Halo Array

File:DeltaHalo.jpg

In Amber Clad approaches Installation 05, otherwise known as Delta Halo.

Halos are fictional megastructures and superweapons in the Halo video game series.

Overview

The Halos are seven ring-shaped, habitable megastructures that exist within the Halo science fiction series. The Halos resemble Larry Niven's Ringworld concept in shape and design, while they are closer to Iain M. Banks' Culture Orbitals in terms of scale and structure, the latter of the two being the inspiration for the Halo rings. While the diameters of Niven's Ringworld and Banks Orbitals are in the millions of kilometers, each Halo is only 10,000 km in diameter, slightly smaller than that of Earth. Like the Culture Orbitals, each Halo orbits a planet, the Ringworld concept of encompassing a star, similar to a Dyson Sphere or Dyson Swarm, being impractical for something of Halo's size in this universe.

The Halo installations were built by the Forerunners, a fictional civilization within the series, to contain and study the Flood, a rampantly infectious alien parasite. To this end, each Halo possesses a network of underground structures, ranging from laboratories to containment areas. Each installation shown in the series has a Monitor, an artificial intelligence construct, to oversee automated installation functions, such as defense and climate control. 343 Guilty Spark, for example, runs Installation 04.

The main purpose of the Halos is to stop the Flood should they multiply beyond a containable level. To accomplish this, each Halo is equipped with a super-weapon capable of destroying all bio-mass of sufficient size to sustain the Flood within a radius of 25,000 light years (roughly one fourth of the Milky Way Galaxy's diameter). The activation of all seven (which is triggered when any single Halo activates) would effectively wipe out every living thing "within three radii of the galactic center", according to 343 Guilty Spark. This encompasses the entire galaxy and would effectively starve the Flood into defeat.

Individual Halos are activated by interfacing the Index, a firing key, with the Halo's primary control center. The primary generators for the weapon take some time to power up, which allows the weapon to be disarmed if necessary. However, as a fail-safe, doing so arms the remaining Halo installations via subspace beacon. The network can then be triggered by a remote activation signal from a core installation known as the Ark, a storyline to be expanded upon in Halo 3.

While the effects of the Halos has been described several times, the actual principle behind the weapons is never explained in the series, apart from the fact that it is radiological in nature. The exact definition of "sufficient bio-mass" is likewise never fully explained, though it is made clear that any sentient life would fall victim to the effect.

File:Halo-landscape.jpg

An island, referred to as Relic, on one of the massive Halos.

The outer surface of a Halo is mechanical in appearance, but its exact nature has not been explained in detail within the series. On the inner surface of the ring is a fully-functioning ecosystem, ranging from arctic to desert terrain, supported by climate control systems and artificial gravity through rotation. The two Halo installations depicted in the Halo series are vertically oriented compared to a system's ecliptic, and thus experience a permanent half-day/half-night situation. This also prevents the ring from casting a shadow on itself. As confirmed by the A.I. Cortana in Halo: The Fall of Reach, additional gravity-generating devices are present on the ring to keep it in orbit, as such an object cannot be a naturally occurring celestial body.

The wildlife of a Halo installation is something of a mystery. Installation 04 features moth-like creatures, as well as distant animal calls indicating other species, but nothing else. Halo 2 features a variety of animals, though none that the player can directly interact with. In the E3 2000 video showcasing an early build of Halo, there are dinosaur-like creatures that roam Halo's surface, as well as another creature (referred to as the "Blind Wolf" in the documentary) intended for use as a vehicle for the player. A "Doberman Gator" was also mentioned in the Halo 2 documentary. The animals were removed for both technical and conceptual reasons; there were difficulties in A.I. interaction and the designers felt that removing the animals would make the appearance of the Flood more terrifying and unexpected.

The Library

File:Library Halo2.jpg

The Library of Installation 05.

In the Halo series, the two Halo installations possess a massive structure known as "The Library". The precise purpose of the Library facilities is unknown, but it serves to house the Index for the Halo installation. In-game, the Libraries are referred to as "security complexes".

The Library can be accessed in one of two ways: by conventional means or by teleportation. The latter method is used by 343 Guilty Spark in Halo: Combat Evolved, while the Library in Halo 2 is entered through the use of explosives, presumably because the Monitor of that installation, having been captured by Gravemind, was unavailable to let them in.

File:C20 29.jpg

The interior of the Library on Installation 04.

As is appropriate for such a facility, each Library is protected by numerous security measures, including massive doors that only Monitors can open, long and extensive approaches via external gondolas, and, on 05 at least, a massive Sentinel Wall that restricts access to a network of heavily guarded tunnels.

Both known Libraries contain (and perhaps exist only for the purpose of containing) the Index for firing the installation's main weapon. The formal route to the Index, the one the Master Chief uses on Installation 04, begins inside the Library and follows a long procession through the Library's inner workings and levels. The slightly more forced method of entry used by several factions on Installation 05 led directly from a gondola to the Index. Installation 05's Library was also severely damaged, with the main elevator destroyed and rubble scattered about the shaft.

Separating the remainder of the installations' environment from the Library security structures are a series of massive walled fortifications supporting a tremendous green energy shield that blocks off all access to the area beyond. These defensive structures are known as Sentinel Walls, due to the fact that they house large numbers of Sentinel security drones to fend off intruders and contain the Flood infestation. Only by bypassing the Sentinels' security can players disengage the shield surrounding the Library, and advance deeper into the complex. Throughout the Sentinel Wall area, players encounter glowing openings in the walls, which slide open when an intruder approaches and release Sentinel drones to engage nearby threats. Beyond these shields is a vast, stretching plain of snow and ice, an environment deliberately cultivated by the ring's security systems to inhibit Flood growth. This area is aptly known as the Quarantine Zone.

The skies over the Quarantine Zones outside the Libraries feature large floating structures, which are identified in The Art of Halo as "Sentinel Factories". These airborne structures are capable of manufacturing armies of Sentinel and Enforcer drones to contain Flood outbreaks. These structures are not immune to Flood attack, however; during the events of the level "Quarantine Zone", the Flood use captured Wraith mortar tanks to shoot down and bombard at least one of these factories.

The Ark

The Ark, first mentioned at the end of Halo 2, serves as a secondary control station for the Halo network. When one Halo is activated but kept from firing, a subspace signal primes the remaining installations to be fired remotely by theArk. Though not mentioned in the game, the Ark is buried between Mount Kilimanjaro, Tanzania, and Mombasa, Kenya. A large structure seen in the Halo 3 trailer released at E3 on May 9, 2006, is thought to be the Ark.

Shield Worlds

In conjunction with the Halo network, the Forerunners constructed an unspecified number of "Shield Worlds" to protect themselves from the weapons, as revealed in the Halo novel Ghosts of Onyx. The Shield Worlds borrow from the Dyson sphere concept, but like the Halos do not orbit a sun, instead being contained within a Slipspace field. Each Shield World only occupies a space about one meter in diameter in normal space. The Slipspace field protects the Shield Worlds from any and all outside interference, namely the activation of the Halo network.

Reclaimer

In both Halo and Halo 2, when Flood infestations break out on a Halo installation, that installation's Monitor attempts to carry out a failsafe protocol. The Monitor locates a "Reclaimer" and instructs them to retrieve the Index, which is then used to activate the weapon. For some reason, the Reclaimer must be the one to perform this procedure, as 343 Guilty Spark explains to the Master Chief that the task is too important to entrust to a construct such as himself.

In the series, only humans have been labeled as Reclaimers, but any precise requirements for a Reclaimer, if any, are unknown. In the final level of Halo 2, it is implied that Covenant forces, or at the very least Brutes, are incapable of being Reclaimers, as 343 Guilty Spark is quite insistent that Miranda Keyes not be harmed, even though Tartarus is in possession of the Index. In addition, Tartarus has to force Miranda Keyes to activate Halo, rather than simply doing so himself. In the Ghosts of Onyx book, a Spartan-III encounters a talking Sentinel which mentions something about a Reclaimer. It is later revealed that Onyx is a Shield World, and the Sentinels were programmed to protect it from anyone who attempted to enter until given a specific phrase, allowing access to the world.

It has been implied (within 343 Guilty Spark's log in "Conversations from the Universe", and Cortana's commentary regarding the destruction of the phase pulse generators during the Halo level "Two Betrayals") that it may be possible for a Monitor to activate Halo without using an Index, or at least a Reclaimer.

Known Halo installations

Installation 04

Installation 04, also known as Alpha Halo, is featured in the first Halo game, Halo: Combat Evolved. The majority of gameplay takes place in areas on or near this installation, such as cruisers hovering near its surface. The only exception is the first level, which takes place on a Halcyon-class UNSC cruiser called the Pillar of Autumn as it is set on a collision course for the ring. Parts of Halo 2 also take place in the atmosphere of the planet Installation 04 orbits.

Installation 04 is managed by the Monitor known as 343 Guilty Spark, who has been doing so for 101,217 local years, a local year being the amount of time it takes Threshold to orbit its star. In an interview with Joe Staten of Bungie Studios, Staten confirmed that the previous firing, to which Guilty Spark alludes in the game, occurred around 100,000 years previous to the events in year 2552 at Installation 04.

Installation 04 is destroyed at the end of the game by the Master Chief and Cortana, who detonate the fusion reactors of the Pillar of Autumn on the ring. The resulting nuclear explosion destroyed enough of the ring to allow the installation's momentum and rotation to over-stress the remainder of the structure, causing it to tear itself apart. Following the destruction of the ring, the remaining segments were baked to an almost molten state. Only two significant pieces of the ring are still in their original orbit, and debris from Installation 04 still rains down on Basis. 343 Guilty Spark escapes the destruction of his installation, relocating to Threshold's gas mining facility and eventually Installation 05.

A diagram showing the five Lagrangian points in a two-body system. Threshold is the yellow circle, Basis is the blue circle, and Installation 04 is positioned at L1.

Installation 04 is located in the Soell system, orbiting a gas giant known as Threshold. Its orbit is at Lagrange point L1, directly between the gas giant and one of its moons, Basis, but closer to the latter. At the Lagrange point L1 the gravity of Basis and Threshold partially cancel out, giving Halo the same orbital period as Basis despite being in a closer orbit. The rotational axis of Halo is perpendicular to the line between Threshold and Basis, placing the two at opposite ends relative to Installation 04, and both are about 90 degrees left or right of the ring of Halo. All three bodies revolve with the same angular speed around their common center of gravity, which is inside of Threshold, but not exactly at the center of gravity of the planet. Their common center of gravity revolves around the star. In contrast to the Lagrange points L4 and L5, the Lagrange points L1, L2 and L3 are metastable positions, similar to a marble placed on the center of a saddle. This indicates that Halo would have to stabilize its position actively (if real laws of physics applied to it), so as not to fall onto either Threshold or Basis.

File:ThresholdHalo.jpg

The gas giant Threshold.

The gas giant Threshold measures about 214,604 kilometers in diameter, making it larger than the planet Jupiter. The atmosphere of Threshold, or at least one layer, is breathable by Covenant Elites, and, by extension, humans.

Threshold's moon, Basis, measures at 23,848 km in diameter, and features a breathable atmosphere. Following the events of Halo: Combat Evolved, debris from Installation 04's destruction litters the lunar surface, and among the pieces of this debris is a temporary base camp set up by the Heretic forces, who later relocate to Threshold's gas mining facility. Halo 2's multiplayer mode also has a map based on this debris called Burial Grounds.

In addition to Installation 04, a large Forerunner gas mining facility is suspended within the breathable atmosphere layer of Threshold, indicated by 343 Guilty Spark to be several hundred years older than Installation 04 itself. The type of gas is not elaborated on, nor is its purpose, but it must be methane-based since the Heretic Grunts are able to breathe it. A portion of the facility hanging below the rest of the structure was refitted into a research lab to study the Flood. The mining facility is featured in Halo 2, where during the time between the two games it has been taken over by a renegade group of Covenant, referred to in-game as the Heretics, who rebel after learning the true purpose of the Halos from 343 Guilty Spark. The Arbiter, one of the two playable characters in Halo 2, is dispatched with a team of special operations Elites and Grunts to quell the rebellion. At some point before their arrival, the Flood specimens stored in the labs break free and attack any forces they find. In response to Heretic movements, the Arbiter cuts the bottom portion of the station loose, kills the Heretic leader, and escapes, leaving the research lab to fall into Threshold's lower atmosphere.

Installation 05

Installation 05, also known as Delta Halo, is the subject of Halo 2, though unlike the first game it is not the sole location of gameplay. Like with the first game, the main focus of activity on Installation 05 is the attempt to retrieve its Index, which the various factions in the series seek for different reasons. This installation remains intact following the end of the game, though as a result of its near-activation, every other Halo installation is primed to fire.

"Delta Halo" is the title of a specific group of levels in the Halo 2 campaign set on the eponymous second Halo installation. Although Installation 05 is known as Delta Halo, it is uncertain if this is the official UNSC designation for the installation.

Installation 05 is managed by the Monitor 2401 Penitent Tangent, a red-glowing counterpart of 343 Guilty Spark. However, by the events of Halo 2, 2401 Penitent Tangent is in the custody of Gravemind, a Flood intelligence who now commands limited control over the ring's systems. Installation 05 orbits a blue gas giant called Substance; though not named in-game, texture files for the planet are named as such.

In Halo 2, when the High Prophet of Regret flees New Mombasa, East African Protectorate, he sets up a base of operations on Installation 05 and attempts to activate it. The Master Chief follows the Prophet and kills him, preventing the installation's activation. After the High Prophets and Brutes betray the Elites (a major plot point in Halo 2), the Brutes set up a base of operations in the control room of this Halo and engage the activation sequence. The Arbiter and a number of Elites launch an offensive against the Brute encampment, and manage to kill the Brute Chieftain, Tartarus, with the assistance of Sergeant Major Avery Johnson and Commander Miranda Keyes. Keyes is instructed by 343 Guilty Spark on how to shut the weapon down, but in doing so activates a fail-safe, priming the remaining Halo installations via subspace beacon for remote activation by the Ark.

See also

• Dyson sphere
• Orbital (The Culture)
• Stanford torus
• Ringworld

External links

• Bungie Studios
• Bungie.org, unofficial
• Halopedia - Halo Knowledge center