/ 13 January 2006

You too can probe the mystery of the universe

Fed up with the daily grind? Eager for something different? A little glory, perhaps?

Well, how about helping a quest to understand the life and death of stars? And how about the reward of making your name immortal?

Scientists are looking for people with keen eyesight, lots of patience and spare time on their home computer to help them sift through the results from an extraordinary space mission.

After a nearly seven-year trek, the United States spacecraft Stardust has hopefully captured what is primeval dust, trailed out by Comet Wild 2 as it raced past Earth in January 2004, that could shed light on how the solar system was formed.

And, it is hoped, Stardust has also snared a sprinkling of particles from stars, millions of light years away, that blew apart in supernova explosions.

The dramatic climax to this $199-million trek across the heavens will come on Sunday when — if all goes well — a capsule containing the precious cargo will parachute safely to earth in Utah at 10.12am GMT.

Then, one might say, comes the hard part.

The samples are imbedded in an ultra-light gel designed to capture dust at very high speed, acting as a soft mattress on which the particles can gently land without burning up or smashing apart.

The substance, called aerogel, is mounted in a grid — a collector that looks roughly like a tennis racket.

The device flipped up to pick up the particles at key points on Stardust‘s voyage. One side of the collector was used for the comet trail, the other side for interstellar dust.

The problem: Before the particles can be analysed for their chemical and radioactive fingerprints, the tiny varmints have to be spotted in the gel, and then gently extracted.

The hunt may be less of a problem for Wild 2’s dusty trail, for thousands of particles should have been caught and, comparatively speaking, at one micron (a millionth of a metre) across they are mammoth-sized.

But as for the interstellar dust… well, there may be as few as 45 grains, if previous research by the Ulysses and Galileo spacecraft is any guide, and they are almost invisible.

“These impacts can only be found using a high-magnification microscope with a field of view smaller than a grain of salt,” say the investigators in their appeal for help.

“The job is roughly equivalent to searching for 45 ants in an entire football field, one 5cm by 5cm square at a time.”

Sifting through the 1,5-million images of the aerogel to look for a trail left by the dust as it braked into the gel, would take the team more than 20 years.

This is where the public — you — come in.

Volunteers who sign up to at a special websitehttp://stardustathome.ssl.berkeley.edu), will be sent cross-section digital images from the gel.

Their task will be to scrutinise each image to look for an impact trail, something which to the uncultured eye looks rather like a hairy carrot.

The “virtual microscope” will be made available to the public from March, says the University of California at Berkeley (UCB), whose researchers have launched the Stardust@home scheme.

Their inspiration comes from SETI@home, in which volunteers allow idling time on their personal computers to help the search for extra-terrestrial intelligence. When the PC is not in use, its processor crunches data of radio signals received from space.

Unlike SETI@home, recruits to Stardust@home will be active, rather than passive — “a neural network, using brains together to find these grains,” says Bryan Mendez of UCB’s Center for Science Education.

This way, a 20-year search could be compressed to just seven months.

Four volunteers will view each image. If two of them separately see a track, that image will be fed to 100 more volunteers for verification. If at least 20 of these report a track, a UCB team will then carry out a confirmation.

If they give the green light, the grain will extracted by a specially-made gadget, dubbed “micro pickle forks,” for analysis.

And the reward? Discover the grain, and you get to name it. – AFP