The spaceshuttle Endeavour rolled out to a Florida launch pad on Friday to stand by for anunprecedented rescue mission NASA hopes it never has to fly.
Endeavour arrivedat Launch Pad 39B at NASA?s Kennedy Space Center in Cape Canaveral, Fla., at 7:17a.m. EDT (1117 GMT), where it will be primed to launch within weeks of anyemergency aboard its sister ship Atlantis during next month?s riskyrepair mission to the Hubble Space Telescope. Atlantis is poised atop itsown launch pad for a planned May 12 liftoff.
?It?s thefirst time that anyone has had a rescue mission standing by,? NASA spokespersonAllard Beutel told SPACE.com from the Florida spaceport. ?We thought itgives us that amount of extra insurance.?
Endeavourhas actually made the trek to the launch pad once before to serve as the upcoming Hubble mission?srescue ship. The shuttle was on standby last September until a failure aboardHubble delayed a planned October launch for Atlantis.
Altogether,two orbiters have been at their launch pads simultaneously only 18 times in NASA?s28-year history of shuttle flight, Beutel said.
?We really doexpect this to be the last time we ever have two space shuttles on the launchpad at the same time,? he added.
Riskyrepair flight
NASA hassaid the likelihood of requiring a rescue mission for the sevenHubble-bound astronauts is extremely remote. But the space agency is takingthe precaution because unlike recent shuttle flights to the International SpaceStation, where astronauts could seek shelter if their spacecraft is severelydamaged, the crew of Atlantis will have no such safe haven.
Commandedby veteran NASA astronaut Scott Altman, Atlantis is poised to launch toward Hubbleon May 12 from Launch Pad 39A, which is near Endeavour?s current perch. The much-delayedmission is NASA?s final shuttle flight to overhaul Hubble and includes fiveback-to-back spacewalks to repair broken equipment, add new instruments andextend the iconic space telescope?s lifetime through at least 2014.
Because Hubbleflies in a higher orbit and different inclination than the International SpaceStation, Atlantis would be unable to reach the orbiting laboratory if it suffers acritical failure or severe damage its vital heat shield. The mission alsoincludes a higher risk ofdamage from orbital debris or micrometeorites, though that risk increase appears to be lower than initially thought, NASA officials have said.
It is becauseof the lack of a safe haven aboard the station that NASA optedto prepare Endeavour for a potential rescue. The shuttle is already slated tofly a space station construction mission in June, but will be primed to launch witha skeleton crew relatively soon after an emergency is declared, Beutel said.
?Withinthat timeframe, we would be prepared to launch Endeavour with a crew of fourastronauts,? Beutel said, adding that the Atlantis astronauts would stageseveral spacewalks to abandon their ship and return home aboard Endeavour. ?Wewould then splash Atlantis down safely somewhere in the Pacific Ocean.?
Shuttle double duty
If Atlantis?sHubble mission goes smoothly as planned, Endeavour would simply bemoved to the adjacent launch pad in late May for a planned June 13 launch to theInternational Space Station, Beutel said.
NASA plansto launch its remaining shuttle missions from Launch Pad 39A and use the nearbyPad 39B for its newAres I rocket and Orion capsules, which will replace the agency?s spaceshuttle fleet, once Endeavour is moved, he added.
Over theweekend, NASA will deliver the hardware for Atlantis?s Hubble mission to theshuttle?s launch pad, offering a relatively rare sight of two shuttles exposed atoptheir pads with their shroud-like service structures retracted. The twospacecraft are expected to be visible through Monday and will be photographedfrom the ground and air, Beutel said, adding that NASA expects about 50,000 peopleto visit the space center during a Saturday employee Family Day.
?I think peopleare really excited about it,? Beutel said.
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