Astroengineering
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There is more information available on this subject at Astroengineering on the English Wikipedia. |
Astroengineering is the name given to the construction of megastructures in space by technologically advanced beings. It is a form of megascale engineering, but deals with structures that are "easily observable" from interstellar distances with 20th century astronomical instruments: e.g. a space elevator is an example of megascale engineering, but it is not an example of astroengineering. A notable example of astroengineering are the Halo rings, built by the technologically advanced Forerunners.
Only civilizations with a minimum Technological Achievement Tier of 2 can construct such megastructures. As a Tier 3 civilization, the United Nations Space Command lacks known astroengineered structures.
Forerunners[edit]
The Forerunners are renowned for their mimicry of natural environments, but it is their engineering achievements that stand as monuments to their extraordinary prowess, centuries after they have passed on. Their Halo Installations, shield worlds, and the Ark are all artificial habitats on a vastly larger scale than anything that either humanity or the Covenant could have accomplished. Forerunner megastructures were typically designed by members of the Builder rate and constructed by the Huragok as well as a wide range of automatons ranging from diminutive Constructors to colossal Retriever Sentinels. Meanwhile, the Miners were tasked with stellar and planetary engineering.[1]
Halo Array[edit]
- Main article: Halo Array
The Halo installations are planet-sized artificial worlds, shaped like a ring. The interior surface contains a breathable atmosphere and seemingly natural terrain, including oceans, lakes, mountains, forests, and tundras. Underneath this is a support layer, upon which this terrain has been put in place, consisting of a vast grid network of metallic plates that provide the base. The Earth-like gravity on a Halo installation is provided by the centripetal force of the ring's spin as well as an artificial gravity field.[2]
The Halos were constructed as weapons of mass destruction on a galactic scale, designed to kill all sentient lifeforms in their radius of effect, approximately 25,000 light-years, by firing a harmonic pulse of cross-phased supermassive neutrinos.[3]
Artificial planets[edit]
The Forerunners were also adept at creating artificial planets in a variety of ways. They were capable of speeding up natural planetary formation by collapsing an asteroid field into a molten mass of a twenty-megameter range, and then form it into a protoplanet which could be fully cooled in less than ten thousand years.[4]
In addition, they employed other methods to construct planetary-scale megastructures, such as Onyx. Internally, Onyx's structure was maintained by, and even composed of, trillions of Sentinels and at least one immense Sentinel constructor factory, while externally the planet can appear like many other terrestrial planets, with a wide variety of terrain.
A variation of the concept also exists, built in a more conventional fashion. Employed in a variation of the shield world concept known as a conservation sphere,[5] this variation is a structure whose surface is composed of an outer shell, with a hollow interior and a habitable inner surface, and a miniaturized artificial star in the center. The interior resembles a Dyson sphere, though on a far smaller scale.
While not intended to mimic planets as much as be employed as weapons of war, the Forerunner fleet employed a kind of warship known as a Castellan, a "moon-sized" colossal battle station.[6]
Onyx[edit]
- Main article: Onyx
The artificial planet Onyx was used as a cover for the slipspace-based Shield World in its core. It was later colonized by the UNSC, oblivious as to its true origins until 2552, when its Sentinels activated to defend the Shield World. It was later damaged by FENRIS nuclear warheads, and destroyed as its Sentinels burst free and set up defensive stations around the Shield World portal.[7]
Shield 0459[edit]
- Main article: Shield 0459
This shield installation was representative of a smaller variation of the shield world concept. Known as a conservation sphere,[5] the facility consisted of a hollow spherical shell with a terraformed inner surface and an internal sun. The installation's outer surface was heavily infested by the Flood.
It was destroyed by the UNSC forces in 2531 when the overloaded Slipspace drive of UNSC Spirit of Fire sent the internal star to supernova state.
Dyson spheres[edit]
- Main article: Dyson sphere
The Forerunners also constructed massive Dyson spheres, such as the shield world known as Shield World 006 held within Onyx. With a diameter of 2 astronomical units, this shield world was encapsulated in a Slipspace field to protect the occupants from the Halo Array as it activated. Essentially a sphere, with its habitable surface on its internal surface rather than external, these "micro" Dyson spheres are also equipped with their own stars,[8] providing warmth, light and energy to the installation. Originally intended as a way to circumvent the Halo effect, the shield worlds were not put into use by the Forerunners due to the rampant actions of one of their own AI constructs.[9]
The interior of Trove was essentially a variation of this concept, albeit on a far smaller scale and not enveloped in slipspace.
Installation 00[edit]
- Main article: Installation 00
Installation 00 is a Forerunner megastructure vaguely similar to an Alderson disk in overall shape.
With a diameter of 127,530 kilometers,[10] and a larger total surface area than a Halo installation, it incorporates many similar elements, including Earth-like gravity and atmosphere and a rich and diverse ecosystem. Located in the center of the installation is a small planetoid, used for raw materials, and a star orbiting nearby despite its location: 218, or 262,144 light years outside of the Milky Way Galaxy, where stars cannot naturally form. It is possible that this is an artificial sun created by the Forerunners.[11]
Rather than being a superweapon, like the Halos, the Ark functions as the control center of the Halo Array. It also served as the lead researching station for the Librarian and as a construction facility for Halos, using the planetoid to provide metals, gases, elements and other resources needed for reconstruction. After the construction is complete, the Halo is transported to its destination via a Slipspace portal.
Originally, an even larger Ark facility existed, known as the greater Ark. This second Ark was used to construct and repair a series of larger Halo rings. Though it differed from Installation 00 in a number of respects, it shared its general flower-like shape and was similarly located outside the galaxy.[12]
Stars[edit]
The Forerunners had the