Moessbauer spectroscopy in astrobiology

摘要

The redox-active element iron and iron-bearing minerals are thought to have played an essential role in the origin and evolution of life on Earth. Even after the great oxidation event and the removal of almost all dissolved iron from the world's oceans, the biogeochemical iron cycle continues to exert a controlling influence on other elemental cycles such as the global carbon cycle. Mars and Europa are the two bodies in our solar system with the highest astrobiological potential. Iron-bearing minerals have dominated on Mars throughout its history, not least by giving the Red Planet its characteristic colour. It is not unreasonable to think that iron also plays a prominent role in Europa's sub-surface ocean. Mossbauer spectroscopy is a powerful tool to investigate iron-bearing solids. The technique enables the determination of iron oxidation states, the identification of iron-bearing mineral phases, and the quantification of the distribution of iron between oxidation states and mineral phases. Applying Mossbauer spectroscopy in contemporary settings to further elucidate the driving forces behind the biogeochemical iron cycle is essential to understand the processes underlying the origin and evolution of life on the early Earth. From there, the suitability for life of other bodies in our Solar System such as Mars or Europa can be assessed.