Editing Halo Array

{{Era|Forerunner|Covenant|Human|UNSC|HCW|Post|FA}}

[[File:TerminalArkArray.jpg|thumb|right|325px|The Array at [[Installation 00]], just before their departure to firing sites across the galaxy.]]

{{Quote|Halo doesn't kill Flood, it kills their ''food''! Humans, Covenant, whatever - we're all equally edible! The only way to stop the Flood is to starve them to death. And that's exactly what Halo is designed to do: wipe the galaxy clean of all sentient life!|[[Cortana]]}}

The '''Halo Array''', known individually as '''Halos''' or '''Halo Rings''',<ref>'''Halo: Combat Evolved''', level ''[[The Truth and Reconciliation]]''</ref> referred to by the [[Covenant]] as the '''Sacred Rings'''<ref>'''Halo: The Flood''', page 38</ref><ref name="gravemind">'''Halo 2''', level ''[[Gravemind (level)|Gravemind]]''</ref>, and labeled '''Fortress Worlds'''<ref>'''Halo: The Flood''', page 193</ref> and '''Installations''' by the [[Forerunners]] and [[Monitor]]s, is a system of colossal ring-shaped superweapons.

The first Halos were constructed by order of [[Master Builder]] [[Faber]] circa [[101,000 BCE]] with the intent of being an ultimate weapon, one that would secure the pre-eminence of the [[Builder]] rate in Forerunner society.<ref name="c274">'''Halo: Cryptum''', ''page 274''</ref> Eventually, eleven were destroyed and/or lost while the remaining [[List of "seven" references in Halo|seven]] were used by the Forerunners as a last resort when combating the parasitic [[Flood]]. All sentient beings in the galaxy were killed, robbing the Flood of hosts and starving it to death.

In addition to serving as weapons of last resort, Halo installations are also research facilities dedicated to containing and studying many different kinds of life forms. The life forms that were hand-selected by the [[Librarian]] included marine life, fauna, and land vertebrates. With the Master Builder's permission, the Librarian would research each animal to detect if their bodies reacted to Flood infection. The research on the animals would be more deeply analyzed if they did become infected. The Librarian's studies also helped determine if the rings could be used to repopulate the galaxy.

==Background==  

[[File:SevenHalos.jpg|thumb|right|175px|Readout of the seven Halos.]]  

[[File:Delta Halo.jpg|thumb|right|175px|[[Installation 05]].]]

[[File:H2_halo_surfaceland.jpg|thumb|right|175px|A section of an Installation's surface.]]

As it is known in modern times, the Halo Array is a network of seven ring-shaped megastructures created by the Forerunners, designed to exterminate all sentient life within the Milky Way galaxy.<ref name="great journey">'''[[Halo 2]]''', level ''[[The Great Journey]]'', '''343 Guilty Spark:''' ''"After exhausting every other strategic option, my creators activated the rings. They, and all additional sentient life in three radii of the galactic center, died, as planned."''</ref> Built following the [[Human-Forerunner War]], these ringworlds were used thousands of years later as a last resort against the Flood, a parasitic extra-galactic species that threatened to consume every sentient life-form in the galaxy. By activating the rings, the Forerunners wiped out every sentient being in the galaxy, effectively starving the Flood to virtual extinction, though specimens were kept in a number of Forerunner containment facilities, including the Halo installations themselves.<ref name="library">'''[[Halo: Combat Evolved]]''', level ''[[The Library]]''</ref>  

A total of eighteen Halo rings existed during the reign of the Forerunners, split into separate arrays of twelve 30,000km rings and six 10,000km rings. Of these, only seven survived to be included in the final Array. The two most well-known Halo installations, [[Installation 04]] and [[Installation 05]], both orbit gas giants, though this is not the case with all Halos; [[Installation 03]] orbits a rocky planet.<ref name="h4composer">'''Halo 4''', campaign level ''[[Composer (level)|Composer]]''</ref> Installation 04 maintained an atmospheric [[Threshold gas mine|mining facility]] in [[Threshold]]'s atmosphere until [[Battle of the Threshold gas mine|it was destroyed]] by the [[Covenant]].<ref>'''[[Halo 2]]''', level ''[[The Oracle]]''</ref>  

Though separated by thousands of light-years, the installations are networked together and capable of remote activation at [[Installation 00|the Ark]], an [[intergalactic space|extragalactic]] megastructure. Each Halo installation has a maximum effective range of 25,000 light-years in every direction.<ref>'''Halo: Combat Evolved Anniversary''', ''[[Terminal/Halo: Combat Evolved Anniversary#Terminal 8|Terminal 8]]'' (''"25,000 light years. That is the effective range of this installation."'')</ref><ref name="radius">'''[[Halo: Combat Evolved]]''', level ''[[Two Betrayals]]'', 343 Guilty Spark: ''"Technically, this installation's pulse has a maximum effective radius of twenty-five thousand light years."''</ref> The method utilized by the array to conduct this "mass sterilization protocol"<ref>'''[[Halo: Combat Evolved]]''', level ''[[The Library]]'', 343 Guilty Spark: ''"Why the Flood is, naturally, simply too dangerous to release, and mass sterilization protocols may again need to be enacted."''</ref> involves the superluminal conveyance of a burst of cross-phased super-massive neutrinos, tuned to emit a harmonic frequency that destroys the nervous system of any life form within range. Simpler organisms lacking a neural system are unaffected, along with inanimate structures. [[Precursor]] technology, however, is extremely susceptible to damage from the Halo effect.<ref> '''Halo: Cryptum''', ''page 132''</ref><ref name="c274"/>

The Halo Array in its entirety has been fired only once in known history, approximately 100,000 years ago, by the [[Didact]]<ref>'''[[Iris]]''', ''Array Recorder Data''</ref> in order to stop the Flood from overwhelming the galaxy. With the exception of the [[Didact]] - who had previously created two separate incarnations of himself, one of which was imprisoned within [[Requiem]] - the Forerunners were wiped out by the Array's pulse.<ref name="great journey"/> The array has come close to activation three times since; Installation 04 was almost activated by the [[John-117|Master Chief]], Installation 05 was activated by Commander [[Miranda Keyes]] at the behest of the [[Brute]] [[Chieftain of the Jiralhanae|Chieftain]] [[Tartarus]], and [[Avery Junior Johnson|Sergeant Johnson]] was forced by the [[Prophet of Truth]] to activate the Array from the Ark. None of these attempts were successful; the first was stopped by Cortana, while the second and third were halted by UNSC and Covenant separatist intervention. A [[Installation 04B|replacement]] Halo for the destroyed Installation 04 was successfully activated outside of the galaxy, eliminating the Flood massed at [[Installation 00]], but it was incomplete and thus not networked to the rest of the Array.<ref name="halo3halo">'''[[Halo 3]]''', campaign level ''[[Halo (Halo 3 level)|Halo]]''</ref>

 

The Array also encompasses [[Installation 00]], an extragalactic construction facility that can create replacement Installations in the event that one is destroyed. All Installations can also be remotely activated from the Ark, as the megastructure is out of the Array's range.<ref>'''Halo 3''', level ''[[The Covenant (level)|The Covenant]]'', '''343 Guilty Spark''': ''"The Ark is out of range of all the active installations!"''</ref> The Forerunners also built [[shield world]]s as a means to escape the effect without having to leave the galaxy.<ref>'''Halo: Ghosts of Onyx''', ''page ??''</ref>

[[File:HaloLatticework.jpg|thumb|right|300px|The foundational latticework of a Halo installation.]]

The Halos were constructed by the [[Faber|Master Builder]] and his Forerunner [[Builder]]s several thousand years after [[prehistoric human civilization|early humanity]] first encountered and drove the Flood from the Milky Way. The most extreme faction of Builders, which at the time controlled the [[Ecumene Council]], claimed that more extreme measures should be used to protect the galaxy against a possible Flood resurgence and proposed building the Array for this purpose. Although they faced strong opposition from the [[Promethean]]s, including the [[Didact]], for thousands of years, the faction eventually won the approval of the Council and commenced work on the Array.<ref name="c274"/>

However, at this point, the [[Librarian]] went to the Council and invoked the Mantle, stating the the Halos should be used as biological preserves in the [[Conservation Measure]], a plan to repopulate the galaxy should the Array ever be activated. The Council approved her request, and ordered that the Halo installations be constructed to have a range of natural environments for the Lifeworkers to preserve their biological specimens in. However, the Master Builder later altered the initial plan, and his researchers began to use these specimens for a series of brutal experiments involving Flood infection.<ref>'''Halo: Primordium''', ''page 188-190''</ref>

Twelve Halos, each 30,000 kilometers in diameter, were originally commissioned by Master Builder Faber and constructed by the [[guild]] of [[Bornstellar's father]] at the [[greater Ark]], one of the two [[Ark]] installations in existence at the time. Only one of these original rings ultimately survived to be used in the Forerunners' final plan; this ring was designated [[Installation 07]]. A separate array of six installations was also constructed and remained under [[the Librarian]]'s control at the [[Installation 00|lesser Ark]].<ref>'''Halo: Cryptum''', ''page 329'' (''"Slowly it dawned on me that I was looking upon another array of installations: six rings, each rising from one of the petals of an enormous flower."'')</ref> The final array, activated at the conclusion of the Forerunners' conflict with the Flood, was comprised of seven rings, each 10,000 kilometers in diameter.

[[File:HaloFiring.png|thumb|right|300px|The Halo Array fires, ending the conflict.]]

The first test of a Halo installation was conducted by [[05-032 Mendicant Bias]], who fired [[Installation 07]] in [[Unidentified star system (Human-San 'Shyuum alliance)|the system]] of [[Charum Hakkor]] and [[Faun Hakkor]] on a low power setting, destroying all of the sentient life on the latter planet and inadvertently releasing [[The Primordial|a Precursor]] from captivity on the former planet. Mendicant Bias then brought the released Precursor to the Halo for study and began a 43-year-long interrogation of it.  

Following the use of Installation 07 by Master Builder Faber to suppress [[Battle of Janjur Qom|a rebellion]] on the [[San 'Shyuum]] homeworld of [[Janjur Qom]], the other eleven Halo installations were taken to the Forerunner [[capital]] during the tribunal against Faber, where it was to be decided whether to decommission them. However, in the midst of the trial, Mendicant Bias, turned rampant by the Primordial, appeared with Installation 07, which had gone missing since the San 'Shyuum rebellion, and assaulted the capital. He attempted to seize control of the remaining Halos and fire them, but was only able to control five out of the twelve. One of those five was destroyed by the combined tidal forces of the capital, the firepower of local Forerunner fleets, and the stress of a recent [[slipspace]] transition. The seven Halos that Mendicant Bias was unable to control were recalled to Installation 00 via slipspace jumps, yet only one escaped before the portal collapsed, with the other six breaking up in-slipspace.

Installation 07 then jumped into a distant system on a pre-designated destructive collision course with [[Unidentified failsafe planet|a planet]] - a security measure put in place in the event that it fell out of Forerunner control. The installation was eventually reclaimed by the Didact's forces, and it survived the passage of the planet despite taking heavy damage. A significant amount of the ring's superstructure was discarded, reducing its size to 10,000 kilometers, in order to allow it to perform a successful slipspace jump to the [[greater Ark]].

Later, as Mendicant Bias prepared his final assault on the [[Maginot Sphere]], the Didact finally accepted that the Halo Array was the only solution to counter the Flood, and activated the Array. The effect left all Flood-controlled ships adrift, allowing [[Offensive Bias]] to defeat and capture the rampant AI.

The seven Halos then remained relatively dormant for approximately one hundred thousand years, though at least [[Installation 05|one]] of them experienced a major Flood outbreak, and at least [[Installation 04|one]] have experienced brief visits by other species, including a [[unidentified alien vessel|major crash-landing]] in [[40,000 BCE]].<ref>''"[[Conversations from the Universe]]"''</ref>  

[[File:HaloDestructionCEA.png|300px|right|thumb|The destruction of the original Installation 04.]]

Eventually, the stellar coordinates of [[Installation 04]] was discovered through the combination of a [[Sigma Octanus IV Artifact|crystal artifact]] on [[Sigma Octanus IV]] and a [[Babd Catha Forerunner complex|huge Forerunner artifact]] buried under the surface of [[Reach]]. The coordinates were utilized by the {{UNSCShip|Pillar of Autumn}}'s shipboard [[AI]] [[Cortana]] to escape from the [[Fall of Reach]]. The cruiser arrived over the Installation's orbit and was subsequently shot down by Covenant ships. Most of the ship's combat personnel escaped and made landfall on the artificial construct, triggering the [[Battle of Installation 04]].  

During their investigations on Installation 04, the Covenant encountered a [[Flood containment facility]] and unknowingly released the dormant Flood; they quickly, but only partially, reestablished containment. Soon, a squad of [[UNSC Marine Corps|Marines]] led by [[Captain (Navy)|Captain]] [[Jacob Keyes]] accidentally broke quarantine again, expecting to find a large Covenant weapons cache. The human-waged guerilla war quickly turned into a massive four-way battle between [[UNSC]] forces, the Covenant, [[Sentinel]]s led by [[343 Guilty Spark]], and the Flood.

The battle finally culminated when [[SPARTAN-II Program|Spartan]] [[John-117]] detonated the fusion engines of the ''Pillar of Autumn'' on the surface of the Installation, which compromised the structural integrity of the ring. The gravitational momentum and inertia still perpetuating the ring in orbit around [[Threshold]] then tore the ring apart. The remains of Installation 04 were scattered as debris in space. The explosion sent massive chunks of the ring careening into [[Basis]]; the moon suffered a constant bombardment of debris from the ring after its destruction.<ref>'''Halo 2''', multiplayer level ''[[Burial Mounds]]''</ref>

Later, the Covenant discovered a second Halo, [[Installation 05]]. On this Halo, the Flood had already been released and much of the ring had been compromised, including its monitor, [[2401 Penitent Tangent]]. Soon, [[Battle of Installation 05|another four-way conflict]] began. The battle ended in the Flood manifesting a [[Gravemind]] and successfully escaping the ring aboard infected Covenant ships. The ring was nearly activated by [[Tartarus]], the [[Chieftain of the Jiralhanae|Chieftain of the]] [[Jiralhanae]], but [[Commander]] [[Miranda Keyes]] pulled the [[Activation Index]] out of the installation's core at the last moment, causing all six functional installations to go into "standby mode", ready for remote activation from the Ark.

The human survivors returned to [[Earth]] and resumed their fight against the Covenant, who had uncovered a large structure on Earth, which they assumed to be the Ark. The Covenant landed the [[Forerunner Dreadnought]] in the center of the structure, activating it. However, the structure was soon revealed not to be the Ark, but [[the Portal|a generator]] of a portal to the actual [[Installation 00|Ark]], a massive artificial world located outside the galaxy. Human and [[Covenant separatists|Covenant separatist]] forces proceeded through the portal to the newly-discovered installation to prevent the Covenant from activating the remaining Halo rings remotely. Eventually, the Gravemind arrived at the Ark aboard ''[[High Charity]]'', the Covenant's capital city, which had been turned into a Flood hive. The hive crashed onto the Installation, releasing the Flood.

Soon, 343 Guilty Spark, John-117, and [[Arbiter]] [[Thel 'Vadam]] discovered that the Ark had been constructing a [[Installation 04B|new Installation 04]], to replace the one which had previously been destroyed. This new installation was only days from being completed. The humans decided to activate the new ring to stop the Flood, resulting in the incomplete ring destroying itself, along with the Ark.<ref>'''[[Halo: The Essential Visual Guide]]''', ''page 14''</ref>  

By [[2553#January|January 2553]], the UNSC had begun an active search for the remaining Halo Installations.<ref>'''Halo: Glasslands''', ''page 50''</ref> By March 2553, the Office of Naval Intelligence had successfully located at least one, [[Installation 03]], and constructed a research station, ''[[Ivanoff]]'', in its orbit.<ref>'''Halo: Glasslands''', ''page 428''</ref> By at least [[2557|July 2557]], UNSC scientists were studying the Array for decommissioning, with facilities at Installations 03 and 05. At the asteroid field orbiting Installation 03, the scientists located the [[Composer]] and accidentally activated it, causing them to become digitized. However, the sensor data left over from the incident led to the discovery of the [[shield world]] [[Requiem]]. Later, the [[Ur-Didact|Didact]] traveled to Ivanoff Station near Installation 03 to retrieve the Composer and used the device to kill the entire research staff before heading for Earth.<ref>'''Halo 4'''</ref>

[[File:343.JPG|right|thumb|275px|343 Guilty Spark, Monitor of Installation 04.]]

The Installations are designed to be run by advanced artificial intelligence constructs specially purposed by the Forerunners. The highest intelligence on each Installation is a single Monitor.<ref>'''Halo: Combat Evolved''', level ''[[343 Guilty Spark (level)|343 Guilty Spark]]''</ref> The Monitor's task is to ensure that the installation's [[Sentinel]]s, which range from [[Constructor]]s to [[Sentinel Aggressor|Aggressors]] and [[Enforcer]]s, repair, maintain, and defend the ring from damage, contain Flood specimens, and ensure that their own installation is ready to fire on demand, including running activation simulations.<ref name="gravemind"/> Monitors also have access to their respective installation's defensive system.<ref>'''Halo: Combat Evolved Anniversary''', ''Terminal 1''</ref>

The Sentinels encompass a broad category of less intelligent constructs which serve virtually any purpose necessary to ensure that the Halo functions properly and are capable of combating small Flood outbreaks. Should a major Flood outbreak occur, heavier automatons, such as the Enforcers and [[Sentinel Major]]s will be created. In the meantime, Constructors are also created to ensure that the Forerunner structures on the Installation are kept in optimal shape, and that they are not damaged by conflict or weather.<ref>'''Halo 2''', level ''[[Sacred Icon]]''</ref>

Save for the Monitor, all automatons can be constructed at specialized [[Sentinel manufacturing facility|production facilities]] that float high in the Halo's atmosphere. They seem to contain almost limitless materials for constructing an almost indefinite number of automatons.

After [[Master Builder]] [[Faber]]'s plans were co-opted by [[the Librarian]], the Halos were given terrestrial surfaces to support catalogued specimens. The Master Builder intended to allow these specimens to be infected by Flood forms contained on the rings, and then subsequently terminated in order to test the Halos' effectiveness.<ref>'''Halo: Cryptum''', ''pages 313, 334''</ref> The Halo installations support a wide range of environments, habitats, ecosystems, and climates. Installation 04 and Installation 05 supported warm, temperate forests<ref>'''Halo 2''', level ''[[Uprising]]''</ref> that were both deciduous and coniferous, swamps, and cold, snow covered tundra environments.<ref>'''Halo: Combat Evolved''', level ''[[Assault on the Control Room]]''</ref><ref>'''Halo 2''', level ''[[Quarantine Zone (level)|Quarantine Zone]]''</ref>  Installation 00 had climate ranging all the way from tundra,<ref name="Cov">'''Halo 3''', level ''[[The Covenant (level)|The Covenant]]''</ref> to forest,<ref name="Cov"/> to desert.<ref>'''Halo 3''', level ''[[The Ark (level)|The Ark]]''</ref> It is unknown whether this range is shared by all the Halos, but the similarity of these environments and that of Installation 00 makes it likely.

While the terrain of a Halo ring may appear to be naturally formed at first glance, it is actually artificially constructed. [[Strato-Sentinel]]s extract raw materials from the source, process them in transit, and deposit building materials at the Installation.<ref>'''[[The Art of Halo 3]]''', page 30</ref> Four huge terraforming factories then move across the face of the installation to "skin" it with landmasses and bodies of water. These factories also hold in the ring's nitrogen-oxygen atmosphere, which is then leaked out to the surface, eventually pouring through the super-structure, and tugged in place by centripetal force.<ref>'''The Art of Halo 3''', ''page 116''</ref> The installation's buildings are then built by Constructors and Sentinels. An intricate layer of metallic panels is laid down several meters below the surface of the terrain, upon which rock, soil, and eventually vegetation is added. Slopes, hills and mountains can be created by sculpting these panels.<ref name="halo3halo"/> Some features, such as landslides, are the result of time, and have been formed naturally. Others, such as the myriad network of tunnels and cave systems that riddle the installation's internal structure, are transit conduits used by the ring's Sentinels and Enforcers. There are also numerous indigenous life-forms that live on the Halos; these were brought on the installations as part of the Lifeworkers' conservation project.

===Technology===

[[File:AnniversaryControlRoom.png|thumb|right|300px|The [[Control Room]] of Installation 04.]]

Each Halo has several assets that are uniform to all installations. Each contains a [[Control Room]] located somewhere upon its inner surface, from which a [[Reclaimer]] must manually insert the installation's [[Activation Index]] to activate it. Each also possesses a [[Library]], a large structure protected by an energy shield, where the Index is housed and protected by Sentinels.<ref name="library"/><ref>'''Halo 2''', level ''[[Sacred Icon]]''</ref> The index itself is a semi-solid holographic representation of the data needed to activate the ring, and can only be directly inserted successfully by a Reclaimer.

Installations also contain advanced [[teleportation grid]]s, allowing instantaneous transportation for a Monitor or Reclaimer to any place on the installation. These grids cannot be controlled by the Flood, though the Gravemind was able to use that of Installation 05 by controlling 2401 Penitent Tangent.<ref name="gravemind"/> For Sentinels, the installation is riddled with tunnel and cave networks for access and transportation.<ref name="Flood240"/> The Sentinel portals are connected to factories via tunnels.

The Halo rings achieve their "gravity" through centripetal force. As the ring spins, centripetal force pushes all spinning bodies away from the center of rotation. The ring is uniform, and because of this, all points are the same distance from the center, therefore centripetal force applies evenly. This force also pushes objects on the surface of the ring away from the center of rotation, or pushes them down on the surface of the ring, translating into gravity. When the {{UNSCShip|Pillar of Autumn}} was detonated, it blasted a large mass from Installation 04; no longer a full loop, the centripetal force applied in much greater strength on the newly formed weak point, causing the ring to rip apart.

The Halo installations are also equipped with drive engines spaced along their rim. In the event of an emergency, a Halo can maneuver itself to avoid damage from a collision or weaponry.<ref>'''Halo: Cryptum,''', ''page 314''</ref> In addition, they possess [[hard light]] reinforcement to stabilize and protect them against tidal and gravitational forces from other objects.<ref>'''Halo: Cryptum''', ''page 311''</ref> One of the most extraordinary systems possessed by the Halos is their ability to lock entire sections of the ring, or, if necessary, the entirety of it, into reflective slipspace stasis. This effectively suspends these sections in time and renders them invulnerable to damage from the outside and allows the occupants of the ring to survive the main weapon's firing. However, it also consumes an enormous amount of energy.<ref>'''Halo: Primordium''', ''page 331-332''</ref>

The Halos are capable of repairing themselves to some degree, replacing damaged plates of foundation material and restoring biological sections.<ref>'''Halo: Primordium''', ''page 77-78''</ref> Rings with a 30,000 km diameter could also be reduced to a smaller size by shedding large portions of the foundation. In order to prevent the ring from falling apart during this process, it can generate a hard light hub with spokes which hold each of the foundation plates in place.<ref>'''Halo: Primordium''', ''page 345-346''</ref>

The rings of the second Halo Array are 10,000 km in diameter; this size is roughly similar to that of Earth, which is 12,756 km in diameter. The surface of each ring is 318 kilometers wide.<ref>'''Halo: The Essential Visual Guide''', ''page 6''</ref> The original twelve Halo rings were 30,000 km in diameter.<ref>'''Halo: Cryptum''', ''page 310''</ref> Each installation in the final array orbits a large, dense planet which serves as a gravitational anchor. For example, Installation 04 and Installation 05 orbited [[Threshold]] and [[Substance]], respectively, which are both large gas giants, while Installation 03 is anchored to a large rocky planet.<ref name="h4composer"/>

When activated, the Halo rings wipe out all sentient life within three radii of the Milky Way's center by sending a burst of cross-phased supermassive neutrinos.<ref>'''Halo: Cryptum''', ''page 274''</ref> This burst of neutrinos is carefully tuned to possess a harmonic frequency, which destroys the nervous system of any macroscopic organism that possesses one, even one as rudimentary as a notochord, as shown in the aftermath of a low-powered test firing of a Halo performed by [[Mendicant Bias]] in the system of Charum Hakkor.<ref>'''Halo: Cryptum''', ''pages 131-133''</ref>

This pulse is propelled across the Halo Array's full radius at superluminal speeds,<ref>'''Halo: Legends''',''"Halo: The Story So Far"'' featurette, minutes 17:40-17:51</ref> covering that area and cleansing it of all affected life, though simpler life forms that do not possess a neural system, such as microbes, fungi, algae, mosses, and traditional plants are unaffected.<ref>'''Halo: Cryptum''', ''page 131''</ref>

21st century paleo-archeological studies gave no indication of the mass extinction caused by the Array's firing. However, in [[2332]] the [[Ross-Ziegler Blip]] revealed a tiny aberration in Earth's fossil records.<ref>'''Halo: Evolutions - Essential Tales of the Halo Universe''', ''From the Office of Dr. William Arthur Iqbal'', page 519</ref>

==Function==

The Halo Array is complex, but each ring can be activated individually by a Reclaimer, also activating the other installations, or they can all be activated simultaneously from Installation 00. In the event of a major Flood outbreak, an installation's Monitor will seek out a Reclaimer if available, whom they will enlist to aid them. It will teleport them to the installation's Library and will assist the individual in retrieving the Index. The Monitor then stores the Index within its data arrays for safe transportation, lest the Reclaimer fall prey to the Flood before they can activate the installation. Once at the control room, the Reclaimer is given back the Index and must insert it into the control panel in order to begin the activation sequence.

The main weapon is amplified by [[phase pulse generator]]s, three of which are close to the control room, at least on Installation 04. Each installation has a maximum effective radius of 25,000 light-years<ref name="radius"/> and functions via form of lethal radiation.<ref>'''Halo: Ghosts of Onyx''', ''page 183''</ref> The pulse is designed to kill all sentient life in the installation's three-dimensional radius, with the array covering the entire galaxy. The pulse targets the nervous system of sentient life forms via the issuing of a harmonic frequency.<ref name="ENC">'''[[Halo Encyclopedia]]''', ''pages 170-174''</ref> The nervous systems of the targeted beings are destroyed, rendering them useless to the Flood; however, the Halo effect does not disintegrate biomass, leaving the victims' bodies mostly intact.<ref>'''Halo 3''', ''Terminal 6'' (''"I toss around [37,654 tonne] dreadnoughts like they were fighters; dimly aware of the former crews being crushed to liquescence."'')</ref> Left untreated, lifeforms killed by the pulse will decay in great masses, which could lead to ecological devastation spread by a miasma of rotten biomatter. Therefore, Lifeworkers sprayed target biospheres with a solute that would cause any animal killed by the Array to instantly decay into its component molecules,<ref>'''Halo: Silentium''', ''String Two''</ref> resulting in flash-desiccation.<ref>'''Halo: Combat Evolved Anniversary''', ''[[Terminal/Halo: Combat Evolved Anniversary|Terminal Eight]]''</ref>

The only known ways to avoid the effects of these pulses are to seek shelter in a [[shield world]] or to escape to Installation 00, which is out of range of the array. Once activated from Installation 00, the other installations will fire simultaneously, eradicating all sentient life in the galaxy, thus starving and killing the Flood.<ref name="great journey"/>

*The Halos are remarkably similar to the eponymous megastructure of [[Wikipedia:Larry Niven|Larry Niven's]] ''[[Wikipedia:Ringworld|Ringworld]]'' series. However, Niven's ringworld encircles a large star, whereas the Halos merely orbit planets, being much smaller than the former. The Halos are also very similar to the [[Wikipedia:Orbital (The Culture)|Orbitals]] from [[Wikipedia:Iain M. Banks|Iain M. Banks']] ''Culture'' series, though considerably smaller.

*The Halo textures for both ''[[Halo: Combat Evolved]]'' and ''[[Halo 2]]'' are the same, and are both symmetrical.

*In a ''Halo: Combat Evolved'' [[Pre-Xbox Halo|prototype]], Installation 04 had a section that was only partially constructed. This feature was dropped from the final game, though it may have inspired the design of the second Installation 04.

*On the screen where Captain Keyes taps his pipe on the opening scene of the ''Pillar of Autumn'', '''TRAJECTORY FD: HALO''' is displayed by the hologram of Installation 04, although the UNSC was not aware of the name at the time.

*In 2011, the Halo Array was the number 1 most "Ridiculously Oversized Videogame Weapon" by PasteMagazine.com.<ref>[http://www.pastemagazine.com/blogs/lists/2011/02/nine-ridiculously-oversized-videogame-weapons.html '''9 Ridiculously Oversized Videogame Weapons''']</ref>

File:Installation_05.jpg|Installation 05 as it aborts its firing sequence.

File:POAEngineRoom.jpg|Sentinels fighting the Flood on Installation 04.

File:Array.png|Installation 00 sending the Halo Array through a [[slipspace portal]] during the [[Forerunner-Flood war]].

File:HaloLegends-Origins-HaloArray.png|A Halo installation, as seen in ''Halo Legends: Origins''.

File:Halo-Legends-Origins-1 HaloArrayFiring.jpg|A Halo being fired in ''Halo Legends: Origins''.

File:HaloLegends-Origins-HaloPostFiring.png|A Halo ring's pulse dimming after its activation in ''Halo Legends: Origins''.

*''[[Halo: Evolutions - Essential Tales of the Halo Universe]]''

**''[[The Mona Lisa]]''

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[[Category:Halos| ]]

[[Category:Astronomy]]