Editing Installation 00

Like the rest of the newer, more efficient Halo installations, Installation 00 was constructed sometime between [[98,445 BCE]] and [[97,445 BCE]] under orders of [[Master Builder]] [[Faber]], to address problems with the [[greater Ark]] and its larger Halos. While plans for the second Ark had existed for some time, its construction was delayed by the [[Old Council]] to avoid the Builders from gaining too much power.<ref>'''[[Halo: Silentium]]''', ''page 45''</ref> The lesser Ark, as it was known at the time, was designed to produce smaller but much more powerful Halo rings, which could be transported more efficiently and could deal far more widespread damage. Until the very last days of the [[Forerunner-Flood war]], the lesser Ark, its new Halos, and its location were kept a well-guarded secret; only the most top-tier Forerunners knew of its existence, and the only one who knew the exact coordinates of the installation was Faber. Whereas the greater Ark acted as the Forerunners' final line of defense and command center, the lesser Ark would serve the function of a last fallback point where its own array of rings could be swiftly distributed to their designated locations across the galaxy and fired to cleanse the galaxy of all sentient life as a last resort.<ref>'''[[Halo: Silentium]]''', ''String 33''</ref>

In the endgame of the Forerunners' war with the Flood, the Forerunner {{Class|Contender|artificial intelligence}} [[Mendicant Bias]], which had been [[logic plague|corrupted]] by the [[Gravemind]] and defected to the Flood, attacked and destroyed the greater Ark, killing the majority of the remaining Forerunners who had taken refuge there. Using coordinates provided by the Master Builder, a handful of survivors, including the [[IsoDidact]], managed to escape to the lesser Ark where they prepared their weapons of last resort. In order to buy the IsoDidact time, the Librarian traveled to [[Earth]], broadcasting a feint transmission intended to draw the Flood's attention to her. She spent her last days in the plains near [[Mount Kilimanjaro]], near the site of the [[Portal at Voi|slipspace portal]] to Installation 00. Mendicant Bias knew of the secret Ark and how to access it through the [[Keyship]]s, though he did not know of its exact location. In order to devise the best possible defense against Mendicant Bias, the Forerunners deployed [[Offensive Bias]], a military AI formerly in control of the greater Ark and Mendicant's replacement, and sent it to counter Mendicant Bias' fleet in advance before it could reach the Ark. While Offensive Bias [[Battle of the Maginot Sphere|engaged Mendicant's fleet]], the IsoDidact completed preparations for the Halo Array and fired the rings from the Ark, purging the galaxy of all life.

===Post-battle===

In [[2553|March 2553]], the [[Office of Naval Intelligence]] deployed an automated probe-carrying spacecraft to the damaged Ark using advanced slipspace technology. The ship arrived in November and dispersed its probes, although all communications with the devices were cut off after initial transmissions confirming the Ark's survival. In response, the {{UNSCShip|Rubicon}} was sent from [[Luna]] in December 2553 to conduct a more thorough investigation of the installation's ravaged surface.<ref name="hitd c2">'''[[Halo: Hunters in the Dark]]''', ''Chapter 2''</ref> Due to the damage dealt to the Ark's life support systems and its artificial sun, heavily inclement weather became the norm.<ref name="EH">'''[[Eleventh Hour reports]]''', ''part 4''</ref>

===Operation: FAR STORM===

{{Main|Operation: FAR STORM}}

==Design details==

Installation 00 resembles a massive flattened dish with a series of eight curved arms, known as spires, four large and four small, arranged around its rim, similar to the petals of a flower. The entire upper surface is [[Terraforming|terraformed]], with oceans, forests and deserts.{{Ref/Reuse|The Ark}}{{Ref/Reuse|Covenant}} Installation 00 is {{Convert|127530|km|mi|sigfig=5}} in diameter and thus one of the largest known Forerunner constructs.{{Ref/Reuse|vis}} Spread throughout the installation are hundreds of [[refugia]], artificial biomes designed to sustain diverse flora and fauna as part of the Conservation Measure. Each of these refugia are separated by massive quarantine walls.<ref name="mythos ark">'''[[Halo Mythos]]''', ''pages 122-123''</ref> Twelve refugia are located on the central hub, while an additional twenty are located on the arms of the structure.<ref name="Refugia">'''[[Halo Wars 2]]''', ''[[Phoenix Logs]]'' - ''Refugia''</ref> The various refugia are intended to mimic common planetary environments - one such refugia known as the Halo Refugia<ref name="HaloRefugia">'''[[Halo Wars 2]]''', ''[[Phoenix Log]]'' - ''Halo Refugia''</ref> bore a notable similarity to Earth's climate, though much more extreme; mountains are higher, chasms are deeper and the sea and sky are a deeper blue.{{Ref/Reuse|HaloRefugia}}