AAS 207th Meeting, 8-12 January 2006
Session 189 Results from the Deep Impact Mission
Oral, Thursday, 10:00-11:30am, January 12, 2006, Ballroom/Salon 2

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[189.07] Temporal Evolution of the Dust Ejected from Comet 9P/Tempel 1 After the Deep Impact Event

D.E. Harker (University of California, San Diego), C.E. Woodward (University of Minnesota), D.H. Wooden (NASA Ames Research Center), S. Fisher, C. Trujillo (Gemini Observatory)

The Deep Impact mission encountered the Jupiter-family comet 9P/Tempel 1 (9P) on 4 July 2005 UT (A'Hearn et al. 2005, Science, 310, 258). The impactor penetrated through the highly processed nucleus surface layers subsequently ejecting large amounts of cometary material into the coma. Pristine materials (i.e., not subject to intensive surface weathering) were excavated providing a possible glimpse into the origins and evolution of materials in the early solar nebula during the epoch of planet formation. Prior to the Deep Impact event, dust released from 9P was comprised mostly of large, processed surface grains of amorphous olivine. After impact, new grains including amorphous olivine, amorphous carbon, and crystalline olivine were clearly detected (Harker, Woodward, Wooden, 2005, Science, 310, 278).

We report on our time series (7 minute time cadence) of GEMINI-N (+MICHELLE) 10~\mum spectrophotometric observations obtained during the impact event. We will present our 24 spectra (extracted from a 0.6 \times 1.0\prime\prime aperture centered on the nucleus) obtained on the night of impact. Six of these spectra were obtained during our last hour of observation on the night of impact, when the slit was rotated to PA~= 225\circ to align along the fan of ejected material. We will also present spectra offset 1.0{\prime\prime} from the nucleus (i.e., the peak of the observed surface brightness distribution) to investigate potential spatial changes in grain properties, including possible fragmentation, as material traveled away from the nucleus (1{\prime\prime} = 692~km).

This work is supported by grants from the NSF (AST03-07466) and the NASA Planetary Astronomy Program (RTOP 344-32-21-04).

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