PI: Dr. Amy Williams

University of Florida Department of Geological Sciences

9/2023 - Present

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One of the greatest questions of astrobiology is whether life is or was present on Mars. Thus far, surficial exploration with rovers has not yielded irrefutable evidence for life. New research suggests that life maybe found a protected niche in the Martian subsurface in basaltic lava tubes. Craters of the Moon National Monument (CotM) is an Earth-based analog for this lava tube environment. CotM is a large igneous province from Cenozoic flood volcanism that preserves extensive lava tubes. These basalts have similar mineral compositions to Martian basalts. An exciting aspect of CotM geobiology involves the unique microbial communities that have colonized the tubes and precipitate rare salts due to their metabolic reactions. Studies are ongoing to investigate the microbial diversity in these lava tubes, but very little work has been done to connect these communities with their organic molecules preserved as biosignatures. I propose to analyze samples from CotM utilizing pyrolysis gas chromatography-mass spectroscopy (py-GC- MS) and tetramethylammonium hydroxide (TMAH) thermochemolysis to determine what organic molecules are present in these microbially diverse cave environments. This method was selected because the Sample Analysis on Mars (SAM) instrumentation on the NASA Mars Curiosity rover hosts the same capability. Thus, results can be used in collaboration with other studies on the microbes of CotM to provide molecules with a biological context that could allow for better interpretation of SAM results from Mars. 

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Laboratory analyses will be modeled after the methods used on the SAM instrument. Around 10 mg of a sample will be placed into the pyrolysis cup with the same volume of TMAH when running thermochemolysis, and 1μL of C19 to serve as an internal standard. Pyrolysis will be used to isolate acyclic hydrocarbons and TMAH will be used to isolate fatty acids. Both classes of molecules can indicate properties of life in these caves that could be applied to the search for life beyond Earth. Ramped pyrolysis at 35°C/min and flash pyrolysis at 600°C will both be performed. The 600°C flash pyrolysis is most successful at isolating fatty acids with TMAH, but ramped pyrolysis mimics the SAM-like technique. Both methods will be used to determine the limitations or benefits of ramped pyrolysis regarding organics isolated from this type of environment. Five of the twelve samples have been analyzed with TMAH, so they only require pyrolysis analyses; the rest of the sample suite will be analyzed with both techniques.

 

Because life exists in these lava tubes, it is expected that there will be organic compounds in abundance. The goal of this study will be to catalog the compounds detectable in these rare salts with space-flight-like techniques. The hope is that these results in combination with an understanding of the microbial communities in the caves could allow for better interpretation of results from GC-MS analyses on Mars, both with current and future missions. Though the rovers are not currently capable of sampling within caves on Mars, the results of this study will serve to guide future Mars missions on what localities to focus on in the search for life beyond Earth.

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