After a journey of 3.5 billion miles the craft passed 110 miles from the nucleus, colliding with dust particles in the comet's halo, or coma. The team converted the collision data into sound, yielding an audio track reminiscent of hailstones intermittently pummeling a tin roof.
During a briefing Tuesday afternoon, the team unveiled the photos of greatest interest – images taken during the flyby's closest approach to the comet.
Among the initial observations:
• In 2005, Deep Impact captured a sharply scarped plateau-like feature roughly two miles long and about 1,300 feet across. During this pass, the plateau showed significant signs of erosion – material lost during heating that liberated ices and gas during the comet's closest approach to the sun.
The plateau is likely a downhill flow of dust triggered by an outburst of gas at some point in the comet's past, Dr. Veverka says.
• 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.
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.