From wire services

SAN JOSE, Calif. – After an epic journey of 2.9 billion miles, the Stardust capsule landed in the Utah desert Sunday morning with a thimbleful of comet dust – the first samples from a comet ever brought back to Earth.

Researchers on a NASA DC-8 research plane whooped with delight as the capsule appeared at 1:57 a.m., midway between Mars and the constellation Pleiades. It flared into a brilliant white fireball that turned reddish-gold and sprouted a long, thin tail of glowing vapor.

“Isn’t it gorgeous?” said Peter Jenniskens, a meteor expert with the SETI Institute in Mountain View, Calif., and lead scientist for the airborne mission. “It’s a meteor – a manmade meteor.”

Carlton Allen, a scientist at NASA’s Johnson Space Center, saw it all unfold live on television at Dugway Proving Ground.

“It’s an absolute triumph,” Allen said after the landing. “This is a mission that will deeply extend our knowledge of the solar system.”

After a seven-year voyage snatching comet and interstellar dust, the Stardust capsule pierced Earth’s atmosphere at a flaming 29,000 mph – the fastest return of any man-made probe. It reached 5,600 degrees Fahrenheit – about 25 times as much heat as the space shuttle endures -and returned its precious cargo for scientists to study.

“This is not the finish line. This is just the intermediate pit stop,” said Tom Duxbury, project manager of the $212 million mission.

A high-definition television camera on board the NASA plane showed a small, glowing object that appeared to come off the capsule just before it passed out of view.

Examining the video, scientists on the flight said they could not tell whether it was a natural meteor that just happened to coincide with Stardust’s manmade fireball or a piece of the capsule’s heat shield that fell away.

If part of the heat shield did come off, the capsule could heat up more than expected, said George A. Raiche, an atmospheric chemist at NASA’s Ames Research Center in Mountain View who works on heat shield development and testing. He added that “a very small particle could give a disproportionately bright signal,” and that the only way to tell if the capsule had been significantly damaged was to look it over.

NASA officials said the capsule, which bounced five times to a muddy landing at the Utah Test and Training Range southwest of Salt Lake City, appeared to be in excellent shape, although bits of the heat shield were found nearby.

It was taken by helicopter to a temporary clean room at nearby Michael Army Air Field. There researchers removed the canister that holds the dust samples and flooded it with ultra-pure nitrogen gas to keep it pristine.

On Tuesday it will be flown to Johnson Space Center in Houston and housed in the same building as moon rocks and meteorites. Bits of dust will be distributed for preliminary analysis to 150 scientists worldwide, including labs at Stanford University, Lawrence Livermore National Laboratory and the University of California, Berkeley.

Comet dust is surprisingly common on Earth. More than 30,000 tons of it fall onto the planet each year; California alone collects a billion times more particles every day than Stardust grabbed in its collector.

But until now there were no pure samples. Scientists longed to get one because it’s the stuff that formed the sun and planets 4.6 billion years ago – “a frozen time capsule from the beginning of the solar system,” said John P. Bradley, head of the Institute of Geophysics and Planetary Physics at Lawrence Livermore.

Comets pummeling the young Earth are thought to have delivered some of the key ingredients for life, from water to carbon-based compounds.

And interstellar dust, which is created in stars, contains virtually all of the elements heavier than helium.

“We have always stressed in this mission that we are stardust,” said Donald Brownlee of the University of Washington, one of the lead scientists for the mission. “Our planet and even our selves have a direct relationship to the particles we brought back.”

Launched seven years ago, the $168 million spacecraft spent months gathering interstellar dust, which is so sparse that only a few dozen particles are thought to have lodged in the collector.

Two years ago it came within 149 miles of Comet Wild 2 – named after its discoverer and pronounced VILT 2 – and grabbed particles from the hazy envelope of gas and dust that surrounds the comet’s nucleus.

The samples are thought to contain millions of specks that, if lumped together, would weigh less than a grain of salt and not quite fill a thimble.

Despite their minuscule size, they should contain enough material to distribute and study for years to come. In fact, some of the bigger bits – those larger than about 1/10 the diameter of a human hair – may be sliced up smaller.