Atlantis' astronauts, arriving home a day before the shuttle program's 10th anniversary, say their spacewalking repair job on an observatory shows the need to send people - not just machines - into space.

After staying in space an extra day because of high winds at the shuttle's desert landing site, Atlantis glided to an early morning touchdown Thursday at Edwards Air Force Base, Calif."It was an eminently successful mission," P.J. Weitz, deputy director of the Johnson Space Center, said Thursday at Edwards. "We had the opportunity to demonstrate the value of manned missions."

"The last 10 years laid the foundation and springboard to go on in expanding our frontiers outward," Weitz said.

Later in the day, when the crew returned to Houston, astronaut Jerry Ross said the spacewalks showed that manned missions are necessary to fix problems and conduct research.

Fellow astronaut Jay Apt agreed, saying that only people can "cope with the unexpected and go out and do the things that no machine can do."

Ross and Apt made the first U.S. spacewalk in more than five years on Sunday to conduct emergency repairs on the $617 million Gamma Ray Observatory.

The Atlantis crew was about to release the 17-ton observatory into orbit 280 miles above Earth when its antenna failed to respond to commands from the ground to move into position.

Ross shook it loose in what was the first successful unscheduled repair conducted in space.

Some space-program critics have argued that the United States should use rockets to put satellites into orbit.