Methane is a central molecule in astrobiology: it is a potential biosignature, a key intermediate in planetary redox cycles, and a tracer of water–rock interactions on Earth and beyond. On our planet, some of the most compelling natural laboratories for methane production and consumption occur in water–rock-hosted ecosystems formed during the geological process of serpentinization, where the resulting reduced, hyperalkaline fluids, low in dissolved inorganic carbon, and abundant hydrogen can mix with more oxidized fluids to create strong energetic disequilibria. These environments provide a window into how microbial life persists under extreme geochemistry that may resemble conditions on early Mars and within possible subsurface oceans of icy worlds such as Enceladus.

In this seminar, I synthesize insights from field and laboratory studies that integrate geochemical modeling, methane isotopic analysis, and microbial genomic studies of methane cycling in terrestrial serpentinizing systems of the Samail ophiolite in Oman to examine how microbial methanogenesis and methanotrophy operate at the extremes of carbon availability, pH, and energy supply. I focus on how microbial metabolisms respond to water–rock-reaction-driven chemistry, how methane isotopic signatures are generated and modified under these conditions, and what these patterns reveal about the coupling between geochemistry, physiology, and ecosystem function.

I then translate these Earth-based observations into an astrobiology framework, asking what methane can—and cannot—tell us about life in ocean-world environments. By integrating constraints on chemical energy, isotopic fractionation, and metabolic adaptation, this talk will highlight how studying methane cycling in water–rock-hosted ecosystems can refine life-detection strategies, inform interpretation of planetary methane measurements, and bridge fundamental astrobiology with broader questions about habitability across the solar system.

*Refreshments: 10:30 AM - 11:00 AM (ES&T L1175)