July 5, 2005
NO WONDER MOST AMERICANS THINK WE'VE ALREADY DEPLOYED SDI:
Comet Show Leaves NASA Speechless: The debris field kicked up by the collision is so large, it will take days to glean a clear image. (Thomas H. Maugh II, July 5, 2005, LA Times)
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.Posted by Orrin Judd at July 5, 2005 6:36 AM
That suggests that the 820-pound impactor, which struck the surface of the comet at a speed of 6.3 miles per second, burrowed into a powdery layer in the nucleus before encountering a solid surface of ice or rock below it, Schultz said.
"We are getting an enormous wealth of data even though we can't yet see the actual impact point," he said.
Late Monday, researchers from the University of Pennsylvania and University College London said ultraviolet observations from NASA's Swift satellite showed that the impactor struck a solid structure beneath the powdery surface layer.
Although researchers are analyzing the spectra, "We don't know exactly what we kicked up yet," said astronomer Keith Mason of University College London.
Images of the impact taken by the mother ship clearly show the shadow of the debris column spreading across the surface of the nucleus.
Initial imaging with Deep Impact's infrared spectrometer also showed big changes in the composition of the comet's corona as the debris from the impact was ejected, Mason said.
There are several unidentified materials in the spectra, strong evidence that the interior of the comet is different from the surface, he said.
Telescopes on the ground reported changes in the abundance of gases observed in the comet's corona, especially a large increase in water vapor.
Researchers believe that comets represent a kind of time capsule of the materials that were present when the solar system was created 4.6 million years ago.
With the $333-million Deep Impact mission, launched from Florida on Jan. 12, researchers hoped to intercept a comet for the first time and determine what lay under its surface. Analysis of those materials should reveal what kinds of compounds were used in the formation of Earth and other planets.
But the mission was an unusually complex one that researchers compared to hitting one high-speed bullet with another bullet, while observing the impact with a third bullet.
Deep Impact traveled more than 280 million miles in six months before inserting the impactor into the comet's orbit, where it was overtaken at a speed of 23,000 mph.