Dust settles as satellite returns to earth after brush with comet

A 13-minute parachute ride, three bounces and the space capsule was finally home. After a 4.7 billion kilometre (2

A 13-minute parachute ride, three bounces and the space capsule was finally home. After a 4.7 billion kilometre (2.9 billion mile), seven-year journey, the Stardust satellite has returned to earth, carrying with it arguably the most precious dust anywhere on the planet.

The US satellite was sent aloft from Florida in 1999 with the sole object of collecting dust - not just any dust, but samples from a comet and the particles that reach us from distant stars.

Its safe return yesterday had scientists on both sides of the Atlantic ecstatic that the Stardust capsule had returned in one piece, bearing its precious samples.

"We visited a comet, grabbed a piece of it and landed here this morning," University of Washington professor and principle investigator Don Brownlee stated yesterday. "It was a real thrill."

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Stardust had to loop the sun three times on its way to a rendezvous with comet Wild-2 in 2004, getting to within 250km (150 miles) of its nucleus.

It used a tennis racquet-shaped collector to grab comet dust but also gathered particles along the way, interstellar dust blown in from distant galaxies.

The tiny grains, measuring just a tenth of the thickness of a human hair, might look like dirt, but are gold dust to the US and British scientists who will analyse them.

Comets are believed to be primordial leftovers from before the birth of our sun and solar system. They could tell us a great deal about the stuff that later became the planets and our home.

Stardust was picked up by helicopter after its touchdown in the Utah desert at 10.12am yesterday (Irish time). It was whisked away to a US army airfield for initial processing before being relayed to NASA's Johnson Space Centre in Houston.

Samples of the dust extracted from the capsule could be on the way to eager scientists in participating universities in as little as 10 days.

Additional reporting: PA

Dick Ahlstrom

Dick Ahlstrom

Dick Ahlstrom, a contributor to The Irish Times, is the newspaper's former Science Editor.