37th DPS Meeting, 4-9 September 2005
Session 43 Deep Impact A
Poster, Wednesday, September 7, 2005, 6:00-7:15pm, Music Foyer

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[43.18] Long-term Temporal Studies of the Coma Grain Size Distribution and Silicate Mineralogy of Comet 9P/Tempel 1 Pre- and Post-Impact

D. H. Wooden, D. E. Harker (UCSD), C. E. Woodward, M. S. Kelley (U. Minn.), Y. R. Fernandez (U. Hawaii), M. Kassis (WM Keck Observatory), P. Ehrenfreund, J.-W. Pel, A. Verhoeff, C. M. Lisse, N. Dello Russo (JHU-APL), A. T. Tokunaga (Inst. for Astronomy, Univ. of Hawaii)

We report on a lengthy campaign to study the dust of Jupiter Family (JF) comet 9P/Tempel 1 (5.5 yr orbit, ~41hr rotation period), pre- and post-impact. We report on both high spatial resolution observations with Keck+LWS pre-impact (25 May 2005 UT) and VLT+VISIR (29 May 2005 UT), and NASA IRTF photometric and spectroscopic observations spanning 29 June 2005 UT -- 27 July 2005 UT. At impact, 9P/Tempel 1 will have a distance of Delta=0.89 AU, so that on the sky 1 arc sec=843 km (cometocentric). Given the range of potential ejection velocities corresponding to canonical coma values up to the impactor speed (0.5 < v < 10 km/s), over a 15 minute time span in principle we may observe the evolution of the grain population in the coma, e.g., via fragmentation, over detectable spatial scales (0.53 < focal plane distance < 10.7 arc sec). At the NASA IRTF, our efforts are to study the coma dust properties 9P/Tempel 1 at 10 and 20 microns to investigate the temporal evolution of the grain size distribution and mineralogy in the coma using IRTF+NASA Ames' HIFOGS aperture spectrophotometry and IRTF+MIRSI images and long-slit spectra. Post-impact we expect to determine the properties of grains excavated from deeper layers of the nucleus as the (potential) jet develops following impact. We anticipate the opportunity to detect crystalline silicates from the nucleus interior, which has implications for thermal processing and radial transport of dust in the early solar nebula. By comparing pre- and post-impact observations, we investigate the co-dependence of dust grain properties and cometary activity, and the affects of parent body evolution on the dust properties of JF cometary comae.

The author(s) of this abstract have provided an email address for comments about the abstract: wooden@delphinus.arc.nasa.gov

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