Infrared Coronagraph for the Terrestrial Planet Finder Mission I: Overview and Design Concept

摘要

NASA wants to launch a Terrestrial Planet Finder (TPF) mission in 2014 to detect and characterize Earth-like planets around nearby stars, perform comparative planetology studies, and obtain general astrophysics observations. The detection of a 30~(th) magnitude planet located within 80 milli-arcseconds of a 5~(th) (Visual) magnitude star is an exceptionally challenging objective. Observations in the thermal infrared (7-17 μm) are somewhat easier since the planet is 'only' 15~m fainter than the star at these wavelengths, but many severe challenges must still be overcome, including: ·Designing a spacecraft, a telescope and an IR coronagraph for star-planet separations equal to λ/D ·Providing a stable (～50K) thermal environment for the optics and isolating them from vibration sources ·Developing a deployment scheme for a 28-m space telescope that can fit in an existing launch vehicle ·Minimizing telescope mass to enable launch to L2 or a driftaway orbit with a single launch vehicle ·Generating a manufacturing plan that will permit TPF to be developed at a reasonable cost and schedule. ·Identifying the key enabling technologies for TPF The paper describes the IR Coronagraph we designed during our recent TPF Mission Architecture study in an effort to meet these challenges.