Stardust's Space Cargo Thrills Scientists - National Geographic

http://news.nationalgeographic.com/news/2006/01/0119_060119_stardust.html


John Roach for National Geographic News
January 19, 2006

Scientists say they're thrilled and awed by their first glimpse at the comet particles and samples of interstellar dust returned by the Stardust spacecraft.

Stardust's canister of samples dropped safely to Utah's desert floor Sunday.

"Now we can bring to mankind a very unique glimpse of the beginning of our solar system," said Peter Tsou, the mission's deputy principal investigator, at a mission briefing today at NASA's Johnson Space Center in Houston, Texas.

"In fact I will say tiny samples from a distant comet open giant windows of our past," Tsou added.

The canister's return marked the final leg of the spacecraft's 7-year, 2.88-billion-mile (4.63-billion-kilometer) flight. (Watch a video of the Stardust mission.)

During its mission, Stardust collected particles swirling off the comet Wild 2, as well as samples of interstellar dust streaming into our solar system from other parts of the galaxy (interactive solar system map).

The spacecraft collected the particles using a tennis-racket-shaped device filled with a light, porous material called aerogel. The light, porous gel is 99.8 percent air and is capable of trapping delicate particles without damaging them.

Donald Brownlee, Stardust's lead scientist, called the collected particles a "cosmic treasure."
After the canister touched down in the Utah desert—just hours before a fierce snowstorm—scientists recovered the capsule and shipped it to Johnson Space Center.

Researchers got their first peek at the contents Tuesday.

First Look

Brownlee said scientists gathered around the racketlike collector and were awed at what they saw.

About a dozen comet particles thicker than a human hair and a least one larger than a millimeter (four hundredths of an inch) were visible to the naked eye, he said.

"We were totally overwhelmed by the ability to actually see this so quickly and so straightforwardly," he added.

The scientists estimate there may be more than a million specks of comet dust embedded in the aerogel.

Researchers will be studying the gel for years to glean clues about the origins of the solar system and the building blocks of life.

At the briefing, Brownlee unveiled the first enlarged image of a comet particle, which has already helped answer a key question about comets.

"It appears to be a transparent mineral grain, which scientifically is great, because there has been lots of discussion whether comets contain minerals, or glass, or whatever," he said.

"We've already got scientific results."

Further Studies

Now that Stardust's canister is safely at Johnson Space Center, mission scientists will prepare samples to send to experts around the world.

"We have something like 150 scientists worldwide poised to grab these samples in their own labs and study them," Michael Zolensky, Stardust's curator and a co-investigator, said at the briefing.

With so many qualified scientists working with the samples, results should come very quickly, he added.

Some groups will study the bulk composition of the samples, comparing them to meteorites.

Other researchers will look at the elements to learn about the history of the samples.

Additional experts will try to answer questions about whether comets delivered water and the building blocks of life to Earth.

In addition, scientists believe the spacecraft collected upwards of 200 grains of interstellar dust no larger than a micron (a millionth of a meter) in size.

The tiny grains, however, are lodged on a relatively large collector, which makes searching for them like looking for ants on a football field.

To help in this task, scientists at the University of California, Berkeley designed a computer program—called Stardust@home—that allows individual computer-users to search through some 1.5 million images of the aerogel for the telltale tracks left by the grains.

"We already have more than 50,000 people signing up for this and we hope for many, many more … [P]erhaps with this effort we'll find interstellar grains rapidly," Zolensky said.