HR: 11:50h
AN: P32B-03 INVITED    [Abstracts]
TI: Electrical Processes on Mars: New Sources and Sinks for Atmospheric Chemistry?
AU: * Delory, G T
EM: gdelory@ssl.berkeley.edu
AF: Space Sciences Laboratory, 7 Gauss Way, MS 7450, Berkeley, CA 94720, United States
AU: Farrell, W M
EM: farrell@faltraz.gsfc.nasa.gov
AF: Laboratory for Extraterrestrial Physics, NASA Goddard Space Flight Center, Greenbelt, MD 20771, United States
AU: Atreya, S K
EM: atreya@umich.edu
AF: Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, United States
AU: Marshall, J
EM: jmarshall@seti.org
AF: SETI Institute, 2035 Landings Drive, Mountain View, CA 94043, United States
AB: In nature, nearly all processes involving the lofting and transport of dust lead to significant electrification through the phenomenon of triboelectricity, in which macroscopic charge separation occurs due to particle contact and friction. Thus active disturbances in the Martian atmosphere such as dust devils and storms are leading candidate mechanisms that could maintain substantial surface electric fields, in analogy with terrestrial thunderstorms. Given the importance of terrestrial lightning in chemical processes such as Nitrogen fixation, a natural question then becomes whether or not the likely presence of electrified dust on Mars has any impact on atmospheric chemistry. While the existence of electric discharges on Mars has yet to be verified, we have shown that the mere presence of a pre-discharge electric field will energize free electrons in Mars` atmosphere, which subsequently dissociate carbon dioxide and water at rates that rapidly increase with electric field strength. One important consequence of these reactions is the possibility for oxidants to be produced in large quantities. In addition, both the energized electrons and the molecules they dissociate can act as a sink for trace species such as Methane. We discuss the theoretical framework for our approach, in which the Martian atmosphere is treated as a weakly-ionized, highly collisional plasma. We will also discuss how the more general problem of chemistry associated with discharges may be approached on Mars, and compare these mechanisms with terrestrial electrochemical processes, where the generation of new products may be dominated more by thermal timescales and "freezing-out" effects.
DE: 2419 Ion chemistry and composition (0335)
DE: 3304 Atmospheric electricity
DE: 3324 Lightning
DE: 5210 Planetary atmospheres, clouds, and hazes (0343)
SC: Planetary Sciences [P]
MN: 2007 Fall Meeting