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The solar cells and their mountingObjectives in development of the solar plant for the Telstar spacecraft were to provide a power source which would withstand launching stresses and the expected space environment, with optimum end-of-life performance. Radiation damage to the silicon solar cells is the primary factor limiting their useful life; the effect of energetic protons or electrons is the generation of recombination centers in the silicon which reduce the minority-carrier diffusion length and therefore the long-wave response of the cell.

The spacecraft solar cells use the n-on-p structure, in preference to conventional p-on-n structure, to obtain a factor of 3 to 10 increased life expectancy. Response to light in the 0.4 to 0.7 micron range is enhanced by using a thin n-layer (about 0.5 micron) and an antireflection coating with minimum reflectance at 0.55 micron wavelength. Early estimates of electron and proton fluxes in the satellite orbit showed that even the best cells would not give sufficient life without radiation shielding. Therefore the cells are protected against electrons of energy up to 1 Mev by 0.3 gm/sq. cm sapphire cover plates. The cell mountings are designed to withstand peak vibration stresses of 200 g and repeated temperature cycles from +65°C to −100°C.

The 3600-cell solar power plant is composed of 300 twelve-cell groups of 1 cm × 2 cm cells, yielding a nominal initial power of 14 watts at 28 volts for any spin-axis orientation relative to the sun. Telemetry information on performance of the solar plant indicates degradation of the shielded solar cells equal to that measured in the laboratory on unshielded cells with a 1-Mev normal incidence flux of 6 × 10^(12) electrons/(sq. cm day). From this comparison it is estimated that the plant will degrade to 68 per cent of its initial output after two years in orbit.
Document ID
19640001176
Acquisition Source
Goddard Space Flight Center
Document Type
Contribution to a larger work
Authors
K. D. Smith
(Goddard Space Flight Center Greenbelt, Maryland, United States)
H. K. Gummel
(Goddard Space Flight Center Greenbelt, Maryland, United States)
J. D. Bode
(Goddard Space Flight Center Greenbelt, Maryland, United States)
D. B. Cuttriss
(Goddard Space Flight Center Greenbelt, Maryland, United States)
R. J. Nielsen
(Goddard Space Flight Center Greenbelt, Maryland, United States)
W. Rosenzweig
(Goddard Space Flight Center Greenbelt, Maryland, United States)
Date Acquired
August 2, 2013
Publication Date
March 28, 1963
Publication Information
Publication: The Bell System Technical Journal
Publisher: Nokia Bell Labs
Volume: 42
Issue: 4
Issue Publication Date: July 1, 1963
ISSN: 0005-8580
URL: https://ieeexplore.ieee.org/document/6779750
Subject Category
Chemistry
Accession Number
64N11085
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Keywords
SPACECRAFT POWER SUPPLY
SOLAR GENERATOR
TELSTAR SATELLITE
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