ST LOUIS, Feb 20: Scientists said on Monday they had begun slicing and dicing the first of hundreds of microscopic specks of comet dust, virtually unchanged since the birth of the solar system, that a NASA spacecraft successfully returned to Earth in late January.

Preliminary analysis shows the dust, captured when the robotic Stardust spacecraft flew past the comet Wild 2 in Jan 2004, is unmistakably cometary in origin, said Don Brownlee, a University of Washington astronomer who is the principal scientist for the $212 million mission.

As such, the grains represent pristine samples of the primitive material that came together to form the sun, the nine planets and everything else in the solar system, including human beings.

“We believe materials coming out of comets now is the same material that went into comets 4.5 billion years ago,” Mr Brownlee told reporters at the annual meeting of the American Association for the Advancement of Science here.

The initial work on the samples shows they contain glassy materials, crystals like olivine and various trace elements, Brownlee said.

Each tiny grain is being sliced, sometimes into hundreds of sections, for detailed analysis. Some grains are just four microns in diameter, meaning it would take 25 of them to equal the width of a human hair.

Eventually, each grain should tell scientists something about its birth billions of years ago in the wake of dying stars, as well as how they came together to form new stars.

“Dust, lowly dust, plays a very important role in both the birth of solar systems and the death of solar systems,” said Lee Ann Willson, an Iowa State University astronomer. —AP