NASA fine-tunes orbital rescue scenario

The big concern for contingency plan
The shuttle-station contingency plan was designed to give astronauts an alternative to returning home with a damaged ship. The plan calls on shuttle crews to take safe haven aboard the space station until a rescue boat could be launched to ferry them back to Earth.

The addition of seven astronauts to the two-person crew of the space station would make for close quarters, but station managers said it is oxygen that could be the concern for such a contingency plan.

"Our system today is designed for a maximum of three to six crew, and for six just temporarily," said space station program manager Bill Gerstenmaier.

With nine astronauts on station, the outpost's managers would have to make the most of supplies aboard the orbital outpost by running the primary source — a finicky Russian oxygen generator called Elektron — as well as use oxygen stored in onboard tanks and solid oxygen-generating candles.

Currently the station has plenty of food and water to support an extended stay by a shuttle crew, and STS-114 commander Eileen Collins has said her orbiter will likely carry added supplies of both as a safety measure. Discounting the Elektron device, which has been working off and on recently, station managers believe the outpost should be able to support a nine-person crew complement for about 45 days.

"I think conditions won’t be good on the station, but they’ll be better than the alternative," Gerstenmaier said. "We kind of always plan for the worst, but hope for the best."

Rescue ship Atlantis
While the loss of one shuttle is certainly a catastrophe, the loss of two would be even worse.

"If we had a catastrophic failure with Discovery, we’d need to figure out how to prevent that same problem from occurring on Atlantis," Hale said.

Veteran astronaut Steven Lindsey, commander of STS-121, said that his crew would likely be cut down to four astronauts to free up space for the STS-114 crew.

After an extended time in orbit and the limited availability of exercise equipment aboard the station, Discovery astronauts would likely suffer at least some bone and muscle loss. New recumbent seats would be used on a rescue flight to allow returning astronauts to ease their return to the gravity by riding out a shuttle landing lying down, Hale said.

ReturntoFlight.org A diagram prepared for the independent "return to flight" panel shows the layout of recumbent seats that would be used by astronauts during an orbital rescue.

NASA officials haven’t ruled out the possibility that a returning rescue flight might, on its own suffer some emergency and could force both shuttle crews aboard to bail out.

Engineers have added extra rings to the shuttle’s bailout pole — which astronauts use to fling themselves clear of the orbiter wing during an emergency egress — to account for an added crew complement during a rescue mission. But depending on the state of Discovery’s crew, should such an action be required, the STS-300 crew may have to assist returning astronauts in the egress maneuver, NASA officials said.

"We have looked at that, and it is a doable thing but the margins are small," Hale said. "It’s better to have a plan, than to not have one."

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