b. Truss Configuration - The truss configuration was conceived as an aid to construction. With the regular geometry of the truss configuration, a construction base concept as illustrated in figure V-A-6-5 is possible. A large space frame, the entire width of the collector array, supports the equipment necessary for completion of the array. A central facility receives and distributes materials for construction. Primary structural trusses are manufactured by automatic machines. Before the array leaves structural support of the construction base, concentrators and solar cell blankets are deployed from their shipment packages. Power distribution cables are installed and checked. The entire process is set up to proceed at a uniform rate such that the array is extruded from the construction base. To preclude stopping the process, in the event of a breakdown, individual machines must be designed to slip relative to the base then make up time when repaired. A construction sequence for the truss configuration is shown in figure V-A-6-6. The equipment to construct the array appears in table V-A-6-5. c. MPTS - Antenna construction parallels construction of the collector array. One antenna construction facility is attached to the construction base, the other is a separate facility attached to the end of the collector array where construction begins. The antenna construction sequence outlined in figure V-A-6-6 begins with fabrication of the support structure and installation of the ball joint and drive mechanism. Then buildup of the primary structure shown in figure V-A-6-7 can take place. The construction concept envisions the concentric installation of the secondary structural units which are used as construction staging for assembly of the primary structure rings. When each ring is in place, the cables to the next inner ring are tensioned to rigidize the structure. The next band of secondary structure is constructed followed by next outer ring until the structure is complete. Subarray installation immediately follows the structural buildup of each ring to take advantage of the position of the construction facility. Tables V-A-6-6 and V-A-6-7 evaluate equipment requirements which are summarized in table V-A-6-5. The antenna subarrays are a prime candidate for manufacture in an orbiting facility. The waveguides should be very light weight which would result in a low density packaging if made on earth and transported to orbit. The microwave generator is a high density item which would be a design penalty to a earth launched subarray. By setting up an orbiting manufacturing facility, probably in LEO, a lightweight precision design appears achievable. d. Modular Truss Configurations in LEO - A third construction option which was considered in less detail is the manufacture of sections of the collector array in LEO. A portion of the solar cell
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