Halo Array

A vast ring-shaped object, thousands of miles in diameter, hovers in space. The outside of the ring is metallic, while the inner portion features land and sea. The ring is under construction; portions of the ring are merely a skeletal framework.
A human ship approaches a Halo under construction. Portions of the Ark are visible at bottom. From the video game Halo 3, 2007.

The Halo Array is a group of fictional megastructures and superweapons in the Halo science fiction franchise, consisting of ringworlds known as Halos built by structures known as the Ark. They are referred to as "Installations" by their artificial intelligence caretakers, and were created by an ancient race known as the Forerunners. The series' alien antagonists, the Covenant, refer to the Halos as the "Sacred Rings", believing them to form part of a greater religious prophecy known as "The Great Journey". In the games' stories, the Forerunners built the Halo Array to contain and study the Flood, an infectious alien parasite. The rings act together as a weapon of last resort; when fired, they kill any sentient life capable of falling prey to the Flood, starving the parasite of its food. The installations are at the crux of the plot progression for the Halo series.

Each Halo features their own wildlife and weather. The constructs resemble Iain M. Banks' Orbital concept in shape and design.[1][2] The structure that Halo: Combat Evolved takes place on was initially to be a hollowed-out planet, but was changed to its ring design later in development; a staff member provided "Halo" as the name for both the ring and the video game after names such as Red Shift were suggested.


Design and developmentEdit

The term "megastructure" refers to artificial structures where one of three dimensions is 100 kilometers (62 mi) or larger. The first use of a ring-shaped megastructure in fiction was Larry Niven's novel Ringworld (1970). Niven described his design as an intermediate step between Dyson spheres and planets - a ring with a radius of more than 93,000,000 miles (150,000,000 km) and a width of 1,000,000 miles (1,600,000 km); these are dimensions far exceeding the ringworlds found in the Halo series, which feature radii of 6,213.712 miles (10,000.000 km)[3] The Halos are closer in proportion to a Bishop Ring, an actual proposed space habitat first explained by Forrest Bishop, though the proportions of the Halos do not exactly match up with Bishop's idea or more accurately the bigger Orbital. As seen in the games, Halo installations feature a metallic exterior, with the interior of the ring filled with an atmosphere, water, plant life, and animal life.[4] What appear to be docking ports and windows dot the exterior surface, suggesting that a fraction of the ring structure itself is hollow and used for maintenance, living, and power generation.[5]

Before the title for game developer Bungie's next project was announced and development of the game that would become Halo was in its early stages, the megastructure that Halo: Combat Evolved took place on was a massive, hollowed-out planet called "Solipsis". The planet became a Dyson Sphere, and then a Dyson Ring.[6] Some Bungie staffers felt the change to a ringworld was "ripping off Larry Niven", according to Bungie artist Paul Russel.[7] Bungie employee Frank O'Connor wrote in a post on Bungie that "the specific accusation that we swiped the idea of a ring-shaped planet wholesale is not accurate", explaining that Bungie used a ringworld because "it's cool and therefore the type of thing a Forerunner civilization would build."[8]

At the time, the game was known as Blam!, but Bungie had always expected to replace the working title with something better. Blam! was used after studio co-founder Jason Jones could not bring himself to tell his mother their next project was dubbed Monkey Nuts.[9] Titles such as The Crystal Palace, Hard Vacuum, Star Maker, Star Shield, and The Santa Machine were suggested.[6] Russel suggested calling it Project: Halo because of the ring. Despite concerns that the title seemed too religious or lacked action, the name stuck.[10] In turn, "Halo" became the ring's name as well.[7][11]

Combat Evolved's Halo was intended to be populated with large animal life,[12] collectively known as Fauna. The Fauna included "pseudo-dinosaurs" and mammals,[13] as well as a Chocobo-like creature—the "Blind Wolf"—that players could ride.[14] The animals were removed for technical and conceptual reasons; there were difficulties in getting herd and behavior action to work, and under pressure to complete the game's more central aspects, the animals were dropped. Bungie also felt that the desolate ring heightened the sense of Halo's mystery, and made the appearance of the parasitic Flood more terrifying and unexpected.[13]

Scientific analysisEdit

The five Lagrangian points in a two-body system. For Halo, the gas giant is the yellow circle, the lone moon is the blue circle, and the ringworld is positioned at L1.

Physicist Kevin Grazier posited in a 2006 essay the composition and problems associated with a Halo installation. The complete Halos seen in Halo: Combat Evolved and Halo 2 orbit gas giants similar to Jupiter, though much larger; the bodies exhibit characteristics of both a jovian planet and a small star.[15] In each system, there are five points where a body of negligible mass would remain stationary to the two much larger bodies in the system, the gas giant and its moon. These areas, known as Lagrange points, are classified by stability; while bodies at 60° angles to the gas giant would remain in the same location relative to the other objects in the system, the other three Lagrange points are meta-stable, having the tendency to be unstable in one direction. As the Halos are located at point L1, the installations must actively correct their orbits.[16] The apparent gravity of the Halo installations is close to Earth normal. A Halo would have to spin with a tangental speed of 7 kilometers (4.3 mi) per second to match Earth's gravity, translating to 19.25 rotations in a day.[17]

Aside from their unstable positions, Halos would have to contend with thousands of meteor and micrometeor impacts which would destabilize or destroy the ring; there is no evidence in the games that the installations project an energy shield to prevent this occurrence.[15] Because of the magnetic environment around the gas giant, a Halo would be exposed to high levels of radiation.[18] Earth is protected from such radiation by charged particles created by the planet's magnetic field. Grazier posits that huge conductive cables could run the circumference of a Halo; when an electric current was run through these cables, a protective magnetic environment could be created to sustain life.[19]

In the games, spectroscopic analysis of the ring's composition proved "inconclusive", implying that the Halos are constructed of an unknown material (unobtainium). Were a Halo to be constructed using conventional materials a light steel alloy would be most feasible. Assuming that the ring structure is 50% empty space, a 5000 km ring composed of steel alloy at an average density of 7.7 grams (0.27 oz) per 1 cubic centimeter (0.061 cu in) would result in a total mass of 1.7x1017 kg.[5] The amount of material required to build such a ring would be akin to the total material available in the asteroid belt.[20]


Installation 03Edit

Installation 03, also referred to as Gamma Halo, appears in Halo 4. It is monitored by 049 Abject Testament and is located in the Khaphrae system, orbiting a damaged planet. Whilst no gameplay takes place on the installation, an extremely dense asteroid field surrounding the installation is the site of the UNSC scientific research base Ivanoff. It is here that UNSC scientists are conducting experiments on the Forerunner artifact called the Composer, which has the ability to convert biological forms, specifically humans, into AIs. After the game's antagonist, the Didact, activates the device, the UNSC base is left uninhabited. Halo: Escalation, a series of comics which follows many events after Halo 4, establishes that 049 Abject Testament has long disappeared from the ring, leading a monitor to arrive at the Installation, just to be ambushed by a still living Didact, using the Installation to use the Composer. At the end of the comics, Abject Testament takes the installation to an unknown location for repairs.

Installation 04Edit

Installation 04, also referred to as Alpha Halo, appears in Halo: Combat Evolved. The majority of gameplay takes place in areas on this installation, and its exploration drives the story.[21] The ring was managed by an artificial intelligence known as 343 Guilty Spark, and is located in the Soell system, dominated by a gas giant known as Threshold.[22] Halo orbits Threshold's only satellite, an extremely large moon known as Basis.[15] A group of humans aboard the ship Pillar of Autumn crash-land on the ring after being pursued by the alien Covenant.[23] The ring holds religious significance to the aliens, while the humans believe it is a weapon that could turn the tide of the war against the Covenant in their favor.[21] In reality, the ring is home to a virulent parasite called the Flood, which is accidentally released by the Covenant and threatens to infest the galaxy. The human soldier Master Chief eventually detonates the Pillar of Autumn's reactors in order to destabilize the ring and cause it to break up, preventing the spread of the Flood and the activation of the Halo network, which would kill all sentient life as a fail-safe to starve the Flood.[24] The Ark was alerted to its destruction and proceeded to create another ring, which, too, was destroyed by Master Chief. During the game's events, Guilty Spark alludes to a previous firing of the network, which Bungie's director of cinematics Joseph Staten said occurred around 100,000 years previous to the events of the game in the year 2552.[25] After Installation 04 was destroyed, a shard of the ring was sent through slipspace to orbit a red giant. The supernova-like detonation of the Pillar of Autumn creates a new element on the ring shard which is fatal to humans. Appearing in Halo: Nightfall, the shard is visited by a team of ONI operatives and colonial militia following a terrorist attack with the new element. With only a limited time before the shard's sunrise kills them, the team struggles to destroy the deposits and capture the smugglers mining it. Only two of the team manage to escape while Colonel Randall Aiken, a former Spartan supersoldier, sacrifices himself to destroy the deposits with a nuclear weapon.

Installation 05Edit

During the events of Halo 2, the Covenant and humans discover a second ringworld, Installation 05, or Delta Halo. It was monitored by 2401 Penitent Tangent, who completely ignored Flood warnings and was captured by their leader, the Gravemind. The Covenant leadership wants to activate the installation, believing it is the key to their salvation.[26] At the same time, the Flood lay siege to the Covenant's city-ship, High Charity. After 343 Guilty Spark informs Halo's true purpose to the Arbiter, a Covenant holy warrior, and warns him of the danger that the Halos truly represent, a group of humans and Covenant Elites prevent the firing of the ring.[27] The unexpected shutdown activates a fail-safe protocol, priming the remaining Halo installations for remote activation from a location known as The Ark.[28] In Halo 4, it is revealed that the UNSC has created an oversight base on the Installation (or around it), as they did with Installation 03. It's mentioned in the novel Halo: Hunters in the Dark that the Elites "scorched the surface to char and ash" to contain the remaining Flood on the ring.

The ArkEdit

The Ark, also referred to as Installation 00, is located outside the Milky Way galaxy and serves as the construction and control station for the Halo weapon system. It does not share the ringworld geometry of the other installations. During Halo 3, the Covenant discover a portal on Earth that leads to the Ark and are pursued by the humans and a breakaway faction of Covenant opposed to activating the rings. Gravemind, having hijacked High Charity, crash-lands on the installation. The remote firing of the rings is halted by Master Chief and the Arbiter. In order to end the threat of the Flood, Master Chief decides to activate Installation 08 under construction in the Ark, the replacement for the Halo that he destroyed in Halo: Combat Evolved. Unknown to everyone but 343 Guilty Spark, a premature firing would destroy the installation; the monitor attempted to defend 'his' ring but was destroyed by Master Chief, who proceeded to fire the weapon. The firing tears apart the incomplete Halo and severely damages the Ark as Master Chief, Cortana, and the Arbiter try to escape through the portal, which closes as they enter, leaving Master Chief and Cortana drifting in space while the Arbiter returns to Earth successfully.

In Halo: Hunters in the Dark, taking place in 2555, the Ark is revealed to have survived, albeit severely damaged and its Monitor 000 Tragic Solitude attempts to harvest Earth for the raw material needed to repair the installation while exacting revenge for damaging it in the first place. A joint UNSC-Swords of Sangheilios team travels to the Ark through the reactivated portal and destroys Tragic Solitude, foiling his plan. The UNSC makes plans to establish research bases on the Ark and to repair it by strip-mining lifeless star systems for the needed resources using the Ark's Retriever Sentinels.

In Halo Wars 2, taking place in 2559, the repaired Ark acts as the primary setting. The portal to Earth having shut down following the events of Halo 5: Guardians, the Ark has been invaded by a rogue faction known as the Banished. The long-lost Spirit of Fire is mysteriously pulled through a portal to the Ark and battles with the Banished for control of the installation. In the Awakening the Nightmare expansion, the Ark faces a renewed Flood outbreak when the Banished breach the containment shield around the ruins of High Charity. However, the Banished and the Ark's defenses are able to contain the outbreak and seal off High Charity once again.

Installation 07Edit

Installation 07, also referred to as Zeta Halo, appearing in several of the novels, is the oldest and most mysterious of the Halo rings. Unlike the other installations, Installation 07 was part of an older, larger array that was unidirectional in nature, unlike the current array's omnidirectional nature. It was originally 30,000 kilometers wide, compared to its current 10,000 kilometer diameter.

First appearing in Halo: Cryptum, Installation 07 falls under the control of the rogue Forerunner AI Mendicant Bias, having acted as both a test-bed for the older array and a prison for the creature known as the Primordial. Falling under the influence of the Primordial, Mendicant Bias used Installation 07 and several of the other twelve rings that made up the original array to attack the Forerunner capital and wipe out much of the government. Subsequently, Installation 07 becomes one of only two surviving rings of the older array, the other being Omega Halo which is destroyed in the Flood attack on the Greater Ark in Halo: Silentium.

Installation 07 acts as the primary setting of the novel Halo: Primordium which is depicted as a story being told to ONI researchers who recovered a damaged Monitor from the Ark following the events of Halo 3. After being shot down during the battle at the capital, Earth human Chakas and his friends attempt to cross the installation which is fraught with dangers, including the Flood, warring Forerunners and the Primordial. Having been badly damaged in the battle, the installation has activated a failsafe protocol that Mendicant Bias can't override which sets it on a collision course with a planet as an act of self-destruct. Installation 07, home to a human population transplanted by the Librarian, is revealed to have been used by the Master Builder Faber as a testing ground for his cruel experiments to find a cure for the Flood. The ring is nearly destroyed, suffering even worse damage in the process, but the IsoDidact arrives with a Forerunner fleet and retakes control from Mendicant Bias before managing to save the ring with Chakas' help. Mortally wounded, Chakas is transformed into 343 Guilty Spark while the IsoDidact executes the Primordial and punishes Mendicant Bias. The badly damaged ring is decreased in size to 10,000 kilometers to make it more manageable and along with being made a part of the newer Halo Array, it is turned into a tomb for the millions who died on the surface. In the present, ONI scientists theorize about the ring that the Monitor, now revealed to be 343 Guilty Spark, has been telling them about. One suggests that due to the installation apparently being covered in perpetual cloud given the Ark's hologram of it, Installation 07 never fully recovered from the damage it sustained.

In Halo: Hunters in the Dark, taking place in 2555, the UNSC has found Installation 07 using records on the Onyx shield world and have set up the Zeta Halo project. The ring is depicted as having repaired itself in the hundred thousand years since the events of Halo: Primordium and life thrives upon the surface once again. Scientists studying the ring are unable to locate the Monitor or the Library, but discover the Control Room where a countdown to activation of the Halo Array in a matter of weeks is found. This forces the UNSC and the Swords of Sangheilios to launch a mission to the Ark to stop the firing of the array which turns out to be part of the plan of the Ark's Monitor, 000 Tragic Solitude.

Installation 08Edit

Installation 08 is a replacement for Installation 04 that is constructed by the Ark upon the original's destruction in Halo: Combat Evolved. Identical to the original ring, the replacement is mostly complete when the Ark is found a few months after the destruction of Installation 04, but is unfinished enough that parts of its superstructure are visible. Cortana describes it as "so new, unfinished." After the death of the Prophet of Truth, the new ring rises from the Ark's Foundry in front of the Master Chief and the Arbiter who realize that the ring, disconnected from the rest of the network and safely outside the Milky Way galaxy, can be fired to destroy the local infestation on the Ark without harming anything else. After rescuing Cortana from High Charity, the Master Chief and Sergeant Johnson attempt to fire the ring, angering 343 Guilty Spark who knows that doing so will destroy the installation in its present state and heavily damage the Ark. Spark kills Johnson, but is destroyed by the Master Chief before Cortana fires the installation. The Master Chief and the Arbiter manage to escape aboard the Forward Unto Dawn, but the ring's firing causes the Portal to close, severing the ship in half and stranding the Master Chief in space. Firing Installation 08 ends the Flood infestation upon the Ark and destroys the Gravemind and itself while severely damaging the Ark. However, in Halo Wars 2: Awakening the Nightmare, Flood infection forms are revealed to have survived in the ruins of High Charity and are accidentally unleashed again by the Banished before the Flood are contained once more.

Installation 09Edit

In Halo Wars 2, Installation 09, a second replacement for Installation 04, is found nearly complete on the Ark by the crew of the UNSC Spirit of Fire. With no way back to human space, the crew decides to launch the replacement ring with a distress beacon aboard to Installation 04's original position, thereby signaling for help. A conflict with the Banished occurs on the installation, but Professor Ellen Anders, after disarming the ring's superweapon, is able to take control of the installation's gravity anchors and launch part of its landmass into space, killing the Banished forces. The ring and Anders enter slipspace, but are pulled out prematurely by a construct known as a Guardian that is loyal to the rogue AI Cortana.

See alsoEdit


  1. ^ Cuddy, Luke (2011-06-07). Halo and Philosophy: Intellect Evolved. Open Court. ISBN 0812697189. [...] Banks put out the Culture series of books, which envisions a slightly smaller structure called an "orbital" -- probably closer to the Halo structures [...]
  2. ^ Sones, Benjamin E. (2000-07-14). "Bungie dreams of rings and things, part 2". Computer Games Online. Archived from the original on 2005-04-08. Retrieved 13 April 2013. we don't want people to think this is the game of Niven's Ringworld, simply because it takes place on a ring-shaped artificial world… you'd be surprised how often people assume this. ... structurally it's more similar to the "orbitals" in Iain M. Banks' Culture novels.
  3. ^ Grazier (2006), 39–40.
  4. ^ Hiatt (1999), 94–96.
  5. ^ a b Grazier (2006), 41.
  6. ^ a b McLaughlin (2007), 1.
  7. ^ a b Jarrard, et al (2008).
  8. ^ Perry (2006), 6.
  9. ^ Trautmann (2004), ix.
  10. ^ Trautmann (2004), 73.
  11. ^ Toyama (2001), 61.
  12. ^ Preston (2000), 19.
  13. ^ a b Bungie.
  14. ^ Lehto, et al (2002).
  15. ^ a b c Grazier (2006), 44–45.
  16. ^ Grazier (2006), 46.
  17. ^ Grazier (2006), 49.
  18. ^ Grazier (2006), 47.
  19. ^ Grazier (2006), 48.
  20. ^ Grazier (2006), 42.
  21. ^ a b Trautmann (2004), 77.
  22. ^ Grazier (2006), 43.
  23. ^ Trautmann (2004), viii.
  24. ^ Barrat (2007), 2.
  25. ^ McLees, et al (2006).
  26. ^ "Cortana: That's what I thought he said. The Prophet of Regret is planning to activate Halo! / Master Chief: Are you sure? / Prophet of Regret: I shall light this sacred ring, release its cleansing flame, and burn a path into the divine beyond! / Cortana: Pretty much."—Bungie (2004). Halo 2. Microsoft Game Studios. Level/area: Regret.
  27. ^ Barrat (2007), 3.
  28. ^ "343 Guilty Spark: Fail-safe protocol: in the event of unexpected shut-down, the entire system will move to standby status. All installations are now ready for remote activation. / Keyes: Remote activation? From here? / 343 Guilty Spark: Don't be ridiculous. [...] the Ark, of course."—Bungie (2004). Halo 2. Microsoft. Level/area: The Great Journey.


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