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Lunar elemental analysis obtained from the Apollo gamma-ray and X-ray remote sensing experimentGamma-ray and X-ray spectrometers carried in the service modules of the Apollo 15 and Apollo 16 spacecraft were employed for compositional mapping of the lunar surface. The measurements involved the observation of the intensity and characteristic energy distribution of gamma rays and X-rays emitted from the lunar surface. A large-scale compositional map of over 10 percent of the lunar surface was obtained from an analysis of the observed spectra. The objective of the X-ray experiment was to measure the K spectral lines from Mg, Al, and Si. Spectra were obtained and the data were reduced to Al/Si and Mg/Si intensity ratios and ultimately to chemical ratios. Analyses of the results have indicated (1) that the Al/Si ratios are highest in the lunar highlands and considerably lower in the maria, and (2) that the Mg/Si concentrations generally show the opposite relationship. The objective of the gamma-ray experiment was to measure the natural and cosmic-ray-induced activity emission spectrum. At this time, the elemental abundances for Th, U, K, Fe, Ti, Si, and O have been determined over a number of major lunar regions. Regions of relatively high natural radioactivity were found in the Mare Imbrium and Oceanus Procellarum regions.
Document ID
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Trombka, J. I.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Arnold, J. R.
(Calif. Univ. La Jolla, United States)
Adler, I.
(Maryland Univ. College Park, United States)
Metzger, A. E.
Reedy, R. C.
Date Acquired
August 9, 2013
Publication Date
January 1, 1977
Publication Information
Publication: The Soviet-Am. Conf. on Cosmochem. of the Moon and Planets, pt. 1
Subject Category
Accession Number
Distribution Limits
Work of the US Gov. Public Use Permitted.
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