Summary: GAO provided information on the National Aeronautics and Space Administration's (NASA) mission to service the Hubble Space Telescope (HST). GAO found that: (1) NASA use of independent review teams and input from individual experts has increased the probability of successfully servicing HST because these sources have effectively identified potential problems and ensured implementation of solutions; (2) NASA could have difficulty in proving that extensive on-orbit maintenance is practical and cost-effective; (3) existing mission limitations involve problems in providing sufficient gravity-free training simulators, potential shuttle reliability problems, limited experience in extensive extra-vehicular space servicing activities, and uncertainties regarding HST durability; (4) the HST mission's complexity and duration will exceed any extra-vehicular activity performed on prior shuttle missions; and (5) NASA needs to notify Congress that unanticipated problems could arise and prevent completion of the HST mission and a second mission could be necessary to eliminate the backlog of desired maintenance.
