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Near-Infrared Spectrophotometry of Phobos and DeimosWe have observed the leading and trailing hemispheres of Phobos from 1.65 to 3.5 micrometers and Deimos from 1.65 to 3.12 micrometers near opposition. We find the trailing hemisphere of Phobos to be brighter than its leading hemisphere by 0.24 plus or minus 0.06 magnitude at 1.65 micrometers and brighter than Deimos by 0.98 plus or minus 0.07 magnitude at 1.65 micrometers. We see no difference larger than observational uncertainties in spectral slope between the leading and trailing hemispheres when the spectra are normalized to 1.65 micrometers. We find no 3-micrometer absorption feature due to hydrated minerals on either hemisphere to a level of approximately 5-10% on Phobos and approximately 20% on Deimos. When the infrared data are joined to visible and nearby data obtained by previous workers, our data suggest the leading (Stickney-dominated) side of Phobos is best matched by T-class asteroids. The spectral slope of the trailing side of Phobos and leading side of Deimos are bracketed by the D-class asteroids. The best laboratory spectral matches to these parts of Phobos are mature lunar soils and heated carbonaceous chondrites. The lack of 3-micrometer absorption features on either side of Phobos argues against the presence of a large interior reservoir of water ice according to current models of Phobos' interior.
Document ID
20020045311
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rivkin, A. S.
(Arizona Univ. Tucson, AZ United States)
Brown, R. H.
(Arizona Univ. Tucson, AZ United States)
Trilling, D. E.
(Pennsylvania Univ. Philadelphia, PA United States)
Bell, J. F., III
(Cornell Univ. Ithaca, NY United States)
Plassmann, J. H.
(Arizona Univ. Tucson, AZ United States)
Date Acquired
August 20, 2013
Publication Date
January 1, 2002
Publication Information
Publication: Icarus
Publisher: Elsevier Science
Volume: 156
ISSN: 0019-1035
Subject Category
Lunar And Planetary Science And Exploration
Funding Number(s)
CONTRACT_GRANT: NAG5-10328
Distribution Limits
Public
Copyright
Other

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