NSSDCA ID: 1966-075A-02
Mission Name: Pioneer 7A multigrid Faraday cup with two semicircular, coplanar collectors was used to study solar wind ions and electrons. The instrument had 14 contiguous energy-per-charge channels between 75 and 9485 V for positive ions and four energy-per-charge channels between 115 and 1600 V for electrons. The instrument view axis was perpendicular to the spacecraft spin axis and parallel to the ecliptic plane. The line separating the two collectors lay in the ecliptic plane, enabling a rough determination of solar wind bulk flow perpendicular to the ecliptic plane. During every second spacecraft rotation and at one voltage level, the sum of the currents from the collectors was obtained in 28 contiguous 11.25-deg angular sectors (from -45 deg to 270 deg, with 0 deg being the spacecraft-sun line). The eight measurements about the sun-earth line (-45 deg to +45 deg) were telemetered, but only the largest measurement in each succeeding 45-deg interval (45 deg to 270 deg) was telemetered. In addition, during this rotation the current from one of the collectors was measured in all twenty-eight 11.25-deg sectors, and the largest was identified and telemetered (both magnitude and sector). A complete set of positive ion measurements and one electron measurement were completed every 32 s. The time between each 32-s group of measurements varied with the bit rate. The experiment worked well from launch until it became inoperable in November 1972. For more complete information, see J. Geophys. Res., v. 71, pp. 3787-3791, August 1966.
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Name | Role | Original Affiliation | |
---|---|---|---|
Prof. Herbert S. Bridge | Principal Investigator | Massachusetts Institute of Technology |