Shuttle Crew Able to Reel in Satellite

A bold bid to turn the space shuttle Atlantis and a tethered satellite into an orbiting electrical generator failed Wednesday, but astronauts saved the $191-million satellite that had been stranded 750 feet above the cargo bay on a snagged connecting line.

Despite the satellite’s recovery, the failure to achieve its primary objective made the mission a sharp disappointment.

With two astronauts preparing for a risky space walk in a last-ditch bid to save the satellite, the jammed tether was finally freed mechanically and the Atlantis crew reeled the satellite back to the spacecraft 24 hours and four minutes after it was first released.

The snagged line was successfully jerked free when a four-story boom in the cargo bay was slightly retracted and then rammed back to its full extension.

As Atlantis approached the coast of Africa about 3 p.m. PDT, mission specialists in the seven-member crew began gently reeling in the balky line.

For an hour, astronaut Jeff Hoffman controlled the satellite by firing tiny nitrogen thrusters to keep tension on the tether, while mission commander Loren J. Shriver gingerly maneuvered the 90-ton shuttle. The satellite was slowly returned to a holding ring atop the boom so that it could be lowered back into the cargo bay.

Just before 4 p.m., as Atlantis crossed the South Pacific toward the coast of Chile, Shriver radioed Houston, “We’ve got a docked satellite.”

While the hopes of generating electricity with the satellite on the end of a 12.5-mile-long string had been dashed, the aborted exercise showed that tethered vehicles probably can be reliably controlled in space.

Mission planners had repeatedly warned that the Atlantis mission was possibly the most difficult in the history of the shuttle program.

Their concern had not been over the equipment analogous to a space-age fishing reel, but over possible difficulty in controlling swinging and bobbing motions of the satellite on the long string.

But throughout the struggle with the snagged line, the 1,000-pound, five-foot-diameter globe remained surprisingly stable.

“From a flight dynamics standpoint, we learned an awful lot,” lead flight controller Charles Shaw told reporters in Houston. He said the tethered operation had actually achieved two of its three objections in the successful launch and recovery. “We didn’t get out quite as far as we wanted to,” he conceded, but the experience proved “very reassuring,” because reality closely matched computer-generated simulations used in training.

And the docking “was far easier than we anticipated,” he added.

When the jammed line was jerked free, astronauts Hoffman and Franklin Chang-Diaz had already begun preparations to leave the Atlantis crew compartment today to try to find and clear the mysterious snag. Cabin pressure was being reduced to allow them to make the transition to space.

The first television picture of the drama showed the satellite again in its docking ring atop the tower in the cargo bay. No live pictures of the recovery were sent because the shuttle’s big antenna was being used for radar tracking during the tense retrieval.

The trouble that had plagued the tether system on Tuesday only worsened when efforts resumed to further unwind the line. Flight controllers thought at first that their problem was a jam on the reel in the cargo bay, but they became increasingly convinced that in fact the problem was at the top of the boom, where an electric motor pulled the tether from the reel below and fed it out to the satellite.

Because the long line operates in weightlessness, an elaborate system of pulleys and tension devices is required to keep it taut.

The satellite became stranded Tuesday shortly after it was released from a four-story boom rising from the spacecraft’s cargo bay. It was supposed to have been reeled out to a distance of 12.5 miles.

Efforts to free it were suspended after astronauts and ground controllers struggled with the problem for hours Tuesday night. When worke resumed on Wednesday morning, the shuttle crew found they could neither resume the deployment nor reel the satellite back to the shuttle.

Lead flight controller Charles Shaw and technical experts huddled for more than three hours in Houston, devising plans to free the tether, with the space walk by the astronauts as a last resort.

The National Aeronautics and Space Administration undertook the ambitious flight in cooperation with the Italian Space Agency, which developed the satellite.

Through no apparent fault of the shuttle itself, the Atlantis mission encountered a major problem even before it turned to the Tethered Satellite experiment.

Because of a communications problem, launch of the European Space Agency’s EURECA micro-gravity laboratory had to be postponed for 24 hours, setting off a ripple of changes in the schedule.

The lab, due to be recovered by another shuttle next April, was successfully launched on Monday, but flight controllers in Germany abruptly stopped its transfer into a higher orbit, fearing that it was headed on an errant course.