Assembling Primitive Cells Under Martian Geochemical Conditions: Implications for the Origin and Survivability of Life on Early Mars

Abstract

Mars has been a focus for decades of investigation, as a place in the solar system that could have been habitable for life as we know it. Despite being habitable early in its history, it is important to consider whether Mars could have originated life; a necessary foundation for understanding whether life could have inhabited Mars. Little work has been done to directly apply current knowledge about the origin of life to the unique conditions and planetary history of Mars. This research aims to take into account broad geochemical differences between Mars and Earth, such as Mars’ iron-rich surface, and assess how conducive early Mars was to originating life. Iron, calcium, and magnesium cations are abundant in hydrothermal settings on both Earth and Mars, which constitute promising environments for life’s origin. The impacts of different ionic compositions on the assembly, stability, and destruction of primitive cells have been investigated for this thesis. Additionally, we investigate other components in ancient hydrothermal settings that could have increased the stability and survivability of primitive cells. We find that iron destabilizes primitive cell membrane formation less than does calcium. The concentrations of cations required to completely destabilize primitive membranes are higher than those found in natural settings on Earth, but could potentially have reached these high concentrations on Mars as a consequence of the loss of surface water. In addition, dehydration-rehydration cycles of primitive membranes in the presence of RNA stabilize them against cations in solution. High concentrations of cations in solution thus could have functioned as a significant selective barrier on Mars. Interaction of membrane vesicles and functional polymers, which stabilize primitive cells against changes in the environment, could have been a mitigating factor. This work initiates an avenue of Mars astrobiology research that considers how cellular life may have evolved under the distinct planetary conditions and selective factors on Mars.