ODG Facility A-331
From Halopedia, the Halo wiki
The Orbital Defense Stations around Reach are powered by large Orbital Defense Generator facilities. Facility A-331 is one of such facilities. It powered MAC Guns in orbit. The facitity was to be protected by the Spartan team arriving on Reach, but when the Covenant broke through the UNSC lines, the station was bombarded with heavy Plasma, and all Spartans and Marines guarding the facility are assumed dead.
