2006年VOA标准英语-US Space Capsule Returns Comet Dust for St（在线收听）

By David McAlary
Washington
15 January 2006
 

Tom Duxbury, Stardust Project Manager for NASA's Jet Propulsion Lab, answers questions during a news conference after the landing of the Stardust capsule  
  
A U.S. space capsule containing precious grains of star dust has landed intact in Utah, giving scientists the chance to study matter dating from the formation of our solar system.

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The landing ended a seven-year, 4.5 billion kilometer round trip journey halfway to Jupiter, where the Stardust spacecraft captured material spewing from Comet Wild-2 as it melted during its approach toward the Sun.

Stardust released its cargo Sunday, 110,000 kilometers above Earth. The capsule raced through the atmosphere faster than any spacecraft before. It came in at 45,000 kilometers per hour, before parachuting to a soft landing at a U.S. Army testing base in the Utah desert.

Stardust project manager Tom Duxbury says the entry and landing were flawless.

"This thing went like clockwork. It hit the atmosphere exactly on time," he said. "When we saw that drogue chute open, we knew we were home safe. So, then, the next thing was, of course, a little later, for our main chute opening, and this thing just gently lowered us to the surface of the Utah Test and Training Range."

A helicopter recovery team retrieved the capsule, and brought it to a nearby sterile room for safekeeping, before it is flown Tuesday to the U.S. space agency's Johnson Space Center in Houston, Texas.

Stardust's encounter with the comet took place in 2004, well within the solar system, but mission scientists say it was as if the spacecraft had journeyed to the solar system's edge and back, to the time 4.5-billion years ago, when the sun and planets formed. That is because comet orbits extend far beyond Pluto and are believed to contain matter originally forged in stars that went into solar system construction.

"We're using this comet as a library that picked up records of the formation of our solar system, and has been storing them far from the Sun at very low temperatures for 4.5 billion years," added mission's principal investigator, Donald Brownlee of the University of Washington. He says the dust grains brought back to Earth can shed light on how our solar system came to be.

"We're learning about the origin of our solar system, the origin of the Sun, the origin of the planets, and something about the origin of life," he added. "Virtually all of the atoms in our bodies and in our Earth were in stardust grains, before the solar system formed."

The Stardust capsule contains hundreds of thousands of grains of matter captured in a wispy glass filter, called aerogel. After the samples reach Houston Tuesday, the space agency will distribute them to scientists all over the world, who will analyze their composition.