The Perseverance rover landed in Jezero crater on Mars, which once contained a lake of liquid water. We report the rock properties encountered by Perseverance during a 10-kilometer traverse extending over 400 meters in elevation, from beneath Jezero's western sedimentary fan to the upper crater rim. These rocks consist of coarse-grained olivine, magnesium and iron carbonates, silica, and phyllosilicates, including some of the oldest materials exposed within Jezero. We infer that these rocks formed by olivine accumulation in an igneous system of layered intrusions, followed by exposure to water and carbon dioxide, which caused extensive carbonation of the silicate minerals. Aqueous alteration was more pronounced at lower elevations. Higher-elevation exposures on the crater rim appear similar to olivine-rich rocks distributed over the wider Nili Fossae region.

We report the in situ detection of amorphous hydrated silica in the Bills Bay abrasion patch, located in the eastern portion of the Margin Unit between the rim of Jezero crater and the western delta. Here, hydrated silica co-occurs with olivine, Fe-Mg carbonates, secondary Fe-Mg silicates, and hydrated Mg-sulfate as determined by UV Raman (SHERLOC) and X-ray fluorescence (PIXL) spectrometers onboard the Perseverance rover. Almost pure hydrated silica fills the intergranular space between olivine and carbonate-bearing domains. We performed Raman analysis of terrestrial opals with various crystallinities including opal-AN, AG, CT, and C. We found that the Si−O symmetric stretching Raman band at ∼800 cm−1 is sensitive to opal crystallinity, yet insensitive to ambient temperature (at ∼77–293 K) and silica hydration. We identified the crystal structure of the Bills Bay Hydrated Silica (BBHS) as opal-A. Furthermore, we developed a Raman methodology to quantify opal-A hydration. We found that the total amount of hydration in the BBHS phases was 1.7 ± 0.2 wt. %. Most of this hydration, 1.5 ± 0.2 wt. %, reflects the presence of silanol groups. Our analysis revealed that the Raman spectrum of BBHS closely resembles that of opal-A that has lost most of its molecular water. The composition and textures of the Bills Bay abrasion indicate that BBHS is derived from olivine carbonation. Opal-A is the only silica polymorph identified in the SHERLOC data. We hypothesized that silica precipitation occurred, either during the late stages of a major carbonation event or during a brief, subsequent aqueous alteration event unrelated to carbonation

Returning surface samples from Mars to Earth has been a major planetary science objective, with the potential for the detection of microbiological life and the possibility of improving our understanding of the origins of life. The National Aeronautics and Space Administration and the European Space Agency assembled a team to assess the level of risk that returned samples could contain potential biohazards. The team was chartered with optimizing previous sample safety assessment strategies, defining what constitutes a biological hazard, developing a protocol to test for biohazards, and establishing a statistical framework to determine if samples may be safe for release from a high-containment facility. This report presents the biological context for a proposed three-step protocol for testing returned samples, including how to determine if microorganisms are present, and if they could be (or were recently) alive.

Doublet fluorescence at 304 and 325-nm under deep ultraviolet (DUV) excitation was detected on Mars at Jezero crater by the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument onboard the Mars 2020 rover Perseverance. The doublet was associated with CaSO4 phases and sourced to organic molecules as the preferred interpretation (Sharma et al., 2023, https://doi.org/10.1038/s41586-023-06143-z). Reported here are coordinated analyses of terrestrial volcanogenic samples that have, under DUV excitation, intrinsic 304 and 325-nm fluorescence whose origin is tightly sourced to anhydrite:Ce3+ (trace-Ce3+ for Ca2+ substitution in natural anhydrous CaSO4). Thermal decomposition products of natural volcanogenic gypsum (CaSO4·2H2O) and sedimentary glauberite (Na2Ca(SO4)2) by aerial heating at more than 450°C and more than 600°C, respectively, are also characterized by 304 and 325-nm fluorescence doublets that are sourced from anhydrite:Ce3+ thermal decomposition products. The 304 and 325-nm doublet fluorescence detected by SHERLOC is fully explainable by inorganic anhydrite:Ce3+ resulting from geogenic processes. The volcanogenic samples are products of leaching and precipitation in hydrothermal environments. Leachates can precipitate in many ways, including intimate or proximal contact with residues and, after aqueous transport, as vein precipitate, fracture fill, and evaporite deposits. Equivalent considerations extend to hydrothermalism driven by impact melts and other thermal sources. Laboratory thermal decomposition of progenitor phases to anhydrite:Ce3+ is an analogous process for contact and burial metamorphism. The coordinated analysis approach additionally includes major element and REE abundances (X-ray fluorescence and inductive coupled plasma—mass spectrometry), X-ray diffraction, DUV Raman spectroscopy, and thermal analysis (thermal gravimetry, differential scanning calorimetry, and evolved gas analysis)

The presence of fossilised fungi within deep crustal rock formations has been established based on fossil evidence from 400 Ma continental crust and 81 Ma oceanic basaltic crust. Moreover, the Palaeoproterozoic Ongeluk Formation contains putative fungal remains reaching 2.4 Ga. The resulting gap of 2 billion years raises questions regarding the history of fungi in marine subsurface environments, in particular the lack of bona fide fossils in ophiolites, sections of layered basalts from mid-ocean ridges. Devonian examples of cryptoendolithic microorganisms preserved in marine pillow basalt stem from the Arnstein locality, Rheinisches Schiefergebirge, and the Kahlleite locality, Thüringer Wald, Germany, and have previously been described as filaments of microorganisms with uncertain biological affinity. The filamentous fossils were investigated using environmental scanning electron microscopy, Raman spectroscopy, confocal microscopy, widefield microscopy, and optical light microscopy. Energy dispersive spectroscopy analyses of several of the inferred microfossils revealed a presence of clay minerals, pointing to a mode of mineralisation in association with organic matter and agreeing with a biological origin. Raman spectroscopy showed carbon localised within the studied filaments and revealed that particularly iron oxide minerals are associated with carbon. Element compositions similar to younger mineralised fungal remains and morphologies resembling sporophores and hyphae agree with the interpretation of the Arnstein and Kahlleite fossils as marine fungi, shedding new light on many of the previously undetermined fossils and plausibly narrowing the fossil gap of oceanic deep subsurface fungi by at least 300 million years

Using a Raman spectrometer onboard the Perseverance rover, we report the heterogeneous distribution of organic carbon within mudstones located in an ancient river valley on Mars. Measurements of two mudstones show hundreds of organic detections, making this the most robust organic detection in Jezero crater thus far, and, to our knowledge, the only detection of macromolecular carbon on a natural rock surface on Mars. Spectra of the interior of one rock reveal an association of organics with secondary carbonate and sulfate minerals, whereas another rock exhibits an association of organics with primary silicate-dominated matrix. Although in situ Raman analyses cannot determine whether these organics denote abiotic or biotic sources, the organic association with both depositional and diagenetic minerals and the detection of organics on the martian surface suggests that the organics observed ubiquitously at the Bright Angel outcrop may be resistant to radiation and oxidation or have been relatively recently exposed. copyright

Investigating the stability of hydrated minerals is integral for examining the preservation of rocks for potential Mars Sample Return and has major implications for models that use rover-based observations to quantify Mars' global water budget. The Mars 2020 Perseverance rover produces abrasion patches to investigate fresh rock surfaces at Jezero crater, Mars. However, due to operational constraints, the full analysis process typically takes several martian days (sols), and freshly exposed hydrated minerals may dehydrate upon atmospheric exposure between abrasion patch creation and their analyses. To assess the potential for short-term dehydration, the SuperCam instrument conducted the first in situ rover-based dehydration experiment on rock exposures of the “Bright Angel formation.” The SuperCam and SHERLOC rover instruments indicated that the primary mineral hydration phases were Fe-hydroxides, Ca-sulfates such as bassanite (mixed with anhydrite), with possible minor contributions from non-interlayer-water phyllosilicates (e.g., hydroxyl-bearing only). The experiment involved a four-sol sequence of observations on the Steamboat Mountain abrasion patch, beginning just 22 min after abrasion. Dehydration was assessed by tracking changes in the 1.93 μm H<inf>2</inf>O absorption feature, which is sensitive to structural, absorbed, and adsorbed water. No significant changes in hydration were observed over the 93 hr, suggesting that the exposed minerals were already in a low hydration state and/or exhibit high stability under current martian surface conditions. These findings imply bulk rocks with low hydration and high stability minerals may not dehydrate upon exposure to the modern martian atmosphere on short time scales, consistent with predictions from laboratory simulations of Mars-like environments

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 ∼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 ∼125 and ∼150 μm, 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.

The search for organic molecules on Mars is central to understanding the planet’s past habitability and potential for ancient life. Although organic molecules have previously been detected on Mars, their nature, origin and preservation mechanisms remain debated. On the floor of the Jezero crater—an ancient delta–lake system on Mars—the Perseverance rover detected Raman features that may be due to organic compounds spatially associated with sulfates, although their origin is uncertain. Here we report the detection of similar Raman features in the Jezero fan top and attribute them to polycyclic aromatic hydrocarbons based on comparisons with laboratory data. We propose that these polycyclic aromatic hydrocarbons may have formed through endogenous igneous processes and were subsequently preserved by sulfate precipitation. These findings align with previous studies on Martian meteorites and at Gale crater, underscoring the role of sulfates in preserving organic matter on Mars. Returning these samples to Earth would be key to assess their astrobiological relevance.