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The spectral reflectance of water-mineral mixtures at low temperaturesLaboratory reflectance spectra in the 0.325-2.5 micron region of bound water, water-mineral mixtures, mineral grains on frost, and frost on minerals are presented. The materials used in this study are montmorillonite, kaolinite, beryl, Mauna Kea red cinder, and black charcoal. It is found that the wavelengths of bound water and bound OH absorptions do not shift appreciably with temperature and can be detected when large amounts of free water ice are present. The decrease in the visible reflectance seen in many planetary reflectance spectra containing strong water ice absorptions can be explained by water-mineral mixtures, mineral grains on frost, or frost on mineral grains. Mineral grains on frost are detectable in very small quantities (fractional areal coverage less than approximately 0.005) depending on the mineral reflectance features, while it takes a thick layer of frost (greater than approximately 1 mm) to mask a mineral below 1.4 microns, again depending on the mineral reflectance. Frost on a very dark surface (albedo about 6%) is easily seen; however, a dark mineral mixed with water could completely mask the water absorptions (shortward of 2.5 microns).
Document ID
19810048187
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Clark, R. N.
(Hawaii, University Honolulu, Hawaii; MIT, Cambridge, Mass., United States)
Date Acquired
August 11, 2013
Publication Date
April 10, 1981
Publication Information
Publication: Journal of Geophysical Research
Volume: 86
Subject Category
Lunar And Planetary Exploration
Accession Number
81A32591
Funding Number(s)
CONTRACT_GRANT: NSG-7312
CONTRACT_GRANT: NSG-7590
Distribution Limits
Public
Copyright
Other

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