The collision of a probe from NASA's Deep Impact spacecraft with comet Tempel 1 blew a plume of debris thousands of miles into space and provided a spectacular first glimpse of the insides of a comet -- ancient bodies that may hold the key to the origins of the solar system -- scientists said Monday.
The collision -- a carefully orchestrated dance at more than 20,000 mph intended to expose the comet's interior -- was much larger than anyone had expected, said researchers at the Jet Propulsion Laboratory in La Canada Flintridge.
For The Record
Los Angeles Times Wednesday July 06, 2005 Home Edition Main News Part A Page 2 National Desk 1 inches; 33 words Type of Material: Correction
Solar system age -- An article in Tuesday's Section A about NASA's Deep Impact spacecraft said the solar system was created 4.6 million years ago. It should have said 4.6 billion years ago.
Telescopes on Earth showed that the light from the comet increased fivefold in the aftermath of the collision at 10:52 p.m. PDT Sunday before slowly fading over several hours.
"I was trying to think how to describe this, but I am just plain speechless," said Andrew Dantzler, the director of NASA's solar system program.
The eruption of debris from the impact was so large that principal investigator Michael A'Hearn of the University of Maryland said it could take scientists a week or more to tease out a reliable image of the impact crater from behind the smokescreen of dust and gas that obscured the comet's surface.
By Monday morning, project scientists had had little time to analyze the information and images that were flooding into their databanks, but what they saw was drawing back the veil from the composition and structure of comets.
The high-resolution images taken before the impact show a comet surface substantially different from that of previously observed comets, such as Borrelly and Wild-2. Although the surface appears white because of reflected sunlight, it is actually jet-black. Small bright patches on the surface are most likely steep slopes that reflect more sunlight than the surrounding landscape.
The surface of Tempel 1 is littered with what appear to be impact craters -- the first time such craters have been observed on a comet surface, A'Hearn said.
There is also a large, flat area that curves around the surface of the nucleus. The only flat area previously observed was a plateau on Borrelly.
"We don't understand the physics of what produces those flat surfaces," A'Hearn said. Tempel 1's "orbital history is very similar to Borrelly's, but the surface looks totally different."
The impact surprised researchers in both its magnitude and its structure. The sequence of images from the Deep Impact mother ship shows a small flash, a slight delay and then a larger flash, said Peter Schultz of Brown University, a project co-investigator.
