Speaker
Description
The atmosphere of Mars is CO2 dominated at lower altitudes, below around 225-250km altitude. Through multiple photochemistry paths, the dominant ion species is O2+. Dissociative recombination of O2+ ions produces neutral O atoms which have sufficient energy to escape from the planet. The amount of oxygen lost over geological time periods due to this process is very large(several meters of equivalent water over the surface). In this talk we describe the results of an investigation of how photochemical loss of O from Mars is altered when the N2 and NO neutral densities are enhanced over current abundances. Higher N2 and NO density profiles lead to higher N2+ density, and more importantly, higher NO+ density, and thus, lower O2+ density. But the dissociative recombination of NO+ does not produce atomic O atoms that exceed the escape energy. Additionally, higher abundances of N2 would lead to more neutral-neutral collisions between N2 and O, which would lead to energy loss of hot O atoms. Thus, for a Mars atmosphere (or a Mars-like exoplanet) atmospheric loss could be inhibited with higher atmospheric N2 abundances.
| Talk Credit? | Yes |
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