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Originally published in Science Express on 2 February 2006
Science 10 March 2006:
Vol. 311. no. 5766, pp. 1453 - 1455
DOI: 10.1126/science.1123632
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Reports

Exposed Water Ice Deposits on the Surface of Comet 9P/Tempel 1

J. M. Sunshine,1* M. F. A'Hearn,2 O. Groussin,2 J.-Y. Li,2 M. J. S. Belton,3 W. A. Delamere,4 J. Kissel,5 K. P. Klaasen,6 L. A. McFadden,2 K. J. Meech,7 H. J. Melosh,8 P. H. Schultz,9 P. C. Thomas,10 J. Veverka,10 D. K. Yeomans,6 I. C. Busko,11 M. Desnoyer,10 T. L. Farnham,2 L. M. Feaga,2 D. L. Hampton,12 D. J. Lindler,13 C. M. Lisse,14 D. D. Wellnitz2

We report the direct detection of solid water ice deposits exposed on the surface of comet 9P/Tempel 1, as observed by the Deep Impact mission. Three anomalously colored areas are shown to include water ice on the basis of their near-infrared spectra, which include diagnostic water ice absorptions at wavelengths of 1.5 and 2.0 micrometers. These absorptions are well modeled as a mixture of nearby non-ice regions and 3 to 6% water ice particles 10 to 50 micrometers in diameter. These particle sizes are larger than those ejected during the impact experiment, which suggests that the surface deposits are loose aggregates. The total area of exposed water ice is substantially less than that required to support the observed ambient outgassing from the comet, which likely has additional source regions below the surface.

1 Science Applications International Corporation (SAIC), Chantilly, VA 20151, USA.
2 University of Maryland, College Park, MD 20742, USA.
3 Belton Space Exploration Initiatives, Tucson, AZ 85716, USA.
4 Delamere Support Services, Boulder, CO 80301, USA.
5 Max Planck Institute for Solar System Research, Katlenburg-Lindau D37191, Germany.
6 Jet Propulsion Laboratory, Pasadena, CA 91109, USA.
7 University of Hawaii, Honolulu, HI 96822, USA.
8 University of Arizona, Tucson, AZ 85721, USA.
9 Brown University, Providence, RI 02412, USA.
10 Cornell University, Ithaca, NY 14853, USA.
11 Space Telescope Science Institute, Baltimore, MD 21218, USA.
12 Ball Aerospace & Technology Corporation, Boulder, CO 80301, USA.
13 Sigma Scientific, Greenbelt, MD 20771, USA.
14 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA.

* To whom correspondence should be addressed. E-mail: sunshinej{at}saic.com

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Spitzer Spectral Observations of the Deep Impact Ejecta.
C. M. Lisse, J. VanCleve, A. C. Adams, M. F. A'Hearn, Y. R. Fernandez, T. L. Farnham, L. Armus, C. J. Grillmair, J. Ingalls, M. J. S. Belton, et al. (2006)
Science 313, 635-640
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