NASA's Deep Impact spacecraft completed a flawless journey to oblivion, slamming into an onrushing comet to vaporize itself in an Independence Day blaze of glory.
Scientists and engineers at NASA's Jet Propulsion Laboratory cheered as spectacular images taken by a flyby spacecraft that was positioned nearby confirmed that the "impactor" had scored a perfect bull's-eye. It smacked into comet Tempel 1 at its lower edge, spewing a column of debris that lit up the heavens.
By assessing the shape and size of the crater and chemically analyzing the debris that belched from it, scientists hope to gain new insights into the composition of the solar system at the time of its formation 4.5 billion years ago.
The flyby spacecraft, stationed 5,350 miles from the comet at impact, used two cameras and an infrared spectrometer to record the event and its aftermath for 13 minutes.
In addition, the impactor carried a camera that sent back crystal-clear pictures of ridgelike features, apparent craters and sinkholes, and other pockmarks that grew to dominate its field of vision as the spacecraft closed on the comet at 6.4 miles per second. The last image was sent only three seconds before the crash.
Besides the spacecraft images, a network of about 60 Earth- and space-based telescopes and thousands of amateur astronomers were standing by to participate in the first globally coordinated effort to watch an object dig a crater in a comet. Early results showed that the impact had caused the comet to brighten fivefold.
Comets, composed mostly of dust and ice, periodically migrate from deep space, their outer layers burning away as they approach the sun. To get to the ancient material within, Deep Impact needed to punch through the boiling crust.
-- Guy Gugliotta