A space capsule that captured interstellar and comet dust during a seven-year voyage through the heavens was finally opened by scientists this week, and they were delighted with what they found.

The Stardust capsule parachuted back to Earth on Sunday, landing in the Utah desert. It was then taken to NASA's Johnson Space Center in Houston.

Scientists opened the capsule's dust-collecting canister on Tuesday, looking for particles that may yield clues to how the solar system formed.

Most of the particles, which appear black under a microscope, are too small to see with the naked eye. But scientist Donald Brownlee said Thursday that researchers were surprised to find some larger specks.

"That's why we were jumping up and down," said Brownlee, a University of Washington scientist who worked on the $212 million mission. "We were totally overwhelmed by the ability to actually see this."

The spacecraft swooped past the comet Wild 2 in 2004 and used a tennis-racket-sized collector containing a gel-like material to snatch dust from space. The spacecraft also looped around the sun three times to capture dust, which hit the gel at a speed six times faster than a bullet fired from a rifle.

Scientists had been concerned that the collector might not open correctly or that the particles could slam with such force into the gel that they blew the precious material out, leaving nothing to study.

So when researchers opened the canister, they "were pleased to find that everything went exactly right — just fabulous," said Michael Zolensky, Stardust's curator. "We couldn't have done a better job catching these particles."

Some of the samples will be shared with 150 scientists worldwide.

Brownlee called the dust samples "an ancient, cosmic treasure from the very edge of the solar system."