NASA has deactivated most of the Stardust spacecraft that collected the first comet dust ever gathered in space, two weeks after the probe jettisoned samples to Earth from its seven-year voyage through the heavens.

A 100-pound capsule from the spacecraft parachuted to the Utah desert Jan. 15 carrying microscopic debris from comet Wild 2 and interstellar dust. But the capsule's mothership remained in orbit around the sun.

On Sunday, engineers powered down all of Stardust's systems except for its solar panels and receiver antenna. The move was necessary to maintain the spacecraft and save fuel for possible future missions.

"Stardust has performed flawlessly these last seven years ... and deserves a rest for a while," project manager Tom Duxbury said in a statement.

The mothership, which has traveled nearly 3 billion miles, is in permanent orbit around the sun. The next time it flies by Earth will be on Jan. 14, 2009.

The Stardust capsule trapped thousands of cosmic debris samples, most of the particles tinier than the width of a human hair, but a surprising number of others were visible to the naked eye, researchers said.

Scientists have spent the past two weeks analyzing the cosmic grains under a microscope. The next step is to ship samples to 150 scientists worldwide for further investigation.

The comet and interstellar dust particles are believed to have originated at the fringes of the solar system about 4.5 billion years ago. Some may be older than the sun and could shed light on the origins of the solar system.