APPENDIX V-A-2 CONSIDERATION OF JOINING PROCESSES FOR SPS CONSTRUCTION J. D. Medlock Structures & Mechanics Division Introduction Joining processes suitable for use during in-space construction of the Satellite Power System (SPS} are highly dictated by the type of materials being joined. The following candidate materials are being considered for use, and will require reliable processes for joining them to each other and to other materials. 1. Graphite composites (epoxy, polysulfone, polimide, etc. matrices) 2. Aluminum alloys 3. Baron/aluminum composites 4. Polyimide (Kapton) and polyester (Mylar) films 5. Polyamide (Kevlar 49) cables 6. Thermal control coated materials 7. Electrical conductive systems Although there are many joining processes adequate for use on these materials in a terrestrial environment, the application of joining processes in the space environment requires additional consideration. The effects of vacuum, temperature extremes, radiation, and zero gravity fabrication difficulty must be fully investigated. The fact that electrical power is readily available to provide energy requirements for the joining process tend to favor electrically powered joining techniques. The following sections discuss candidate joining requirements and methods for joining materials proposed in the SPS construction. Joining Requirements The major structural joining requirements for the SPS reference configurations involve graphite composite materials. The graphite/binder matrix material in "green" tape form, may be heated (activated), shaped, and cured in a continuous process to produce structural beams. Because of the high volume of structure required in a relatively short time, automatic equipment for high-speed wrap and joining fabrication of the structure is presently visualized as a necessity, although manual operations for equipment maintenance, specialized repair, alignment, etc., will probably also be required. The maximum anticipated exposure temperature (500°K on the antenna structure) indicates that the fabri- cation/joining of the graphite composite can be accomplished with epoxy
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