Comet reveals its secrets

Comet reveals its secrets
http://physicsweb.org/articles/news/9/9/4/1

6 September 2005

The first results from the Deep Impact mission to the comet Tempel 1
have shown that the material inside the comet is different to that on
the surface. This is confirmed by data from the Rosetta spacecraft --
which is on its way to another comet -- and a host of ground-based
telescopes. The Deep Impact mission consisted of a flyby spacecraft and
an impactor - roughly the size of a washing machine - that crashed into
the comet in the outer reaches of the solar system on 4 July this year.

Comets are the "undercooked leftovers" that remained after clouds of
dust and gas condensed to form the Sun and planets some 4.5 billion
years ago. Unlike other objects in the solar system, comets have barely
changed with time and contain pristine material - such as ice, dust and
gas - from the early days of the solar system. Some scientists also
believe that comets could have carried the organic molecules needed to
start life on Earth.


See: http://physicsweb.org/articles/news/9/9/4/1

Sam Wormley wrote:
Comet reveals its secrets
http://physicsweb.org/articles/news/9/9/4/1

6 September 2005

The first results from the Deep Impact mission to the comet Tempel 1
have shown that the material inside the comet is different to that on
the surface. This is confirmed by data from the Rosetta spacecraft --
which is on its way to another comet -- and a host of ground-based
telescopes. The Deep Impact mission consisted of a flyby spacecraft and
an impactor - roughly the size of a washing machine - that crashed into
the comet in the outer reaches of the solar system on 4 July this year.

Comets are the "undercooked leftovers" that remained after clouds of
dust and gas condensed to form the Sun and planets some 4.5 billion
years ago. Unlike other objects in the solar system, comets have barely
changed with time and contain pristine material - such as ice, dust and
gas - from the early days of the solar system. Some scientists also
believe that comets could have carried the organic molecules needed to
start life on Earth.


See: http://physicsweb.org/articles/news/9/9/4/1



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/ .



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