factor of 1.12:1 (about 12%) for Case 16, and to factor of 1.14:1 (about 14%) for Case 13. These results indicate that for the LEO and MEO cases, in which the non-recurring costs constitute a much larger proportion of the total “cost to first power”, that the benefit to financial performance of external support for non-recurring investments is greater, as might be expected. SSP Share of Ground Segment Costs. The last of these cases examined the potential economic impact of variations in ground segment costs. The nominal assumption for this SSP study was that a space power venture would be required to fund no more than 50% of the overall costs of ground segment system manufacturing and deployment (with the remainder to be funded by local investors, national governments, etc.). The sensitivity cases examined included varying the SSP “venture’s” responsibility from the baseline by factors of 50% of ground segment costs (he., 50% of the baseline 50% - or 25% of the total ground segment cost), 75%, 125% and 150% of baseline ground segment non-recurring costs. This could correspond to greater or lesser degrees of local investor or national government support for deployment of ground segment systems. In general the economic benefits of these scenarios were found to vary greatly for differing cases. There were no benefits for Case 4 (in which the ground segment is an extremely small proportion of the total investment), to a factor of 1.34: lincrease in IRR (about 34%) for Case 16. These results indicate that for the LEO and MEO cases, in which the ground segment costs constitute a much larger proportion of the total “cost to first power”, that the benefit to financial performance of external support for this specific area of non-recurring investments is much greater than for GEO scenarios. Special Scenarios. In addition to the cases noted above, for the SunTower, a special scenario was examined that involved assuming that a portion of the non-recurring costs (50% of manufacturing and 80% of the space segment) were covered by government-sponsored investments in an exploration mission application (such as the “Solar Clipper” concept for multi-megawatt solar electric propulsion system (SEPS) Mars transportation systems). For the SolarDisc a special scenario was considered, again based on a investment in key SSP systems for exploration mission applications, that assume that the nonrecurring costs for in-space transportation were covered by the government. Impact of Concentrator Array Specific Mass on Economic Performance. For both the LEO and MEO SunTower cases, the achieved “specific mass” (system mass per kilowatt of electrical power generated on the SSP satellite) has the potential to dramatically affect the performance of the overall architecture. A trade study was conducted in order to determine the impact on the economic performance of the chosen cases that resulted from varying this achieved “specific mass”. Cases examined included specific masses of250 kilowatts/kilogram, 500 kilowatts/kilogram, 750 kilowatts/kilogram, 1000 kilowatts/kilogram, and 1250 kilowatts/kilogram.
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