Direct detection of earth-like planets: Physics, techniques, and requirements

NASA's Terrestrial Planet Finder Coronagraph mission seeks the direct detection of terrestrial planets by searching nearby stars in the visible wavelength band. Detecting terrestrial planets is extremely challenging requiring extraordinary suppression of star light, and stability in a complex large optical system. TPF-C uses new coronagraphic techniques for starlight suppression, and adaptive optics for extreme wavefront control. This paper discusses four mayor areas. It discusses planets: what type of stars should be searched, where we should search for planets around those stars, and the characteristics for habitability. Second, it discusses techniques for direct planet detection; these are coronagraphy, adaptive optics, and polarization, using a combination of metal coatings and dielectric material to mitigate polarization. It then discusses the errors that affect the performance of the TPF-C; these errors are dynamic errors such as errors induced by vibrations and thermal inputs. Last and most important is the discussion of the development of a tool we call the TPF-C Error Budget, capable of predicting the performance of the TPF-C; this is done by modeling all the errors that affect its performance, by budgeting those errors to a required level of planet to star contrast.