Editing Installation 04

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{{era|H1|H2|H3|RE|FOR|TF|FS|GOO|HE|HGN|LE|ILB}}
<center>''Were you looking for the [[Installation 04B|second Installation 04]], the replacement for the first?''</center>

{{Quote|Whoever controls Halo, controls the fate of the Universe.|[[Captain Jacob Keyes]]}}

{{Haloring
|name=Installation 04 / Alpha Halo
|image=[[File:Alpha Halo.jpg|300px|The destruction of Installation 04.]]
|Location=[[Soell|Soell System]], in orbit around [[Threshold]]
|terrain=Earth-like
|Monitor=[[343 Guilty Spark (Monitor)|343 Guilty Spark]]
|Status=Destroyed by overloaded fusion cores
|Date of Construction=98,665 BCE
|Date of Destruction=[[2552#September|September 23, 2552]]
|Range=25,000 light years
|Firing Record=1.2 trillion simulated, 1 actual
|Diameter=10,000 kilometers (6,210 miles)
}}

'''Installation 04''', famously known among fans as '''Alpha Halo''', was one of a series of gigantic ring worlds (the [[Halo Array]] from which the series gets the name) left behind by the enigmatic, technologically-advanced, and apparently extinct [[Forerunner]]s.
The [[Covenant Empire|Covenant]] reverentially described Installation 04 as either the '''First Holy Ring''', or the '''First Sacred Ring'''. It is the main setting of ''[[Halo: Combat Evolved]]'', the first game in the Trilogy. After its destruction at the end of the [[Battle of Installation 04]], the Ark started to construct [[Installation 04B|a replacement for Installation 04]]. 

== Summary ==
The purpose of Installation 04, along with its brethren, was to preclude and thwart the parasite forms known as the [[Flood]] from consuming all sentient life in the galaxy by destroying all sentient life to prevent eventual consumption. In the event of a [[Flood]] outbreak, one of the seven installations could be triggered (in turn setting the rest of the array on stand-by) to annihilate all sentient life within 25,000 light years. Once one ring is set off all remaining rings would activate. All seven rings could be fired at once if need be.

Installation 04, until its destruction by the [[Master Chief]], was controlled by the [[Forerunner]] artificial intelligence construct ([[Monitor]]), [[343 Guilty Spark (Monitor)|343 Guilty Spark]].

The climate of Installation 04 is very similar to [[Earth]]'s climate. There have been hurricanes over the oceans on the ring.<ref>'''[[Halo: The Flood]]''', page 14</ref> The weather is, however, extremely unpredictable - rain and snowfall can occur at random, leading [[Cortana|some]] to wonder if the weather is intentionally irregular, or if it follows a pattern such as snow being deliberately made at the control room to slow the Flood.<ref>'''[[Halo: The Flood]]''', page 107</ref><ref>''[[Assault on the Control Room (Level)|Assault on the Control Room]]''</ref>

== History ==
[[File:AlphaHaloview1.jpg|right|200px|thumb|Halo with Threshold in the background.]]
[[File:Ddd03.jpg|thumb|right|Part of the wreckage of Installation 04.|200px]]
=== Ancient History ===
Installation 04 was built by the Forerunners over 100,000 years before the [[Battle of Installation 04]] (It was 101,217 years old in [[2552]] A.D., but this is measured in "local time"). 

The Installation was activated sometime thereafter and all Forerunner and most of the Flood were killed. Installation 04 lay dormant for a hundred thousand years, with [[343 Guilty Spark (Monitor)|343 Guilty Spark]] and his [[Sentinels]] ready to keep the [[Flood]] confined in the [[Flood Containment Facilities]] and keeping the infrastructure of the Halo in perfect working order.

=== Destruction ===
{{quote|Halo... It's finished..."<br />"No, I think we're just getting started.| [[Cortana (AI)|Cortana]] talking to the [[Master Chief]] after the destruction of Installation 04.}}

[[File:Haloce-20090913-211532.png|thumb|left|168px|Halo, as it explodes.]]
The Covenant discovered the location of Installation 04 after the Covenant [[Fleet of Particular Justice]] followed the single [[UNSC]] cruiser, the {{UNSCShip|Pillar of Autumn}}, which was fleeing from the [[Fall of Reach]] through slipspace. It is assumed that the Covenant knew about the Ring prior to the events of The [[Battle of Installation 04]], as the [[Prophets]] all have a holographic representation of them on their headdresses and [[Cortana]] stated previously that she used the coordinates received by the beam in ''[[Halo: The Fall of Reach]]''. Due to the Covenant's faster [[Slipspace]] capabilities they arrived before the ''Pillar of Autumn''.

The ''Pillar of Autumn'' arrived around September 19, 2552 and was promptly shot down by the warding Covenant space forces. At around the same time, the Covenant ground forces on Installation 04 accidentally unleashed the Flood from captivity. The ensuing four-day battle that took place all over the ring was called The Battle of Installation 04. [[Human]]s, [[Flood]], and the Covenant fought massive battles against one another as the Forerunner [[Construct]]s tried to control the outbreak by activating Halo. The ring's AI, [[343 Guilty Spark]], also known simply as The Monitor, tried to convince the [[Master Chief]] to activate Halo. Not knowing the truth of what it did, he attempted to light the Ring but was stopped by his AI friend and companion Cortana who was in [[The Core]]. She informed the Master Chief of Halo's true purpose and stashed the [[Index]] in her memory banks. The Monitor betrayed the two and tried to kill the Master Chief and retrieve Cortana, but the two escaped and started plotting against him. In the end the Master Chief detonated the ''Pillar of Autumn''<nowiki>'</nowiki>s fusion reactors which destroyed the Halo ring.

Only a handful of humans and Covenant survived the battle. 343 Guilty Spark floated through space until he was rescued by a group of Covenant near [[Threshold]]. Inspired by his words, they began a [[Heretic]] rebellion against the greater Covenant. Installation 04's destruction is seen as the first step in the chain of events that led to the [[Covenant Civil War]]. The Heretics were quelled by The Arbiter who silenced their leader, but the seeds of a rebellion were planted. The Monitor was then captured by the loyal Covenant and later defected to the humans' side until he was destroyed on the replacement Alpha Halo by [[Spartan-117]] with the help of Sergeant Johnson.

Installation 04 was the first Halo installation encountered by Humans and first to be destroyed. Its destruction triggered the activation of a portal leading to a [[Micro Dyson Sphere]] on [[Onyx]] and also caused the [[Ark]] to start building a [[Installation 04 (II)|replacement ring]].

There is now a large field of debris where Installation 04 was, though a few large chunks of the ring remain. Some smaller pieces of the Installation 04 have landed on [[Basis]] and others have burnt up in Threshold's atmosphere upon entry. The remaining large chunks are molten and unlikely to be capable of supporting any kind of life and are thus likely free of Flood.

According to the Halo: Evolutions story The ''Mona Lisa'', all of the pieces of the Installation are being gradually pulled into [[Threshold]]'s atmosphere where they will presumably burn up and be destroyed.

===Replacement===
{{main|Installation 04B}}

Shortly after the destruction of the [[Halo]], the [[Ark]] began to automatically construct a new Halo to replace Installation 04. This exact copy of the first Halo ring was nearing completion only a few months after the first ring was destroyed, but was also subsequently destroyed when it was fired before it was ready by the [[Master Chief]] and [[Cortana (AI)|Cortana]].  343 Guilty Spark attempted to prevent this, but was finally destroyed by the Master Chief with the help of Sergeant Johnson in this new ring's [[Control Room]].

==Astronomy==
''See full article:'' [[The Halos#Astronomy|The Halos]]

The "Ringworld" of Halo is much smaller than [[Wikipedia:Larry Niven|Larry Niven's]] [[Wikipedia:Ringworld|Ringworld]], by a magnitude of 300,000. While the diameter of Niven's ring world is close to the diameter of Earth's orbit of 300,000,000&nbsp;km, the 10,000&nbsp;km diameter of Halo is much closer to the diameter of Earth itself, which is 12,756&nbsp;km. The ring world has a star similar to our sun in its center, and Halo is orbiting a planet, but does not encircle it.

Circumstantial evidence from [[Bungie]] indicates that Alpha Halo may be located in the [[Soell|Iota Horologii]] System, only 50 Light years from Earth.{{verify source}}

== Speculation ==
[[File:HaloPlanets.jpg|500px|left|thumb|A size comparison between [[Alpha Halo]], [[Threshold]], and planets in the Solar System]]
It is unclear why the gas giant [[Threshold]] was specifically chosen to be the planet which Installation 04 orbited, but it is supposed that the large number of [[Forerunner]] machines already operational in Threshold (explicitly the network of Gas Mines), may have played a role in their decision. It could also be because it was the only planet in the system that had enough gravity to hold [[Halo]] in place. 

Another common theory is that it was placed there mathematically in order to cover the whole of the galaxy with the spread of the [[Halo]]s main weapon. It is probable that the Forerunners had chosen Threshold as the staging point for constructing Installation 04 in a fail-safe to attempt to isolate any major [[Flood]] outbreak. It may have been as simple as its proximity to the Gas Mine stations on Threshold, which the Forerunner may have used for power.

=== Survivors of Installation 04 ===
After the destruction of Installation 04, [[Spartan-117]] and [[Cortana]], who were responsible for the ring's destruction, fled the installation in a [[Longsword]]. Shortly afterward, they reunited with four other survivors on a [[D77-TC Pelican Dropship|Pelican]]. The survivors of the [[Battle of Installation 04]] were as follows:

==== On a Longsword ====
* [[Master Chief Petty Officer]] [[John 117]]
* [[UNSC]] [[AI]] [[Cortana]]

==== On a Pelican ====
* [[Sergeant Major]] [[Avery J. Johnson]]
* [[Corporal Locklear]]
* [[Lieutenant (UNSC)|Lieutenant]] [[Elias Haverson]]
* [[Warrant Officer]] [[Sheila Polaski]]

====Other====
*[[343 Guilty Spark (Monitor)|343 Guilty Spark]]
*[[Linda-058]]

==== Unknown ====
The following two [[UNSC Marine Corps|Marines]] have been seen after having a part in the Battle of Installation 04, but it is unknown how they made it off [[Halo]] before the explosion. Note that there may have been other survivors.

*[[Staff Sergeant]] [[Pete Stacker]]
*[[Private (UNSC)|Private First Class]] [[Chips Dubbo]]

===The Survivors of the Human-Covenant War===

{{Main|Human-Covenant War}}
Not all of the survivors of the battle survived the rest of the war. By the time the Prophet of Truth was killed (Truth's death signified the end of the war), the only survivors of the battle of Installation 04 who were still alive were Sergeant Johnson, the Master Chief, Cortana, Thel Vadamee, and 343 Guilty Spark.

== Trivia ==
*Alpha Halo is where Humanity first comes into official and recorded contact with the [[Flood]]. But Humanity's first true contact with the Flood was actually 21 years earlier, when the {{UNSCShip|Spirit of Fire}} sent troops to the surface of an unnamed [[Shield World (Halo Wars)|Shield World]], though the ship was lost in space, not allowing for it to notify anyone about the parasite.
*Johnson describes it as "God's own anti-son-of-a-bitch-machine" and a "giant hula-hoop", the earlier description being suprisingly acurate to it's purpose.
*The numbering of the rings concerning the IWHBYD ring sequence is the opposite to the rings' actual installation numbers and should not be confused.
*It is possible to see falling debris from Installation 04 on [[Burial Mounds]].
*Installation 04 was monitored by [[343 Guilty Spark]], the only Monitor to look over two [[Installation 04 (II)|Halo Rings]].
*It is possible that other races came to Alpha Halo before Humans and Covenant, as was stated in [[Conversations from the Universe|''Conversations from the Universe'']].<ref>'''[[Conversations from the Universe]]''', 343 Guilty Sparks Log</ref>
*This is the only known ring to be destroyed and thus to be rebuilt.
*In the [[Pillar of Autumn]]'s bridge, if looked at closely, you can see that the ring is very small and that the front of the ship is "inside" the ring.

==Gallery==
<gallery widths="120" orientation="portrait"> 
File:1211311449 Installation 04.jpg|The symbol representing Installation 04.
File:5c68d2ee5948405b19de4d1bfce9969b214c9aec.jpg|One of Alpha Halo's three [[Phase Pulse Generator]]s.
File:Broken Ring.jpg|A piece of the broken ring.
</gallery>

==Sources==
<references/>

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[[Category:The Forerunner]]
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[[Category:Installation 04]]
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