Fed II Star - January 15, 2006

REAL LIFE NEWS: CATCH A COMET

It's been a long, long journey for the spacecraft Stardust. Seven years ago it set out on a trip that saw it travel five billion kilometres. And now it's home again, carrying with it the thing it was set to fetch - a smidgeon of comet dust. Early this morning it dropped a capsule containing this precious cargo over the US state of Utah. This dust will give us our first close look at the material that built the Solar System 4.6 billion years ago.

"If this works, there will be a huge queue of people with their hands up wanting bits of this cometary material," David Hughes said a few weeks ago. He's a comet specialist at the University of Sheffield, UK.

Stardust was launched in February 1999 and travelled for five years to reach the comet Wild 2, which orbits the sun between Mars and Jupiter. It flew to within 150 miles of the comet and extended a collector, shaped like a tennis racket, to trap dust particles. The goal was to collect about 500 particles wider than 15 micrometres, but the spacecraft probably bagged five times as many.

Close-ups of the comet revealed that Wild 2 has countless depressions, with very high cliffs, bizarre pillars and pinacles. It vents gasses at close to the speed of sound and these pelted Stardust with dust and rocks.

Sample-return missions are notoriously accident-prone. NASA's Genesis mission, which collected solar particles, crash-landed in September 2004 when its parachute failed to open because of a design flaw. But pre-launch tests of Stardust's capsule confirmed that it doesn't have the same flaw, and a dress rehearsal, in which three helicopters chased a dummy capsule dropped from about 2 miles high, went well. Then this morning the real capsule, weighing just over 100 lbs, touched down safely on a military base southwest of Salt Lake City. During its re-entry into the Earth's atmosphere it reached speeds of 29,000mph and was visible from parts of the American northwest as a streak of light in the sky.

For the latest news go to the Stardust web site.