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DC Electric Field Measurement

NSSDCA ID: 1971-096A-06

Mission Name: S-Cubed A
Principal Investigator:Dr. Nelson C. Maynard


The electric field antenna consisted of two 13.97-cm-diameter metal spheres mounted on the ends of two booms with a 5.08-m separation. Determination of the potential difference between the spheres yielded electric fields with a sensitivity of 0.1 mV/m. The rotation of the spacecraft allowed a two-component dc measurement to be made. Over most of the orbit the dc measurements were contaminated by spacecraft photosheath-induced potentials and should not be used for determination of dc electric fields. A calibration plate on the spacecraft was used to change the spacecraft potential, thus checking on sheath overlap errors. In addition to the dc measurement, four rms spectrometer channels and a broad-band channel sampled low-frequency variations. The rms spectrometer channels sampled low-frequency variations from 0.3 to 1, 1 to 3, 3 to 10, and 10 to 30 Hz. About 1300 orbits of data were obtained, covering magnetic local times from 0800 to 2300 h through the noon sector. The instrument was used to locate the plasmapause because its amplifiers became saturated by the fields within the spacecraft photosheath when the electron density was below about 60 per cc. About 900 measurements were obtained of the plasmapause boundary throughout the useful lifetime of the instrument.

Alternate Names

  • Measurement of Electric Fields
  • S-CubedA/DCElectricFieldMeasurement

Funding Agency

  • NASA-Office of Space Science Applications (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
Prof. Donald A. GurnettOther InvestigatorUniversity of Iowa
Dr. Nelson C. MaynardPrincipal InvestigatorNASA Goddard Space Flight
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