CONSIDERATIONS FOR DETECTING AND PRESERVING BIOSIGNATURES IN UNSTABLE SULFATE MINERALS

Sulfate minerals discovered on Mars have provided valuable insights into the planet's geological history and their potential to preserve biosignatures. This study addresses the challenge of detecting and preserving biosignatures in unstable sulfate minerals, specifically mirabilite (Na₂SO4∙10H₂O), a Mars-analog mineral that forms in Utah's Great Salt Lake, USA. Hydrated sulfate minerals pose challenges in maintaining their stability during lab analyses due to rapid dehydration, sometimes occurring within minutes depending on environmental conditions. Our focus is on developing optimal, non-destructive preparation methods for mirabilite using commonly available laboratory supplies. The goal is to prevent dehydration to enable the utilization of advanced microscopy and spectroscopy, including transmitted light, UV-vis light, and laser Raman. Through simple experiments, we visually assess the degree of dehydration in mirabilite chips over a span of one month, comparing various methods: chips exposed to open air as a baseline, chips with a drop of water or Great Salt Lake brine, chips coated in mineral oil, acetate, or cyanoacrylate (super glue), chips sealed in plastic wrap, chips sealed within a sample chamber with a drop of brine, and chips submerged in mineral oil. Our results indicate that sample chips sealed within a sample chamber or submerged in mineral oil exhibit the least dehydration over the long term, making them the most effective in preserving biosignatures, particularly within fluid inclusions. These findings can inform future research on mirabilite and the preservation and storage of other hydrated minerals for the study of biosignatures. Furthermore, they contribute to the exploration of life beyond Earth and provide essential insights for the Mars Return Sample and future Mars missions.