Updated

It is a scenario NASA hopes it never has to try out.

If Discovery is damaged during Saturday's launch, NASA could land the space shuttle without any astronauts aboard after the crew found refuge at the international space station.

"If we got into that scenario, we would really have to hustle," John Shannon, deputy manager of the space shuttle program, said Thursday. "We would really have to work ... until we felt a high degree of confidence that we weren't going to cause more problems."

NASA would only take such action if the space shuttle were damaged to the point that it could not be repaired while it is docked to the space station, and if it were unsafe for the astronauts to return in it, Shannon said. The astronauts could stay for as long as 81 days at the space station until a rescue vehicle arrived.

In that case, space shuttle Atlantis would be launched to the space station to bring back Discovery's crew members. Discovery would have to be undocked from the orbiting space lab to make room for Atlantis.

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Up until recently, Discovery's fate likely would have ended with a watery crash into the Pacific Ocean, but now NASA has a new plan using a remote-controlled orbiter cable that can be attached to control systems in the shuttle by astronauts.

Flight controllers could then guide the space shuttle back to Earth, allowing the vehicle to lower its landing gear, power itself down and deploy a drag chute, Shannon said.

Vandenberg Air Force Base in California would be the likely destination for the landing since its runway starts near the Pacific Ocean and landing there would not endanger populated areas.

"The one thing we're not going to do is put a dead orbiter out into space to just fall where it may," Shannon said.