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Deep Impact Findings - 2
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''Your paradigm is so intrinsic to your mental process that you are hardly aware of its existence, until you try to communicate with someone with a different paradigm.'' - Donella A. Meadows
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Harvard-Smithsonian Center for Astrophysics Press Release No.: 05-23, July 8,
2005,
http://www.cfa.harvard.edu/press/pr0523.html. Scientists report seeing only
weak emission from water vapor and a host of other gases that were expected to
erupt from the impact site. Short-period comets like Tempel 1 have been baked
repeatedly by the sun during their passages through the inner solar system. The
effects of that heat are estimated to extend more than three feet beneath the
surface of the nucleus. But the Deep Impact indicates that these effects could
be much deeper. And theories about the volatile layers below the surface of
short-period comets will have to be revised. Post-impact measurements showed the
comet was releasing only about 550 pounds of water per second – an emission rate
very similar to pre-impact values, and less than seen during natural outbursts
in the weeks before the impact. Related gas production rates (such as hydrogen
cyanide) remained so low that only an upper limit on the total could be
measured. Scientists remained hopeful that major outgassing from the impact site
might still occur in the coming weeks.
NASA/JPL/U.Maryland RELEASE: 05-177,
http://www.nasa.gov/deepimpact. Data from Deep Impact's instruments indicate
an immense cloud of fine powdery material was released when the probe slammed
into the nucleus of comet Tempel 1 at 6.3 miles per second. The cloud indicated
the comet is covered in the powdery stuff. The opacity of the plume the impactor
created and the light it gave off suggest the dust excavated from the
comet's surface was extremely fine, more like talcum powder than beach sand; and
that the surface is definitely not an ice cube. Scientists are still analyzing
the data to determine the exact size of the crater. They say the crater was at
the large end of original expectations, which was from 50 to 250 meters. [tvf:
“Still analyzing” means they probably haven’t seen the crater yet, but just the
ejecta layer from the crater, which is naturally considerably larger.]
ESO Press Release 19/05: 14 July 2005,
http://www.hq.eso.org/outreach/press-rel/pr-2005/pr-19-05.html. From the
current analysis, it appears most likely that the impactor did not create a
large new zone of activity and may have failed to liberate a large quantity of
pristine material from beneath the surface. The appearance of a new plume-like
structure diffused away in the days following impact, with the comet taking
again the appearance it had before the impact. The same jets were visible before
and after impact, demonstrating that the comet activity survived widely
unaffected by the spacecraft crash. Normal gas activity and activity from a
pre-existing “active” region are still being measured. Spectropolarimetric
observations have confirmed the surface of the comet to be rather evolved, and
found that the dust is not coming from beneath the surface.
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