Seeing the Universe in a Grain of Dust
Imagine traveling halfway to Jupiter--3.2 billion kilometers--for a small handful of comet dust. That's the mission for the National Aeronautics and Space Administration's (NASA's) Stardust spacecraft launched on February 7, 1999. This past January, Stardust flew by Comet Wild 2's nucleus and through a halo of gases and dust at the comet's head, collecting cometary dust particles released from the surface just hours before. In 2006, the spacecraft will deliver the less than 1 milligram of particles to Earth. A Lawrence Livermore team is perfecting ways to extract and analyze the tiny particles using its new focused-ion-beam instrument and SuperSTEM, a scanning transmission electron microscope. Stardust is the first NASA space mission dedicated solely to collecting comet dust and will be the first to return material from a comet to Earth. Comets are the oldest and most primitive bodies in the solar system. They are formed from frozen gas, water, and interstellar dust and may have brought water to Earth, making life possible. Wild 2--pronounced ''Vilt 2'' after the name of its Swiss discoverer--was formed with the Sun and the rest of the solar system 4.5 billion years ago. For billions of years, it has circled the Sun in the Kuiper Belt, a region beyond the orbit of Neptune. Scientists think comets from this region have escaped the warming, vaporization, and collisions that have altered matter in the inner solar system. Unlike Halley's Comet, which has been altered as a result of orbiting the Sun for a long time, Wild 2's pristine composition is expected to offer a rich source of information about the solar system's potential building blocks. As the 5-meter-long Stardust spacecraft traveled through Wild 2's dust and gas cloud, to within about 100 kilometers of the comet's nucleus, particles were captured in the spacecraft's collector grid. The 1,000-square-centimeter grid is filled with the silica-based material aerogel, whose lightness minimizes damage to the grains as they encounter the spacecraft at a speed of about 21,000 kilometers per hour--or six times faster than a bullet. In the late 1980s, Livermore scientists developed an aerogel made up of 99 percent air, making it ideal for NASA projects. Mission planners expect to have collected more than 1,000 grains between 2 to 5 nanometers in diameter. Most of the grains will be heterogeneous aggregates of carbonaceous matter, glass, and crystals.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 883604
- Report Number(s):
- UCRL-TR-215559; TRN: US200615%%169
- Country of Publication:
- United States
- Language:
- English
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