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Proton Precessional Magnetometer

NSSDCA ID: 1959-007A-01

Mission Name: Vanguard 3
Principal Investigator:Dr. James P. Heppner


This experiment had a proton precessional magnetometer to measure the earth's magnetic field at altitudes ranging from 514 to 3714 km and at latitudes between plus or minus 33.4 deg. The measurements were made on command as the spacecraft passed seven minitrack stations in North and South America and one each in Australia and South Africa. When switched on by command, the polarization coil around the proton sample (normal hexane) was turned on for 2 s followed by a 2-s readout of the precession signal. Several readings were taken during each pass over a station. The experiment worked well during its 85-day active life, and approximately 4.3E3 readings were recorded. The experiment is described in J. C. Cain et al., "Measurements of the geomagnetic field by the Vanguard 3 satellite," NASA TN D-1418, Goddard Space Flight Center, Greenbelt, Md., 1962. The overall accuracy of the field measurements was approximately 10 nT (gammas).

Alternate Names

  • Vanguard3/ProtonPrecessionalMagnetometer

Funding Agency

  • Department of Defense-Department of the Navy (United States)


  • Space Physics: Magnetospheric Studies

Additional Information

Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office



NameRoleOriginal AffiliationE-mail
Dr. James P. HeppnerPrincipal InvestigatorNASA Goddard Space Flight Center

Selected References

  • Cain, J. C., et al., Measurements of the geomagnetic field by the Vanguard 3 satellite, NASA, TN D-1418, Wash., D.C., Oct. 1962.
  • Vanguard 3 (1959 Eta 1) proton precision magnetometer, NASA-GSFC, NSSDC 67-26, Greenbelt, MD, May 1967.
  • Cain, J. C., et al., Vanguard 3 magnetic-field observations, J. Geophys. Res., 67, No. 13, 5055-5069, doi:10.1029/JZ067i013p05055, Dec. 1962.
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