floor units; fine- and coarse-grained delta facies, the former with potential to preserve organic matter and/or biosignatures, the latter to possibly constrain the type and timing of sediment deposition; chemical sediments with the potential to preserve biosignatures; a sample of crater rim bedrock; and at least one sample of regolith. The region of southern Nili Planum, directly outside the western rim of Jezero crater, is geologically distinct from Jezero crater and contains diverse Early or even Pre-Noachian lithologies, that may contain records of early planetary differentiation, magnetism, paleoclimate and habitability. The notional sample collection from this region will include: layered and other basement rocks; megabreccias, which may represent blocks of (pre-)Noachian crust; basement-hosted hydrothermal fracture fill; olivine+carbonate rocks that are regionally significant and may be related to units within Jezero crater; and mafic cap unit rocks. The samples described are notional and may change with ongoing surface investigations. However, the samples we anticipate collecting align well with community priorities for Mars exploration, addressing geologic diversity, potential ancient biologic activity on Mars, planetary evolution, volatiles, and human health hazards. *Many other Mars 2020 team members were involved in this planning