what is phobos
Chariot of Fear. Phobos [FOH-bohs] is the innermost of Mars' moons and is the largest. It is closer to its planet than any other moon in the Solar System. It is also one of the smallest moons in the Solar System. Phobos was named after Fear, one of the charioteers of the Roman god, Mars.
(Fear) Phobos is the larger of the two heavily-cratered Martian moons and is dominated by three large craters. The largest of Phobos' craters, Stickney, was named after the wife of Asaph Hall, the astronomer who discovered the moons of Mars. Stickney crater is 10 km in diameter, which is almost half of the average diameter of Phobos!