X50

X50 is a artificial satellite of the former Forerunner world of Draetheus V. The UNSC conducted a number of research projects on the moon, in particular the plentiful ice-covered sinkholes in its northern continent. 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 's SPARTAN-IV contingent.

During the battle, the Covenant discovered that X50 was actually a giant Forerunner device that built and destroyed planets. The Covenant used the device to destroy Draetheus V, but were stopped by the Spartan Davis. Although the Spartan managed to stop the artifact, it managed to destabilize Draetheus V. Later, the Spartan Sarah Palmer went to the moon to kill Merg Vol and destroy the artifact.

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."

List of appearances

 * Halo: Spartan Assault