Hypothesis Paper Adsorption Water-Related Potential Chemical and Biological Processes in the Upper Martian Surface

Mars Odyssey has given strong evidence for the existence of water in the upper martian sur-face at equatorial latitudes. The water content, which corresponds to the hydrogen in the soil, can regionally reach values up to about 15%. This water is mainly in the form of structurally and partially irreversibly bound “crystal ” water, and of reversibly bound and partially un-frozen adsorption water. This adsorption water, which has “liquid-like ” properties as a two-dimensional fluid or film, can trigger—in the presence of ultraviolet light and in concentra-tions similar to what has been measured on Mars—photocatalytic processes that are important for martian surface chemistry. The consequences of the diurnally variable presence of ad-sorption water on the chemistry and hypothetical biological processes at and in the upper martian surface at equatorial and mid-latitudes are discussed in terms of water-related envi-ronmental aspects for chemical and hypothetical life processes on Mars. Key Words: Liquid-like adsorption water—Martian surface—Adsorption water-triggered chemistry—Adsorption water-based life processes. Astrobiology 5, 770–777