U.S. capsule returns to Earth with comet dust

After a seven-year mission, NASA's Stardust space capsule has returned to Earth with comet dust that scientists hope will yield clues to the origins of the solar system.

With the help of a parachute, the 45-kilogram capsule softly touched down early Sunday morning on a remote stretch of desert in northwest Utah and was taken to a nearby army base.

The canister containing the samples will be flown on Tuesday to the Johnson Space Center in Houston where scientists will study the tiny fragments of comet and interstellar dust.

The samples will then be distributed to the international science community for detailed analysis, said Lockheed Martin, the company that designed and built Stardust.

"Inside this thing is our treasure," said principal mission scientist Don Brownlee of the University of Washington.

Most of the granules are so small that a microscope will be needed to study them. Scientists believe each is thinner than a strand of human hair.

Stardust is the first spacecraft to return to Earth with comet dust. Two years ago, it flew through a halo of gas, dust and debris enveloping the comet Wild 2.

Comets come from deep space beyond Neptune and are composed of ice, dust and debris in a mix virtually unchanged since the solar system's birth about 4.5 billion years ago.