Probe enters halo of dust, gas around comet

PASADENA, Calif. -- A NASA spacecraft flew through the bright halo of a distant comet Friday to scoop up less than a thimbleful of dust that could shed light on how our solar system was formed.

The National Aeronautics and Space Administration said its Stardust spacecraft passed within an estimated 143 miles of the comet Wild 2 as it plowed through the gossamer cloud that cloaks the dirty ball of ice and rock.

Mission members said the unmanned probe made its closest approach at 1:44 p.m., while traveling at a relative speed of 13,650 mph.

"We passed the closest approach point without any injury, apparently," said scientist Donald Yeomans, of NASA's Jet Propulsion Laboratory.

Stardust was designed to gather hundreds if not thousands of dust particles streaming from Wild 2 (pronounced Vilt-2) during the flyby 242 million miles from Earth.

The unmanned spacecraft also was to snap 72 black-and-white close-ups of the comet's nucleus, thought to be just 3.3 miles across.

Mission members warned comet flybys are risky, given the violent battering dust particles can give a spacecraft. Engineers gave Stardust armored bumpers to shield it during the encounter.

Scientists want to return samples of the particles to Earth for study because they represent pristine examples of the building blocks of our solar system dating back 4.6 billion years. They also believe the dust contains many of the organic molecules necessary for life.

Members of the $200 million mission planned for Stardust to sweep back past the Earth in January 2006 and jettison a canister containing the particles, allowing it to fall to the ground in Utah.

The data from the encounter will be played back to Earth over the next 30 hours. But scientists will not know for sure what the mission has collected until the sample canister is returned to Earth.