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Planetary News: Stardust (2006)

Stardust Samples Returned from Space In Excellent Condition

By Amir Alexander
19 January, 2006

Stardust mission scientists are thrilled at the apparent condition of the samples captured by the spacecraft and brought back to Earth , team members said in a press conference from the Johnson Space Center (JSC) in Houston this morning . The Stardust sample return canister, which landed in the Utah desert on January 15, was opened yesterday in the Cosmic Dust Clean Room in JSC's building 31. The canister contains the aerogel plates, which collected cometary and interstellar dust particles during Stardust's 7-year voyage through the solar system. They are the first samples returned from space to Earth in more than 30 years.

On one side of the collector are embedded dust particles picked up from comet Wild 2 during Stardust's dramatic flight through the cloud of gas and debris surrounding the comet on January 2, 2004. On the other side are embedded minute grains of interstellar dust, particles from distant stars that found their way to our solar system. These were collected during Stardust's passage through a stream of interstellar dust particles on its way to Wild 2.

Scientists in the clean room were thrilled when the capsule was first opened, revealing the interstellar dust side of the collector. "This is Fantastic" said Andrew Westphal of the Space Sciences Laboratory at U.C. Berkeley, member of the Stardust mission team and leader of the Stardust@home project. "The aerogel seems to be in great shape and no tiles are missing" he said, observing that the cracking in the aerogel seemed to be minimal. The good condition of the aerogel is particularly important for Stardust@home, a project in which volunteers will search for as few as 40 miniscule interstellar dust particles among the cracks and flaws in the aerogel.

Stardust celebration
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Stardust celebration
Scientists at the clean room in building 31 at the Johnson Space Center were thrilled at what they found when they got their first view of Stardust's aerogel collector plates on January 18, 2006. Flashing the victory sign is Stardust mission Prinicipal Investigator Donald Brownlee of the University of Washington. Credit: NASA

The interstellar dust side of the collector also showed signs of two particles from Wild 2 that impacted with such force that they shot clean through the cometary side of the collector and into the interstellar dust side. This was a promising sign for what would be found on the opposite side of the collector, and to these the scientists now turned. Unlike the few and microscopic interstellar dust particles, the grains from Wild 2 vary in size and some can actually be seen with the naked eye. Also, there are a lot more of them -- possibly more than a million.

Comets, explained Brownlee, are extremely primitive objects left over from the creation of the solar system. Wild 2, like most short period comets, was formed in the Kuiper belt region at the outer edge of the solar system, and spent billions of years there before being diverted into the inner solar system by an encounte with another body. The dust grains Stardust captured from Wild 2, said Brownlee, are therefore "an ancient cosmic treasure from the edge of the solar system, 4.5 billion years old.

Each particle captured by the collector leaves a carrot-shaped tunnel in the collector, at the end of which can be found the particle itself. "It exceeds all expectations" said Donald Brownlee of the University of Washington, Principal Investigator of the Stardust mission, when the cometary side of the collector was revealed. "We can see lots of impacts -- there are big ones, there are small ones." One track, he added, was almost large enough to put a finger through. Overall, he said, "it's a huge success."

Once the aerogel is removed from the collector, scientists will begin to systematically locate and extract the particles from the aerogel before sending them to expectant researchers around the world. For the interstellar dust particles, this process will be conducted by Stardust@home, a project that recruits computer users from around the world to search for the minute dust grains embedded in the aerogel.

Cometary dust impact onto Stardust aerogel
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Cometary dust impact onto Stardust aerogel
Although most of the dust impacts onto Stardust's aerogel collectors are too small to be seen with the naked eye, a few dramatic impacts of large aggregates of cometary material made dramatic pits, like the one at the center of this image. Credit: NASA