GREAT SALT LAKE AS AN ASTROBIOLOGY ANALOGUE

Great Salt Lake (GSL) is a hypersaline ecosystem, a model extreme environment, and an analog for salty sites on other space bodies in the Universe, in particular, Mars. On Earth, we see evidence of the minerals left behind when lakes dry up, and these evaporites are key to studying the ancient aquatic ecosystem that was once there. GSL is a critical analog as it provides a modern salt lake at the same location as an ancient evaporate, the Bonneville Salt Flats, which is a halite deposit left from the evaporation of ancient Lake Bonneville. GSL evaporites may be a harbinger for biomarkers in the rock record, or biosignatures, from preserved molecules in the halite and gypsum, which can be used to probe ancient life forms in the paleontological record. These minerals form crystalline structures with fluid inclusions inside, in which biological materials can be stored within the mineral-saturated fluid, offering shelter from potentially damaging processes over geologic time scales in highly protected microenvironments. Molecules from the modern GSL fluid inclusions and those of ancient evaporites on Earth, can provide clues about potential mineral fluids on other space bodies. Which biological molecules can be preserved and for how long? Modern GSL studies in halite and gypsum will help us identify the parameters for preservation in minerals, considering the stability of each type of molecule and the environmental radiation exposure over time. Here we examine the preservation of microorganisms and biological molecules (DNA, RNA, proteins, carbohydrates and lipids) in GSL modern and ancient halite. We correlate our work with potential halophilic microbial life in evaporite and brine sites on Mars. The Earth’s salt lakes, such as GSL, remain powerful analogs to understanding life in high salt, one of the more likely possibilities for life on Mars and elsewhere in the Universe.