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Photochemical Escape of Oxygen from Early Mars

Status Report From: arXiv.org e-Print archive
Posted: Friday, January 23, 2015

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Jinjin Zhao, Feng Tian

(Submitted on 19 Jan 2015)

Photochemical escape is an important process for oxygen escape from present Mars. In this work, a 1-D Monte-Carlo Model is developed to calculate escape rates of energetic oxygen atoms produced from O2+ dissociative recombination reactions (DR) under 1, 3, 10, and 20 times present solar XUV fluxes. We found that although the overall DR rates increase with solar XUV flux almost linearly, oxygen escape rate increases from 1 to 10 times present solar XUV conditions but decreases when increasing solar XUV flux further. Analysis shows that atomic species in the upper thermosphere of early Mars increases more rapidly than O2+ when increasing XUV fluxes. While the latter is the source of energetic O atoms, the former increases the collision probability and thus decreases the escape probability of energetic O. Our results suggest that photochemical escape be a less important escape mechanism than previously thought for the loss of water and/or CO2 from early Mars.

Subjects:Earth and Planetary Astrophysics (astro-ph.EP)

DOI:10.1016/j.icarus.2014.12.032

Cite as:arXiv:1501.04423 [astro-ph.EP] (or arXiv:1501.04423v1 [astro-ph.EP] for this version)

Submission history

From: Jinjin Zhao 

[v1] Mon, 19 Jan 2015 08:59:03 GMT (1142kb)

http://arxiv.org/abs/1501.04423

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