'Dusters' Look For Interstellar Dust Tracks

When science gets too big, it's time to either automate or call in volunteers. Sometimes, you have to do both.

Pieces of aerogel on NASA's Stardust spacecraft not only picked up samples of comet Wild 2, they also captured, separately, particles of interstellar dust on a side of the collector not exposed to the comet. The comet particles are easily detectable, but scientists estimate that the interstellar dust collector may have nabbed only a dozen or so. Finding the tracks of these micrometer-sized particles in a 1,000-cmm² collector area is akin to finding the needle in the proverbial haystack.

"By the time you've set the microscope magnification high enough to see the particles, you have to look through millions of images," says Zack S. Gainsforth, a researcher in the space sciences laboratory at the University of California, Berkeley.

Inspired by SETI@home—the project that harnesses volunteered home computers to analyze radio signals for traces of intelligent life—just down the hall, Andrew J. Westphal, an associate director of the space lab, created a website called Stardust@home (stardustathome.ssl.berkeley.edu). He and his colleagues set up an optical microscope to log sets of images, then put out a call to volunteers—anyone with a computer—who could pore over the 1.5 million sets in hopes of spotting the elusive dust.

Stardust@home has spawned an avid online community of some 20,000 science buffs around the world who have dubbed themselves "dusters." Some are casual users and others spend hours every night perusing images. There's a carrot involved—the first people to identify particles will be listed as coauthors on a paper announcing the results. So far, Gainsforth says, they have some promising leads. At least four people scan each segment, and if it's flagged as promising, it gets more scrutiny from dusters and scientists. Would-be dusters register online at the Stardust@home site and take a short test to make sure they can correctly identify potential particles. "I think it's wonderful—the fact that we do need people," Gainsforth says. "It's exciting to deal with 10,000 active volunteers all the time."