Science News

Distant comet contains minerals from early sun

Mar 14, 2006, 9:16 GMT

Washington - Comet particles collected from the far-flung corners of the solar system may include minerals ejected from the sun during the system's early development - a surprise for scientists who revealed the findings Monday. This picture made available by the European Space Agency (ESA) shows an artist's impression of NASA's Stardust spacecraft. EPA/HANDOUT

This picture made available by the European Space Agency (ESA) shows an artist's impression of NASA's Stardust spacecraft. EPA/HANDOUT Samples of the Comet Wild 2 - collected and brought back to earth by NASA's Stardust capsule after a seven-year, 4-billion-kilometre journey - have been extracted and analysed by scientists since the capsule returned in January. 'We are finding these high-temperature minerals in materials from the coldest place in the solar system,' said Stardust principal investigator Donald Brownlee of the University of Washington. The discovery has forced scientists to re-evaluate their theories of how comets develop and may offer unexpected insights into the solar system's origins. Comets were thought to be cold clouds of dust and gases, formed on the solar system's edges. But the high-temperature minerals discovered suggest that comets may consist of particles of varying temperatures and origins. Some of these may have been particles propelled by the sun to the outer reaches of the solar system during the early stages of its development. Stardust's return to Earth in January marked only the second time that spacecraft has returned samples from outer space. The first time was the moon rocks from the 1972 Apollo mission. Speaking at a briefing Monday at NASA's Johnson Space Centre in Houston, Texas, Brownlee said that Stardust's collection of particles would shed light on the solar system's evolution. But Brownlee refused to be drawn on whether the particles were more important than the lunar rocks returned to earth in 1972. 'The moon was a fabulous place but didn't contain anything that dated back to the beginnings of the solar system. In Stardust we have primitive materials that may date back to the early solar system, but tells us little about the evolution of planetary bodies,' as was provided by the lunar rocks, Brownlee said. 'They are both fabulous things,' he added. NASA scientists have also been surprised by the number of particles captured and extracted from the Stardust capsule. 'If we had one particle that we could see we would be happy. I gave (Brownlee) 40, so it was very successful,' said Peter Tsou, Stardust's deputy principal investigator from the Jet Propulsion Laboratory in Pasadena, California. Scientists expect to spend the next decade examining the comet pieces and stardust particles, after extracting them from the Stardust's capsule's aerogel substance, designed especially to capture comet particles and interstellar dust particles. The search for particles still hidden in the aerogel, the largest of which are no wider than the diameter of a single human hair, is to be aided by an army of internet volunteers, who NASA expects to spend about 30,000 hours looking for the smaller interstellar dust particles in the aerogel through a web-based microscope. Successful participants will get to name any particle they find. © 2006 dpa - Deutsche Presse-Agentur