Space probe sputters en route to comet

Drawing of the Stardust spacecraft

February 21, 2001
Web posted at: 2:53 p.m. EST (1953 GMT)

By Richard Stenger
CNN.com Writer

(CNN) -- NASA engineers are trying to determine why a spacecraft tracking down a comet is experiencing a propulsion problem.

Mission scientists reported this week that software on the Stardust probe was commanding the deep space vessel to fire its thrusters excessively.

Stardust, the first probe designed to collect and return material from beyond the moon, is still moving in the right direction, but the misfirings have confounded mission scientists for months.

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"Every once in awhile, a thruster will fire twice instead of once. We just don't know why it's doing it. We can't get it to happen in our simulations," said Tom Duxbury, Stardust project manager at NASA's Jet Propulsion Laboratory.

The $200 million mission should not be in jeopardy due to economical fuel use, Duxbury said.

Project engineers were studying tranmissions from Stardust to correct the glitch. They already have recent experience in patching up the ailing probe from a distance.

In January, Stardust experienced a marked improvement after months of blurry vision. By ordering the craft to heat up the optical surface, mission scientists managed to boil off an unknown contaminant on its navigation camera.

The refrigerator-sized probe regained its vision days before a near Earth flyby, which gave it a gravitational slingshot boost on its way to a rendezvous with Comet Wild-2 in 2004.

Two years after the rendezvous, Stardust should return to drop a payload of comet and interstellar dust particles in a Utah desert.

By studying what Stardust returns, scientists hope to learn if comets provided the water and organic material necessary for life to form.

Comets, possibly the oldest bodies in the solar system, could contain a record of the original material that formed the sun and planets 4.5 billion years ago.

Comet probe regains eyesight before Earth flyby
January 12, 2001
NASA's Stardust mission develops case of blurry vision
September 12, 2000
Stardust spacecraft enters 'safe' mode; transmits first image from space
March 23, 1999

Stardust
NASA's Jet Propulsion Laboratory

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