Kavli Affiliate: Sara Seager
| First 5 Authors: Daniel Duzdevich, Collin Nisler, Janusz J. Petkowski, William Bains, Caroline K. Kaminsky
| Summary:
Venus has become a target of astrobiological interest because it is
physically accessible to direct exploration, unlike exoplanets. So far this
interest has been motivated not by the explicit expectation of finding life but
rather by a desire to understand the limits of biology. The venusian surface is
sterilizing, but the cloud deck includes regions with temperatures and
pressures conventionally considered compatible with life. However, the venusian
clouds are thought to consist of concentrated sulfuric acid. To determine if
any fundamental features of life as we understand them here on Earth could in
principle exist in these extreme solvent conditions, we tested several simple
lipids for resistance to solvolysis and their ability to form structures in
concentrated sulfuric acid. We find that single-chain saturated lipids with
sulfate, alcohol, trimethylamine, and phosphonate head groups are resistant to
sulfuric acid degradation at room temperature. Furthermore, we find that they
form stable higher-order structures typically associated with lipid membranes,
micelles, and vesicles. Finally, results from molecular dynamics simulations
suggest a molecular explanation for the observed robustness of the lipid
structures formed in concentrated sulfuric acid. We conclude with implications
for the study of Venus as a target of experimental astrobiology.
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