Ceilidh

Michael Zey
1 and the Deep Impact probe on July 4, 2005 and in order to put the projectile in the right place for the encounter, Deep Impact must be launched by January 28. Deep Impact's flyby spacecraft and smaller impactor spacecraft are seen approaching Tempel 1 in this artist's rendering. Photo by Nasa/Reuters

Mon Jan 10,12:48 PM ET
By Irene Klotz

MELBOURNE, Fla. (Reuters) - On a quest for the frozen remains of the solar system's formation, NASA (news - web sites) is preparing to launch its Deep Impact probe that will smash a hole in a comet 82 million miles from Earth.


Reuters Photo


AP Photo  
Slideshow: 'Deep Impact' Comet Probe

Defend Yourself
Stop and destroy PC scourges, and kill spyware with an arsenal of tools.  

NASA plans to stage the collision of Comet Tempel 1 and the Deep Impact probe on July 4, and in order to put the projectile in the right place for the encounter, Deep Impact must be launched by Jan. 28.


The earliest NASA plans to attempt the launch is at 1:48 p.m. EST on Wednesday from Florida's Cape Canaveral Air Force Station.


Scientists don't know exactly what will happen when the comet barrels into Deep Impact's 820-pound copper-tipped projectile at about 23,000 mph. The speeding comet is expected to be 82 million miles from Earth when the collision occurs.


They expect, however, a giant explosion -- equivalent to the energy released by 4 1/2 tons of dynamite -- and a gouge into the comet's surface that could be as big as a football field and as deep as a 14-story building.


"We put the impactor in the comet's path so that the comet overtakes it," said Rick Grammier, mission project manager at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "It's like standing in the middle of the road with a semi-truck bearing down on you."


Added lead scientist and University of Maryland astronomer Michael A'Hearn, "There is an outside chance that we could break the comet. We don't think that will happen."


The comet is quite a bit larger than the projectile. Tempel 1 has an approximate radius of 1.9 miles, while the impactor spacecraft is about the size of a living room coffee table.


While the collision is expected to obliterate the impactor, two telescopes aboard Deep Impact's mother ship will monitor the crash, then fly by the comet for close inspections.


By probing below the comet's surface, scientists hope to learn about the conditions that existed more than 4 billion year ago when the solar system was formed.


Comets are believed to contain frozen remains from the solar system's early years.


"My interest in comets all along has been trying to understand the chemical composition," A'Hearn said.


"What we see coming out of comets as gas and dust is stuff that has been modified because it is very near the surface," he added. "Every time the comet goes around the sun, the surface gets heated. So there have been changes in the surface layers ... What I really want to do is figure out how different the surface is from what's inside."


Astronomers are organizing a world-wide comet watch during the mission to collect as much information as possible during the encounter. NASA also plans to train the Hubble, Spitzer and Chandra space observatories on the comet during and immediately after the collision.

PHOTO: On a quest for the frozen remains of the solar system's formation, NASA (news - web sites) is preparing to launch its Deep Impact probe that will smash a hole in a comet 82 million miles from Earth. NASA plans to stage the collision of Comet Tempel 1 and the Deep Impact probe on July 4, 2005 and in order to put the projectile in the right place for the encounter, Deep Impact must be launched by January 28. Deep Impact's flyby spacecraft and smaller impactor spacecraft are seen approaching Tempel 1 in this artist's rendering. Photo by Nasa/Reuters