MULTIRESOLUTION-ELEMENT IMAGING OF EXTRASOLAR EARTHLIKE PLANETS

It has been suggested recently that imaging of extrasolar Earthlike pl anets should be considered as a possible future goal of the NASA space program. As an aid to discussing what would be required in order to u ndertake imaging, a partial design is described for a separated spacec raft interferometer which could achieve images in the visible with 10 resolution elements across the planet. Between 15 and 25 large collect or telescopes or clusters of telescopes spread out over roughly a 200- km baseline in solar orbit at 1 AU from the Sun or possibly in high Ea rth orbit are required. A very preliminary approach to the use of mult ispectral remote sensing techniques is discussed also. Finally, the ge neralization of this approach to larger numbers of resolution elements across the planet is considered. Clearly, imaging is possible only if the truly staggering problem of avoiding the 10(10) times stronger sc attered light from the nearby star can be overcome. However, even if t his can be done, the amount and precision of the required hardware for even poor-quality images appears to present an obstacle to such a pro gram which would be extremely difficult to overcome.