Diffractive Interfero Coronagraph Exoplanet Resolver (DICER): Detecting and characterizing all Earth-like exoplanets orbiting Sun-like stars within 10 pc

We propose a novel space observatory designed to find and characterize habitable, Earth-like planets around all Sun-like stars within 10 parsecs, using technology that could conceivably be available in the near future. At 10pc, the diffraction limit requires a telescope more than 20m in diameter to resolve the Earth from the Sun. We achieve the diffraction limit of a 20m telescope by collecting the light with two similar to 10m primary objective gratings. Even with a collecting area of this size, and even if the telescope operates in the infrared (10 mu m) where the ratio of planet brightness to star brightness is maximized, a coronagraph is required to reduce the contrast between the host star and the planet. We collect the light near grazing exodus from each grating with two similar to 3.5m secondary optical elements that focus the light on an adaptation of an Achromatic Interfero Coronagraph. The light from the host star that is incident on one of the two primary objective gratings is nulled by the light from the other primary objective grating. With this optical design, a small piece of the emission spectrum from the planet is observed. This optical design is easier to launch into space than a monolithic 20m telescope, and would provide orbital periods, semimajor axes, and infrared luminosities for the discovered planets. By observing several small wavelength ranges (sampling on each side of and in the absorption line) with gratings of differing pitch, we could potentially estimate surface temperature and detect ozone absorption in the infrared.