Scientists surprised by comet anatomy

Findings from a recent encounter between a spacecraft and a comet have offered new insight about space rocks, surprising NASA scientists -- including a leading UW astronomer.

Stardust, a spacecraft launched in 1999, recently flew by comet Wild 2 and gathered the most detailed, high-resolution comet images ever.

"It was mind-boggling to see the diverse landscape in the first pictures from Stardust, including spires, pits and craters," said Donald Brownlee, Stardust principal investigator and UW astronomy professor, in a NASA press release earlier this month.

Brownlee said he expected Wild 2 to be "like a dirty, black, fluffy snowball."

Instead, the project's scientists found the comet had a rigid surface and was dotted with towering pinnacles, plunging craters, steep cliffs and dozens of violently spewing jets.

The team was especially surprised by the abundance and power of jets shooting particles from the comet's surface. Shooting millions of comet particles outward, the jets damaged the Stardust spacecraft as it passed 147 miles away.

"[Wild 2] may turn out to be typical of other comets, but it is unlike any other type of solar-system body," said Brownlee, who also is the lead author of one of four Stardust papers published earlier this month.

Stardust is expected to return to Earth in January 2006, offering scientists a chance to physically analyze the thousands of particles it collected during its seven-year space mission.