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The distribution of water ice in the interior of Comet Tempel 1 |
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| Authors: | Jessica M Sunshine Olivier Groussin Michael F A'Hearn Tony L Farnham |
| Institution: | a Department of Astronomy, University of Maryland, Computer and Space Sciences Building, College Park, MD 20742, USA b Laboratoire d'Astrophysique de Marseille, Observatoire Astronomique de Marseille-Provence, Traverse du Siphon - Les 3 Lucs, BP8-13376 Marseille Cedex 12, France c Department of Geological Sciences, Brown University, Box 1846, Providence, RI 02912, USA d Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109, USA |
| Abstract: | The Deep Impact flyby spacecraft includes a 1.05 to 4.8 μm infrared (IR) spectrometer. Although ice was not observed on the surface in the impact region, strong absorptions near 3 μm due to water ice are detected in IR measurements of the ejecta from the impact event. Absorptions from water ice occur throughout the IR dataset beginning three seconds after impact through the end of observations, ∼45 min after impact. Spatially and temporally resolved IR spectra of the ejecta are analyzed in conjunction with laboratory impact experiments. The results imply an internal stratigraphy for Tempel 1 consisting of devolatilized materials transitioning to unaltered components at a depth of approximately one meter. At greater depths, which are thermally isolated from the surface, water ice is present. Up to depths of 10 to 20 m, the maximum depths excavated by the impact, these pristine materials consist of very fine grained (∼1±1 μm) water ice particles, which are free from refractory impurities. |
| Keywords: | Comet Tempel-1 Comets composition Interiors Spectroscopy Infrared observations |
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