Atlantis ‘Doing Beautifully’ as Last Hours of Countdown Near

Launch crews moved steadily through the countdown Thursday in preparation for the launching of the space shuttle Atlantis, aiming for a liftoff at 6:56 a.m. PDT today.

They delayed a rollback of the service structure around the vehicle for eight hours so that technicians could relieve a pressure buildup in a tank serving an auxiliary maneuvering unit, but with that problem fixed they were to begin fueling its gigantic external tank with liquid hydrogen and liquid oxygen shortly after midnight.

“The vehicle is doing absolutely beautifully,” said Leonard Nicholson, the National Aeronautics and Space Administration’s shuttle program manager. He described the spacecraft as “absolutely clean” as the last hours of the countdown approached.

Air Force weather forecasters put the odds at 95% for weather conditions suitable for launch. The mission is considered one of the more demanding undertaken in the entire shuttle program. If Atlantis gets off on schedule, its crew is to release a European microgravity laboratory on Saturday. On Monday, astronauts will begin reeling-out to an eventual distance of 12.5 miles a 1,140-pound satellite, due to remain tethered to the shuttle for about 30 hours, on a line smaller than a shoe lace.

Cutting through the Earth’s magnetic field lines, the shuttle-tether-satellite combination will become a giant electrical generator. Scientists and engineers want to know not only the potential for such a system to generate useful amounts of electricity, but also whether the long tether can be safely and successfully handled by the shuttle and its crew.

Plans are to wind the satellite back into the shuttle’s cargo bay and return it to Earth at the end of the seven-day mission, but since such an operation has never been attempted, space officials acknowledge there are uncertainties. They emphasized again on Thursday that Col. Loren J. Shriver, the Air Force colonel commanding the flight, will have the option of cutting the satellite loose at anytime if he deems the operation dangerous the shuttle and its crew.

“If we get the satellite out and get the data, that’s a success,” said Jeremiah Pearson III, NASA’s associate administrator for space flight. “If they get the satellite back, we’re heroes.”

This will be the last flight for Atlantis until 1994. In mid-October, it will be taken to Rockwell International Corp., shops at Palmdale, for a major refitting, including modifications that will enable it to dock with the Russian space station, Mir.