Interstellar Dust in the Wind

NASA's STARDUST probe is collecting samples of a cloud of gas and dust that is moving through our solar system from interstellar space.

April 24, 2000 -- Like an excited kid hoping to snag a fly ball at a professional baseball game, NASA's Stardust spacecraft has extended its high-tech "catcher's mitt" to collect a valuable space souvenir -- a batch of interstellar dust particles.

The dust is contained in a stream of particles that flows through our solar system, and scientists are anxious to study it so they can learn more about the formation of Earth, other planets and life.

"We can see this material with the naked eye as a black zone running along the center of the Milky Way," said Dr. Donald Brownlee of the University of Washington in Seattle, principal investigator for Stardust. "These particles contain the heavy chemical elements that originated in the stars. Since every atom in our bodies came from the inside of stars, by studying these interstellar dust particles we can learn about our cosmic roots."

Stardust is equipped with a special collector containing aerogel, a unique substance that can trap the particles and store the precious cargo safely until it's returned to Earth. The aerogel collector has two sides, one designed to gather the interstellar dust and one for comet dust collection, which will take place later in the mission. Engineers orient the spacecraft to control which side of the collector is exposed to a dust stream.

Right now, Stardust is oriented so that the interstellar dust particles are hitting the backside of the collector. This collection began on February 22, when the spacecraft's sample return capsule opened and the aerogel collector was moved out of the capsule. It will remain in this configuration until May 1, when the collector will return to its stowed position for safe storage until mid-2002, when another period of interstellar dust collection is scheduled.

Right: Nobody really knows what a typical interstellar dust grain looks like. By studying how dust absorbs, emits, and reflects light, astronomers do know that interstellar dust is much different than the cell and lint based dust found around a typical house. Recent work indicates that most dust grains are not spherical. The above picture shows the result of a fractal adhesion model for dust grains involving random conglomerates of spherical compounds of different properties, here artificially highlighted by different colors. [more information]

"The project's name, 'Stardust,' reflects the importance of this event," said Stardust Project Manager Dr. Kenneth Atkins of NASA's Jet Propulsion Laboratory (JPL), Pasadena, Calif. "It's the first time anyone has attempted to catch anything like this and bring it home. After all the design, building, testing, and now the flying of this spacecraft over the past four years, the moment of truth for the collector is here. These tiny particles zip by at 20 to 25 kilometers per second (about 45,000 to 56,000 miles per hour) relative to the spacecraft. The aerogel must slow them to a stop in fractions of an inch."

Left: Dust particles shot into a sample of aerogel during ground tests created these microscopic tracks in the translucent, ultra-lightweight material.

In late December 2003, the collector will be deployed again in preparation for the gathering of comet dust samples when Stardust flies by Comet Wild-2 on January 2, 2004. Once the samples of both interstellar dust and comet dust are tucked safely inside the aerogel collector, it will be retracted into the sample return capsule. Stardust will begin the return trip to Earth and make a soft landing at the U.S. Air Force's Utah Test and Training Range in 2006. The sample canister will be taken to the planetary material curatorial facility at NASA's Johnson Space Center, Houston, Texas. The samples will be carefully extracted and then examined by scientists.

"I'm thrilled at the thought of being able to look at and study these particles firsthand," Brownlee said.

More information on the Stardust mission is available at http://stardust.jpl.nasa.gov/ .

Stardust was launched on February 7, 1999. The mission is managed by JPL for NASA's Office of Space Science, Washington, D.C. Lockheed Martin Astronautics, Denver, Co, built and operates the spacecraft. Science instruments were provided by JPL, the University of Chicago and the Max Planck Institute, Garching, Germany. JPL is a division of the California Institute of Technology, Pasadena.

Related Links:

STARDUST Mission home page -- from JPL

The Science of STARDUST -- from JPL

STARDUST Education web page -- from JPL

Why comet Wild-2? -- from the JPL STARDUST team

Where is comet Wild-2 right now? -- from the JPL STARDUST team, updated every 5 minutes

Orbital elements of comet Wild-2 -- from the JPL STARDUST team

More about aerogel -- from JPL

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