Orbital defense platform

An Orbital Defense Platform was a small UNSC space station used to defend locations of great importance. Many stations were placed in a geosynchronous orbit over planets. Primary armament was a Mk. V "Super" MAC gun, capable of causing severe damage to even a shielded Covenant warship with a single hit.

Facilities
Internally, the stations were remarkably spacious, complete with high ceilinged common areas and a monorail system to move personnel and equipment. In addition to numerous small craft bays there were two docks for larger ships, such as freighters or even frigates. The design incorporated many features against potential hostile boarding action, including security stations and small arms racks situated at strategic locations.

Reach
By August 2552, Reach was protected by twenty Super MAC platforms powered by planetside generators. During the Battle of Reach, marines and Spartans were deployed to protect these powerplants but were ultimately unable to do so against determined enemy assaults. The disabling of the defense platforms was a major factor on the battles outcome.

Earth
The outbreak of the Human-Covenant War prompted a massive expansion of Earth's defenses. Even as late as the Battle of Reach preparations had not yet been completed. By October 2552, some 300 ODPs were operational. Many of Earth's ODPs were named after points of interest that they roughly kept station over.

A portion of the 300 platforms saw action at the First Battle of Earth. Athens Station and Malta Station were each destroyed by an Anti-Matter Bomb placed by Covenant boarding parties, with Cairo Station narrowly avoiding the same fate.

The ODPs would again fire in anger at the Second Battle of Earth.