Using the EPOXI Mission to Measure the Dust Heterogeneity of Comet 103P/Hartley

Kelley, Michael S.; Harker, D. E.; Woodward, C. E.; Licandro, J.; DIXI Team
Bibliographical reference

American Astronomical Society, AAS Meeting #217, #306.06; Bulletin of the American Astronomical Society, Vol. 43, 2011

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1
2011
Number of authors
5
IAC number of authors
1
Citations
0
Refereed citations
0
Description
The Deep Impact spacecraft will fly by comet 103P/Hartley on 4 Nov 2010 with a targeted closest approach distance of 700 km providing better than 50 m/pixel spatial resolution at the nucleus. In addition, comet 103P will fly by the Earth in October 2010 with a closest approach distance of 0.12 AU providing better than 100 km/arcsec resolution to Earth-based observers. Taking advantage of both flybys will help us connect nucleus geology observed by Deep Impact with coma morphology and composition, as measured by Deep Impact and Earth-bound telescopes. Because the Deep Impact spacecraft will only provide limited information on the composition of the dust coma, ground-based mid-infrared observations of comet 103P become especially important. Comet dust composition varies greatly from comet-to-comet. For example, comae range from the silicate rich comet C/1995 O1 (Hale-Bopp) (Harker et al. 2002, ApJ, 580) to the more moderate silicate composition of comet C/2002 V1 (NEAT) (Ootsubo et al. 2007, P&SS, 55) and the apparently silicate poor comet 2P/Encke (Kelley et al. 2006, ApJ, 651). But with our close encounters with comet 103P in 2010, we have an opportunity to instead examine the heterogeneity of a single comet nucleus. We present mid-infrared spectra of comet 103P along with near-infrared spectra from the Deep Impact spacecraft. We will discuss our effort to determine if the coma of this comet is homogeneous in terms of its dust grain properties (size, shape, and composition) and its implication on the dust of comets as a whole.