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Communication Dans Un Congrès Année : 2010

Possible oxidants at Mars surface and their impact on organic matter

Résumé

In 1976, the Viking probes did not provide any results demonstrating the presence of extant life or even organic molecules in the soil samples collected at their landing sites, unlikely to what it could be expected at that time. The results obtained by the biological experiments on board of Viking probes have been discussed for a long time. The most relevant hypothesis is the presence of oxidants in the martian soil. Klein et al. (1978) proposed different oxidizing agents among which “superoxides”, hydrogen peroxide and iron oxides. The presence of H2O2 has been confirmed by its detection in the atmosphere (Clancy et al. 2004; Encrenaz et al. 2004). Moreover, the recent detection of perchlorate by the Phoenix mission confirms the oxidants hypothesis (Hecht et al. 2009). We propose here a review of oxidants potentially present in the martian environment, focusing on their formation pathways and their reactivity on organic molecules. It appears that a synergy between atmosphere, soil, UV radiation and water ice content in the soil could lead to the formation of very reactive species able to degrade organic matter at the surface. Several oxidants could diffuse or directly be formed in the subsurface and thus potentially lead to organic degradation in depth (see the figure). This review work could give guidelines on the oxidizing potential of the martian surface/subsurface and could estimate the stability of organic matter under these conditions. Based on this review work, we have developed an experimental device (MOMIE for Martian Organic Molecules Irradiation and Evolution) to simulate the formation of oxidants in the martian environment and their impact on organic matter. This laboratory experiment will help to determine the fate of organic matter at the martian surface and to define the most relevant detection protocol to highlight organic molecules at Mars by the future in-situ missions. Clancy, R.T., et al., 2004. Icarus 168:116-121 ; Encrenaz, T., et al., 2004. Icarus 170:424-429 ; Hecht, M.H., et al., 2009. Science 325:64-67 ; Klein, H.P., 1978. Icarus 34:666-674.

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Dates et versions

hal-04115188 , version 1 (02-06-2023)

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A. Noblet, P. J. Coll, Cyril Szopa, F. Stalport. Possible oxidants at Mars surface and their impact on organic matter. American Geophysical Union Fall Meeting 2010, Dec 2010, San Francisco California, United States. pp.abstract id.P13B-1385. ⟨hal-04115188⟩
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