The Life Span and Detectability of Biospheres
Blue Marble Space Institute of Science
The long-term carbon cycle on Earth provides an important thermostat on regulating a habitable climate for life and also underlies the concept of the "habitable zone" for exoplanets, which describes the orbital distance at which a terrestrial planet can maintain above-freezing conditions. In this talk, I will discuss the history of Earth’s biosphere from its formation into the distant future when models predict it will end in about one billion years, which provides a basis for understanding possible habitable exoplanets. I will present results from a hierarchy of climate models that constrain the limits of the habitable zone in an effort to identify exoplanets that would be good candidates to search for life. I will then discuss several candidates for spectral biosignatures and technosignatures that would serve as evidence of extraterrestrial biospheres and could be observed with upcoming missions and future mission concepts.