NSSDCA ID: 1961-020A-06
Mission Name: Explorer 12Four banks of p-on-n solar cells were cemented to the satellite skin to measure the effects of the deterioration caused by direct exposure to radiation in the Van Allen belts. On bank of cells remained unprotected, while the others had 3-, 20-, and 60-mil-thick coatings of protective glass. The unshielded strip of cells degraded very rapidly during the first two orbits. On each orbit, severe degradation began about 2.5 hr before perigee, when the altitude of the satellte was approximately 33,000 km. After the first two orbits, the remaining output of the cells was only 50 percent of the initial output. The periods of severe degradation coincided with periods of peaked directional intensities of protons with energies between 150 kev and 4.5 mev. It is known that protons of this level would not penetrate the 20-mil glass shields. When the satellite ceased transmitting, the output of the unshielded cells had further degraded to 29 percent ot the initial value. The solar cells with 3-mil glass shields degraded by approximately 6 percent over the lifetime of the satellite. No solar cell degradation was indicated of the banks with 20- and 60-mil shielding when their outputs were compared on September 19 and December 3, when the incident-sun angle was the same.
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Name | Role | Original Affiliation | |
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Mr. Gerald W. Longanecker | Principal Investigator | NASA Goddard Space Flight Center |