Delivering HST to orbit

NASA's STS 31 mission will involve the lofting of the Hubble Space Telescope into orbit by the Space Shuttle Discovery. The Discovery Remote Manipulator System RMS will be used to robotically lift the HST out of the payload bay and position it for release on the 19th orbit. The Discovery Orbiter will then be slowly backed away from the HST; if there is any indication of an HST aperture door malfunction, Discovery will still possess enough time and propellant to return to the HST and open it with the RMS, but not without risk of the HST optics' contamination by thruster exhaust gases.