Comparison of the surface grooves on gaspra and phobos

A morphological analysis of the linear features on asteroids 951 Gaspra and 243 Ida as well as on the Martian moon Phobos is presented. On all of these small bodies there are different groove systems. In every case the most numerous grooves constitute a system with a characteristic direction almost perpendicular to the long axis of the body, and a coverage of the visible surface. It is supposed that these are indications of their layered inner structure. Together with some kind of magnetism discovered at Gaspra and Ida they suggests that these small bodies of the Solar System may originate from the near surface of some ancient, already differentiated planetary bodies of larger dimension.