After 3 Billion Miles, Craft Returns Sunday Bearing Cosmic Dust Older Than the Sun - New York Times

New York Times: "In a blaze across the night sky, it should be a spectacular homecoming at the end of a very, very long journey. After covering 2.88 billion miles over seven years, the Stardust spacecraft is nearing home with its minute but precious cargo: samples of what are believed to be the oldest materials in the solar system.Tucked away in what looks like a giant fly swatter of a collector is dust swooped up from a close encounter with the comet Wild 2 and an accumulation of particles picked up in three circuits of the Sun.'This has been a fantastic opportunity to collect the most primitive material in the solar system,' said Donald Brownlee of the University of Washington, the principal investigator for the mission. 'We fully expect some of the comet particles to be older than the Sun.' Comets, icy bodies that normally inhabit a region near Pluto's orbit, are made of material many scientists believe is virtually unchanged since the Sun and the planets formed about 4.6 billion years ago. Studying comets not only provides clues to how the solar system was created but could also help explain how certain materials and conditions combined to form life, researchers said. 'Comets are a library of our history,' said Thomas Duxbury, project manager at the National Aeronautics and Space Administration's Jet Propulsion Laboratory in Pasadena, Calif., which is supervising the mission.After its launching in 1999, the Stardust circled the Sun and flew by Earth for a gravity boost to rendezvous with Wild 2 (pronounced vilt 2) near Jupiter. On Jan. 2, 2004, the Stardust came within 149 miles of the comet, deploying shields to protect itself from cometary dust while extending a 160-square-inch collector filled with a material called aerogel. This low-density silicon material, composed of 99.8 percent air, gently slowed and trapped particles without significantly altering or damaging them. Stardust also spent 195 days collecting interstellar particles that flow through the solar system.The challenge now is to bring them home safely. If all goes as planned, a capsule bearing the space dust will dive into the atmosphere early Sunday morning and gently parachute the samples to the Utah desert."