[meteorite-list] NASA's Spitzer and Deep Impact Build Recipe for Comet Soup

[Ron Baalke]

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

Whitney Clavin (818) 354-4673		
Jet Propulsion Laboratory, Pasadena, Calif.	

News Release 2005-144			    Sept. 7, 2005

NASA's Spitzer and Deep Impact Build Recipe for Comet Soup

When Deep Impact smashed into comet Tempel 1 on July 4, 
2005, it released the ingredients of our solar system's 
primordial "soup." Now, astronomers using data from 
NASA's Spitzer Space Telescope and Deep Impact have 
analyzed that soup and begun to come up with a recipe 
for what makes planets, comets and other bodies in our 
solar system. 

"The Deep Impact experiment worked," said Dr. Carey 
Lisse of Johns Hopkins University's Applied Physics 
Laboratory, Laurel, Md. "We are assembling a list of 
comet ingredients that will be used by other scientists 
for years to come." Lisse is the team leader for Spitzer's 
observations of Tempel 1. He presented his findings this 
week at the 37th annual meeting of the Division of 
Planetary Sciences in Cambridge, England.

Spitzer watched the Deep Impact encounter from its lofty 
perch in space. It trained its infrared spectrograph on 
comet Tempel 1, observing closely the cloud of material 
that was ejected when Deep Impact's probe plunged below 
the comet's surface. Astronomers are still studying the 
Spitzer data, but so far they have spotted the signatures 
of a handful of ingredients, essentially the meat of comet 
soup. 

These solid ingredients include many standard comet 
components, such as silicates, or sand. And like any good 
recipe, there are also surprise ingredients, such as clay 
and chemicals in seashells called carbonates. These 
compounds were unexpected because they are thought to 
require liquid water to form. 

"How did clay and carbonates form in frozen comets?" asked 
Lisse. "We don't know, but their presence may imply that 
the primordial solar system was thoroughly mixed together, 
allowing material formed near the Sun where water is 
liquid, and frozen material from out by Uranus and Neptune, 
to be included in the same body." 
 
Also found were chemicals never seen before in comets, such 
as iron-bearing compounds and aromatic hydrocarbons, found 
in barbecue pits and automobile exhaust on Earth. 

The silicates spotted by Spitzer are crystallized grains 
even smaller than sand, like crushed gems. One of these 
silicates is a mineral called olivine, found on the 
glimmering shores of Hawaii's Green Sands Beach.

Planets, comets and asteroids were all born out of a thick 
soup of chemicals that surrounded our young Sun about 4.5 
billion years ago. Because comets formed in the outer, 
chilly regions of our solar system, some of this early 
planetary material is still frozen inside them.

Having this new grocery list of comet ingredients means 
theoreticians can begin testing their models of planet 
formation. By plugging the chemicals into their formulas, 
they can assess what kinds of planets come out the other 
end. 

"Now, we can stop guessing at what's inside comets," said 
Dr. Mike A'Hearn, principal investigator for the Deep 
Impact mission, University of Maryland, College Park. 
"This information is invaluable for piecing together how 
our own planets as well as other distant worlds may have 
formed." 

NASA's Jet Propulsion Laboratory, Pasadena, Calif., 
manages the Spitzer Space Telescope mission for NASA's 
Science Mission Directorate, Washington. Science 
operations are conducted at the Spitzer Science Center 
at Caltech. The University of Maryland, College Park, 
conducted the overall mission management for Deep Impact, 
and JPL handled project management for the mission for 
NASA's Science Mission Directorate.

For more graphics and more information about Spitzer, 
visit 

http://www.spitzer.caltech.edu/Media/index.shtml .

For more information about Deep Impact, visit 

http://deepimpact.jpl.nasa.gov or 

http://www.nasa.gov/deepimpact .

For more information about NASA, visit 

http://www.nasa.gov/home/ .

      -end-