Venus in the Context of Exoplanet Demographics

The prime focus of astrobiology research is the search for life elsewhere in the universe, and this proceeds with the pragmatic methodology of looking for water and Earth-like conditions. In our solar system, Venus is the most Earth-like planet, yet at some point in planetary history there was a bifurcation between the two: Earth has been continually habitable since the end-Hadean, whereas Venus became uninhabitable. Indeed, Venus is the type-planet for a world that has transitioned from habitable and Earth-like conditions through the inner edge of the Habitable Zone (HZ); thus it provides a natural laboratory to study the evolution of habitability. A parallel approach to studying the intrinsic properties of Venus and its evolutionary history is a statistical analysis of the vast (and still rapidly growing) inventory of terrestrial exoplanets. Characterizing the atmosphere of numerous terrestrial planets and will provide critical insight into the prevalence of Venus analogs and the possible diversity of their atmospheric chemistry. In this presentation, I will describe how the current limitations in our knowledge of Venus are impacting present and future exoplanetary science, including remote sensing techniques that are being or will be employed in the search for and characterization of exoplanets. I will discuss Venus in the context of defining the boundaries of habitability, and how exoplanets are enabling tests of potential runaway greenhouse regimes where Venus analogs may reside. I will discuss specific outstanding questions regarding the Venus environment and the relevance of those issues to understanding the atmospheres and interior structure of exoplanets.