Seminar: Eddie Schwieterman [UC Riverside]
Earth as a Laboratory for Exoplanet Biosignatures
Oct 25, 2018 11:00 AM to Oct 25, 2018 12:00 PM at Building 8 - Room 241
As the state of exoplanet science moves from exoplanet detection to characterization, we are inching ever closer to studying the atmospheric and surface properties of rocky planets within the “habitable zones” of their host stars. But how would we recognize the signs of habitability and life on a distant exoplanet? We must begin with the only known example of a habitable and inhabited world—our own. Life on Earth, through its gaseous products and reflectance and scattering properties, has left its indelible fingerprints on the spectrum of our planet. But Earth affords more than one glimpse into the prevailing conditions on a life-bearing world. Throughout geologic time the prevailing atmospheric and chemical state of our planet has undergone titanic shifts from a “reducing” methane-rich, oxygen-free biosphere to a heavily “oxidized” pale blue dot with concomitant shifts in its remotely detectable signatures. This presentation will provide an overview of how we can use our understanding of Earth and its atmospheric evolution to study potentially habitable exoplanets. Additionally, I will discuss how coupled climate, photochemistry, and spectral models—developed and validated using the Earth example—can be used to predict the atmospheric properties and spectral signatures of Earth-like planets orbiting other stars with a specific application to our closest exoplanet neighbor, Proxima Centauri b. Such studies are essential for the proper interpretation of future transmission spectra from JWST and inform the design of future mission concepts like LUVOIR, HabEx, and OST.