Trove

Shield 0459 was a Forerunner shield world located in the Korinth Prior system. A variation upon the shield world concept known as a conservation sphere, it was intended to protect sentient lifeforms from the effects of the Halo Array and the the Flood, in addition to serving as a military outpost housing a port for a fleet of Forerunner dreadnoughts.

Despite the fact that the Shield Worlds were created as a haven from the Array and the Flood, the external surface was heavily infested with Flood biomass, with forms of various types freely roaming across the surface. Sentinels were a rarity on the outside, but this changed within the center, where the many Forerunner constructs worked to prevent the Flood from claiming the interior as well.

During the Human-Covenant War, Shield 0459 was discovered by the Covenant during the Battle of Arcadia and was subsequently destroyed during a battle in February 2531.

Overview
This Shield World's main structure consisted of the outer surface, the superstructure and tunnel system inside the crust, and the inner miniature Dyson sphere, along with its own miniaturized artificial sun to provide illumination. A series of latitudinal support ribs encircled the megastructure; these were clearly visible on the inner surface. The outer surface, as well as parts of the superstructure, were largely infested with the Flood. Some of the Flood even reached to the interior of the world through openings like vents, but because of the larger numbers of Sentinels, never managed to fully infest it.

The ecosystems of the interior and the exterior were radically different, the outer surface being a rocky wasteland with large bodies of water and Flood biomass in some areas. The atmosphere was thick with dust, which may have been a defensive measure to disable starships and prevent them from carrying the Flood off-world. Parts of the superstructure could be seen on the surface, with chasms reaching deep down into the interior.

The inner Dyson shell was completely terraformed and full of plant and animal life, much like the Halo installations or the Ark. It featured different types of Forerunner structures, ranging from spires to various walls or embankments and rifts leading into the interior of the structure. Like many other Forerunner installations, Shield 0459 possessed a translocation grid in form of a network of teleporters.

Access tunnels
The surface of Shield 0459 had multiple access portals, which could be used to gain access to the interior of the planet. Most of them were likely hidden, for example covered under large bodies of water, such as the one the used to enter the Shield World. The AI in control of these access portals would activate docking sequence when a ship passed over one, forcibly dragging the vessel inside by way of a series of field-projecting pylons on the outer surface.

Within the tunnels inside the superstructure, there was a cleansing system, which prevented the Flood from entering the interior. This quarantine system consisted of several "cleansing rings", which generated energy fields within their diameter, which would destroy any Flood biomass on a passing ship. On the interior, these portals had six interlocks that needed to be opened in order to unlock the access to the tunnel, and like other significant systems on the installation, they could only be operated by a Reclaimer.

The Apex
The Apex site was an installation comprised of a control center on a platform high above the inner surface of Shield 0459, and numerous docking towers containing a fleet of Forerunner dreadnoughts. The control center was accessible from the ground by a teleporter referred to as Apex Base Site, which was situated on top of a plateau with a series of ramps leading up to it.

Construction
Shield 0459 was constructed during or prior to the Forerunner-Flood war to serve as both a military outpost to combat the Flood, and to preserve the lifeforms within from the Halo Array's pulse.

At some point, the Installation became heavily overrun by Flood. Exactly how this occurred is unknown; it would seem that they either escaped containment facilities some time after the Halo Array's activation, or managed to survive by seeking shelter in the interior of the Shield World and later colonized the outside.

Human-Covenant War
"This world shall be the birthplace for an invasion fleet beyond imagining!"

- Prophet of Regret

Shield 0459 was discovered by the Covenant in 2531 using information from a Forerunner complex on the planet Arcadia. After recovering the information, the Arbiter Ripa 'Moramee and the Prophet of Regret traveled to the Shield World, to discover the Apex site and the dormant Forerunner fleet. With the Human-Covenant War ongoing, the Covenant hoped to use Shield 0459's stored warships to crush the UNSC quickly, rather than wage the protracted war that would characterize the Human-Covenant War. However, they soon discovered that while they were able to access the installation, they were unable to reactivate the fleet.

After the Covenant had observed Professor Ellen Anders activating the Forerunner relic on Harvest, the Prophet of Regret ordered the Arbiter to go to Arcadia and capture the human scientist, as she seemed to have unusual knowledge about the Forerunners. The Arbiter returned to Arcadia, captured Anders and brought her to the Shield World.



The Spirit of Fire followed the Covenant in close pursuit, tracking Anders' transponder signal. When the Spirit of Fire arrived to Shield 0459, a new horrific enemy was discovered: the Flood. Some time later, when the Spirit's shipboard AI Serina scanned the planet for Anders' signal, which seemed to be originating from an ocean, the ship was suddenly pulled into the Shield World's internal docking mechanism. After passing the tunnels inside the installation's superstructure, the Spirit of Fire emerged into the internal Dyson sphere.

Some time later, the Arbiter used Anders, who had been kept prisoner within the Apex, to activate the fleet of Forerunner ships. However, as the awestruck Elites watched the fleet's activation, Anders managed to escape via the installation's teleportation grid and regroup with the other humans. She quickly came up with a plan to prevent the Covenant from using the Forerunner fleet: They overloaded the Spirit of Fire's Shaw-Fujikawa Translight Engine to create a chain reaction in the artificial sun in the center of the Shield World, sending it to supernova state and destroying it from within. The Spirit of Fire was able to escape the Shield World's destruction.

Trivia

 * In the cutscenes that show the inner surface of the shield world, lines of Forerunner structures can be seen across the land, dividing the interior environments into latitudinal slices. As seen in the video to the right, these appear to be structural support ribs.
 * While in the pre-rendered cinematics the lines on the inner surface of the shield world are latitudinal, they are longitudinal in-game in the level Repairs. The appearance of the surface is also different, which is likely due to the disparity between the in-game graphics engine and the pre-rendered cutscenes.
 * The concept of a hollow planet with a habitable inner surface is similar to that of a Globus Cassus, a conceptual idea for a megastructure in which the Earth is used as building materials to construct an enormous hollow sphere with a partially terrestrial interior surface.

List of appearances

 * Halo Wars