Constraining The Odd-Hydrogen Chemistry In The
Atmosphere Of Mars With The Exomars Trace Gas Orbiter
J. Alday, J. A. Holmes, M. R. Patel, J. P. Mason, School Of Physical Sciences, The Open University, Milton
Keynes, Uk (Juan.Alday@Open.Ac.Uk), A. Trokhimovskiy, A. A. Fedorova, D. A. Belyaev, O. Korablev,
Space Research Institute (Iki), Moscow, Russia, F. Lefèvre, F. Montmessin, L. Baggio, A. S. Braude,
Latmos, Guyancourt, France, K. S. Olsen, P. G. J. Irwin, Aopp, Department Of Physics, University Of Oxford, Uk, C. F. Wilson, European Space Research And Technology Centre (Estec), Noordwijk, Netherlands.
Al., 2013).
Introduction:
Odd-Hydrogen (Hox) Species Such As Oh And
Ho2 Have A Key Role In Regulating The Chemistry Of
The Atmosphere Of Mars. This Role Was First Evidenced By The Slow Recombination Rate Of The
Photolysis Products Of Co2 (I.E., Co + O), Which
Required A Catalytic Pathway To Maintain A 95% Co2
Atmosphere On Mars. Mcelroy & Donahue (1972)
And Parkinson & Hunten (1972) Demonstrated That
The Stability Of Co2 In The Martian Atmosphere Holds
Due To Reactions Of Its Photolysis Products With Hox
(Co + Oh  Co2 + H), Evidencing The Importance
Of These Photochemical Species In The Composition Of
The Atmosphere.