Snags Mar Deployment of Satellite From Shuttle : Space: Jammed reel prevents total release of tethered craft. Atlantis crew will seek to salvage mission today.

With flight controllers serving as choreographers, the shuttle Atlantis on Tuesday stepped out on a daunting dance through space with a diminutive partner held on a string as thin as a shoelace.

The orbital ballet saw astronauts reeling a 1,000-pound satellite out of the shuttle’s cargo bay on a mission hailed as the harbinger of future orbital operations.

But the experiment hit a potentially ruinous snag almost immediately.

The reel letting out the tether jammed Tuesday night after unwinding only 570 feet, and for about two hours the Atlantis crew and flight controllers struggled to free it. They finally succeeded by pulling the satellite back in by about 30 feet, creating slack in the line. They then released it, firing the satellite’s small thrusters to help it gather speed, and jerking the fouled line loose. In the following minutes, the satellite climbed to a distance of 855 feet above the shuttle where its ascent again stopped.

Mission Control said the fouled line problem was believed to have been resolved, but when it tried to resume reeling the satellite out, it again refused to budge. Concerned because shuttle commander Loren J. Shriver, mission specialists Jeff Hoffman, Marsha Ivins, and Franklin Chang-Diaz had been on duty for more than 20 hours, operations were then called off. Their relief crew, pilot Andy Allen and mission specialists Claude Nicollier and Franco Malerba, were to keep watch overnight. Renewed efforts to salvage the mission were to begin at 5 a.m. PDT today.

The venture is considered perhaps the most exacting exercise ever attempted by the shuttle. It was designed to send the satellite to a distance of 12.5 miles about 5 1/2 hours after its deployment.

Once the satellite is successfully reeled out, the tether and the shuttle will form a huge electrical generator in orbit as the combined vehicle flies through the Earth’s magnetic field. With the satellite collecting electrons as it passes through the Earth’s ionosphere, the system is expected to generate an electrical potential of 5,000 volts, sending a current of about 1 ampere down the tether to the shuttle.

The release procedure began Tuesday afternoon, with Atlantis flying backward with its nose pointed down at the Pacific. The gleaming white satellite rose from a four-story boom extended from the shuttle’s open cargo bay.

Bathed by the setting sun, the satellite was pushed from its cradle by tiny thrusters shooting bursts of nitrogen gas. At a snail’s pace, the satellite rose from the mother ship.

The beginning of the deployment at 2:50 p.m. PDT came after hours of frustration, including one aborted release when astronauts saw unexpected movement in the tether linking the satellite to the shuttle.

Because of the delays, flight planners scrambled to devise a new plan.

During the early portions of its ascent into the black sky, the satellite rose so steadily that its movement was barely perceptible. Half an hour after its release, it had moved upward 138 feet, its speed had reached one-tenth of a foot per second, and it was accelerating.

Then came the snag, which raised the additional concern that a prolonged problem with an immobile reel would use up maneuvering fuel required for the satellite to carry out several scientific experiments planned as it flies at the end of its line.

Initial plans had called for the satellite, designed and owned by the Italian Space Agency, to remain at its 12.5-mile distance for about 10 hours, and to be reeled back into its cradle some 30 hours after its release.

But because of the long delay in carrying out the deployment Tuesday, flight controllers tentatively planned to extend the operation by another eight hours so that astronauts could rest before the recovery operation.

Although the satellite rose straight upward on its tether, computer projections were that it would eventually begin to sway from side to side, requiring shuttle commander Shriver to move Atlantis about to remain beneath it.

The operation is sufficiently delicate and mysterious that NASA Administrator Daniel S. Goldin ordered an additional safety review before giving the mission final clearance.

While the plan is to reel the satellite back, recapture it and return it to Earth, officials emphasized that the mission will be successful as long as they carry out the electrical generating exercise and other scientific experiments and gain an understanding of tethered vehicles’ behavior.

The United States’ only experience thus far in flying tethered objects in space came during the Gemini flight program in 1966, but as many as 50 potential applications are foreseen for the technique.

Besides the generation of electricity, they include exploration of altitudes beyond the reach of balloons and conventional aircraft and below safe operating altitudes for orbiting vehicles.

Tuesday’s first delay came when a plug at the end of an umbilical cord carrying communications and electrical power to the satellite from the shuttle failed to disconnect.

But when astronaut Hoffman sent a command for a small motor to pull out the electrical plug, nothing happened.

For more than two hours, Mission Control in Houston and the shuttle crew struggled with the problem, first turning the shuttle so the cable remained in the sunlight, hoping that the warmth might encourage it to disconnect.

When that did not work, tension on the tether between the spacecraft and the satellite was released, leaving only the umbilical holding it in its cradle atop the boom.

After 10 fruitless tries, flight controllers produced an elaborate scheme combining everything they had unsuccessfully tried before.

Atlantis flew more than half an hour with the balky plug and umbilical connection facing the sun, until the temperature reached about 150 degrees. The last bit of tension on the tether line was released, and shuttle commander Shriver was ordered to fire maneuvering thrusters, pushing the vehicle downward.

Suddenly, the plug came out. In the Mission Control room in Houston, a cheer went up.