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Identification of lunar rock types and search for polar ice by gamma ray spectroscopyThis paper examines the possibility of mapping the surface composition of the moon from an orbiting spin-stabilized spacecraft, using gamma ray spectroscopy and a cooled germanium solid-state device as a detector. A design for accommodating the germanium detector gamma ray spectrometer was devised, and the detection sensitivity was applied to typical lunar-rock compositions. For sets comprising nine highland and 16 mare types, the most useful elements were found to be Mg, Al, K, Ti, Fe, U, and Th. An analysis of the expected instrument response to the gamma ray and neutron fluxes of water ice indicated that a neutron mode added to the spectrometer will be more sensitive than the gamma ray mode to the possible presence of polar ice. It was calculated that, with a pair of selected neutron absorbers and a model which provides that 2.5 percent of the area above 75-deg latitude is occupied by trapping sites, the instrument will provide a 1-yr mission detection limit of 0.056 percent H2O by weight for each polar region.
Document ID
19900035900
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Metzger, Albert E.
(JPL Pasadena, CA, United States)
Drake, Darrell M.
(Los Alamos National Laboratory NM, United States)
Date Acquired
August 14, 2013
Publication Date
January 10, 1990
Publication Information
Publication: Journal of Geophysical Research
Volume: 95
ISSN: 0148-0227
Subject Category
Lunar And Planetary Exploration
Accession Number
90A22955
Distribution Limits
Public
Copyright
Other

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