Study of the Stability of Gly·MgSO4·5H2O under Simulated Martian Conditions by In Situ Raman Spectroscopy.

Identification of spectroscopic fingerprints that correspond to relevant molecules/minerals in a Mars-like environment is a crucial search in astrobiology. Therefore, we studied the stability of Gly·MgSO4·5H2O under Mars-like surface conditions and compared it to the behavior of epsomite and glycine. Gly·MgSO4·5H2O has been identified as a molecule of astrobiological interest since an amino acid and water molecules, which are essential for life, are part of its structure. Furthermore, this compound may form by the interaction of sulfate minerals with glycine-bearing aqueous solutions, and both could be present on Mars. The main analyses were performed by using in situ Raman spectroscopy, a ground-breaking technique for NASA and ESA Mars planetary missions. We have integrated a Raman spectrometer in a Planetary Atmosphere and Surfaces Chamber (PASC) and have identified the processing of molecules exposed to a simulated martian atmosphere, UV irradiation, and temperature. Our results show that pressure is critical to provoke amorphization of Gly·MgSO4·5H2O, and the release of glycine from the compound; the stabilization effect at low temperature and stability of Gly·MgSO4·5H2O is greater than to glycine and epsomite. The strategy employed here allows us to evaluate the effect of diverse simulated martian environmental conditions on molecular preservation by using Raman spectroscopy.