Installation 05

"This installation has a successful utilization record of 1.2 trillion simulated and one actual. It is ready to fire on demand."

- 2401 Penitent Tangent

Installation 05, or Delta Halo as it is called by Humans, is one of the seven massive Halo fortress worlds built by the Forerunners. It is also the second Halo ring to be discovered by the Humans.

Details
Planet of Orbit: Substance

Monitor: 2401 Penitent Tangent

Status What happened to Installation 05 after the events of Halo 3 is unknown. The heavy damage done to The Ark could have put the Halo out of standby, or it could be unaware of the Ark's status, and still be awaiting remote activation. Its buildings seem to be more 'ancient' looking than Installation 04. The aging of it could be due to the damage the Flood has done to it as well as the battles that take place, hinting that this is where the majority, or the most intense of the Forerunner/Flood battles took place. Some also believe that the relics found are not Forerunner, but Precursor, as the Forerunner favor metallic structures. It is also possible, that each Halo, while similar in architecture (I.E angular design, and same basic functional structures), has a different style from the next, an example being 05's Control Room having similarity to 04's Control Room in purpose, but with a new look, including a spherical shape at the center of the building. This is different from both versions of Installation 04, which look almost exactly the same (being of the same style), and have the same surroundings. However, a combination of this,and the weathering caused by battles with the Flood could be why Delta Halo's structures look so dissimilar.

The Installation may be smaller than Alpha Halo, described as being the size of a moon, rather than a planet, although the relevance of this is unknown. Whether this theorized size difference is common among Halo installations, or whether Installation 05 represents a different Halo Installation model to Installation 04, is unknown. Its should also be noted that it is unclear what the size of the moon the halo is being compared with is as Threshold's moon Basis was about 3 times the size of Earth, and Installation 04 was slightly smaller than Earth's diameter.

Its terrain, with the exception of the ice and snow-filled Quarantine Zone, is mostly lakes and jungle.

History
It is assumed that Installation 05 was built around the same time as Installation 04, around 98,665 BC. It was activated shortly thereafter by the Forerunners, eradicating all sentient life in the galaxy and, presumably, destroying the Flood as well, with the exception of those specimens kept in the Halos for research. As of 2552, it had a record of 1.2 trillion simulated firings and one actual activation.

Flood Disaster
About 200 years prior to 2552, the Flood on Installation 05 escaped and evaded containment due to negligence on the part of the installation's Monitor, Penitent Tangent. The Flood quickly grew out of control around the area of the Installation's Library. The Flood were kept contained by a Sentinel Wall built around the Library, but 2401 Penitent Tangent was captured. Without it, the Sentinels of the Halo lacked a controlling intelligence and so many of the structures around Installation 05 fell into horrible conditions, and most of the Installation came to look like a jungle strewn with ruins.

At the time of the Human-Covenant War, a Gravemind was holding 2401 Penitent Tangent captive. Even with the addition of Forerunner Sentinel Majors and Enforcers, the Flood were able to remain loose, albeit contained within the Quarantine Zone by the Sentinel Wall. This stalemate is believed to be the cause of the slow decline into the horrible condition of the structures of the Installation. The Gravemind itself resided in the chamber directly below the Index Chamber in the center of the Library. A battle record has been recently shown on Bungie.net:

Discovery
In 2552, the High Prophet of Regret, a Covenant Hierarch, discovered the location of Installation 05 during The First Battle of Earth. He made a Slipspace jump from Earth to the Halo, followed closely by Miranda Keyes' ship UNSC In Amber Clad.



When they arrived, Commander Keyes ordered the Master Chief to capture the Prophet of Regret. After fighting the Covenant in various temples and structures, the Master Chief and Cortana overheard Regret talking about activating the ring, which according to him, would start the "Great Journey." Miranda Keyes ordered the Chief and Cortana to find and kill Regret, while she and her Marines on board In Amber Clad went to the Library to retrieve the Index.

The Master Chief fought through waves of Covenant enemies onboard gondolas, through underwater structures, and more mysterious structures until he finally located Regret in a huge temple over the lake and killed him just as the Covenant city High Charity arrived with hundreds of thousands of ships. One ship destroyed the Prophet of Regret's temple, which caused the Master Chief to fall into the lake and ultimately be captured by the Gravemind.

The Covenant landed on the Installation and foolishly deactivated the Sentinel Wall in order to retrieve the Index. Flood were able to infect much of the Human and Covenant forces, even taking control of the In Amber Clad and High Charity. The Covenant Arbiter retrieved the Index, believing it to be necessary to begin the Great Journey, but he was almost killed by the Brute Tartarus and leaving the icon to Tartarus. He fell into the chamber of the Gravemind, where he met the Master Chief, 2401 Penitent Tangent, a Prophet Form of Regret and the Gravemind. There they "edified" him of the true nature of the Installation. Meanwhile, Tartarus brought the Index to the Halo's Control Room. Starting The Battle of Delta Halo with his failure of making Keyes to start it. He activated the station, but was killed by Johnson and The Arbiter (with remaining elites and zealots) before it could fire. The Index was removed from the chamber, but the installation had a fail-safe protocol which activated and sent a signal to the other Halos, putting them on standby mode, ready for remote activation through The Ark.

When Installation 05 was last seen, Flood were running loose as well as in High Charity and the surrounding Fleet. The Flood appear to be in control of the Installation and the High Charity, as the Civil War of the Covenant has caused fighting between the remaining Covenant forces on the ring. The extent of the Flood control in Delta Halo after Halo 3 is unknown, since they were never eradicated. With the Gravemind killed at the end of Halo 3, it is most likely that the Flood reverted to their original feral and disorganized state and would be easily controlled by the Sentinels and Covenant forces present there although it is not for sure due to the unknown fate of 2401 Penitent Tangent. The UNSC AI Cortana had suggested that the Installation be destroyed via the use of a NOVA Bomb, but it is unknown if the idea was ever followed.

There is confusion surrounding the Halo Installations in a holographic representation on the Citadel of Installation 00 believed to be showing Installation 05 with a blood red and cracked surface (whereas this is more likely the volcanic surface of Installation 03). It is possible that the Covenant Separatist Quarantine Fleet situated above Delta Halo have glassed the entire Installation, although had this been their intention, they would have more likely completely destroyed the ring much like Installation 04. Another possible explanation is the red surface texture, which appears as a solid, untextured band if the IWHBYD ring code has been entered, is an alert indicating that the Installation is infested by uncontained Flood or that the Installation's Monitor has been captured.

Astronomy
See full article: The Halos

The "Ringworld" of Halo is much smaller than Larry Niven's Ringworld, by a magnitude of 3,000. While the diameter of Niven's ringworld is close to the diameter of Earth's orbital of 300,000,000 km, the 10,000 km diameter of Halo is much closer to the diameter of Earth itself, which is 12,756 km. The Ringworld has a star similar to our sun in its center, and Halo is orbiting a planet, but does not encircle it.

Trivia

 * This is the only known ring that has 2 Monitors; 2401 Penitent Tangent and the Cold Storage Monitor.
 * 2401 Penitent Tangent was the first known Monitor to be captured by the Flood.
 * The Halo 3 Multiplayer map Cold Storage is present on Installation 05.
 * Delta Halo's star is likely to be HD 108147, which coincidentally, has a small gas giant orbiting it.
 * The numbering of the rings concerning the IWHBYD ring sequence is the opposite to the rings' actual installation numbers and should not be confused.
 * There are six Halo 2 levels that take place on Installation 05; Delta Halo, Regret, Sacred Icon, Quarantine Zone, Uprising, and Great Journey.

Gallery
 Image:Tanget.JPG|The Monitor of Installation 05, 2401 Penitent Tangent. Image:Jungle.jpg|Jungles and Lakes on Installation 05. Image:Argodaemon-DeltaHaloTank-1600-1200.jpg|A structure and a bridge on Installation 05. Image:Uprising.jpg|The Control Room of Installation 05. Image:Control Room3.jpg|The Control Room of Installation 05. Image:Llibraryday.jpg|The Library of Installation 05. 