Photos: Join the search for stardust

The Stardust@Home site has officially opened its doors to let PC users participate in a project to identify minute comet particles trapped by NASA's Stardust space probe. As of Monday, 115,000 people had pre-registered to take part in the program.

The Stardust spacecraft launched in 1999 and reached Comet Wild2 in 2004. Twice, aerogel collectors were opened to capture particles from the comet. It safely returned to Earth on Jan. 15, 2006, and scientists have been studying the particles since.

Stardust@Home volunteers will be asked to examine one of 1.6 million "focus movies" from sections of the aerogel collectors to see if they can spot a particle that could be a micron in size. And to make it an even tougher task, volunteers will need to pass a test in the use of a virtual microscope that works with their Web browser before they earn the privilege to study samples.

Pictured here is a composite of Comet Wild2 produced from Stardust photographs.

This is a 2-micrometer piece of comet sample that scientists were able to extract from the aeorgel in the Stardust space probe. NASA described the sample this way: "The particle is made up of the silicate mineral forsterite, also known as peridot in its gem form. It is surrounded by a thin rim of melted aerogel, the substance used to collect the comet dust samples."

It is estimated that about 40 tiny pieces from the comet's tail were captured and returned to Earth. The problem is finding them.

This is what the aerogel collector looked like before it was sent on its mission.

A side view of the particles trapped by aerogel.

This photo shows the tracks of comet particles after they were captured in the aerogel. The actual pieces are at the bottom.

Volunteers can locate tracks from the comet particles by zooming in through their virtual microscope. The upper picture here is what the surface looks like, and the track of a particle (lower picture) can be detected by moving a mouse over the bars on the right.

This image shows the track of a comet particle before and after it was magnified. Volunteers who think they find a piece of comet dust are to notify Stardust@Home. Scientists will examine the findings and, if it's appropriate, will extract the particle from the actual aerogel returned by Stardust spacecraft.

The Stardust@Home site features a Community page where volunteers can discuss the program and their results. The Top-100 volunteers will even get special recognition.