Scientific rationale for exoplanet characterization from 3-8 microns: the FKSI mission

Abstract

During the last few years, considerable effort has been directed towards large-scale (> $1 Billion) missions to detect and characterize earth-like planets around nearby stars, such as the Terrestrial Planet Finder Interferometer and Darwin missions. However, technological issues such as formation flying, cryocooling, obtaining sufficient null depth for broadband signals, and control of systematic noise sources will likely prevent these missions from entering Phase A until at least the end of the present decade. Futhermore, a large mission like TPF-I will also need the endorsement of the next Astronomical Decadal Survey to obtain a Phase A start in the next decade. Thus, given the present circumstances, we can expect TPF-I to launch no earlier than about 2020 or even as late as 2025. Presently more than 168 planets have been discovered by precision radial velocity survey techniques, and little is known about the majority of them. A simplified nulling interferometer operating in the near- to mid-infrared (e.g. ~ 3-8 microns), like the Fourier Kelvin Stellar Interferometer (FKSI), can characterize the atmospheres of a large sample of the known planets. Many other scientific problems can be addressed with a system like FKSI, including the imaging of debris disks, active galactic nuclei, and low mass companions around nearby stars. We discuss the rationale, both scientific and technological, for a competed mission in the $450-600 Million range, of which FKSI is an example. Such a mission is essential to develop our community and keep the larger community, including young scientists, engaged in the long-term effort towards the detection of Earth-like planets.