The unusual dynamical environment of Phobos and Deimos

The nonintuitive dynamical environment of Phobos and Deimos is explored using a three-dimensional numerical model. Surface gravity, escape speeds, and ejecta impact contours are calculated, both for the satellites at their present orbit distances and for orbit distances they may have had in the past. Impact loci for Stickney ejecta are computed and compared with the observed groove locations in order to evaluate a possible secondary impact origin for the grooves on Phobos. Possible effects of the dynamical environment on shaping the satellites' surfaces are discussed.