Imaging unresolved rotating asteroids

Most asteroids subtend extremely small angles in the sky so it is impossible to directly discern either surface reflectivity, shape variations, or the spin axis using existing ground-based telescope systems. A super-resolution inversion technique relates the lightcurves of a rotating asteroid, which is represented as a polyhedron with planar surface facets, to the unknown radial vertex distances. Any number of lightcurves at different aspect angles can be incorporated into the formalism. Generalizations to delay-Doppler echo radar imaging are also discussed, as well as some of the issues associated with these inversion methods.