Space shuttle Endeavour is on a launch pad, ready to rocket off on a rescue mission if shuttle Atlantis needs help when it flies to repair the Hubble Space Telescope next month.
Endeavour rolled out early Friday to a launch pad at the Kennedy Space Center and is on standby in case the astronauts on Atlantis need a safe ride home. Atlantis is on a separate launch pad less than two miles (3 kilometers) away.
Ever since space shuttles resumed flying following the 2003 Columbia tragedy that killed seven astronauts, NASA has had a rescue plan in case of irreparable damage. Most of those missions have been to the space station, though, where astronauts could camp out for two months. The Hubble mission doesn't offer a safe haven.
