^{1,2 3}M.Millan et al. (>10)
Joournal of Geophysical Research (Planets) (in Press) Open Access Link to Article [https://doi.org/10.1029/2021JE007107]
¹Department of Biology, Georgetown University, Washington, DC, USA
²NASA Goddard Space Flight Center, Solar System Exploration Division, Greenbelt, MD, USA
³Laboratoire Atmosphère, Observations Spatiales (LATMOS), LATMOS/IPSL, UVSQ Université Paris-Saclay, Sorbonne Université, CNRS, Guyancourt, France
Published by arrangement with John Wiley & Sons

The Sample Analysis at Mars (SAM) suite instrument on board NASA’s Curiosity rover has characterized the inorganic and organic chemical composition of seven samples from the Glen Torridon clay-bearing unit. A variety of organic molecules were detected with SAM using pyrolysis (up to ∼850°C) and wet chemistry experiments coupled with evolved gas analysis (EGA) and gas chromatography-mass spectrometry (GCMS). SAM EGA and GCMS analyses revealed a greater diversity and abundance of sulfur-bearing aliphatic and aromatic organic compounds in the sediments of this Gale crater unit than earlier in the mission. We also report the detection of nitrogen-containing, oxygen-containing, and chlorine-containing molecules, as well as polycyclic aromatic hydrocarbons found in Glen Torridon (GT), although the sources of some of these organics may be related to the presence of chemical reagents in the SAM instrument background. However, sulfur-bearing organics released at high temperature (>600°C) are likely derived from martian sources (e.g., igneous, hydrothermal, atmospheric, or biological) or exogenous sources and consistent with the presence of recalcitrant organic materials in the sample. The SAM measurements of the GT clay-bearing unit expand the inventory of organic matter present in Gale crater and is also consistent with the hypothesis that clay minerals played an important role in the preservation of ancient refractory organic matter on Mars. These findings deepen our understanding of the past habitability and biological potential of Gale crater.

¹G. Schmidt,²E. Luzzi,²A.P. Rossi,³M. Pondrelli,¹A. Apuzzo,¹F. Salvini
Journal of Geophysical Research (Planets) (in Press) Link to Article [https://doi.org/10.1029/2022JE007320]
¹Department of Science, Università degli studi Roma Tre, Rome, Italy
²Department of Physics and Earth Sciences, Jacobs University Bremen, Bremen, Germany
³International Research School of Planetary Sciences, Università d’Annunzio, Pescara, Italy
Published by arrangement with John Wiley & Sons

The formation of layered mounds on Mars remains a major topic of debate, with the relationship between their deposition and chemical alteration a major aspect still to be constrained. The association these deposits have with hydrated minerals indicates aqueous processes were active in their past, however the extent and duration of this aqueous period has yet to be fully realized. We studied compositional, stratigraphical, and structural characteristics of two separate layered deposits within Becquerel crater, Arabia Terra, to constrain their origins and the intensity of past aqueous activity. We find that due to key differences in composition, layering, and deformation between the two deposits, the timing of important depositional changes within Becquerel can be identified. We propose a scenario involving differences in fluid expulsion intensity and water level between the two layered deposits, in which diverse depositional and post-depositional environments were able to form. Furthermore, internal collapsing and deformation of the main mound might reflect that fluid upwelling persisted below the mound after formation. Determining the relationship between these two deposits is an important step in unraveling the past climate of Arabia Terra, and more broadly Mars. The evidence of protracted fluid expulsion represents a unique opportunity for future missions searching for signs of past life.