Comet Tempel 1: Stardust photos reveal crater that 'partly healed itself'
Photos from the Stardust-NExT rendezvous with comet Tempel 1 are streaming in. Some show a crater that was created by a different NASA mission but never sucessfully photographed.
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• The Deep Impact crater was barely discernible in the images the team released. But Brown University's Pete Schultz, a member of the Deep Impact and Stardust-NExT science teams, said the crater was readily apparent in stereo images as well as in new shots of the nucleus with in oblique sunlight.Skip to next paragraph
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The subdued crater is roughly 500 feet across and has a discernible mound in the middle, evidence Dr. Shultz says, that much of the ejecta the Deep Impact collision kicked up fell back onto the comet.
"The crater partly healed itself," he says.
• Views of never-seen-before features on portions of the comet Deep Impact didn't image "are simply amazing," Veverka says. The surface displays extensive layering, pits, and craters – clues he and his colleagues will sort through to uncover the geological history of Tempel 1 and the forces beyond solar heating that shaped it.
• A dust analyzer uncovered evidence for carbon and carbon bound with nitrogen – chemicals and chemical constructs that, in part, form the scaffolding for biologically important molecules, noted Donald Brownlee, another team member and a researcher at the University of Washington in Seattle.
The dusty coma surrounding the comet is "a very dramatic environment," he said, in which material is released from the nucleus "in bursts and puffs of clods and ice.
Stardust-NExT's initial objective when it launched in 1999 was to visit comet Wild 2 and return dust samples to Earth that the craft collected. The cost of the mission was on the order of $200 million.
But once it had dropped off its precious cargo – material that scientists are still studying – in 2006, the craft was in perfect health. At that point, Veverka proposed sending it back to visit Tempel 1 to follow up on Deep Impact's observations for an additional $29 million.
From all indications, the craft still is in great shape, notes Tim Larsen, the Stardust-NExT project manager at NASA's Jet Propulsion Laboratory in Pasadena., Calif. He says it will continue to take pictures of the comet for another week or two as the distance between the two grows.