Space Shuttle program to the International Space Station (ISS), as the station could be used as a safe haven for the crew awaiting rescue in the event that damage to the orbiter on ascent made it unsafe for re-entry. The board recommended that for the remaining flights, the shuttle always orbit with the station. Prior to STS-114, NASA Administrator Sean O'Keefe declared that all future flights of the shuttle would go to the ISS, precluding the possibility of executing the final Hubble Space Telescope servicing mission which had been scheduled before the "Columbia" accident, despite the fact that millions of dollars worth of
Space Shuttle two different upper stages developed for the STS (single-stage Payload Assist Module or two-stage Inertial Upper Stage). The Space Shuttle was stacked in the Vehicle Assembly Building, and the stack mounted on a mobile launch platform held down by four frangible nuts on each SRB, which were detonated at launch. The Shuttle stack launched vertically like a conventional rocket. It lifted off under the power of its two SRBs and three main engines, which were fueled by liquid hydrogen and liquid oxygen from the ET. The Space Shuttle had a two-stage ascent. The SRBs provided additional thrust during liftoff and