STS operations cost is the major cost driver. Over 80% of the cost for assembly are related to STS per flight launch costs. These costs can be significantly reduced by introducing the Fly-Back Boosters. Data generated during the Shuttle Phase A studies indicated that launch costs could be reduced by a factor of two or three with a Fly-Back Booster. A heavy lift vehicle, which utilizes the current Shuttle system external tanks, SSME and solid rockets could be utilized in a deploy only flight mode and increase throw weight performance to $120,000 lb per flight without increasing launch costs. Launch cost of $25 to $50/lb could be achieved with these STS modifications. Recurring costs for support equipments were found not to be as significant a cost driver as was expected. The unit costs to purchase the Space Stations, additional Shuttles, manufacturing modules, etc. represent only 1/6 the cost to assemble each SSPS. The development cost of Space Stations, Shuttle payload bay support modules and free flying teleoperators can be shared or fully absorbed by programs which are more near term than SSPS. The function of the manufacturing modules and SEPS, may be so unique to SSPS that these elements may have to be accounted as part of the SSPS development costs. 3.5.2.4. 2 Sensitivity To Shuttle Packaging Density - A review of packaging factors for all elements of the SSPS has shown that most components and/or subassemblies can utilize the full payload performance capability of the Shuttle. The exception is perhaps the antenna waveguides. Structural subassemblies, can be packages as flat stock and fabricated in space with relatively simple auto manufacturing modules. Solar cell blankets can be rolled into tightly packages bundles for transport. Electrical wiring and equipments can also be densely packaged. The waveguides, however, may require fabrication on earth where the tight dimensional tolerances necessary for efficient microwave performance can be closely controlled. The design of close tolerance hinges and locking mechanisms as an integral part of the waveguide subarray offers a packaging approach with reasonable densities. Figure 3.5-14 is a parametric presentation of total waveguide weight and packaging density as a function of waveguide wall thickness. The final selection of thickness will be determined by analysis of the operational thermal requirements of the waveguides. An increase in thickness will increase conductivity of heat from the hot surface where the microwave conversion electronics are mounted to the cooler slotted face of the subarray. This thermal transfer is required to minimize the thermal gradients between the surfaces thereby minimizing thermal distortion. The packaging approach shown in Fig. 3. 5-14 utilizes the
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