Prospects for High-Contrast Imaging of Rocky Exoplanets from Space: Coronagraphy and External Occulters
N. Jeremy Kasdin

With the combined results of radial velocity surveys and Kepler, we now know that there is an abundance of planets, particularly small, rocky planets. These data provide tantalizing hints that there are many Earth-sized planets in the Habitable zones of nearby stars. This has provided momentum to development efforts on technology for directly imaging planets in reflected light from a space observatory. Such direct imaging could not only detect planets, but perform spectroscopy to characterize their atmospheres. These technologies fall into two categories: coronagraphs that uses internal optics to separate the planet light form the diffracted starlight and external occulters that block the stellar light before entering the telescope but allow the planet light to pass. Coronagraphs need only a single telescope, but must be accompanied by complicated wavefront control systems. Occulters can use simple telescopes with no stability or control requirements, but involve two separate spacecraft flying in formation and a large screen built to exacting precision. In this talk I will describe efforts at Princeton, along with colleagues at JPL, to raise the technology readiness of both approaches. I will also describe the various NASA design studies underway for a potential mission this coming decade.