Self-Sterilizing Properties of Martian Soil: Possible Nature & Implications

As a result of the Viking missions in 1970s, the presence of a strong oxidant in Martian soil was suggested. Here we present a testable, by near-term missions, hypothesis that iron(VI) contributes to that oxidizing pool. Ferrate(VI) salts were studied for their spectral and oxidative properties and biological activities. Ferrate(VI) has distinctive spectroscopic features making it available for detection by remote sensing reflectance spectra and contact measurements via Mössbauer spectroscopy. The relevant miniaturized instrumentation has been developed or is underway, while XANES spectroscopy is shown to be a method of choice for the returned samples. Ferrate(VI) is capable of splitting water to yield oxygen, and oxidizing organic carbon to CO₂. Organic oxidation was strongly abated after pre-heating ferrate, similar to the observations with Mars soil samples. Using UV spectra and PCR studies, it was shown that ferrate(VI) destroys genetic material in the form of nucleotides or nucleic acids, as well as amino acids in proteins. This imposes severe limitations on the location of life as we know it on Mars, due to self-sterilizing properties of its soil.