Deimos

deimos photo – NASA

Deimos is the smaller and outermost of Mars' two moons, also discovered in 1877. It is the smallest known moon in the solar system, only 12.6 km in diameter. In Greek mythology, Deimos is one of the sons of Ares (Mars) and Aphrodite (Venus). Deimos is the Greek word for "panic".

 Deimos and Phobos are composed of carbon-rich rock and ice. Both are heavily cratered. Deimos and Phobos are probably asteroids perturbed by Jupiter into orbits that allowed them to be captured by Mars.