Beyond Kepler: Direct Imaging of Earth-like Exoplanets

Is there another Earth out there? Is there life on it? People have been asking these questions for over two thousand years, and we finally stand on the verge of answering them. The Kepler space telescope has already revealed that many stars have planets close to Earth size in regions close to their habitable zones. The next natural step after Kepler is spectroscopic characterization of exo-Earths, which would tell us whether they possess an atmosphere, oxygen, liquid water, as well as other biomarkers. In order to do this, directly imaging an exo-Earth may be necessary (at least for Sun-like stars and small planets).

Directly imaging an exo-Earth is challenging and may require a 4m flagship-size optical space telescope with a high contrast imaging system (a coronagraph or starshade) capable of achieving contrasts of 1e10 very close to the diffraction limit. Such a telescope will probably not be launched until the 2030s. On the path towards that mission, NASA may launch smaller missions, ranging from Explorer class to coronagraphic instruments on a 2.4m telescope. In addition, if there is an Earth around Alpha Centauri (the closest star system to the Sun), it may be possible to detect and take its spectrum with a telescope as small as ~25cm. The Ames Coronagraph Experiment group at NASA Ames has been successfully maturing high contrast imaging technologies and mission concepts, which Rus will describe in his talk.

Speaker: Ruslan Belikov, NASA Ames