Comet Dust Streaking Towards Earth

The last time NASA scientists hunkered down at a remote desert Army base, they stared wide-eyed as a space probe hauling solar wind atoms crashed into the salt flats and split open like a giant clamshell.

Flash forward two years.

Nerves are on edge as scientists anxiously await the return of another space probe — this one named Stardust and bearing the first comet samples ever carried to Earth. Hovering 69,000 miles up, the spacecraft released the shuttlecock-shaped capsule late Saturday, putting it on course for a blazing re-entry at the Army's remote Dugway Proving Ground early Sunday.

During its mission, the Stardust captured comet dust, collecting a pay load that will barely fill a teaspoon – and yet the incredibly tiny samples were swirling about four and a half billion years ago, reports CBS News correspondent Jerry Bowen.

Scientists believe studying comets could shed light on how the solar system formed.

Memories of the ill-fated 2004 Genesis landing, in which the space probe's parachutes failed to open, are still vivid.

Scientists later found that gravity switches installed incorrectly caused the failure. Despite the mishap, they were able to salvage the tiny cosmic samples for study.

Afterward, engineers performed a thorough check on Stardust's systems and feel certain that it won't suffer the same fate as Genesis.

"They built this thing like a tank. They do believe that even if the parachute system failed, that they could still recover these samples," said CBS News space consultant Bill Harwood .

"I don't think you can ignore the Genesis situation. You just have to embrace it and apply the lessons learned from it," said Ed Hirst, mission system manager at NASA's Jet Propulsion Laboratory, which is managing the $212 million project.

Stardust left on a seven-year, 2.9 billion-mile journey that was highlighted by a flyby of comet Wild 2, a jet-black ball of ice and dust that was about 500 million miles away from Earth when the probe was launched in 1999.

The 850-pound Stardust, outfitted with armored bumpers, survived a harrowing blast of debris as it flew past Wild 2 to collect dust in 2004. During its journey, it also captured interstellar dust — tiny space particles believed to be from ancient stars that exploded and died.

Scientists believe about a million microscopic comet and dust samples — most tinier than the width of a human hair — are now safely locked away in a canister inside Stardust.

Late Saturday, the space probe must release a 100-pound capsule, which will then nosedive through the Earth's atmosphere toward a target landing at Dugway Proving Ground, about 80 miles southwest of Salt Lake City.

It will plummet through the atmosphere at a record-setting 29,000 mph, the fastest re-entry of any man-made probe. Meanwhile, the mothership must fire its thrusters to remain in perpetual orbit around the sun.

The capsule's blazing return is expected to produce a pinkish glow as bright as Venus that should be visible with the naked eye across the Northwest.

The capsule must deploy its first parachute at 100,000 feet at supersonic speed, followed by a larger chute, which will guide it to a landing.

During Genesis, Hollywood stunt pilots were dispatched in helicopters to snatch the probe in mid-air. But Genesis' parachutes never opened, and the capsule crash-landed at nearly 200 mph.

For Stardust, a helicopter recovery team flies to the landing site only after the capsule has touched down. One of the choppers must fetch the capsule and bring it to a clean room on the base for processing.

The capsule will then be shipped to NASA's Johnson Space Center in Houston where scientists will pry open the canister and probe the samples under a microscope.

Scientists hope the samples will build on their knowledge of comets gleaned by NASA's Deep Impact mission last year, which smashed a probe into a comet, revealing its pristine interior.