"overhead weight burden," i.e., the ratio of total mass to be lifted into LEO to total mass of the finally assembled satellite, suggests that this ratio may range as high as 3.6, and is likely to be approximately 2.7 (Ref. E6) . With an "overhead" ratio of 2.7, it would be necessary to launch 2.7 Ibm into LEO for every Ibm in the final assembled satellite. If the cost/lbm were $40-100, that would mean that the transportation cost/lbm of the finally assembled satellite would be $104-270. Assuming, in turn, a mass of 8 Ibm/kWh in the finally assembled satellite, the total transportation cost would be approximately $832-2160 per kilowatt of final capacity. Among the specific and more optimistic projections of transportation cost/kW are $656 by ECON for solar photovoltaic (Ref. All), and $190 and $270 by JPL for photovoltaic and thermal, respectively, (Ref. A9). Among the critical techno-economic issues that emerge from the analysis of transportation costs are: • The reduction of final system mass (related in turn to the mass efficiency of the solar collection system in Ibm/kW. • The selection of assembly and inter-orbit transfer methods and systems which minimize the mass overhead factor. • The development of an economical Heavy Lift Launch Vehicle with a high degree of reusability. • The scheduling of a sufficiently large number of launches and, by extension, a sufficiently large number of separate SSPS satellites, to effect substantial reductions in the per unit fixed fabrication and support costs. An important collateral issue raised in several references concerns the appropriate basis for the allocation of that portion of the transportation cost which could have significant benefits outside the limited framework of SSPS development. For example, the massive launch and ground support resources required for a program of this magnitude might well permit substantial cost reductions in other space activities dependent on launching substantial payloads into LEO. Similarly, the proposed HLLVs could be reused for other than SSPS purposes. Although all
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