Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site

doi:10.1126/science.1172466

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Science 3 July 2009:
Vol. 325. no. 5936, pp. 64 - 67
DOI: 10.1126/science.1172466

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Detection of Perchlorate and the Soluble Chemistry of Martian Soil at the Phoenix Lander Site

M. H. Hecht,¹^,* S. P. Kounaves,² R. C. Quinn,³ S. J. West,⁴ S. M. M. Young,²^, D. W. Ming,⁵ D. C. Catling,⁶^,7 B. C. Clark,⁸ W. V. Boynton,⁹ J. Hoffman,¹⁰ L. P. DeFlores,¹ K. Gospodinova,² J. Kapit,² P. H. Smith⁹

The Wet Chemistry Laboratory on the Phoenix Mars Lander performedaqueous chemical analyses of martian soil from the polygon-patternednorthern plains of the Vastitas Borealis. The solutions contained~10 mM of dissolved salts with 0.4 to 0.6% perchlorate (ClO₄)by mass leached from each sample. The remaining anions includedsmall concentrations of chloride, bicarbonate, and possiblysulfate. Cations were dominated by Mg²⁺ and Na⁺, with smallcontributions from K⁺ and Ca²⁺. A moderately alkaline pH of7.7 ± 0.5 was measured, consistent with a carbonate-bufferedsolution. Samples analyzed from the surface and the excavatedboundary of the ~5-centimeter-deep ice table showed no significantdifference in soluble chemistry.

¹ Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA.
² Department of Chemistry, Tufts University, Medford, MA 02155, USA.
³ SETI Institute, NASA Ames Research Center, Moffett Field, CA 94035, USA.
⁴ Invensys Process Systems, Foxboro, MA 02035, USA.
⁵ Astromaterials Research and Exploration Science Directorate, NASA Johnson Space Center, Houston, TX 77058, USA.
⁶ Department of Earth Sciences, University of Bristol, Wills Memorial Building, Bristol BS8 1RJ, UK.
⁷ Department of Earth and Space Sciences, University of Washington, Seattle, WA 98195, USA.
⁸ Space Science Institute, Boulder, CO 80301, USA.
⁹ Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721, USA.
¹⁰ Department of Physics, University of Texas at Dallas, Richardson, TX 95080, USA.

Present address: Chemistry Department, University of New Hampshire,Durham, NH 03824, USA.

^* To whom correspondence should be addressed. E-mail: michael.h.hecht{at}jpl.nasa.gov

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:

H2O at the Phoenix Landing Site.: P. H. Smith, L. K. Tamppari, R. E. Arvidson, D. Bass, D. Blaney, W. V. Boynton, A. Carswell, D. C. Catling, B. C. Clark, T. Duck, et al. (2009)
Science 325, 58-61
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