Abrasion Patch Dehydration Experiment at Bright Angel, Jezero Crater, Using SuperCam Onboard the Mars 2020 Perseverance Rover

Kurzfassung

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 H2O 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.