NASA Moves Rescue Shuttle for Risky Hubble Repair Mission

NASA?s rescue ship for a risky May shuttle mission to the Hubble Space Telescope moved a step closer to its Florida launch pad on Friday.

Shuttle workers at NASA?s Kennedy Space Center moved the space shuttle Endeavour from its hangar to the cavernous Vehicle Assembly Building at the Cape Canaveral, Fla.-based spaceport, where they will attach the spacecraft to its 15-story fuel tank and twin solid rocket boosters over the next week.

The work will accomplish two goals at once for NASA to prepare Endeavour for a planned June mission to the International Space Station, while priming the spacecraft to pull double duty as a standby rescue ship for NASA?s planned May 12 launch of the shuttle Atlantis toward Hubble.

?They actually finished up a little bit ahead of schedule and things are going quite well,? NASA spokesperson George Diller told SPACE.com from the spaceport.

Endeavour?s sister ship Atlantis is already atop its own seaside launch pad for its May 12 blast off for the Hubble repair mission. NASA plans to move Endeavour out to a nearby launch pad on April 17, but hopes it never has to launch the shuttle on the rescue mission it is on reserve for.

NASA has been preparing Endeavour for an unprecedented rescue mission to retrieve the seven-astronaut crew of Atlantis in the event that shuttle suffers critical damage and is unable to return to Earth. As designed, the mission would launch Endeavour and a skeleton crew of four astronauts on relatively short notice to rendezvous with Hubble, where Atlantis astronauts would perform a series of spacewalks to leave their stricken ship.

NASA has said the chances of needing the rescue mission is extremely remote, but Atlantis?s mission to Hubble is considered more risky than other recent shuttle flights to the International Space Station.

The space agency opted to have a rescue shuttle on standby because - unlike space station-bound shuttle astronauts, which can return to the orbiting laboratory if their spacecraft is damaged - the crew of Atlantis will have no safe haven. The Hubble Space Telescope flies in a higher orbit and in a different inclination than the space station, so Atlantis would be unable to reach the safety of the orbiting lab if it suffered critical damage, NASA officials have said. There is also an increased risk of damage from space debris, they have added.

Atlantis astronauts are expected to perform five back-to-back spacewalks during their 11-day mission to add new instruments to Hubble, replace gyroscopes and batteries, attach a docking ring for possible use in the future and make repairs to equipment that was never designed to be fixed in space. If all goes as planned, the mission is expected to extend Hubble?s lifetime through at least 2014.

Once Atlantis returns to Earth, Endeavour will switch from its rescue mission to a planned space station construction flight. That mission is slated to launch in mid-June to deliver a porch-like experiment platform for the space station?s Japanese Kibo module and swap out one member of the outpost?s astronaut crew.

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