Phobos

A mosaic of three separate images of Phobos, taken by Viking 1 on October 19, 1978. The impact crater is called Stickney.

Phobos (/ˈfoʊbəs/ foh-bəs; Greek: Φόβος; Barsoom: Thuria; systematic designation: Mars I) is the larger and closer of the two moons of Mars. After it has been colonized, the capital (so far as it goes) will be Argon City. However, due to its short orbital period and tidal interactions, Phobos's orbital radius is decreasing and it will eventually either impact the surface of Mars or break up into a planetary ring.

It was named for the Greek god of fear, a son of Ares (Mars).