Survivability of D. radiodurans, Halobacterium sp. NRC-1 and Its Mutants, Cyanobacterium Chroococcidiopsis sp. 029, and Escherichia coli Bacteria in Theorized Atmospheric Conditions on the Surface of Ancient Mars




Ewell, Mary

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Life on the Martian surface today is unlikely due to its thin atmosphere, although the possibility of extinct and subsurface life is possible and therefore, life on ancient Mars is an open question. Martian morphology and mineralogy indicate that Mars had surface water and active volcanoes in the past, which together imply warmer climates. Sulfur species have been linked to an increased greenhouse e ect and o er additional UV shielding. Previous studies have used pulsed inputs of atmospheric sulfur species modeling the ancient Martian surface during periods of volcanic erup- tions but leaving open the e ect of atmospheric sulfur species during quieter periods of surface outgassing. Using surface mineralogy data from landers and orbiters, to- tal volcanic sulfur deposition was estimated and an averaged upward ux for sulfur species found for the lifetime of volcanic activity on Mars. Using a one-dimensional photochemical model, concentrations of plausible atmospheric constituents including sulfur species were calculated to model di erent atmospheric conditions in Martian history. The amount of UV shielding obtained from the models determine UV sur- vivability of Earth life. Earth bacteria D. radiodurans and cyanobacteria Chroococ- cidiopsis sp. 029 and an Archaean halophile sp. NRC-1 are shown as likely UV survivors in the modeled 350mbar atmosphere but questionable survival is found in thinner modeled atmospheres. Finally, reported surface data was used to determine likely surface locations on Mars for chosen microorganisms.



Mars atmosphere, Survivability, UV radiation, Ancient Mars