Reflectance of Jezero Crater Floor: 2. Mineralogical Interpretation

Abstract

The Perseverance rover, Mars 2020 mission, landed on the surface of the Jezero Crater, on February, 18 th 2021. This Martian crater is suspected to have hosted a paleolake as evidenced by the numerous detections of aqueously-altered phases and thus is a promising candidate for the search for past Martian life. The SuperCam instrument, elaborated by a consortium of American and European laboratories, plays a leading role in this investigation thanks to its highly versatile payload providing rapid, synergistic, fine-scale mineralogy, chemistry, and color imaging. After its landing, the first measurements of Martian targets with the infrared spectrometer of SuperCam (IRS) showed new instrumental behaviors that had to be characterized and calibrated to derive unbiased science data. The IRS radiometric response has thus been calibrated using periodic observations of the Aluwhite SuperCam Calibration Target (SCCT). Parasitic effects were understood and mitigated, and the instrumental dark and noise are characterized and modeled. The reflectance calibrated data products, provided periodically on the NASA Planetary Data System, are corrected from the main instrumental features.

Reflectance of Jezero Crater Floor: 1. Data Processing and Calibration of the Infrared Spectrometer (IRS) on SuperCam

“…The band at 1.9 μm (related to the presence of molecular water) is almost omnipresent in the targets of Séítah and Máaz with a very high BDNR, except in the holey rocks where it is practically absent probably because of photometric effects, see Mandon et al. (2022). On the other hand, the bands diagnostic of specific secondary phases between 2.1 and 2.5 μm are weaker: they are shallower than the 1.9 μm band, which explains the BDNR difference.…”

“…Their detection corresponds to a signal drop on one or two spectral channels. However, most of the detections have a higher BDNR and are unambiguously identified (see Mandon et al., 2022).…”

“…The method for calculating the position and depth of each absorption band is described in Mandon et al. (2022). We summarize here the main results in order to evaluate their accuracy from the calibration results.…”

“…Mandon et al. (2022) provide a complete study of these spectral features and propose various mineral assemblages to explain them. Both units are characterized by the presence of a variety of spectral signatures related to aqueous alteration (1.4, 1.9, and 2.1–2.5 μm bands) but they differ by nature of their alteration minerals: Máaz is dominated by the signatures of Fe‐oxyhydroxides and Fe‐bearing phyllosilicates (2.28 μm Fe–OH band, Table 2), whereas Séítah additionally contains spectral features related to Mg‐bearing phyllosilicates and presumably carbonates (2.3 and 2.5 μm bands, Table 2 3 4).…”

Regolith of the Crater Floor Units, Jezero Crater, Mars: Textures, Composition, and Implications for Provenance

“…The diagnostic 2,000 nm pyroxene band is detected in Jezero by the CRISM imaging spectrometer from orbit, and Horgan et al (2020), using CRISM data to map both low and high Ca pyroxene, showed the region comprising the Máaz formation as being dominated by clinopyroxene. Mandon et al (2022aMandon et al ( , 2022b suggested that an intermediate Ca-pyroxene was a good candidate to explain some of the SuperCam infrared spectra of fine-grained regolith in the Máaz formation. Using both SuperCam LIBS and VISIR data, Cousin et al (2022) and Mandon et al (2022b) have shown that the fine-grained regolith at Jezero is a mixture of minerals containing pyroxene and plagioclase and has a more felsic composition than the coarse-grained regolith.…”