Comet mission returns safely


NASA's Stardust mission, a seven-year effort to learn more about the origins of the solar system by capturing particles from the tail of a comet and returning them to Earth, ended successfully yesterday when the spacecraft's scorched capsule parachuted into the Utah desert, its cargo intact.

The desk-size capsule glowed red as it streaked across the morning sky over the northwest United States on its way to a soft-landing at the Air Force Test and Training Range in Dugway, Utah.

The mission was a major victory for NASA's Jet Propulsion Lab in Pasadena, Calif., and Lockheed Martin Space Systems in Denver, which jointly oversaw the spacecraft on its nearly 3-billion-mile journey to snatch a piece of a speeding comet and bring it back to Earth for a bull's-eye landing.

"This is really a great day for NASA and the exploration of our solar system," said Andy Dantzler, head of NASA's solar system division.

Tom Duxbury, project manager at the Jet Propulsion Lab, said: "This thing went like clockwork."

Launched Feb. 7, 1999, Stardust made two loops around the sun before meeting up with comet Wild-2 in January 2004, between Mars and Jupiter. It flew as close as 147 miles to the hamburger-shaped comet, passing through its tail of dust and exotic gases.

At its closest approach, the capsule opened a tennis racket-shaped collector, packed with a material called aerogel, to capture comet particles, thought to be the original building blocks of the solar system.

Scientists won't know how much of the comet they grabbed for a few days, but they were delighted with early evidence pointing to a successful mission.

As it neared Earth, the spacecraft released its sample return capsule just before 10 p.m. Saturday. The capsule, protected by a thick heat shield, entered the atmosphere just before 2 a.m. High winds in the mountains of Utah pushed the capsule slightly off course during its descent.

NASA program managers still called it a "bull's-eye" landing on a surface muddied by recent rain.

Controllers were pleased to see the parachute open after last year's near-disastrous end to NASA's Genesis mission. Like Stardust, Genesis was a difficult sample-return mission, the first U.S. attempt since Apollo 17 brought back the last moon rocks in 1972.

Genesis was bringing back microscopic evidence of solar wind, the energy particles flowing out from the sun, when its parachute failed to open and the capsule "pancaked" in the Utah desert.

Scientists have spent months trying to reassemble its delicate collector array. Like Genesis, Stardust was built by Lockheed Martin.

In contrast, everything went near perfectly for Stardust.

The only apparent damage was the loss of small bits of the heat shield because of the tremendous temperatures the capsule experienced on its return trip. Because of the complicated geometry of the journey, Stardust re-entered the Earth's atmosphere at a higher speed than any spacecraft in history -- 29,000 mph.

Technicians at Dugway removed the science materials yesterday, including the aerogel collector in which the particles bury themselves like a baseball going into a mitt, for shipment to the Johnson Space Center in Houston.

Mission scientists hope they captured thousands of particles. The largest they expect to find are still tiny, about two-tenths of an inch in diameter. Most will be in the range of microns, thinner than a human hair.

"The real touchdown will be when we open it up Tuesday and figure out how many particles we did capture," said Joe Vellinga, Lockheed Martin's Stardust manager.

The dust and ice particles captured by Stardust will help scientists understand the complex chemical and physical processes that lead to the formation of planets around stars.

Comets are some of the oldest and least-tainted objects in the solar system.

"The most interesting thing about comets is, they are libraries with the stored records of our formation," said Donald Brownlee, an astronomer at the University of Washington, the mission's principal investigator.

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