Preservation of carotenoids in salts and Mars regolith in various conditions

Abstract

The search for life on Mars requires new tools and techniques. Among them, Raman spectroscopy is a powerful and non-destructive method for detecting biosignatures during missions to Mars such as NASA’s Perseverance and ESA/ROSCOSMOS’s Rosalind Franklin rovers. It is therefore important to study the detection possibilities of model biosignatures and their preservation in various conditions over time in order to guide future missions and interpret future data. Cyanobacterial photoprotective pigments (namely carotenoids) have been extensively used as suited targets for such measurements and to serve as biosignature models thanks to their stability and easy identification by Raman spectroscopy. Carotenoid decomposition can be caused by oxidation1 (prevented by higher humidity) and irradiation (prevented by lower humidity2). Carotenoids seem to be decomposing at different rates in different sets of conditions and on different matrices. During the preparation phase of BioSigN (BioSignatures and habitable Niches) we explore the possibility that different matrices enhance or diminish preservation of detectable carotenoid signal under different storage conditions. Both pure molecular β-carotene and cyanobacterium Nostoc sp. (strain CCCryo 231-06) were used.