Comets: Stardust particles, made of ‘fire and ice’

Rather than the balls of ice, dust and gas astrophysicists thought they were, comets turn out to be celestial bodies of complex and varied origins, said the University of Washington professor.

"It seems that comets are a mixture of materials formed at all temperatures, at places very near the early sun and at places very remote from it," said Michael Zolensky, Stardust curator and co-investigator at JSC.? The Wild 2 particles include olivine, a rock found in abundance in the green sand on some Hawaiian beaches. Its presence in the comet's dust trail was a surprise, scientists said. Olivine's components include iron, magnesium and other elements. The Wild 2 samples have other high-temperature materials containing calcium, aluminum and titanium.

A Stardust capsule carrying a teaspoonful of space dust parachuted to Earth in the Utah desert on January 15 after a nearly seven-year journey across 4,63-billion kilometres. - MG