HR: 10:50h
AN: SA52A-03 INVITED     [Abstracts]
TI: Similarities and Differences in the Nightglows of Venus, Earth, and Mars
AU: * Slanger, T G
EM: tom.slanger@sri.com
AF: Molecular Physics Laboratory SRI International, 333 Ravenswood Ave., Menlo Park, CA 94025 United States
AB: Although the atmospheres of Earth and its sister planets Venus and Mars are quite different, their nightglows have several features in common. These similarities are caused by the fact that all three planets contain N₂ in their atmospheres, and all contain a molecule that photodissociates to give oxygen atoms, i.e. O₂ in the terrestrial case, and CO₂ for Venus and Mars. As a result, we find for example that two-body N + O recombination occurs on all three planets, as we know from terrestrial rocket/satellite observations, the Pioneer Venus results, and the recent observations from the Mars Express mission. The very different rotation periods of Earth and Mars on the one hand and Venus on the other presents no impediment to the generation of these emissions. The long-studied terrestrial 557.7 nm green line is now known to have its counterpart at Venus, with every expectation of observing it at Mars when the visible nightglow is finally studied. The presence of water in the terrestrial atmosphere and that of Mars differentiates them from Venus, and we do not yet know if the strong OH Meinel band emissions of the terrestrial mesosphere are duplicated at Mars, although the necessary chemical ingredients, H-atoms and ozone, are present. Comparative studies of these atmospheres lead to insights that will ultimately be useful as we start to probe the atmospheres of extrasolar planets.
DE: 0310 Airglow and aurora
DE: 5408 Aurorae and airglow
DE: 6225 Mars
DE: 6295 Venus
SC: SPA-Aeronomy [SA]
MN: Fall Meeting 2005