January 25, 2008
Contrary to scientists' expectations, much of the comet dust returned by NASA's Stardust mission formed very close to the young sun and was somehow differentiated from the other materials that are believed to have formed in the early solar system.
When NASA's Stardust mission returned to Earth with samples from comet Wild 2 in 2006, scientists knew the material would provide new clues about the formation of our solar system, but they didn't know exactly how.
New research by scientists at Lawrence Livermore National Laboratory, Livermore, Calif., and collaborators reveals that, in addition to containing material that formed very close to the young sun, the dust from Wild 2 also is missing ingredients that would be expected in comet dust. Surprisingly, the Wild 2 comet dust samples better resemble a meteorite from the asteroid belt rather than an ancient, unaltered comet.
The team, using Livermore's SuperSTEM (scanning transmission electron microscope), specifically searched for two silicate materials in Stardust that are believed to be unique to cometary interplanetary dust particles: amorphous silicates known as Gems (glass with embedded metal and sulfides); and sliver-like whiskers of the crystalline silicate enstatite (a rock-forming mineral).
Stardust is a part of NASA's series of Discovery missions and is managed by NASA's Jet Propulsion Laboratory. Stardust launched in February 1999 and set off on three giant loops around the sun. It began collecting interstellar dust in 2000 and met Wild 2 in January 2004, when the spacecraft was slammed by thousands of comet particles. It is the first spacecraft to safely make it back to Earth with cometary dust particles in tow.
The follow-on mission for the Stardust spacecraft, Stardust-NExT, is a low-cost mission that will expand the investigation of comet Tempel 1 initiated by NASA's Deep Impact spacecraft. JPL, a division of the California Institute of Technology, Pasadena, manages Stardust-NExT for the NASA Science Mission Directorate, Washington, D.C. Joseph Veverka of Cornell University is the mission's principal investigator. Lockheed Martin Space Systems, Denver Colo., manages day-to-day mission operations.
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