SAM Chlorine Observations at Gale Crater

Pamela Gales Conrad1, Kenneth A Farley2, Paulo Marcos Vasconcelos3, Charles Malespin1, Heather B. Franz4, Amy McAdam5, Brad Sutter6, Jennifer C Stern7, Benton C Clark8, Sushil K Atreya9, Paul R Mahaffy10, Javier Martín-Torres11 and María-Paz Zorzano12, (1)NASA Goddard Space Flight Center, Greenbelt, United States, (2)California Institute of Technology, Pasadena, CA, United States, (3)University of Queensland, St Lucia, QLD, Australia, (4)NASA Goddard Space Flight Center, Center for Research and Exploration in Space Science and Technology, Greenbelt, MD, United States, (5)NASA Goddard Space Flight Center, Planetary Environments Laboratory, Greenbelt, MD, United States, (6)Amentum, NASA Johnson Space Center, Houston, United States, (7)NASA Goddard Space Flight Center, Greenbelt, MD, United States, (8)Space Science Institute, Boulder, CO, United States, (9)University of Michigan Ann Arbor, Climate and Space Sciences and Engineering, Ann Arbor, United States, (10)NASA Goddard Space Flight Center, Planetary Environments Laboratory, Greenbelt, United States, (11)Instituto Andaluz de Ciencias de la Tierra, Granada, Spain, (12)Centro de Astrobiologia, Madrid, Spain
Abstract:
The Sample Analysis at Mars investigation has detected Cl-bearing phases of various oxidation states in its thermally evolved gas measurements of both a wind drift deposit of fines and three different rock samples delivered as sieved drill powders to the instrument suite. In addition to HCl (Leshin et al, 2013; Ming et al, 2013) and chlorinated hydrocarbon detections (Glavin et al, 2013; Freissinet et al, in review), oxygen releases consistent with the decomposition of perchlorate salts are also observed. We have also measured chlorine isotope ratios of the four different solid samples, which yielded variable and more negative δ37Cl than typically observed in SNC meteorite analyses. We summarize our chlorine observations in the context of other gases observed in the SAM solid sample analyses, including water, sulfur- and nitrogen-bearing compounds, and REMS observations of Relative Humidity and Temperature, and compare with knowledge of martian chlorine obtained from the SNC meteorites. Finally, we examine the implications of surface/atmosphere Cl interactions and isotopic ratios for the rise and decline of habitable surface environments on Mars.

This research was supported by the National Aeronautics and Space Administration (NASA) Mars Science Laboratory mission.

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