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Photochemistry and evolution of Mars' atmosphere: A Viking perspective

McElroy, Michael B. and Kong, Ten Ying and Yung, Yuk Ling (1977) Photochemistry and evolution of Mars' atmosphere: A Viking perspective. Journal of Geophysical Research, 82 (28). pp. 4379-4388. ISSN 0148-0227. doi:10.1029/JS082i028p04379.

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Viking measurements of the Martian upper atmosphere indicate thermospheric temperatures below 200°K, temperatures much colder than those implied by remote sensing experiments on Mariner 6, 7, and 9 and Mars 3. The variability in thermospheric temperature may reflect an important dynamical coupling of upper and lower regions of the Martian atmosphere. Absorption of extreme ultraviolet solar radiation can account for observed features of the ionosphere and provides an important source of fast N and O atoms which may escape the planet's gravitational field. Isotopic measurements of oxygen and nitrogen impose useful constraints on models for planetary evolution. It appears that the abundance of N_2 in Mars' past atmosphere may have exceeded the abundance of CO_2 in the present atmosphere and that the planet also has copious sources of H_2O. The planet acquired its nitrogen atmosphere early in its history. The degassing rate for nitrogen in the present epoch must be less than the time-averaged degassing rate by at least a factor of 20.

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Yung, Yuk Ling0000-0002-4263-2562
Additional Information:© 1977 by the American Geophysical Union. Received April 21, 1977; revised June 8, 1977; accepted June 8, 1977. Paper number 7S0558. This work was supported by the National Aeronautics and Space Administration under grant NAS-1-10492 and by the National Science Foundation under grant NSF-ATM75-22723, both to Harvard University. We are indebted to E. Anders, T. Owen, and S. Wofsy for illuminating discussions.
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Issue or Number:28
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Official Citation:McElroy, M. B., T. Y. Kong, and Y. L. Yung (1977), Photochemistry and evolution of Mars' atmosphere: A Viking perspective, J. Geophys. Res., 82(28), 4379–4388, doi:10.1029/JS082i028p04379
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:49267
Deposited By: Tony Diaz
Deposited On:05 Sep 2014 22:28
Last Modified:10 Nov 2021 18:41

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