37th DPS Meeting, 4-9 September 2005
Session 57 Moon, Mercury and Venus
Poster, Thursday, September 8, 2005, 6:00-7:15pm, Music Recital Room

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[57.16] Comparative sulfur chemistry of Venus and Mars

A. S. Wong, S. K. Atreya (University of Michigan)

The atmospheric chemistry of Venus is dominated by sulfur species, whereas no trace of sulfur in any form has yet been been found in the Martian atmosphere. Nevertheless, possibility of localized plumes of SO2 or H2S, or both on Mars cannot be ruled out, especially in view of the recent detection of trace quantities of methane. Wong et al. (2003, 2005) studied the fate and distribution of sulfur species from any such ``hotspots" on Mars using a photochemical model. We now extend this model to Venus. Due to the large opacity, solar UV photons do not penetrate to denser parts of the Venusian atmosphere to dissociate SO2/H2S/COS. Hence, on Venus the sulfur ``photochemistry" occurs primarily above 50 km. On the other hand, thermochemical processes near the surface of Venus are responsible for supplying the SO2, H2S, and COS gases to the upper atmosphere. In this presentation we compare the photochemical modeling results of Venus with Mars, emphasizing the sulfur chemistry as it might have relevance also to primordial Martian atmosphere.

Wong, A.S, Atreya S.K., Encrenaz, T., JGR 108(E4), 5026, 2003; Wong, A.S, Atreya S.K., Encrenaz, T., (an update of above), JGR, 2005, in press.

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Bulletin of the American Astronomical Society, 37 #3
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