Working models for the gravitational field of Phobos

Models for the gravitational field of Mars moon Phobos were developed using the latest shape model and assuming homogeneous density distribution. Three methods were applied in our study. Comparisons were made between these methods and all were shown to yield consistent results. Notably, the most accurate shape model of Phobos to date, complete up to degree and order 17 was used for the first time in our analysis. A set of spherical harmonic coefficients up to degree and order 17 were derived for the gravitational field of Phobos. Also considered was the gravitational field on the surface of Phobos. Typical characteristics as well as some pronounced surface features of this irregular-shaped small body could be conveniently identified. The results are readily applicable for such purposes as spacecraft orbit analysis and assessing the dynamical environment of Phobos.