¹E. Clavé et al. (>10)
Journal of Geophysical research (Planets) Link to Article [https://doi.org/10.1029/2022JE007463]
¹CELIA, Université de Bordeaux, CNRS, CEA, Bordeaux, France
Published by arrangement with John Wiley & Sons

Perseverance explored two geological units on the floor of Jezero Crater over the first 420 Martian days of the Mars2020 mission. These units, the Máaz and Séítah formations, are interpreted to be igneous in origin, with traces of alteration. We report the detection of carbonate phases along the rover traverse based on laser-induced breakdown spectroscopy (LIBS), infrared reflectance spectroscopy (IRS), and time-resolved Raman (TRR) spectroscopy by the SuperCam instrument. Carbonates are identified through direct detection of vibrational modes of CO3 functional groups (IRS and TRR), major oxides content, and ratios of C and O signal intensities (LIBS). In Séítah, the carbonates are consistent with magnesite-siderite solid solutions (Mg# of 0.42-0.70) with low calcium contents (<5 wt.% CaO). They are detected together with olivine in IRS and TRR spectra. LIBS and IRS also indicate a spatial association of the carbonates with clays. Carbonates in Máaz are detected in fewer points, as: (i) siderite (Mg# as low as 0.03); (ii) carbonate-containing coatings, enriched in Mg (Mg# ∼0.82) and spatially associated with different salts. Overall, using conservative criteria, carbonate detections are rare in LIBS (∼30/2000 points), IRS (∼15/2000 points), and TRR (1 /150 points) data. This is best explained by (i) a low carbonate content overall, (ii) small carbonate grains mixed with other phases, (iii) intrinsic complexity of in situ measurements. This is consistent with orbital observations of Jezero crater, and similar to compositions of carbonates previously reported in Martian meteorites. This suggests a limited carbonation of Jezero rocks by locally equilibrated fluids.

¹L.Mandon et al. (>10)
Journal of Geophysical research (Planets) Link to Article [https://doi.org/10.1029/2022JE007450]
¹LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, Meudon, France
Published by arrangement with John Wiley & Sons

The Perseverance rover landed in the ancient lakebed of Jezero crater, Mars on February 2021. Here we assess the mineralogy of the rocks, regolith, and dust measured during the first year of the mission on the crater floor, using the visible and near-infrared spectrometer of SuperCam onboard the Perseverance rover. Most of the minerals detected from orbit are present in the bedrock, with olivine-bearing rocks at the bottom of the stratigraphy and high-Ca pyroxene-bearing rocks at the top. This is distinct from the overall low-Ca pyroxene-bearing composition of the watershed of Jezero, and points towards an igneous origin. Alteration mineral phases were detected in most of the rocks analyzed in low proportions, suggesting that aqueous alteration of the crater floor has been spatially widespread, but limited in intensity and/or time. The diverse aqueous mineralogy suggests that the aqueous alteration history of the crater floor consists of at least two stages, to form phyllosilicates and oxyhydroxides, and later sulfates. We interpret their formation in a lake or under deeper serpentinization conditions, and in an evaporative environment, respectively. Spectral similarities of dust with some rock coatings suggest widespread past processes of dust induration under liquid water activity late in the history of Jezero. Analysis of the regolith revealed some local inputs from the surrounding rocks. Relevant to the Mars Sample Return mission, the spectral features exhibited by the rocks sampled on the crater floor are representative of the diversity of spectra measured on the geological units investigated by the rover.

^1,2Wen-Ping Liu,^1,2Wei Yin,³Bin-Long Ye,^1,2Tian-Lei Zhao,⁴Qi-Zhi Yao,^1,3Yi-Liang Li,⁵Sheng-Quan Fu,^1,2,6Gen-Tao Zhou
Icarus (in Press) Link to Article [https://doi.org/10.1016/j.icarus.2023.115440]
¹Deep Space Exploration Laboratory, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China
²CAS Key Laboratory of Crust-Mantle Materials and Environments, University of Science and Technology of China, Hefei 230026, China
³Department of Earth Sciences and Laboratory for Space Research, University of Hong Kong, Hong Kong 999077, China
⁴School of Chemistry and Materials Science, University of Science and Technology of China, Hefei 230026, China
⁵Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China
⁶CAS Center for Excellence in Comparative Planetology, Hefei 230026, China
Copyright Elsevier

Mars has become the preeminent target of astrobiology due to its many Earth-like features. Serpentinized environments on Mars are increasingly of astrobiological interest because they imply the presence of several of the “key elements” for life. The Mars 2020 rover carries a compelling set of spectral instruments with the intent to characterize past habitable serpentinized environments, search for potential biosignatures, and collect samples for potential return to Earth. Reliable spectroscopic identification of serpentinization minerals is, of course, a prerequisite for mission accomplishment. The current assignment of spectroscopic features is based on the databases derived from pure minerals. However, many studies have confirmed that mineral assemblage can complicate spectrum identification, often leading to misinterpretation of the data. Therefore, a rock-based library should be built, which will increase our capability to interpret the Martian spectroscopic data. As such, we performed a comprehensive mineralogical and spectroscopic survey of several rocks sampled from an ophiolite complex in Qaidam Basin, one of the largest Mars analogs on Earth, to build an ophiolite spectral database. X-ray fluorescence (XRF), visible and near-infrared (VNIR), Raman spectroscopy, and XRD were used to identify minerals in the rocks. The results show that serpentine in the rocks with talc could be misinterpreted as sepiolite only relying on the Raman vibrations, while the VNIR spectra can identify serpentine well in all rocks. In addition, the camera and Raman spectrometer on the Mars rover should work together to identify different polymorphs of serpentine, i.e., antigorite, lizardite, and chrysotile. Raman and/or VNIR spectroscopy is effective for other minerals associated with serpentinization, including brucite, dolomite, magnesite, magnetite, talc, and quartz. Our study provides a framework for detecting serpentinization minerals on Mars with spectrometers and can be used for data interpretation by the Mars 2020 mission. All the spectral data presented in the supplementary material facilitate further comparison with future in situ and orbital measurements on Mars.