Spacecraft makes comet fly-by

A Nasa spacecraft flew through the bright halo of a distant comet today to scoop up less than a thimbleful of dust that could shed light on how our solar system was formed.

Nasa said its Stardust spacecraft passed within an estimated 143 miles of the comet Wild 2 as it ploughed through the gossamer cloud that cloaks the dirty ball of ice and rock.

Mission members said the unmanned probe made its closest approach at 7.44pm Irish time, while travelling at a relative speed of 13,650mph.

“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 during the fly-by 242 million miles from Earth.

The unmanned spacecraft also was due 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 fly-bys are risky, given the violent battering dust particles can give a spacecraft. Engineers gave Stardust armoured 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 $200m (€158.9m) 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, said project manager Tom Duxbury.

If returned, the particles would represent the second robotic retrieval of extraterrestrial material since 1976, when the unmanned Soviet Luna 24 mission brought back samples of rock and soil from the moon. Nasa’s Genesis spacecraft should be the first since then come September, when it returns samples of the solar wind it has collected in space.