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Alpha-Scattering Surface Analyzer

NSSDCA ID: 1967-112A-02

Mission Name: Surveyor 6
Principal Investigator:Prof. Anthony L. Turkevich


The alpha-scattering surface analyzer was designed to measure directly the abundances of the major elements of the lunar surface. The instrumentation consisted of an alpha source (curium 242) collimated to irradiate a 10-cm-diameter opening in the bottom of the instrument where the sample was located and two parallel but independent charged particle detector systems. One system, containing two sensors, detected the energy spectra of the alpha particles scattered from the lunar surface, and the other, containing four sensors, detected energy spectra of the protons produced via reactions (alpha and protons) in the surface material. Each detector assembly was connected to a pulse height analyzer. A digital electronics package, located in a compartment on the spacecraft, continuously telemetered signals to earth whenever the experiment was operating. The spectra contained quantitative information on all major elements in the samples except for hydrogen, helium, and lithium. Curium collected on the collimator films and was scattered by the gold plating on the inside bottom of the sensor head. This resulted in a gradually increasing background and reduction of the sensitivity technique for heavy elements. One proton detector was turned off during the second day of operation because of noise. A total of 43 hr of data was obtained from November 11 to November 24, 1967. The final data were obtained 4 hr after local sunset. However, after the spacecraft 'hopping' maneuver on November 17, 1967, the sensor head was upside down. Measurements were continued in order to obtain information on solar protons and cosmic rays. Therefore, data for the purpose of the chemical analysis of lunar surface material were obtained only during the first 30 hr of operation. During this period, 27 hr and 44 min of data were known to be noise free.

Alternate Names

  • Surveyor6/Alpha-ScatteringSurfaceAnalyzer


  • Planetary Science: Geology and Geophysics

Additional Information

Questions and comments about this experiment can be directed to: Dr. David R. Williams



NameRoleOriginal AffiliationE-mail
Mr. Ernest J. FranzgroteOther InvestigatorNASA Jet Propulsion Laboratory
Prof. Anthony L. TurkevichPrincipal InvestigatorUniversity of Chicago

Selected References

  • Turkevich, A. L., et al., The alpha-scattering chemical analysis experiment on the Surveyor lunar missions, Surveyor Program Results, NASA SP-184, Wash., DC, 1969.
  • Turkevich, A. L., et al., Chemical analysis of the Moon at Surveyor VI landing site: Preliminary results, in Surveyor 6, Prelim. Rept., NASA SP-166, Wash., DC, 1968.
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