Mission planners have been working since last fall, when the flight was announced, to determine the best time in the shuttle launch schedule to support the needs of Hubble while minimizing the impact to International Space Station assembly.

NASA also will support a "launch on need" flight during the Hubble mission. In the unlikely event a rescue flight became necessary, space shuttle Endeavour would be launched for the Kennedy Space Center.

NASA said shuttle missions beyond the Hubble flight are still being assessed. The shuttles are to be retired when construction of the space station is completed.

The Hubble Space Telescope is an international cooperative project between NASA and the European Space Agency.