Oxidant Enhancement in Martian Dust Devils and Storms II

The failure of the Viking Life Sciences Experiments to find organics on Mars has been suggested as being due to the presence of oxidants. In particular, hydrogen peroxide (H₂O₂) has been proposed as the most likely oxidizer of the surface of Mars. H₂O₂ was detected in 2003, and the measured mixing ratio, 20-30 ppb, agrees well with global photochemical models. However, this abundance of H₂O₂ is perhaps not large enough to account for the above Viking result. In this presentation, we will discuss a new mechanism that can produce substantially greater abundance of H₂O₂. Delory et al. (see previous companion presentation) have shown that triboelectric fields in martian dust devils and storms may be near 20 kV/m, and have determined the production rates of OH and O- from dissociation of H₂O and CO₂ via electric field driven electrons. Using a chemical model, we calculate that the abundance of H₂O₂ due to electrochemistry in dust devils and storms greatly exceeds that produced photochemically. Since the aeolian processes must have been prevalent throughout the martian geologic history, this effect of H₂O₂ enhancement, together with the large UV radiation reaching the martian surface, implies that the martian surface and near-surface environment are unlikely to be hospitable to life.