Atlantis' five astronauts orbited 170 miles above the world amid military secrecy Saturday after accomplishing their major objective, delivering a spy satellite into space.

The crew deployed the spacecraft from the shuttle Friday, sources said. The satellite reportedly is to spy on Iraq by eavesdropping on communications or conducting photo surveys.NASA refused to discuss the Defense Department flight, and Mission Control issued only terse status reports. The last update was Friday evening, when it was announced Atlantis would return to Earth on Monday.

"Things are going well since we don't hear otherwise," said Billie Deason, spokeswoman for the National Aeronautics and Space Administration.

Ted Molczan, an amateur astronomer in Toronto who tracks spacecraft, said Atlantis is 170 miles high. Two amateur astronomers, one in Florida and the other in Texas, spotted a bright satellite orbiting in front of the shuttle at a slightly lower altitude Friday night, he said.

One of the observers said the satellite was rotating in flashing shades of red, gold and a yellowish white, Molczan said.

Atlantis returned to space for the first time in eight months with a flawless liftoff Thursday. It is scheduled to land at Edwards Air Force Base, Calif., Monday.