Atmospheric origins of perchlorate on Mars and in the Atacama
David C. Catlinga b, Mark W. Clairec d, Kevin J. Zahnlee f, Richard C. Quinne g, B. C. Clarkh i, M. H. Hechtj, Samuel P. Kounavesk l m n
- aDepartment of Earth Sciences University of Bristol Bristol UK
- bDepartment of Earth and Space Sciences, Astrobiology Program University of Washington Seattle Washington USA
- cDepartment of Astronomy, Astrobiology Program University of Washington Seattle Washington USA
- dDepartment of Astronomy, Astrobiology Program, University of Washington, Seattle, Washington, USA
- eNASA Ames Research Center Moffet Field California USA
- fNASA Ames Research Center, Moffet Field, California USA
- gSETI Institute Moffett Field California USA
- hSpace Science Institute Boulder Colorado USA
- iSpace Science Institute Boulder, Colorado, USA
- jJPL, California Institute of Technology Pasadena California USA
- kDepartment of Chemistry Tufts University Medford Massachusetts USA
- lDepartment of Chemistry
- m
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Abstract
Isotopic studies indicate that natural perchlorate is produced on Earth in arid environments by the oxidation of chlorine species through pathways involving ozone or its photochemical products. With this analogy, we propose that the arid environment on Mars may have given rise to perchlorate through the action of atmospheric oxidants. A variety of hypothetical pathways can be proposed including photochemical reactions, electrostatic discharge, and gas‐solid reactions. Because perchlorate‐rich deposits in the Atacama desert are closest in abundance to perchlorate measured at NASA's Phoenix Lander site, we made a preliminary study of the means to produce Atacama perchlorate to help shed light on the origin of Martian perchlorate. We investigated gas phase pathways using a 1‐D photochemical model. We found that perchlorate can be produced in sufficient quantities to explain the abundance of perchlorate in the Atacama from a proposed gas phase oxidation of chlorine volatiles to perchloric acid. The feasibility of gas phase production for the Atacama provides justification for future investigations of gas phase photochemistry as a possible source for Martian perchlorate.