Geology Club Seminar

Theme: Biosignature Detection and the Origins of Life

From essential biomolecules and nutrients to metabolic products, organosulfur compounds are intrinsically linked to all of biology as we currently know it. However, there is a lack of known abiotic and facile pathways to carbon-sulfur bond formation from simple, common precursors. This has generated commonly accepted hypotheses, including that the earliest life must have begun without sulfur and that atmospheric organosulfur gases, such as dimethyl sulfide (DMS), are likely robust signs of extant life on exoplanets. In this talk, I will present results from laboratory experiments meant to broadly represent likely common atmospheric photochemistry of reducing and mildly-reducing planetary atmospheres, including those of the early Earth and perhaps exoplanetary atmospheres. The experiments comprise of far-UV photochemistry of simple gas mixtures (CO 2 , CH 4 , H 2 S, and N 2 ) that yield a variety of organosulfur products, both in the particle phase and the gas phase. These results thus challenge the above-mentioned hypotheses and have broad implications for the environments of the early Earth, biosignatures of exoplanets, and, perhaps, the role of organosulfur in prebiotic chemistry.

For more information, please contact Simon Andren by email at [email protected].