NASA set for dramatic shuttle rescue

James Oberg NBC News space analyst

HOUSTON - As NASA prepares for its final service call to the Hubble Space Telescope, it's also preparing for something never attempted in the history of the shuttle program: a rescue operation so dramatic that Hollywood would be hard-pressed to come up with a more outlandish plot.

If the Hubble repair crew due for liftoff on Monday got into the deepest sort of orbital trouble, yet another shuttle would have to be launched into orbit as little as a week later. NASA hasn’t launched two piloted spacecraft so close together in more than 40 years. But that's just the first act of the drama.

The rescue shuttle, Endeavour, would have to pull within about two dozen yards of the stranded shuttle Atlantis, and then help Atlantis' crew members make their way across a lifeline to refuge. Then Endeavour, full to capacity, would have to leave Hubble as well as Atlantis behind and return home — but not before Atlantis' controls are set for a self-destruct sequence.

The rescue mission, known as STS-400, would be NASA's last resort for saving the lives of Atlantis' astronauts in case of emergency. If Atlantis suffers irreparable damage to its thermal protection system — perhaps during ascent, perhaps from a space debris impact, perhaps from other less likely but not impossible hazards — it would no longer be able to return safely to Earth.

Because Atlantis is in an orbit different from that of the international space station, it wouldn't be able to reach that safe haven, even though the station will periodically zoom below the shuttle. The only hope for survival would be STS-400’s arrival.

STS-400 would be arguably the most perilous journey ever planned for space travelers. And no matter what the outcome, the mission would probably bring the 28-year space shuttle program to an early end.

Doubled-up shuttles
The possibility of a rescue mission is the reason why Endeavour and Atlantis are both sitting on launch pads at NASA's Kennedy Space Center — a double vision that's been seen only a handful of times in the past and almost certainly will never be seen again.

Two crews are on alert for launch: The seven astronauts for the final Hubble servicing mission, known as STS-125, and the four astronauts for the STS-400 rescue mission. When STS-125 launches, the countdown for STS-400 will be at L-minus-7 days and counting. As STS-125 proceeds, the STS-400 countdown continues to L-minus-3 days, and then enters a "hold" just before fueling.

In a perfect world, the STS-400 team would just mark time until Atlantis heads back to Earth, after which Endeavour would be put back into preparation for a flight to the space station in mid-June. But if STS-400 is needed — and the need might not be discovered until the final few days of the STS-125 mission — the countdown would resume, and Endeavour would launch three days later. A day after that, using an abbreviated rendezvous path, it would be hovering back to back, 75 feet (23 meters) from Atlantis.

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Already on board are the extra spacesuits and other equipment needed to ferry STS-125's seven astronauts across the gap into Endeavour. That could take two days, maybe three. Just before he left, Atlantis commander Scott Altman would configure the shuttle's flight deck so that ground controllers could bring it down safely into the ocean by remote control. Then it would be time to check the rescue ship itself for damage, do any necessary repair work and head back to Earth.

The rescue operation will almost certainly never be needed. But if it is needed, all the preparations and all the training must already have been performed. There just won’t be time to throw it together on the spot.

Preparing for possibilities
In the wake of 2003's Columbia catastrophe, NASA has always designated one shuttle crew to rescue another crew in the event of an emergency, so the concept itself is no big deal. But on every previous shuttle mission, and on all remaining shuttle missions after this one, a stranded crew could hold out aboard the international space station. There, air and food and power supplies give them a good chance of lasting 70 or 80 days before needing a pickup.

Consequently, the designated rescue vehicle did not need to be standing by for quick launch. Usually it was not even "stacked" to its external tank and solid-rocket boosters. If the mission ever needed to be called up, ground processing teams could go to double shifts and prepare it in time.

Not this time. Like the doomed Columbia, Atlantis will be following an orbital path that makes reaching the shelter of the space station impossible. The only supplies the crew can use to extend their lives and await rescue are those that they bring along with them.

So for this mission only, the potential urgency of the situation requires the rescue ship to be ready to go within a few days of a launch decision. The last time NASA had two different manned space vehicles in a similar situation was the dual flight of Gemini 7 and Gemini 6 in December 1965.

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