Jan 19, 2006, 18:52 GMT
Washington - An excited group of NASA scientists Thursday presented a picture of the first comet particle examined on Earth - and it's larger than they had dared to hope, even visible to the naked eye.
A recovery team member inspect the inside of NASA's Stardust particle space capsule and prepare to remove the main canister in a cleanroom at the Dugway Proving Ground Sunday 15 January 2006 at Dugway, Utah. The capsule spent seven years in space and traveled over 2.88 billion miles collecting comet and interstellar dust particles before it's return to space. EPA/GEORGE FREY
It appeared to be a transparent mineral grain about 11 microns in diameter, said principal investigator Don Bronlee.
The image, introduced to reporters at the Johnson Space Centre in Houston, confirmed the successful retrieval of space material from the Stardust mission that returned to Earth on Sunday in Utah.
The collection of this 'ancient cosmic treasure ... exceeded all expectations,' said Brownlee on NASA television.
He showed pictures of the white-gowned-and-masked science team getting their first look at the contents of the capsule in Houston on Tuesday. One of them held up his hands far apart, in the classic signal from a fisherman that he had caught a 'big fish.'
The U.S. space agency's seven-year, 4.8 billion kilometre mission to the comet Wild 2 brought back an estimated 1 million particles larger than 1 micron.
Some of them, surprisingly, are visible to the naked eye, the scientists said. Only about a dozen are thought to be larger than the diameter of a hair, Brownlee said.
Scientists had expected only smaller pieces, and were not prepared for the relatively large holes some of the particles left as they examined the specially designed aerogel that caught them.
One image showed a brownish hole one-half centimetre across. A 'small finger would fit into the contour', Brownlee said.
The lightweight aerogel - which is more than 99 per cent air - was the key to the mission's success, said Peter Tsou, who played a key role in developing the project.
The aerogel has the 'lowest density of any substance on Earth', Tsou said, but had to do an even tougher job than catching a speeding bullet. The comet particles hit the aerogel at an estimated speed of about 36,000 kilometres an hour, he said.
The comet particles will be farmed out to at least 150 scientists around the world to study - research that is expected to shed more light on the origins of the solar system.
'These tiny samples from a distant comet open giant windows on our past,' Tsou said.
The aerogel also collected much smaller pieces of stardust, which will be harder to find. That's why NASA is throwing open the hunt to volunteers on the internet, who will be allowed to view virtual microscopic images after qualifying through a test.
Michael Zolensky, a coordinator and curator of the mission, said NASA had already signed up 50,000 internet volunteers since the idea was announced last week, and is hoping for more.
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UserJan 19th, 2006 - 22:05:26
Returned to earth....not space.
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