FIGURE 3.3-1, SPS OVERALL STRUCTURAL CONFIGURATION The material selected for the beams is Alum num. A premilinary study on the feasibility of using aluminum alloys for a silicon planar structure of the same configuration with Aspect Ratio (AR) of 4 and output power of 10 GW has been done by Grumman under the Boeing contract.(1) The structure is designed to be assembled in space. Assembly of the structure in space is a technology which is not fully developed, but preliminary studies have been done. Structural assembly can be done by robots (2,3,4,7) or by manned work stations located in orbit (5,6,8). The studies done on these problems show that the technology for such an operation is possible in the near future. The Boeing study,(1) which uses a composite material for the structure, uses low earth orbit (LEO) as the construction site for the modules. The modules are then transferred from LEO to geosynchronous orbit (GEO) by thrusters attached to the four corners of each module. This transfer requires higher load capacities for the beams than construction of the satellite in GEO, The higher load requirements result in about 35Z more massive composite structure, according to the Boeing study. The aluminum structure described in this report uses the mass statements of a structure designed for handling the higher load requirements, although construction in GEO is assumed here. The Grumman study does not include a mass estimate for an aluminum structure constructed at GEO. It is certain that the lower loads will require less stiffness and therefore a lighter
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