What a smashing article! :^)Excerpt from The Dallas Morning News:
NASA spacecraft expected to collide with comet on July 4
11:01 PM CST on Saturday, December 18, 2004
In mid-January, NASA plans to launch its Deep Impact spacecraft from Florida. If all goes as planned, on the Fourth of July it will run head-on into a comet 83 million miles from Earth – on purpose.
"We expect to provide some great fireworks," said Richard Grammier, project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif.
The celestial crackup could dig a crater big enough to swallow Texas Stadium. Scientists say it will provide their first-ever glimpse inside the heart of a comet, those icy visitors from the edge of the solar system.
Because comets spend most of their time in the deep freeze of outer space, only occasionally swinging past the sun in a fiery blaze, their interiors act as time capsules – preserving chemical records of the solar system's early days.
"These are literally the leftover building blocks of our solar system," said Thomas Morgan, Deep Impact program scientist at NASA headquarters in Washington, D.C.
By blasting a hole into Comet Tempel 1, scientists hope to scrutinize the exposed interior of a typical comet.
The $330 million mission actually packs two spacecraft in one: the washing-machine-sized, copper-plated "impactor" and the larger mothership that will watch the collision from a distance. Both carry cameras to capture the most close-up photos of a comet ever taken.
Deep Impact got its name long before the movie of the same name, and scientists don't expect any Hollywood overtones. Smashing into the spacecraft will alter the comet's orbit imperceptibly, but Tempel 1 will never hit Earth as the rogue comet threatened in the movie, said the mission's principal investigator, Michael A'Hearn of the University of Maryland.
Deep Impact's journey is scheduled to begin just after noon on Jan. 12, when it should soar into space from Cape Canaveral aboard a Delta rocket. If weather or other problems arise, mission controllers have until Jan. 28 to get it off the ground. (After that, Tempel 1 will move out of range, and NASA would have to pick another comet for the mission.)
Tempel 1 is the target precisely because it is so ordinary, said Dr. A'Hearn.
Its heart, or nucleus, is a chunk of ice and rock several miles across. When it comes closer to the sun every six years, the sun's warmth begins to vaporize the ice, causing the comet to spray a dramatic tail of gas and dust. The tails make comets some of the most dramatic celestial sights.
Tempel 1 is neither as well known as Halley's comet nor as bright as Comet Hale-Bopp in 1997. But it's in the right place at the right time for Deep Impact to run into it, Dr. A'Hearn said at a NASA news briefing.
After traveling nearly 270 million miles through space, Deep Impact's mothership will release the smaller craft, letting it drift just ahead of the comet. Tempel 1 will then barrel into the impactor at 23,000 miles per hour, marking the first time a spacecraft has ever touched the surface of a comet.
The crash could send a cone of pulverized rock and ice spraying outward, then falling back to the comet's surface. Or it could create long cracks throughout the nucleus. Or it might just compress the surface material, forming a small dent.
But Dr. A'Hearn is hoping for a full-fledged crater that could engulf a football field.
Meanwhile, the mothership will fly alongside, taking pictures with the most powerful telescope ever launched into deep space. It will radio data back to Earth, where scientists will be waiting to see what happened.
The comet might brighten momentarily at the time of impact, a change that could be visible even to amateur astronomers. Telescopes around the world, including some at McDonald Observatory in West Texas, will also be watching the collision and its aftermath.
Click HERE for the rest of the article.
E-mail awitze@dallasnews.com
Go here to get an ID and Password to read the rest of this article: BugMeNot
Here is the URL to enter for this source: http://www.dallasnews.com/
If the first ID and password don't work for you, click on the button marked "This Login Didn't Work" for another one.