2. Accurate thermal analysis and control, 3. New filter designs to control temperature, 4. Technology for coating large area plastic panels with filters and mirrors, 5. Light-weight structures to support and control orientation of mirrors, and 6. Low-cost filter/mirror structures. f. Key Issue No. 6 - Long Life of Solar Array in Space Environment The goal of the SSPS is to produce power at high voltage in a relatively stable thermal environment (except during predictable eclipses) over a 30-year period. The cell must be extremely light in weight, yet afford protection from the space environment. The exposure of the solar blanket to the ultraviolet radiation, as well as the particulate radiation, will require protection to ensure long life. The objective is 6% degradation over 5 years. The thermal cycling of the solar blanket during the eclipse period must be accounted for in the system and cell design. The method of cell interconnect and bussing will determine the local thermally induced stresses and ultimately determine the mean time to failure due to fatigue. Techniques to reduce the environmental effects include: 1. Improved radiation-resistant materials, 2. Radiation spectral tailoring to minimize unusable solar radiation, 3. High-voltage plasma protection, 4. Low internal electrical resistance to allow higher current flow, 5. Circuit optimization to balance high voltage versus magnetic moment, 6. Material selection to prevent thermal cycling fatigue, 7. Selection of absorption and emission coefficients for optimal thermal control, and 8. Meteorite hardening optimized with weight and power loss considered. g. Key Issue No. 7 - Minimization of Energy Input to Processes Preliminary investigations of the amount of energy utilized in producing silicon solar cell arrays by present processes indicate that it would take the SSPS several years of operation to return the energy used to make the array. Although the energy is supplied directly by both chemical (coal) and electrical sources, the electrical energy requirements are of primary concern. The objective is to
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