The Stardust probe flew through at least two significant jets of debris during its approach to comet Wild 2 today and captured a stunning image of the comet's icy heart showing overlapping pits and depressions where material boiled off in the past. At least five active jets can be seen in the black-and-white navigation camera image, along with a huge, partially shadowed pit that would hold dozens of Rose Bowl stadiums.

Comet Wild 2 is shown in this image taken by the Stardust navigation camera during the spacecraft's closest approach to the comet today. The photo was taken within a distance of 500 kilometers (about 311 miles) of the comet's nucleus with a 10-millisecond exposure. Credit: NASA/JPL

While dusty material blowing away from the comet is optically thin, project manager Tom Duxbury said an astronaut hitching a ride on the Stardust probe would have been ripped to shreds as the spacecraft moved through the Wild 2's coma, the vast cloud of gas and dust released through sun-driven sublimation. Duxbury called it "your worst nightmare of a dust storm."

A spacesuited astronaut exposed to such debris "wouldn't exist anymore," he said. "You would have been sand blasted to little particles as fine as the dust."

But Stardust, protected by thick bumpers, survived intact as it flew within 143 miles of Wild 2's nucleus at 2:22:20 p.m. EST (1922:20 GMT) today. Signals confirming the event reached Earth at 2:44 p.m. Scientists did not expect - and did not want - to fly through any active jets of debris out of fear large particles could damage the spacecraft. No such jets were predicted, but the comet had other ideas.

"The data is just being looked at on the jets," said Don Brownlee, the principal investigator. "It certainly was surprising because we expected to see the flux increase at close approach and then decrease. What we saw was this big burst of particles, which would have terrified us and made our job much more difficult if we would have known about it ahead of time!"

Said Duxbury: "There's a saying that ignorance is bliss. And this is something I was sure glad I was ignorant of. ... There were two significant jets we barreled right through. But as we know, we're here smiling, we did survive."

Five active jets are seen coming from the comet's surface. Credit: NASA/JPL

Stardust snapped 72 pictures of Wild 2's nucleus during today's approach. All of them will be downlinked over the next day or so and some may show more detail than the single photo released today.

"These pictures are really going to open up a new window into understanding how comets actually work," Brownlee said. "Seeing those pits, you realize there's some process going on you didn't realize even existed before."

The primary goal of the mission, however, is the collection and return to Earth of dust samples blown off the comet. Instruments on board the spacecraft clearly measured the bombardment as Stardust approached, leaving no doubt millions of particles were captured by the probe's aerogel-filled collector. The collector will be stowed over the next day or so and returned to Earth in two years when Stardust flies past.

"It was a very thrilling day for us," Brownlee said. "This is a very challenging and daring mission - Stardust flying into really unknown territory, the rock and dust clouds surrounding an active comet. We have successfully collected samples from a comet and we're bringing them home for analysis in laboratories all over the world."

Video coverage for subscribers only:
   VIDEO: STARDUST SURVIVES CLOSEST APPROACH TO COMET QT
   VIDEO: FIRST IMAGES RELEASED AT NEWS CONFERENCE QT

   VIDEO: PRE-ENCOUNTER INTERVIEW WITH PROGRAM MANAGER QT
   VIDEO: MISSION PLANNER DESCRIBES STARDUST'S CHALLENGES QT
   VIDEO: DESCRIPTION OF THE STARDUST SCIENCE PROGRAM QT
   VIDEO: REPORT ON THE STARDUST SCIENCE INSTRUMENTS QT
   VIDEO: INTERVIEW EXPLAINS STARDUST'S CAMERA SYSTEM QT
   VIDEO: LEARN MORE ABOUT THE EXOTIC AEROGEL MATERIAL QT
   VIDEO: AN INTERVIEW WITH STARDUST'S NAVIGATOR QT
   VIDEO: A LOOK AHEAD TO DEEP IMPACT COMET MISSION QT

   VIDEO: OVERVIEW OF THE SEVEN-YEAR STARDUST MISSION QT
   VIDEO: ANIMATION OF STARDUST COLLECTING COMET SAMPLES QT
   VIDEO: STARDUST RETURNS TO EARTH AND PARACHUTES TO UTAH QT
   VIDEO: ENCOUNTER DETAILED BY 39-MINUTE NEWS CONFERENCE QT
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