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Published September 8, 1972 | public
Journal Article

Microanalysis of Materials by Backscattering Spectrometry


After its successful soft landing on the moon on 9 September 1967, Surveyor 5 transmitted back to earth signals which contained the first factual information on the chemical composition of the lunar soil. The data were obtained from the "alpha-scattering experiment" performed by a relatively simple instrument placed on the lunar soil. A radioactive source emitted alpha particles which were directed at the lunar surface. The particles were then scattered back by collisions with the constituent atoms of the lunar material and counted by suitably positioned, energy-sensitive detectors. From such measurements one can determine the mass of the collision partner and therefore identify the elements present in the soil (1, 2). These backscattering analyses agree remarkably well with the chemical analyses later made on samples of moon rocks returned to earth by the Apollo 11 and Apollo 12 missions (3).

Additional Information

© 1972 American Association for the Advancement of Science. We are grateful to J. Feng for making estimates of the accuracy with which compositions can be measured by this method. We also thank the many colleagues who have drawn our attention to preprints and unpublished data or who have offered advice and comments. In particular, we thank the research groups at Aarhus University, Aarhus. Denmark; Bell Telephone Laboratories, Murray Hill, New Jersey; California Institute of Technology; Chalk River Nuclear Laboratories; Hughes Research Laboratories, Malibu, California; Kernforschungs-zentrum. Karlsruhe, Germany; North American Rockwell Science Center, Thousand Oaks, California; Research Institute for Physics, Stockholm, Sweden; and Sandia Laboratories, Albuquerque, New Mexico. Work supported in part by the Office of Naval Research and the National Aeronautics and Space Administration. Langley Research Center.

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