In an unprecedented step, a space shuttle was moved to the launch pad Friday for a trip NASA hopes it will never make – a rescue mission.
The shuttle Endeavour is on standby in case the seven astronauts who go up on Atlantis next month need a safer ride home.
Atlantis and its crew are headed into space for one last repair job on the 18-year-old Hubble Space Telescope. It's a venture that was canceled when first proposed a few years ago because it was considered too dangerous.
The risk is this: If Atlantis suffers serious damage during launch or in flight, the astronauts will not be at the international space station, where they could take refuge for weeks while awaiting a ride home. They would be stranded on their spacecraft at the Hubble, where NASA estimates they could survive for 25 days.
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Endeavour and four more astronauts would need to blast off on a rescue flight as soon as NASA determined Atlantis was too damaged to fly home.
On Friday, Endeavour was parked at its launch pad just a mile from where Atlantis is tentatively set to lift off Oct. 10.
It is the first time since 2001 – when flights were more closely spaced – that both of NASA's shuttle pads have been occupied. And it will probably be the last.
Atlantis astronauts say there's a slim chance any rescue will be needed, and they say they would fly to Hubble even if there were no such backup plan.
Scott Altman, Atlantis' commander, said it may seem like overkill, but having a rescue ship on the pad is the right thing to do.
“It's kind of a belt-and-suspenders approach. But if you need the belt after your suspenders fail, you would be glad you had it,” said Altman, a retired Navy captain and former fighter pilot.
On top of the usual launch and landing dangers, the Atlantis crew faces an estimated 1-in-185 chance that a piece of space junk or a micrometeoroid will cause catastrophic damage to their ship. Those are greater odds than for a typical shuttle flight because of Hubble's extremely high and debris-littered orbit.
Before reaching Hubble and again after leaving it, Atlantis astronauts will inspect their spacecraft for damage, just as crews always do while in orbit.
Once Atlantis is aloft, “if it even begins to smell” like a rescue is needed, final preparations for Endeavour will begin, said launch director Mike Leinbach. He said Endeavour could lift off within six days.
The rescue craft would fly to Atlantis and use a 50-foot robot arm to grab the damaged shuttle. Atlantis astronauts would don spacesuits and float, a few at a time, to Endeavour over the course of three spacewalks. Endeavour would return home with all 11 astronauts.
The toughest call, officials say, would be deciding Atlantis had serious enough damage that a rescue should be tried.
“This will be an emotional thing,” Leinbach said.
Such a rescue would put four more astronauts at risk and would mean the end of Atlantis, and undoubtedly the space shuttle program, which is set to be phased out in 2010. Atlantis would be sent into the Pacific once its astronauts were aboard Endeavour.