X50

X50, designated OR-3-212 e by the Forerunners, is an artificial satellite of the former Forerunner world of Draetheus V. The United Nations Space Command conducted a number of research projects on the moon, in particular the plentiful ice-covered sinkholes in its northern continent. X50 has an icy surface with numerous rocky formations.

History
X50 was a device capable of building and destroying planets, constructed by the Forerunners Miners. It was orbiting the former Forerunner colony of Draetheus V. Following the Human-Covenant War, the United Nations Space Command discovered the Draetheus system and set up a colony on Draetheus V. Numerous research facilities were placed on both the planet and on X50 to study Forerunner artifacts.

Battle of Draetheus V
X50 became a battleground during the Battle of Draetheus V sometime between 2553 and 2557, when Merg Vol's Covenant forces invaded the system, seeking to claim the Forerunner relics present on the planet and the moon for themselves. This engagement saw one of the first major deployments of the SPARTAN-IVs.

The UNSC ground forces on X50 were lead by Spartan Edward Davis. The Covenant forces attacked the UNSC station Research Facility Alpha on Mirror Flats in large numbers, but the UNSC was able to hold their ground. Davis noticed the Covenant's heavy reliance on drop ship insertion on the moon. Spartan Davis realized they would be vulnerable to focused anti-aircraft fire, so, using M9 Main Anti-Aircraft Tanks, he began establishing air defenses west of the facility at a location designated Glacial Perch.

During the battle, the Covenant discovered that X50 was actually a giant Forerunner device that built and destroyed planets. The Covenant attempted to use the device to destroy Draetheus V, but were stopped by Spartan Davis. Although the Spartan managed to stop the artifact before being overrun and killed by a large group of Sangheili, it managed to destabilize the planet. Later, Spartan Sarah Palmer went to the moon to kill Merg Vol and sabotaged the artifact.

Shortly after the battle, the UNSC discovered a looping transmission of low-frequency static from X50. Palmer and UNSC forces returned to the moon to investigate. However, the UNSC quickly realized that Covenant forces remained on the moon. After fighting through numerous Covenant soldiers, Palmer discovered that the message had originated from Davis, moments before his death. She shut the device down in order to allow her friend to pass away peacefully.

Locations

 * Arid Ripple
 * Arid Sea
 * Cistern
 * Basalt Maze
 * Glacial Perch
 * Mirror Flats
 * Research Facility Alpha

Production note
X50's status as a spherical, planet-destroying superweapon is likely an homage to the Death Stars of the Star Wars universe. The superweapon's disguise as a moon may be a nod to Obi-Wan Kenobi's iconic line, "That's no moon. It's a space station." Additionally, the firing sequence of X50's planet-destroying weapon, consisting of several green beams combining into one in the middle, closely resembles that of the main weapon of the Death Stars.

List of appearances

 * Halo: Spartan Assault