Phobos And Deimos & Mars Environment Deimos by studying: In addition, PADME would assess potential resources (water, organics, regolith) and potential hazards (dust) that Phobos and Deimos might present for future human exploration in Mars orbit. Once in Mars orbit, PADME would carry out 16 flybys of Phobos followed by 9 flybys of Deimos. Flybys would take place at two-week intervals. Flyby altitudes at closest approach to Phobos and Deimos would be ~2 km. Following completion of its primary mission, PADME could remain in high Mars orbit for long-term monitoring of the martian system and search for potential additional moonlets around Mars. Alternatively, PADME could be
Lithobraking launched, including penetrators on the two Phobos probe landers targeted for Mars' moon Phobos and ones for Mars itself on Mars 96 and Deep Space 2, but so far none have succeeded. The cancelled LUNAR-A probe would have carried penetrators to the Moon. Lithobraking as a method for de-orbiting a spacecraft has not been used due to the extremely high orbital velocities of most bodies (e.g. for the Moon it is over 7000 km/h). However, some small moons and asteroids have very low gravity and it could conceivably be used there (e.g. Phobos has an "escape velocity" of 40 km/h.)