Pegasi Delta

Pegasi Delta is a small world in the 51 Pegasi System. The surface of the planet was made of red rocks and sand. Orange dust permeated the sky and had a faint yellow sun, 85 Pegasi-194A around which the world orbited. It had seas that were unusually rich in Deuterium and Tritium which the Covenant used in their plasma reactors, and it was used to refuel their ships.

History
During the Human-Covenant War, the Covenant forces constructed a massive refinery on Pegasi Delta. With its close proximity to UNSC space, Pegasi Delta became a massive forward resupply and refueling line for the Covenant ships making incursions in UNSC space.

The UNSC tried many times to neutralize the refinery, using nukes dropped from slipspace. However, the plutonium that lined the nukes let off an aura of Cherenkov radiation upon reentering normal space, which therefore made the nukes stealth coatings useless. The Covenant easily found and destroyed the nukes. Similarly, there were too many Covenant ships near the planets moon to send a slow, distantly launched nuke. Neither a regular invasion force or Helljumpers were worth the attempt.

In 2545, the UNSC sent in 300 Spartan-III super-soldiers from Beta Company to destroy the refinery in Operation: TORPEDO. They successfully destroyed the refinery, crippling the Covenant supply lines, but came out with the apparent death of 296 out of the 300 Spartans of Beta Company. Because of this, Lucy-B091, one of the three surviving Spartans, was so shocked from the incident that she became mute and could not (or chose not to) speak anymore.

Known locations

 * Target Area Apache

Trivia

 * Pegasi Delta is the UNSC designation for the Covenant colony. It is likely that the Covenant had their own name or designation for it, unrelated to that used by the UNSC.
 * In the novel Ghosts of Onyx it is stated that Only two of the 300 survived, but two other survivors are stated to be Kat-B320 and Spartan-312 of noble team in Halo: Reach