Effects of UV and Calcium Perchlorates on Uracil Deposited on Strontium Fluoride Substrates at Mars Pressure and Temperature.

Organic matter is actively searched on Mars with current and future space missions as it is a key to detecting potential biosignatures. Given the current harsh environmental conditions at the surface of Mars, many organic compounds might not be preserved over a long period as they are exposed to energetic radiation such as ultraviolet light, which is not filtered above 190 nm by the martian atmosphere. Moreover, the presence of strong oxidizing species in the regolith, such as perchlorate salts, might enhance the photodegradation of organic compounds of astrobiological interest. Because current space instruments analyze samples collected in the upper surface layer, it is necessary to investigate the stability of organic matter at the surface of Mars. Previous experimental studies have shown that uracil, a molecule relevant to astrobiology, is quickly photolyzed when exposed to UV radiation under the temperature and pressure conditions of the martian surface with an experimental quantum efficiency of photodecomposition (φ