Capsule return like precision clockwork

DUGWAY PROVING GROUND — Watching the re-entry of the Stardust space capsule on live video early Sunday, scientists and engineers knew their priceless samples were safe when the capsule suddenly disappeared from view.

A big concern was that the craft's parachute might not open — as happened in September 2004 with NASA's Genesis capsule. But when Stardust disappeared, it was like a bobber vanishing when a fish bites the bait.

It meant the drogue parachute had popped out as planned at around 105,000 feet, slowing Stardust's descent so dramatically that the camera continued to track downward past it.

Seeing the capsule safely back almost brought a tear to the eye of Don Brownlee, the principal investigator, he said.

Stardust was one of America's most ambitious sample collection projects. Launched in February 1999 from Cape Canaveral, Fla., aboard a Delta II rocket, it rounded the sun three times on its long odyssey.

From February through May 2000, Stardust collected samples of interstellar dust grains. In January 2004, it maneuvered close to Comet Wild 2 and collected particles of dust blowing from the comet, notes NASA.

The dust struck collectors at 13,684 mph, according to the space agency. To capture the grains without harming them, Stardust deployed a grid packed with material called "aerogel," a silicon dioxide substance that is exceptionally porous. The dust stuck to the aerogel and was brought back into the capsule.

On Saturday, when Stardust was 68,805 miles away, it released the 100-pound sample return capsule with aerogel and samples locked inside. This is what landed at Dugway on Sunday after hitting the atmosphere at just under 29,000 miles per hour.

Stardust's main craft remains in orbit and may be sent to encounter other comets and make measurements, though it carried only one return capsule.

Brownlee, of the University of Washington, Seattle, said the trip back from space went fine. "One major concern was having it break open," he said.

"Or my biggest fear was having it hit a way that we'd get water on the inside." If the Dugway range happened to be flooded by a rainstorm, he worried, it could have landed in a puddle or mud.

Instead, the parachute worked great, and when crews reached the capsule it "looked fine," he said.

"All the engineers who built it seemed to be happy," Brownlee said. "It's very strong."