Astrobiological Potential of Rocks Acquired by the Perseverance Rover at a Sedimentary Fan Front in Jezero Crater, Mars

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.