Stardust@home: Calling All Dust Hunters

Think you have the right stuff to spot interstellar dust? The Planetary Society, in conjunction with the University of California at Berkeley, is looking for good dust-spotters to join Stardust@home, a project where internet users search for microscopic interstellar dust particles captured by NASA's Stardust spacecraft. Volunteers can begin looking for dust particles at 11:00 a.m. (Pacific Daylight Time) on Tuesday, August 1, 2006. Find out how to participate.

Like cosmic needles in a haystack, only a few dozen particles will be scattered through the collection medium of aerogel, a foamy material that is the lightest known manmade solid substance. In addition to its mission of gathering particles from comet Wild 2, Stardust also gathered miniscule grains of dust from distant suns, which float between the galaxy's stars. Using the back side of its aerogel collector, the spacecraft captured the particles while cruising through space on its way to the comet.

"Think of this mission as the ultimate cosmic road trip," said Bruce Betts, The Planetary Society's Director of Projects. "On long journeys you're bound to end up with a few bugs -- or dust particles -- smashed against the windshield, but in the case of Stardust, the research team wanted to collect them intact without smashing or vaporizing them."

Stardust@home Project Director Andrew Westphal, a UC Berkeley senior fellow and associate director of the campus' Space Sciences Laboratory, developed the technique NASA is using to digitally scan the aerogel in which the interstellar dust grains are embedded. Johnson Space Center (JSC) has now scanned 11 of the 130 aerogel tiles, and will be scanning four additional tiles every week until the entire surface of the aerogel collector has been scanned.

The team expects to find only a few dozen microscopic dust grains embedded in the aerogel collector. Spotting these few tiny particles is no simple matter. To resolve the problem, Westphal and his team took a page from the phenomenal success of SETI@home -- another project on which the Planetary Society collaborated with UC Berkeley -- and called in the public's help.

Just as SETI@home was a wildly successful distributed computing program that brought together millions in a search for extraterrestrial intelligence, Stardust@home will draw together users from around the world to search for tiny grains of interstellar dust. And once again The Planetary Society is helping to recruit the volunteers needed.

Westphal and his team at UC Berkeley's Space Sciences Laboratory are taking about 700,000 "focus movies" of the aerogel collector, each covering a different minute portion about the size of a grain of salt. Each movie focuses on 40 different depths within the aerogel, from a little above the surface to a depth of 100 microns.

Each Stardust@home user will use an online "virtual microscope" to look for signs of interstellar grains in focus movies fed to the virtual microscope at random. Anyone on the internet can sign up to help scan the aerogel for tracks left by speeding grains of interstellar dust. The human eye, along with good old-fashioned human intelligence, is better at spotting interstellar dust grains than a computer program.

Unlike SETI@home, where the computer processed all the data, Stardust@home is a hands-on activity. Each volunteer scanner will need to pass a test by spotting tracks made in test samples. The team will also keep scanners vigilant by regularly throwing "ringers" into the mix in the form of an artificially made track to see if it is found. Only results from users with a proven track record (spotting real or created dust tracks) will be considered in pinpointing the location of real interstellar dust particles. Discoverers will then have the chance to help name the dust grains that they find.

In addition to helping recruit Stardust@home volunteers, The Planetary Society also offers on its website at extensive background information on both the Stardust mission and the science of interstellar dust.

What might we learn from these first interstellar dust particles collected outside our planet's atmosphere? Scientists hope they will reveal more about the internal processes of supernovas, red giants, or neutron stars that generate the heavy elements like carbon, nitrogen, and oxygen necessary for life. Most importantly, scientists look to compare these particles from distant stars with the familiar elements of our own solar system. By placing our Sun and planets in the context of the other stars of the galaxy, interstellar dust could provide clues to the truly "big" questions: where do we come from, and where are we heading?

The Society has a second connection with the Stardust mission. The names of all its members around the world at the time of launch were included on a CD on the spacecraft, the first such collection of names from the public to have made a round trip to space and back.

The virtual microscope was developed by computer scientist David Anderson, the director of the SETI@home project, along with physics graduate student Joshua Von Korff.