Phobos was one of the two natural satellites of Mars, the other being Deimos. Its name means "fear" in Greek.
The first humans to arrive on it were a team of the First Hundred led by Arkady Bogdanov upon the arrival of the Ares in Mars space. During their initial settlement, they domed Stickney crater. They also secretly placed a system of remote controlled guidance jets that could drive Phobos out of its orbit and burn it in the atmosphere. At that time it was used as a communications satellite.
It was later used as a weapons platform by UNOMA and transnational forces. Arkady gave the remote control to the jets to Nadia Cherneshevsky, who used them and destroyed Phobos during the First Martian Revolution in 2061.