From Halopedia, the Halo wiki
The Master Chief investigates a Forerunner signal coming from a Banished outpost called Annex Ridge. After discovering the Banished are using the base to transport Forerunner artifacts for further study, he proceeds to disable the facility in order to halt the Banished's research efforts on the Ring.
The Chief approaches Annex Ridge.
If an adjacent FOB has been recaptured:
If an adjacent FOB has not been recaptured yet:
The Chief enters the Base and engages the guards.
The Chief fights his way deeper into the base and finds the artifact that the Weapon detected.
If the none of the Ring artifacts have been scanned yet:
The control console is marked on the Chief's HUD.
The Chief enters a tunnel, leading to an underground section of the base. After fighting his way past the Banished troops inside, he finds a gravity lift and uses it to enter the base's command center. He eliminates the Banished personnel inside, then accesses the control console at a Holotank. There are also some imprisoned Marines on the upper level that he can free.
The Chief heads back outside.
A Banished Phantom drops off enemy reinforcements. The Chief deals with them, then enters another structure, where he locates the silo controls. He proceeds to raise the fuel silo.
The Chief destroys the fuel silo. The subsequent chain reaction destroys the transport next to it.
If House of Reckoning has been completed:
Mission is completed.