• Introduction
    • Stardust



      Stardust was the first space mission dedicated to studying a comet and the first solid sample return mission in over 30 years. Stardust captured thousands of particles of comet dust during a daring close encounter with comet Wild 2. It also brought back samples of interstellar dust that may consist of ancient presolar grains that are older than our solar system. Analysis of these fascinating celestial specks will yield important insights into the nature and origin of comets, the evolution of our solar system, and possibly even the origin of life itself.



      Mission Management

      Dr. Donald Brownlee
      Dr. Donald Brownlee,
      Principal Investigator

      The Stardust mission was managed by the Jet Propulsion Laboratory, Pasadena, CA. The Principal Investigator was Dr. Donald Brownlee of the University of Washington, Seattle. The Stardust spacecraft was designed and built by Lockheed Martin Astronautics of Denver, Colorado.

  • Objectives & Details
    • Objectives

      Stardust's science objectives were to:

      Collect solid samples from a comet that formed beyond Neptune

      Return the samples to Earth for laboratory analysis



      Stardust launched on February 7, 1999, aboard a Delta 2 rocket from Cape Canaveral Air Force Station, Florida. After two dust collection sessions and a close flyby of comet Wild 2, the sample return capsule returned safely to Earth on January 15, 2006.

      To collect particles without damaging them, Stardust used an extraordinary substance called aerogel. Aerogel is a silicon-based solid with a porous, sponge-like structure that is 99.8 percent air and 1,000 times less dense than glass. When a particle hits the aerogel, it buries itself in the material, creating a carrot-shaped track up to 200 times its own length. This slows it down and brings the sample to a relatively gradual stop. Scientists use these tracks to find the tiny particles in the nearly transparent aerogel.


      Dust Collector with Aerogel.
      Dust Collector with Aerogel.





      Stardust scientist Peter Tsou
      Stardust scientist Peter Tsou displays a large cube of aerogel.
  • Collection & Return
    • In February 2000, the Stardust spacecraft successfully deployed its aerogel collector and captured interstellar dust for four months. The collector was then stowed until 2002, when the second interstellar dust collection took place from August through December. The stardust analysis through the Stardust@Home project is expected to yield important insights into the evolution of the Sun and planets.

      On January 2, 2004, Stardust's clever trajectory slowed the probe as it flew through the treacherous coma-cloud of dust and gas that surrounds the comet's solid nucleus and allowed it to get as close as 149 miles from the comet's surface. Thousands of tiny cosmic particles were captured in the aerogel-filled tennis-racquet size collector grid, without altering their shape or chemical composition. After the flyby, scientists were stunned by the pictures and the data sent back from the instruments on board. But the best was yet to come, when the samples returned to Earth.

      On January 15, 2006, the Stardust sample return capsule parachuted into the U.S. Air Force Utah Test and Training Range after a 288 billion mile journey through the solar system. It entered the Earth's atmosphere faster than any human-made object on record. It slowed from a speed of nearly 29,000 miles per hour to about 10 miles per hour in 13 minutes. Two days later, it was transported to a curation facility at NASA's Johnson Space Center in Houston.

      The captured grains are tiny, most smaller than a hair's width, although about two dozen large tracks are visible to the unaided eye. Thousands of grains appear to be embedded in the aerogel. A single grain of 10 microns, .0004 inch, can be sliced into hundreds of samples. Samples have been distributed to approximately 150 scientists worldwide for study and analysis.

      Stardust Sample Return Capsule
      Stardust Sample Return Capsule as seen from NASA's DC-8 Airborne Laboratory streaking throught the sky above Utah during reentry.

      The Sample Return Capsule on the ground in Utah
      The Sample Return Capsule on the ground in Utah after landing









  • Results
    • Scientists have discovered that comet Wild 2 is a collection of materials that probably came from all regions of the young solar system and is an odd mix of low and high temperature components. This suggests that materials from the center of the solar system could have traveled to the outer reaches where comets formed, altering the way scientists view the formation and composition of comets. They may prove to be more diverse and complex than previously thought.

      Scientists have learned that the surface of comet Wild 2 is very rugged and unlike that of other comets that have had spacecraft flybys. They found flat floor depressions bounded by cliffs, erosional features like mesas and pinnacles, and a lack of obvious impact craters. They saw 22 active jets of gas and dust. They discovered olivine in the comet dust. This common mineral is a primary component of the green sand found on some Hawaiian beaches and it is abundant throughout the universe, but scientists were surprised to find it in cometary dust.

      One of the most remarkable particles found in the Stardust collection is a group of rock fragments that are all related in mineralogical, isotopic and chemical composition to rare components in meteorites called "Calcium Aluminum Inclusions" or CAI's for short. CAI's are the oldest materials that formed in the solar system, and they contain a remarkable set of minerals that form at extremely high temperature. These fragments also have tiny inclusions that may have been the first generation of solids to condense from hot gas in the early solar system.

      Scientists discovered glycine, a fundamental building block of life, in the Stardust samples. Glycine is an amino acid used by living organisms to make proteins. The discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts. Details are in Meteoritics and Planetary Science, Volume 44, No. 9, October 16, 2009

      The June 18, 2004 issue of Science contained a special section on Stardust's close encounter with comet Wild 2. The December 15, 2006 issue of Science featured results to date after sample return.

      A collection of articles on Stardust was published in Meteoritics and Planetary Science, Volume 44, Number 10, November 20, 2009. Findings were reported at the 41st Lunar and Planetary Science Conference (LPSC) in 2010 in a session on Stardust Mission to Comet Wild 2.

      The Stardust samples will be analyzed by hundreds of scientists for decades to come. They offer a fabulous way to explore the early solar system and to test ideas about its origin, part of the continuing quest to discover the building blocks of life on Earth.


      The surface of comet Wild 2
      The surface of comet Wild 2 as imaged by Stardust.
      Stardust scientists
      V is for Victory in the cleanroom when excited Stardust scientists first see actual particles of comet dust returned to Earth.

      A CAI particle found in the Stardust collection
      A CAI particle found in the Stardust collection
      Comet particle
      Comet particle that penetrated the aluminum foil holding the aerogel block, leaving an impact crater in the foil and ejecta in the aerogel.













  • Noteworthy
    • The aerogel used by Stardust to collect comet particles is listed in the Guinness Book of World Records as the lightest known solid material.

      The Stardust sample return capsule is on display in the Smithsonian's National Air and Space Museum in Washington D.C. in the Milestones of Flight Gallery, along with the Wright brothers' 1903 Flyer, Charles Lindbergh's Spirit of St. Louis and the Apollo 11 command module that carried the first men to walk on the Moon.  

      The Stardust display at the National Air and Space Museum.