12. 2. 6 Mechanical Systems and Flight Operations The following summarizes significant conclusions for the mechanical systems and flight operations. a. Rectangular grid structural arrangement with triangular hat section is recommended for basic members of the transmitting antenna structure. b. Aluminum, graphite epoxy, and graphite polyimide are recommended candidate materials. c. Aluminum materials result in the probable lowest cost and development risk program with thermal limits being their most critical area. d. Composites are attractive for low thermal distortion and high temperature operation (polyimide), but ultra-violet compatibility, and outgassing leading to rf generator contamination need investigation. e. Assuming the Shuttle as the transportation system, low altitude assembly is recommended. The associated transportation and assembly cost for $10. 5M/launch is estimated to be near 600 $/kg. f. Advanced transportation system needed for low cost of large payloads to low earth orbit at relatively low launch packaging densities for the payload. Low cost advanced transportation system required to transport assembled or partially assembled systems from low earth orbit to geosynchronous equatorial orbit. g. Orbital assembly requires remote controlled manipulators. h. Maximum on orbit manufacturing and assembly will be necessary when using the Shuttle transportation or other options with small volume capacity requiring high launch packaging densities to achieve payload performance. Technology issues for mechanical systems are listed and discussed in Section 4 of Section 8 (Mechanical Systems and Flight Operations). This listing identifies areas in technology where more work needs to be done and suggests approaches for accomplishing these tasks. The following simplified list is incorporated here as recommendations for further detailed investigation.
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