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Project Progress

We have been working on two separate, but related, projects. The first is concerned with predicting the concentration and climatic impact of methane in Earth’s early atmosphere. Work performed by former graduate student Alex Pavlov and colleagues Matt Hurtgen and Mike Arthur here at Penn State has shown that methane concentrations could have been high during the Mid-Proterozoic, as well as during the Archean. This could explain Mid-Proterozoic warmth and could provide a trigger for Neoproterozoic Snowball Earth events if methane levels were to suddenly decline near the end of this period. Current work by graduate student Pushker Kharecha, in collaboration with biologist Janet Siefert at Rice, is focused on estimating methane fluxes from an anaerobic Archean biosphere.

Our other major project has been a collaboration with Vikki Meadow’s VPL Astrobiology group. Former student Kara Krelove and current postdoc Antigona Segura have run coupled photochemical-climate simulations of Earth-like planets with various amounts of O₂ in their atmospheres circling different types of stars (F2V, G2V, and K2V). Vikki and her colleagues have produced simulated visible and thermal-infrared (IR) spectra of these atmospheres. The goal is to build up a library of spectra of possible Earth-like planets for future use in interpreting data from NASA’s proposed Terrestrial Planet Finder (TPF) mission. A second goal is to produce estimates of surface ultraviolet (UV) fluxes on such planets and determine what constraints these might provide on biological evolution.