Image: Stardust and Earth
NASA
In this artist's conception, the Stardust spacecraft zooms toward Earth in preparation for releasing its sample return capsule.
By Senior space writer
updated 1/13/2006 12:53:06 PM ET 2006-01-13T17:53:06

If the incoming Stardust spacecraft fails to deliver its capsule carrying a grab bag of interstellar and cometary goodies to Earth this weekend, scientists will have to wait several years before another attempt is possible.

As the spacecraft now speeds toward Earth at 4 miles (6.4 kilometers) per second, still ahead for mission engineers is a go/no-go capsule separation decision. Space engineers need to assure themselves that all is precisely on track for the capsule’s deployment and skyrocketing descent into Utah.

After nearly seven years and 2.88 billion miles (4.6 billion kilometers) of space travel, the NASA Stardust mission is slated to drop off its sample return capsule carrying interstellar dust and comet particles early Sunday.

If the sample capsule is not ejected by the Stardust main spacecraft as it swings by Earth, Stardust and its still-retained capsule would be diverted to a course that permits both spacecraft and Earth to be back together again — but three years later. The capsule deployment would then be attempted.

"We do have a backup … but we expect to come in Sunday," Tom Duxbury, project manager for Stardust at NASA’s Jet Propulsion Laboratory, said during a Stardust capsule pre-landing briefing Friday. The meeting was conducted at a command conference room at the U.S. Army’s Dugway Proving Ground in Utah.

Stardust’s sample return capsule is heading for a landing within the U.S. Air Force Utah Test and Training Range, or UTTR, at the Dugway Proving Ground, southwest of Salt Lake City.

Stardust’s sample capsule is to blaze across the western United States as it plunges toward the target zone. The capsule should touch down at 3:12 a.m. MT (5:12 a.m. ET) Sunday.

Light up the sky
"We will light up the sky," said Duxbury. The fireball itself could be visible up to 30 seconds during the capsule’s high-speed, heat-shield protected plunge, he said.

The sky show is expected to be visible from central California through central Oregon, on through Nevada and into Utah, Duxbury said.

Duxbury said the return capsule "is our knight in shining armor," wrapped in material designed to take the heat generated during the speedy atmospheric dive. Tucked inside the capsule, a collector grid contains the precious cargo of interstellar and comet particles.

"We are nearing the end of quite a fantastic voyage," said the University of Washington's Don Brownlee, principal investigator for the Stardust science mission. During the probe’s collection route, Stardust snagged interstellar dust specimens as well as particles cast off by Comet Wild 2 when the probe flew by that object in 2004.

A glimpse back in time
The primitive materials snared by Stardust will give scientists a glimpse back in time — 4.5 billion years ago — to help learn more about the origin of the sun and our solar system as well as the origin of life, Brownlee said.

As the probe descends, mission planners expect a drogue chute to deploy, followed by the main parachute. That would ease the capsule's rate of descent to 10 mph (16 kilometers per hour) for a soft touchdown on the desert floor.

The weather for landing looks favorable at the moment, said Michael McGee, recovery operations manager for Lockheed Martin Space Systems of Denver, the firm that designed, built and has operated Stardust.

McGee said the recovery team has undergone numerous trial runs and is ready to reach the landed capsule via helicopter or ground track vehicles — depending on weather conditions during touchdown.

Coordinates of the capsule’s actual landing spot will be yielded by radar and infrared tracking systems, McGee said.

"We’re looking forward to going out and retrieving this Sunday … regardless of whatever the conditions may be and whatever is presented to us," McGee told reporters during the press briefing.

Getting to the finish line
The $212 million Stardust mission was launched on Feb. 7, 1999. It is part of NASA's Discovery program, aimed at doing relatively low-budget space science.

Stardust mission scientists and engineers expect they won’t see a replay of the Genesis smashdown that occurred September 8, 2004. Incorrectly placed gravity switches caused the Genesis capsule parachute system not to deploy.

In the event that Stardust’s sample return capsule undergoes a hard landing, "we have a smaller and more rugged return capsule than Genesis," Duxbury noted. The collector grid, he said, is very tough—a device that looks like a tennis racket, loaded with aerogel that holds the trapped interstellar and comet particles.

"Aerogel is a very robust material. We’ve tested it … pounded it into the ground at more than a few hundred G’s, and it survives fine," Duxbury explained. "Even with a hard landing, we believe we will recover most, if not all, of our science."

Duxbury said that landing "is not the finish line." The recovered Stardust samples are to be transported to, studied and distributed at NASA’s Johnson Space Center in Houston, he said, "and that’s where we will get the fruits of all of our labor."

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