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[57.12] Venus Middle Atmosphere Chemistry

F.P. Mills (RSPhysSE and CRES, ANU), M. Sundaram (RSPhysSE and Physics, ANU), T.G. Slanger (SRI International), M. Allen (JPL, Caltech), Y.L. Yung (Caltech)

Venus is the most similar planet to Earth, and years of research have sought to understand their similarities and differences. Yet, it is still not clear what chemical processes maintain the long-term stability of Venus’ primarily CO₂ atmosphere. CO₂ dissociates into CO and O after absorbing photons at wavelengths < 210 nm. These O atoms should combine to form O₂, and observations of intense airglow confirm rapid production of O₂ on both day and night sides. CO and O₂ are sufficiently stable that an initially pure CO₂ atmosphere would rapidly evolve to have 7-8% CO and 3.5-4% O₂ [1]. The observed upper limit on O₂ (0.3 ppm [2]), however, indicates catalytic mechanisms [3], rapidly convert CO and oxygen into CO₂. The current understanding of Venus middle atmosphere chemistry, the state of lab data, and prospects for advances based on Venus Express will be reviewed. Recent work evaluating newly proposed mechanisms for producing CO₂, which could be important depending on the rates of poorly constrained reactions, will be described.

This research was supported by funding from NASA's Planetary Atmospheres program and the Australian Research Council. Part of this work was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.

[1] Nair, et al., Icarus 111, 124 (1994), [2] Trauger and Lunine, Icarus 55, 272 (1983), [3] Pernice, et al., PNAS 101, 14007 (2004)

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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.