NASA’s Deep Impact spacecraft lived up to its name early Monday when it slammed into a comet with such force that the resulting blast of icy debris stunned scientists with its size and brightness.With the flyby stage of the two-part spacecraft watching from a safe distance, an 820-pound, copper-core “impactor” craft smashed into the nucleus of comet Tempel 1 at 23,000 miles per hour, sending a huge, bright spray of debris into space. “The impact was spectacular,” said Dr Michael A’Hearn of the University of Maryland, the project’s principal scientist. “It was much brighter than I expected.”Culminating a six-month journey to a point 83 million miles from Earth, the impactor guided itself to a sunlit point near the bottom of the elongated comet where they collided with a force equal to 4.5 tons of dynamite at 1.52 a.m. Eastern time. “We’ve had a far bigger explosion than we anticipated,” said Dr Donald Yeomans, a mission scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California, which controlled the flight. Depending upon the composition of the comet, scientists speculated that the impact could excavate a crater as large as a sports stadium or as small as a house. Dr A’Hearn told an early morning news conference that the blast was so bright that initial images did not reveal the size and depth of the impact crater. This hopefully will be revealed in later images that will have been recorded by the flyby spacecraft when they are received and processed on Earth, he said.“Obviously, it was a very big impact,” he said. “Presumably, we have a large crater in one of those images that hasn’t played back yet.” A quick look at data streaming down to Earth indicates the best is yet to come, said Dr A’Hearn. The impact was observed by scores of telescopes at ground observatories, as well as NASA’s Hubble, Spitzer and Chandra observatories in Earth orbit, and other spacecraft. Voyage into deep space
