Model Crystals to Test Techniques in Astrobiological Exploration of Evaporites on Mars

Introduction: The search for life on Mars involves many potential strategies for the analysis in situ of surface samples or the analysis of returned samples in a controlled environment, in particular analyses seek evidence of tangible life and/or biomolecules. It is important to develop mineralogical standards suitable for testing the techniques that will be used for these analyses. Evaporites have been previously suggested as potential hosts to microbial life on Mars [1]. In particular much interest has recently been focused upon evaporite deposits that are associated with impact crater lakes [2]. For example, the feature on Mars known as White Rock is believed to be a potential evaporite deposit contained within an impact crater site as it appears as a significant albedo feature within orbital camera images. Within Martian evaporite basins the mineralogy may include epsomite (hydrated magnesium sulphate), gypsum (hydrated calcium sulphate) and halite (sodium chloride). Halite and epsomite are therefore of particular relevance to astrobiology. They both occur in Martian meteorites [3] and are thought to be a significant component of Martian soils [4]. It is important to investigate the astrobiological potential of such evaporite minerals and we have undertaken an experimental study of halite and epsomite. These minerals are ideal candidates for laboratory experiments as they have a high solubility and can be readily precipitated. The study was particularly concerned with the entrapment of organic materials within fluid inclusions.