Evidence That the Reactivity of the Martian Soil Is Due to Superoxide Ions
A. S. Yen,1*
S. S. Kim,1
M. H. Hecht,1
M. S. Frant,2
B. Murray3
The Viking Landers were unable to detect evidence of
life on Mars but, instead, found a chemically reactive soil capable of decomposing organic molecules. This reactivity was attributed to the
presence of one or more as-yet-unidentified inorganic superoxides or
peroxides in the martian soil. Using electron paramagnetic resonance
spectroscopy, we show that superoxide radical ions
(O2-) form directly on Mars-analog mineral
surfaces exposed to ultraviolet radiation under a simulated martian
atmosphere. These oxygen radicals can explain the reactive nature of
the soil and the apparent absence of organic material at the martian
surface.
1 Jet Propulsion Laboratory, California
Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
2 Chemotics Consulting, 131 Westchester Road,
Newton, MA 02458, USA.
3 California Institute of
Technology, Division of Geological and Planetary Sciences, 1200 East
California Boulevard, Pasadena, CA 91125, USA.
*
To whom correspondence should be addressed. E-mail:
Albert.Yen{at}jpl.nasa.gov
