Installation 03

Installation 03, also known as Gamma Halo,  is one of the seven rings in the Halo Array. Its monitor is 049 Abject Testament. The ring appears to have a red and cracked surface, indicating the presence of vast deserts, as well as volcanic activity.

Unlike Installations 04 and 05, which orbit large gas giants, Installation 03 was originally anchored in orbit around a rocky planet, the face of which has been shattered as a result of a fairly recent impact event; the debris from the impact, still aglow as of 2557, has collected to form a dense asteroid field in orbit over the planet as well as the Halo.

Forerunner-Flood war
Shortly before the activation of the Halo Array at the end of the Forerunner-Flood war, the IsoDidact convened a meeting of the surviving Lifeworkers and the monitors who would serve as the rings' caretakers at Installation 00. 049 Abject Testament was designated as Gamma Halo's monitor and was given the Halo's activation index. Along with the other six rings, Installation 03 was fired, killing all sentient life within its effective radius. Afterwards, it entered an inactive state along with the rest of the Array.

Discovery
During the Battle of Tribute in August 2552, the freighter Floral Express fled the planet while carrying colonial refugees. Presumably following a random slipspace trajectory per the Cole Protocol, the ship arrived near Installation 03 on October 8. Based on intelligence gleaned from the Battle of Installation 04, ONI teams had established and enacted neutralization protocols on Gamma Halo by October 25.

Standby and deactivation
On November 3, 2552 during the Battle of Installation 05, a signal was sent to this Halo from Installation 05, putting it on standby mode and preparing it to fire on demand. On December 11, 2552, the installation was still in standby mode and was about to be fired at the behest of the High Prophet of Truth, who had seized Installation 00's control room. However, the Array was deactivated by Spartan John-117 and the Hierarch was assassinated by Arbiter Thel 'Vadam before this could occur.

Post-war
By March 2553, the top-secret research station Ivanoff had been built in Installation 03's orbit. That month, Dr. Catherine Halsey was indefinitely detained there by Admiral Margaret Parangosky, CINCONI, as retribution for lying to the admiral about the creation and deployment of flash clones during the SPARTAN-II program's early phases. Spartan teams were deployed to reconnoiter the surface, to quarantine areas of potential Flood contamination, and to recovery any notable Forerunner artifacts. The MJOLNIR Pioneer variant first saw field use during these exploratory deployments.

The Composer
The ONI science teams retrieved various artifacts from the surface of Installation 03 and brought them on Ivanoff Station for study, including the installation's activation index, a war sphinx's "eye", and a Composer. An accident with the Composer killed the team researching the device; however, it provided coordinates which led the to the shield world known as Requiem. When the Ur-Didact was awakened, he traveled to Ivanoff in his ship Mantle's Approach and acquired the Composer on July 24, 2557, using it to digitize Ivanoff's staff before jumping to slipspace to travel to Earth to use the recovered weapon on humanity's homeworld. However, SPARTAN-117 and Cortana followed the Didact into slipspace in an F-41 Broadsword in hopes of foiling his plan, ultimately defeating him.

By the time of the Didact's attack, SPARTAN-II Black Team had been assigned to Gamma Halo, along with a research attaché. The science team established a camp in one of the Halo's deserts. On July 25, Team Black and the scientists were killed by the Didact and his Promethean machines, who had been flung to the Halo through the Composer's slipspace portal aboard Mantle's Approach during the New Phoenix Incident. Around the same time, 859 Static Carillon, the monitor of the Composer's Forge, attempted to contact Gamma Halo's monitor after a service portal between the Halo and the Composer's Forge was reopened. Receiving no response, Static Carillon traveled through the portal to the Composer's Abyss on Installation 03, where he encountered the Didact. At the Promethean's request, the monitor led him to the portal to the Composer's Forge.

The Conduit
During these events, Covenant forces landed in a jungled region of Gamma Halo where they took the artifact known as the Conduit to a Forerunner structure they termed the Altar in order to open slipspace portals all over Gamma Halo and take control of the ring. A large number of UNSC forces, including Marines and a Spartan Headhunter, were sent to the area to reacquire the Conduit from the Altar. After securing the Conduit, the Spartan was redeployed to Earth in hopes of using the Conduit to deter an ongoing Promethean invasion of New Phoenix.

Relocation
On July 25, 2557, Blue Team arrived on Installation 03 to investigate the loss of contact with Black Team on Admiral Terrence Hood's orders. Upon discovering the fate of Black Team and the scientists, and destroying some of the Knights responsible for the massacre, they soon came across the Composer's Abyss and the slipspace portal within. Entering the service portal, Blue Team arrived at the Composer's Forge, where they encountered the Didact once again. At the Didact's request, 859 Static Carillon transported Installation 03 through slipspace to orbit over the planet housing the Composer's Forge. The Didact used the portal to return to Gamma Halo, taking one of the Composers with him. Blue Team followed in close pursuit and were confronted by the Didact again at the top of the Composer's Abyss. Though the Spartans were nearly killed by the Didact, Static Carillon arrived to the site in time to save them, incapacitating the Didact and sending him into Gamma Halo's control room by utilizing the local teleportation grid.

Wielding Gamma Halo's Activation Index which Didact had dropped when the monitor ambushed him, John-117 followed the Didact into the control room with Static Carillon's help while the other Spartans returned to their Longsword. The Master Chief used the Index to give 859 Static Carillon control of Gamma Halo, enabling the monitor to detach the segment of the ring housing the control center. This caused massive cracks to appear in the landscape surrounding the removed plate. Static Carillon was momentarily preoccupied with stabilizing the Halo as the plate's sudden removal would have otherwise resulted in the ring's destruction. Although the plates on both sides of the removed portion were not immediately connected, thus closing the loop of the ring, Gamma Halo was able to maintain structural integrity. After teleporting John-117 to safety just as the removed fragment impacted the Composer's Forge and destroyed it, Static Carillon took Installation 03 for safekeeping and repairs in an undisclosed location.

List of appearances

 * Halo 2
 * Halo 3
 * Halo Legends
 * Origins
 * Halo: Glasslands
 * Halo: Combat Evolved Anniversary
 * Terminals
 * Halo 4
 * Halo: Escalation
 * Halo 2 Anniversary (Holographic representation)
 * Halo: Spartan Strike