Installation 08

The Replacement for Installation 04 was a partially constructed Halo which was started at the Ark after the destruction of the original Installation 04.

Background
This Installation was designed as an identical replacement to be previous Installation 04. This was to ensure that the Forerunner's plan of the "Halo Network", that was to use all seven Halo rings that encompasses the entire galaxy, for the elimination of all sentient life from the threat of the Flood, was to be achieved.

Replacement
Immediately after the Battle of Installation 04 and the destruction of Installation 04. The Ark was notified, and an automatic function started rebuilding a replacement for the missing Installations position. The explosive device to eradicate sentient life was built first with the surrounding circular metal structure after it. Before it is released into space the Installation has a number of primary features available even though it was still not complete, these included the environment, atmosphere and main structures.

Destruction
The new Installation was released into space, but was still incomplete. Seeing that the Flood had followed them to The Ark and radiply spreading, John-117 and the Arbiter decided to activate the incomplete Installation. 343 Guilty Spark who had allied himself with the two of them was ecstatic about being able to finally activate the Installation.

The Arbiter questions about how they will be able to activate the Installation. Seeing a Flood consumed High Charity, John-117 decides that Cortana has an Activation Index from the first Installation in the events of Halo and persuades the Arbiter the quickest and easiest course of action would be to brave the Flood consumed High Charity to retrieve Cortana, and the Activation Index.

While aboard High Charity, John-117 finds Cortana, and is persuaded by her to destroy the plasma reactors of High Charity, to slow the Flood and Gravemind down, which he does. The trio find a pelican and use it to travel to Installation 04 (II) control room core. The pelican crash lands in a snowy canyon near the control room. Flood dispersal pods land as the three reach the base of the control room. Slowly climbing up the walk ways to the top where the control room is, they are helped by Sergeant Major Avery J. Johnson. After eliminating the waves of surrounding Flood, all four enter the control room.

Final Moments
Guilty Spark who is already inside the Installations control room informs the team of the current status of the Installation, and that it would require several more days to become fully operational, and that a premature firing could destroy the Installation.

Due to the gravity of the situation, Johnson disregards Spark's warnings and prepares to connect Cortana into the Core so that she can start the firing sequence. Spark who has already seen "his" previous Installation destroyed is outraged by Johnson's reckless behaviour, and fully submits to his insanity. Johnson is attacked by Spark's energy weapon, this mortally wounds Johnson.

John-117 and the Arbiter now attempt to stop the rampant construct, but are both subdued by Spark's energy weapon. He lectures John-117 about "that even though he is descended from his creators, "...this ring is mine." Chief battles with Spark, but finds that he is unable to penetrate the monitor's shielding. With the last of his strength, Johnson attacks Guilty Spark with his Spartan Laser, this damages the neurotic monitor's casing of Spark. Johnson gives the John-117 the Spartan Laser and after several direct hits, Spark is destroyed. Johnson hands the John-117 Cortana's data chip, pleading with him to leave him and activate the ring, before dying. Cortana broadcasts herself to the console of the control room and beginning the activation sequence.

As Spark predicted, the ring was not ready to fire, and it begins to shake itself apart and disintegrate. John-117 and the Arbiter escape through the first Phase Pulse Generator room, and then to Johnson's Warthog. The vibration of the activation begins to tear the Installation apart, causing explosive reactions all across incomplete sections of the installation. John-117 and the Arbiter barely managed to reach the UNSC Frigate, Forward Unto Dawn, before the ring detonates. Cortana states that the explosion "[does] a number on The Ark."