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Electric Field Meter

NSSDCA ID: 1960-014A-06

Mission Name: Explorer 8
Principal Investigator:Mr. John L. Donley


A rotating-shutter-type electric field meter was mounted at the forward end of the satellite's spin axis to obtain measurements of the distribution of charges that accumulate on the satellite surface due to interaction of the satellite with the plasma sheath. The meter consisted of an exposed four-blade, motor-driven shutter (rotor), grounded to the satellite skin by brushes, and a four-blade stator, or sensor, located directly behind and having the same configuration as the rotor. The stator, which was connected to ground through a resistive load, was alternately exposed and shielded by the 7500-rpm rotor. Exposed surfaces on the meter were goldplated. Rotor-stator spacing was 3 mm. Because of the experiments large power demand (3 W), it was turned on from the ground. After 2 min of operation, the experiment was automatically turned off by a command program module. The total daytime potential difference between the spacecraft and environment was found to be 0.15 V when the medium's electron density was about 1.E4 electrons/cc. At apogee, where electron density was about 1.E3 electrons/cc, the potential reversed and became a few tenths of a volt positive.

Alternate Names

  • Explorer8/ElectricFieldMeter

Facts in Brief

Power (avg): 3 W


  • Space Physics: Ionospheric Studies
  • Space Physics: Thermospheric Studies

Additional Information

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



NameRoleOriginal AffiliationE-mail
Mr. John L. DonleyPrincipal InvestigatorNASA Goddard Space Flight Center
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