Multi-spectroscopic detections of hydrated-silica in the Jezero crater

Introduction: Hydrated silica has been detected from orbit in Jezero crater Tarnas et al., 2019 and holds great promise for the astrobiology science goals of the M2020 mission and the MSR Program. Early entombment within an hydrated silica matrix has been shown to minimize the molecular degradation of microorganisms during advanced diagenesis Alleon et al., 2016a,b; Alleon et al., 2018. On sol 0910, a float rock was automatically selected by the AEGIS system after a rover drive when entering the margin unit from the Jezero delta top. The target is a light-toned partially buried float with lustrous appearance. LIBS: The chemistry of 9/10 points reveal a homogeneous composition, enriched in SiO2. The average SiO2 for these 9 points is 75.0 wt.% while the average total of quantified oxides is 83.5 wt. %. VISIR reflectance: The reflectance spectra share an overall blue slope, and exhibit absorptions at 1.9 m (H2O), 2.2 m (X-OH) and 1.4 m (OH H2O). The chemistry derived from LIBS (mean Al2O3 500 targets), but may be linked to high SiO2 points observed in the carbonate-rich delta bedrock units. Based on IR, this rock seems more akin to a micro-crystalline type silica, in contrast to previous observations of silica from the ground. Such a target may have trapped and preserved biosignatures, together with unique information on the paleoenvironmental conditions of the Jezero crater.