Spending a busy Christmas in space, the Discovery astronauts released the repaired and now-healthy Hubble Space Telescope today to resume its cosmic observations.

French astronaut Jean-Francois Clervoy, operating the shuttle's 50-foot-long robot arm, unlatched the 24,000-pound telescope at 6:03 p.m. EST as the two spacecraft sailed 373 miles above the South Pacific northeast of Australia.

As the arm pulled smoothly away from the towering four-story observatory, mission control commentator Kyle Herring called it "a Christmas present to the world, now-refurbished after three spacewalks, now being returned to space to conduct the scientific investigations for which it was designed."

A few moments later, ground controllers at the Goddard Space Flight Center near Greenbelt, Md., reported the spacecraft was operating normally on its own, using its just-installed gyroscopes to maintain stability. "Thank you, Houston, for that good news," commander Curt Brown radioed Houston amid cheers from his crewmates. Mission controllers quickly joined in.

If all goes well, Discovery will return to Earth on Monday evening to close the millennium's final manned space mission. Hubble controllers at Goddard, meanwhile, expect to resume science operations in two weeks, ending a two-month hiatus.

It was only the third mission in U.S. space history to be in orbit over Christmas--the others were Apollo 8 in 1968 and Skylab 4 in 1973--and the first in the 96-flight history of the shuttle program.

After releasing Hubble, Discovery's crew--Brown, Clervoy, pilot Scott Kelly, John Grunsfeld, Steven Smith, Michael Foale and Swiss flier Claude Nicollier--radioed Christmas greetings to the world.

"The familiar Christmas story reminds us that for millennia, people of many faiths and cultures have looked to the sky and studied the stars and planets in their search for a deeper understanding of life and for greater wisdom," Brown said. "We . . . are very proud to be part of this ongoing search beyond ourselves."

Working in two-man teams, Smith, Grunsfeld, Nicollier and Foale carried out three spacewalks Wednesday, Thursday and Friday to repair the crippled telescope and to upgrade critical components. Hubble went into scientific shutdown Nov. 13 when the fourth of six stabilizing gyroscopes failed. All six were replaced Wednesday to accomplish the primary goal of Discovery's mission.

The astronauts also installed voltage regulators to keep Hubble's aging batteries from overheating; a faster flight computer that will improve data processing and efficiency; and a refurbished fine-guidance sensor to help the telescope lock onto and track astronomical targets.

In addition, the spacewalkers installed a new solid state data recorder in place of an old reel-to-reel model, replaced a broken S-band radio transmitter and installed insulation blankets over three equipment bays housing sensitive electronic gear.