[Previous] | [Session 43] | [Next]
R.C. Quinn (SETI Institute), A.P. Zent (NASA Ames Research Center)
The return and analysis of pristine material that is relict of a putative period of chemical evolution is a fundamental goal of the exobiological exploration of Mars. In order to accomplish this objective, it is desirable to find oxidant-free regions where pristine material can be accessed at the shallowest possible depth (ideally directly from the surface). The objective of our ongoing research is to understand the spatial and temporal distribution of oxidants in the martian regolith and the redox chemistry of the soil; in effect, to understand the chemical mechanisms and kinetics relating to the in-situ destruction of organics and the formation of the reactive species responsible for the Viking biology results. Variety of electrophilic oxygen species with differing stability and chemical reactivity can form on the surface metal oxides when exposed to gaseous oxidants or irradiated by UV light. The role of these adsorbed oxygen species in the catalytic oxidation of organic compounds has been extensively explored. In addition to the potential role these types of reactions may play in the in-situ destruction of organics on Mars, we believe that the GEx oxidant may likewise be accounted for by adsorbed oxygen species. If highly reactive adsorbed oxygen species are present in the martian regolith, it likely that they may play a dominate role in both the chemical weathering of the surface material as well as the destruction of organic compounds. In this work, we report on experimental studies of oxidizing processes which may operate on either organics or soil minerals on Mars. The oxidizing processes examined include: gas-phase oxidants, UV photolysis, and UV-assisted heterogeneous catalysis. This work is supported by the NASA Research in Exobiology Program.