In the activation of Installation 4.1,the Master Chief escaped using Sgt.Avery Johnson's Warthog.After making a jump into the hangar of Forward Unto Dawn,he uploaded Cortana into the ship's computer.She activated the ship's engines,thus propelling the Master Chief,the Arbiter,and Cortana into space.the ship passed through the portal, but not all of it made it back to Terra-firma(earth).the Master Chief and cortana wre thrown to a position somewhere in the orbit of an ancient forerunner world....