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SAN FRANCISCO - Detailed observations from the first comet samples returned to Earth are debunking some of science's long-held beliefs on how the icy, celestial bodies form. Scientists expected the minute grains retrieved from a comet Wild 2 to be made up mostly of interstellar dust — tiny particles that flow through the solar system thought to be from ancient stars that exploded and died. Instead, they found an unusual mix of primordial material as if the solar system had turned itself inside out. Hot particles from the inner solar system migrated out to the cold, outer fringes beyond Pluto...

Two of the most common materials found in Tempel 1 are an iron-silicon mineral called ferrosilite and a glassy form of a magnesium-iron mineral called olivine, which make up 33% and 17% of the comet, respectively, according to observations by the Spitzer Space Telescope. However, these minerals are entirely absent from the Wild 2 samples analysed so far... It is not clear how to explain this difference, says Stardust mission leader Donald Brownlee of the University of Washington in Seattle, US. But he says one possibility is that the material on Tempel 1 was chemically modified by ancient collisions --...

ST. LOUIS - Scientists said Monday they have begun slicing and dicing the first of hundreds of microscopic specks of comet dust, virtually unchanged since the birth of the solar system, that a NASA spacecraft successfully returned to Earth in late January. Preliminary analysis shows the dust, captured when the robotic Stardust spacecraft flew past the comet Wild 2 in January 2004, is unmistakably cometary in origin, said Don Brownlee, a University of Washington astronomer who is the principal scientist for the $212 million mission. As such, the grains represent pristine samples of the primitive material that came together to...

SPACE CENTER, Houston (AP) - A honeycomb cluster of cells on NASA's Stardust spacecraft captured thousands of samples of interstellar and comet dust that scientists said Thursday could give them the first definitive evidence about how the solar system formed. "Its cargo was an ancient, cosmic treasure from the very edge of the solar system - a treasure that formed when the solar system formed 4.5 billion years ago," said Donald Brownlee, a University of Washington scientist who worked on the Stardust mission managed by the Jet Propulsion Laboratory in Pasadena, Calif. Some of the samples collected during the seven-year,...

DUGWAY PROVING GROUND, Utah - A space capsule ferrying the first comet dust samples to Earth parachuted onto a remote stretch of desert before dawn Sunday, drawing cheers from elated scientists. The touchdown capped a seven-year journey by NASA's Stardust spacecraft, which zipped past a comet in 2004 to capture minute dust particles and store them in the capsule. "It's an absolutely fantastic end to the mission," said Carlton Allen, a scientist with NASA's Johnson Space Center. A helicopter recovery team located the capsule Sunday and was transferring it to a clean room at the nearby Michael Army Air Field....

WASHINGTON (Reuters) - A sample of comet dust, collected by a robotic space probe with what looks a bit like a big tennis racket, is scheduled to parachute down to Earth next month, NASA scientists said on Wednesday. The spaceship Stardust is coming to the end of its seven-year, 2.9 billion mile round-trip mission to fly by comet Wild 2, catching dust that could give astronomers clues about how the planets formed some 4.5 billion years ago. The ship will remain in space but a 101-pound (46 kilogram) capsule loaded with dust culled from the comet is expected to land...

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. 2004 January 19 STARDUST Flyby of Comet Wild 2 Credit: STARDUST Team, JPL, NASA Explanation: Flying past a comet nucleus is dangerous. On January 2, the robot spacecraft STARDUST became one of the first to plow through the surrounding cloud of dust and grit to photograph the very heart of a comet. Pictured above is a short movie of the encounter showing unprecedented surface details of the icy...

Spacecraft to Fly Through Tail of Comet By ANDREW BRIDGES, AP Science Writer PASADENA, Calif. - A spacecraft is on track to fly through the tail of a comet on Friday, collecting hundreds of specks of the primitive material from which the sun, the planets and all living creatures are made, NASA said. The National Aeronautics and Space Administration's Stardust spacecraft is expected to pass within 186 miles of the comet Wild 2 as it catches the shimmering gas and dust cloud that envelops the dirty ball of ice and rock. The unmanned probe should make its closest approach...