Deep Impact Findings - 2

''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

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.