Thousands Greet Shuttle’s Touchdown : Space: About 125,000 view the desert landing. Rescue of satellite highlights Endeavour’s maiden voyage.

Space shuttle Endeavour sounded its signature twin sonic booms and touched down on a concrete runway at Rogers Dry Lake at 1:57 p.m. Saturday, ending a historic, nine-day maiden voyage.

“Welcome to California and congratulations on a spectacular and historic flight,” Jim Halsell, a National Aeronautics and Space Administration official at the Johnson Space Center in Houston, told the seven-member crew after the Endeavour coasted to a stop.

“Thank you, Houston,” replied Navy Capt. Daniel C. Brandenstein, the shuttle’s commander.

Moments earlier, a red, white and blue drag chute, making its first appearance on a shuttle mission, fell away from the orbiter as it slowed to a speed of 60 knots.

Donald Puddy, an official at the Johnson Space Center, pronounced the crew in “absolutely superb shape.”

The public response to Endeavour’s mission, which featured an unprecedented three-astronaut capture of a stranded communications satellite, was the most enthusiastic since the shuttle program resumed in 1988, NASA officials said.

A crowd estimated at 125,000 turned out in the high desert to watch the landing.

Endeavour, which blasted off May 7 from the Kennedy Space Center in Florida, was built at a cost of $2 billion to replace Challenger, lost Jan. 28, 1986, in an explosion that killed seven crew members and stalled America’s manned space program for 2 1/2 years.

The astronauts’ dramatic capture of the marooned Intelsat 6 satellite, using nothing but their gloved hands, represented a triumph for the manned space program. The crew clamped a new rocket motor onto the satellite, which fired Thursday, boosting the Intelsat 6 into its proper orbit 22,300 nautical miles above the Atlantic Ocean.

The feat involved the longest spacewalk in history and the first three-astronaut walk. It was the product of 36 hours of intense planning and rehearsal on the ground and in space.

“To call what we’ve all witnessed in the last few days exciting, I think is a gross understatement,” Leonard Nicholson, director of the space shuttle program, said at a post-landing news conference.

However, the failure of the tool designed to snare the satellite, a “capture bar” that took two years and $7 million to develop, raised questions about NASA’s ability to simulate conditions in space.

The simulation issue will become increasingly important as NASA moves toward construction in late 1995 of the space station Freedom. The station may cost as much as $40 billion by the end of the decade.

“We don’t have a simulator that can put all the components together--the orbiter, the (shuttle’s robot arm), myself, the capture bar and the satellite, basically five bodies that are all dynamic. . . . So that was probably the area that was most difficult,” astronaut Pierre J. Thuot said Friday during an in-flight news conference.

Thuot was repeatedly frustrated last Sunday and Monday as he worked alone trying to snag the $150-million satellite with the capture bar. But the Intelsat 6 proved much more sensitive to force than NASA had expected and spun away every time Thuot attempted to snare it with the bar. That prompted the decision to send three astronauts outside the orbiter Wednesday to grab the satellite with their hands.

The Johnson Space Center simulator developed to train Thuot in capture techniques is a spinning, 12-foot-wide wheel suspended from posts on a platform that rests on a special “air-bearing floor.” Air that gushes from jets in the floor suspends the platform and the wheel in an attempt to duplicate weightlessness.

However, engineers concluded that the satellite orbiting in space is at least 10 times more sensitive to forces applied to it than the simulated satellite on which Thuot practiced.

NASA engineer Calvin Seaman, who designed the capture bar, this week blamed incorrect data provided by the satellite’s builder and owner for the failure of the instrument.

However, an official at Hughes Aircraft Co. of El Segundo, which built the Intelsat 6, said the data provided by Hughes was correct.

“We supplied them with the data and it was accurate data,” said Charles P. Rubin, Hughes’ program manager for the Intelsat rescue.

“What I think (Seaman) was trying to say is that there is a lot of difficulty in building a simulator, even when you have the data. Sometimes you just can’t achieve what the data tells you.

“I think you can always build a simulator better, but I don’t think you can duplicate the (space) environment,” Rubin said.