Serpentinization and Abiotic Methane Formation by Fischer-Tropsch-Type Reactions in Present Martian Conditions: an Experimental Study

Search for life in the Universe is one of the main reasons for space exploration and has been blooming since the 1960’s, as being one of the most fundamental questions for Humankind: “are we alone in the universe?”. For now, extraterrestrial life has not been detected anywhere in the Universe. Nevertheless, the notion of habitability, i.e. the capacity of an environment to sustain life as we know it, has emerged, with the nearest planetary bodies we have access to being the best candidates, particularly Mars due to its many similarities with Earth, including proficient liquid water activity at some point in its history. Liquid water is the main parameter when considering extraterrestrial life since it is a universal solvent and requires temperatures adequate for biological reactions. One way to investigate extraterrestrial life is to look for molecules that are produced by biological activity. As such, an important component has been detected in the martian atmosphere: methane (CH4). On Earth, it is mainly a product of microorganism activity, thus making it a main element for life consideration on Mars. Methane can be a biological product, but it can also be produced by abiotic reactions, with rock-gas-water interactions without life intervention. On Earth, hydrothermal systems such as the ones observed in the abyss sustain ecosystems based on favorable temperature-pressure-pH conditions, and on local production of dihydrogen (H2) and CH4, both used as an energy source by microorganisms. On Earth, these hydrothermal systems are based on serpentinization, a redox reaction oxidizing Fe2+ in mafic minerals (olivine and pyroxene), and which can form serpentine (reaction’s characteristic mineral product), clays, talc, (hydr)oxides, … and H2. In addition to being a potential energy source for microorganisms, this H2 is a fuel for Fischer-Tropsch-Type (FTT) reactions: abiotic gas-rock reactions using a metallic catalyst present in rocks to sustain H2 interaction with a car
Doctorat en Sciences
info:eu-repo/semantics/nonPublished