The $100 million communications satellite launched by Discovery was responding perfectly to commands from the ground Friday as the five astronauts aboard the spacecraft enjoyed such a leisurely voyage that they found themselves with little to do.

There were a few nagging, minor problems to deal with, but Milton Heflin, a flight director at the Johnson Space Center, conceded that the astronauts are not exactly overloaded with chores."The commander and the pilot and the other folks will be doing Earth observations," Heflin said. That is NASA-speak for looking out the window.

But he added quickly that is appropriate since this is primarily a test flight for a vastly redesigned system. Later flights, he said, will require morefrom the crew.

"But you get the lid off the bucket and you go on from there," he said.

Several experiments aboard the orbiter were turned on by mission specialist George D. Nelson, 38, an astronomer, but most of the experiments are similar to others that have flown on longer missions in the past.

Under the command of Frederick H. Hauck, 47, the astronauts spent part of their time fussing with some minor problems, including a faulty cooling system that has left the interior of the shuttle a balmy 84 degrees, Heflin said.

That's a little warmer than normal, NASA officials said, but not too warm for five astronauts who live in Houston.

If the cooling system cannot be fixed, some unnecessary electronic equipment will be turned off during descent Monday to keep the cabin from getting too warm, Heflin said. The Discovery is scheduled to land at Edwards Air Force Base in Southern California Monday at 10:33 p.m. MDT.

The crew also struggled with an antenna that was so wobbly it could not be used. After trying unsuccessfully to steady it, the crew shifted the antenna back into its storage position in the cargo bay and locked it in place for the rest of the flight.

Another antenna aboard the ship will be able to take over its work load, so the loss was not expected to be significant. It could cause some rearranging of the television schedule, however.

The best news of the day for the astronauts was the word that the sophisticated satellite they deployed six hours into their flight seemed to be "100 per cent healthy," Heflin said.

The Tracking and Data Relay Satellite "is where it's supposed to be and doing what it's supposed to be doing," he added.

The 21/2-ton satellite, built by TRW Space & Technology Group, is the largest and most complex communications satellite in orbit. With solar panels that unfurl to 57 feet, it can generate 1,700 watts of electric power. And with seven antennae, including twin 16-foot diameter dishes that open like giant umbrellas, the satellite is capable of transmitting 300 million bits of information per second. That is equivalent to sending 100 volumes of an encyclopedia every second.

This is the third satellite of that type that NASA has attempted to put into high Earth orbit 22,250 miles above the ground, and it is the first to go there without any problems.