In situ identification of Palaeoarchaean biosignatures using co-located Perseverance rover analyses: perspectives for in situ Mars science and sample return

The NASA Mars 2020 Perseverance rover is currently exploring Jezero crater, a Noachian locality that once hosted a delta–lake system with high habitability and biosignature preservation potential. Perseverance conducts detailed appraisals of rock targets using a synergistic payload capable of geological characterisation from kilometre to micron scales. The highest-resolution textural and chemical information will be provided by correlated WATSON (imaging), SHERLOC (deep-UV Raman and fluorescence spectroscopy) and PIXL (X-ray lithochemistry) analyses, enabling the distributions of organic and mineral phases within rock targets to be comprehensively established. Herein, we analyse Palaeoarchaean microbial mats from the ~3.42 Ga Buck Reef Chert (Barberton greenstone belt) – considered astrobiological analogues for a putative Martian biosphere – following a WATSON–SHERLOC–PIXL protocol identical to that conducted by Perseverance on Mars during each sampling activities. Correlating deep-UV Raman and fluorescence spectroscopic mapping with X-ray elemental mapping, we show that the Perseverance payload has the capability to detect thermally and texturally mature organic materials of biogenic origin and can highlight organic–mineral interrelationships and elemental co-location at fine spatial scales. We also show that the Perseverance protocol obtains very similar results to high-performance laboratory imaging, Raman spectroscopy and µXRF instruments. This is encouraging for the prospect of detecting micro-scale organic-bearing textural biosignatures on Mars using the correlative micro-analytical approach enabled by WATSON, SHERLOC and PIXL; indeed, laminated, organic-bearing samples such as those studied herein are considered plausible biosignatures for a potential Noachian–Hesperian biosphere and would make compelling targets for sampling during the mission

Aqueous alteration processes in Jezero crater, Mars—implications for organic geochemistry

The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments

Identifying Shocked Feldspar on Mars Using Perseverance Spectroscopic Instruments : Implications for Geochronology Studies on Returned Samples

The Perseverance rover (Mars 2020) mission, the first step in NASA’s Mars Sample Return (MSR) program, will select samples for caching based on their potential to improve understanding Mars’ astrobiological, geological, geochemical, and climatic evolution. Geochronologic analyses will be among the key measurements planned for returned samples. Assessing a sample’s shock history will be critical because shock metamorphism could influence apparent sample age. Shock effects in one Mars-relevant mineral class, plagioclase feldspar, have been well-documented using various spectroscopy techniques (thermal infrared reflectance, emission, and transmission spectroscopy, Raman, and luminescence). A subset of these data will be obtained with the SuperCam and SHERLOC (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals) instruments onboard Perseverance to inform caching decisions for MSR. Here, we review shock indicators in plagioclase feldspar as revealed in Raman, luminescence, and IR spectroscopy lab data, with an emphasis on Raman spectroscopy. We consider how this information may inform caching decisions for selecting optimal samples for geochronology measurements. We then identify challenges and make recommendations for both in situ measurements performed with SuperCam and SHERLOC and for supporting lab studies to enhance the success of geochronologic analyses after return to Earth

Mars Astrobiological Cave and Internal habitability Explorer (MACIE): A New Frontiers Mission Concept

Martian subsurface habitability and astrobiology can be evaluated via a lava tube cave, without drilling. MACIE addresses two key goals of the Decadal Survey 2013–2022) and three MEPAG goals. New advances in robotic architectures, autonomous navigation, target sample selection, and analysis will enable MACIE to explore the Martian subsurface

Aqueous alteration processes in Jezero crater, Mars-implications for organic geochemistry

The Perseverance rover landed in Jezero crater, Mars, in February 2021. We used the Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals (SHERLOC) instrument to perform deep-ultraviolet Raman and fluorescence spectroscopy of three rocks within the crater. We identify evidence for two distinct ancient aqueous environments at different times. Reactions with liquid water formed carbonates in an olivine-rich igneous rock. A sulfate-perchlorate mixture is present in the rocks, which probably formed by later modifications of the rocks by brine. Fluorescence signatures consistent with aromatic organic compounds occur throughout these rocks and are preserved in minerals related to both aqueous environments

SuperCam on the Perseverance Rover for Exploration of Jezero Crater: Remote LIBS, VISIR, Raman, and Time-Resolved Luminescence Spectroscopies Plus Micro-Imaging and Acoustics

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