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G. T. Delory (U. C. Berkeley), W. M. Farrell (NASA/GSFC), D. D. Sentman (U. Alaska), N. O. Renno, S. K. Atreya, A.-S. Wong (U. Michigan), S. A. Cummer (Duke U.), J. R. Marshall (SETI Inst.), S. C. R. Rafkin (SWRI), D. Catling (U. Washington)
Laboratory studies, numerical simulations, and desert field tests indicate that aeolian dust transport can generate atmospheric electricity via contact electrification or "triboelectricity". In convective structures such as dust devils or dust storms, grain stratification (leading to charge separation) gives rise to an overall electric dipole moment to the aeolian feature, similar in nature to the dipolar electric field generated in terrestrial thunderstorms. Previous simulation studies indicate that this storm electric field on Mars can approach the ambient breakdown field strength of 20 kV/m. In terrestrial dust devils, coherent dipolar electric fields have been measured near 20 kV/m.
Given the expected electrostatic fields in Martian dust devils and storms, electrons in the low pressure CO2 gas can be energized via the fields to values exceeding the electron dissociative attachment energy of both CO2 and H2O, resulting in the formation of new chemical products CO and O- and OH and H- within the storm. Using a collisional plasma physics model, we present a calculation of the CO/O- and OH/H- reaction and production rates. We demonstrate that these rates vary geometrically with the ambient electric field, with substantial production of dissociative products when fields approach breakdown levels 20-30 kV/m. These storm-related chemical products are key ingredients for the generation of oxidants which can ultimately affect the habitability of Mars, as discussed in the following presentation.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.