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Triaxial Low Field Helium Magnetometer

NSSDC ID: 1967-060A-05
Mission Name: Mariner 5
Principal Investigator: Dr. Edward J. Smith


For this experiment a low-field helium magnetometer was used to obtain triaxial measurements of interplanetary and Venusian magnetic fields. Its operation depended on the variation in absorptivity of excited helium to circularly polarized infrared light with applied field. Swept Helmholtz coils nulled the ambient field by use of feedback circuits. Mounted on a 1.5-m boom, the instrument's dynamic range was plus or minus 204 nT per axis, with a measurement precision determined by telemetry constraints of plus or minus 0.2 nT. Offset fields were correctable to within 0.25 nT per component. The experiment operated in a high (low) bit-rate mode of 3 vector samples spaced 1/7, 2/7, and 4/7 of the sequence every 12.6 (50.4) s; thus the Nyquist frequencies were about 0.12 and 0.03 Hz respectively. High-rate data were obtained from June 14 to July 24, 1967, and for 4 hours on October 25, 1967. Low bit-rate data were obtained for the remainder of the experiment's useful lifetime. Quality of data was high except during September 23 to October 1, 1967, when telemetered data were of uncertain quality. NSSDC has all the data from this experiment.


  • Planetary Science: Fields and Particles
  • Space Physics: Heliospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Dr. Edward J. SmithPrincipal InvestigatorNASA Jet Propulsion
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