Enhancing the Characterization of Extrasolar Planets via Direct Detection with a Coronagraphic Terrestrial Planet Finder
Eric B. Ford (University of Florida)
The direct detection of extrasolar planet will enable the characterization of planet's physical properties. Such research will provide valuable context for interpreting the physical properties of planets in our own solar system. While extreme adaptive optics at large ground-based observatories and intermediate-scale space missions may be capable of directly detecting some giant planets, large spaced-based observatories appear to offer the best prospects for directly detecting and characterizing distant Earth-like planets. Previous designs for Terrestrial Planet Finder missions were constrained by the physical size of currently available launch vehicles. Should larger launch vehicles become available, the design of large space missions optimized for planet characterization should be revisited. Clearly, a larger collecting area would reduce the integration times needed to search for terrestrial mass planets and increase the practical temporal/spectral resolution of observations performing follow-up characterization. In this talk, I will outline several additional benefits. For example, a larger aperture would allow for surveys of a larger number of stellar/planet targets, both because of the increased collecting area and the reduced inner working angle.
Thus, planets in the habitable zones of more distant stars and more nearby sub-solar-mass stars could become accessible. Further, when operated in detection mode, the number of epochs needed to obtain a significant null detection would be significantly reduced. As another example, a larger aperture could enable near infrared observations of planets in the habitable zone of a modest number of nearby stars, even with a monolithic observatory. If combined with appropriate instrumentation, increasing the aperture to allow for observations extending to two microns could enable searches for several new absorption bands, including those due to water, carbon dioxide, methane, and perhaps even ammonia. Such extended spectral range could provide valuable information that would greatly aid the spectroscopic characterization of terrestrial planets, particularly given the relatively low spectral resolution and signal to noise that are inevitable for such challenging observations.