Scientists overjoyed with comet samples

What's next?
Michael Zolensky, the curator of the cosmic dust at Johnson Space Center, outlined the next steps in the process during a pre-landing interview.

Scientists dressed in the classic "bunny suits" of white coveralls and hats will use microscopes, micro-manipulators and a computer-controlled set of diamond blades to cut the aerogel into thin slices. They'll catalog all the embedded dust particles, and then cut them away for shipment to bigger laboratories around the world.

As researchers study the samples, they'll be looking for organic molecules as well as water molecules and materials from beyond the solar system. Preliminary results will be reported at a special session of the annual Lunar and Planetary Science Conference in Houston in mid-March, Zolensky said.

A public science project called Stardust @ Home is due to start up at about the same time. The project will distribute images of the aerogel samples to Internet users willing to help scientists look for interstellar dust trails. More than 72,000 users pre-registered for the project as of Wednesday.

Solving scientific puzzles
Zolensky said the comet bits and the interstellar dust could solve a puzzle that scientists didn't even know existed when the project began: where Earth’s water originally came from.

NASA In a practice run conducted before the Stardust capsule landed, a scientist looks at a collection grid containing blocks of aerogel.

“It was calculated that comets had enough water to fill Earth’s oceans,” he explained, and for years that was the leading theory for their origin. But the results from new observational techniques go against that idea: The water from comets appears to have a different chemical signature than the water on Earth.

“This was discovered in the past 10 years, using spectroscopy of starlight observed passing through the coma – it’s changed in subtle ways depending on the isotopes,” Zolensky said. Analyzing the fresh cometary samples will help validate the results from remote sensing.

NASA aircraft have been collecting dust high in Earth’s atmosphere for 20 years, and much of it is probably cometary dust as well. “These new samples will validate these existing collections,” Zolensky explained.

New techniques, new missions
In the 37 years since the first lunar samples arrived, Zolensky explained, analysis technology has advanced so far that scientists could get better results from one grain today than they extracted from the "bulk samples" of rock and soil brought back by astronauts, Zolensky said.

Many of the tests being performed today were not available back in the Apollo era. Fortunately, some of the Apollo moon samples were put into storage to await the invention of just such new technologies.

Zolensky said the $212 million Stardust mission could provide a model for future sample return missions. “It’s not designed for very heavy samples — maybe a few grams at most,” he said. But the technique could well be used to capture atoms of noble gases from comet tails, or even catch samples of gas and dust from the upper atmosphere of Mars.

Meanwhile, the Stardust probe flies on, its return capsule jettisoned but its cameras and other scientific instruments still fully functional. “It has plenty of fuel remaining,” Zolensky said. The potential targets for future flybys — comets, asteroids or even planets — are still under discussion.

NBC News space analyst James Oberg spent 22 years at NASA's Johnson Space Center as a Mission Control operator and an orbital designer.

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