6.3.2. Sensitivity Analysis Results Summary of Results by Sensitivity Area Earth to Orbit Transportation Costs. Extremely low cost access to space is an essential prerequisite for any major new space industry; this is certainly true for space solar power. The nominal ETO cost (not including initial fleet purchases) used in the study was approximately $125/Ib (where the scenario and concepts involved in achieving these costs are described elsewhere). A trade study was conducted in order to determine the impact on the economic performance of the chosen SSP cases that resulted from varying the cost of Earth-to-orbit (ETO) transportation (to low Earth orbit). Launch costs examined included SlOO/lb, $200/Ib, $500/lb, SlOOO/Ib and$2500/lb. As expected, all three cases examined were very sensitive to variations in ETO costs, showing increases of about 3:1 in IRR for each in going down from $ 1000/Ib to SlOO/lb. The higher altitude scenarios - Cases 4 and 16 - showed the greatest benefit from ETO reductions from $500/Ib to SlOO/lb, with increases in IRR of about 1.6:1 for the former (from an IRR of 13.2% to one of 21.3%) and 1.7:1 for the latter (from an IRR of 8.72% to one of 14.53%). However, the cases showed only moderate increases in IRR in going from $200/Ib to SlOO/lb - including increases of 1.11:1 (Case 4), 1.08:1 (Case 13), and 1.14:1 (Case 16). Refurbishment Intervals. The repair and maintenance requirements of large SSP satellites systems is believed to be a key factor in achieving a viable system Another trade study was conducted in order to determine the impact on the economic performance of the chosen cases that resulted from varying the intervals when refurbishment of the SSP space segment would be performed. The objective in this analysis was to evaluate the importance of achieving long-life in key SSP systems. Refurbishment intervals that were examined included 2 years, 5 years, 10 years, 20 years, 30 years, 40 years and 50 years (all examined at the baseline refurbishment mass for the case involved). It was found that there was essentially no financial benefit in seeking to increase the refurbishment interval above 20 years: all three cases showed a factor of 1.01:1 (about 1%) or less benefit in IRR. The financial benefits of increasing the refurbishment period above 10 years was larger, but still moderate, with improvements of 1.04:1 (about 3.6%), 1.03:1 (about 3%), and 1.07:1 (about 6.7%) for cases 4,13 and 16 respectively in going from a refurbishment period of 10 years to 20 years, hi the actual cases examined, a successful effort was made to match the refurbishment interval to the pace of initial system deployment in order to minimize the ETO and/or in-space transportation fleet requirements. Refurbishment Mass. A similar trade study was conducted to determine the impact on the economic performance of the chosen cases that resulted from varying the percentage of the space segment mass that was involved whenever refurbishment of the SSP space segment was conducted. Refurbishment percentages that were examined included 0%, 25%, 50%, 75% and 100% (all examined at the baseline refurbishment interval for the case involved). For the SolarDisc case (Case 4), since the refurbishment times were exceedingly long in the baseline, it was found that there was little impact on IRR of variations in the refurbishment mass. The impact for Case 16, again with longer refurbishment times, was moderate (less than a 10% change in IRR), while the impact on Case 13 was greatest (with IRR decreasing by almost 40% across the range considered). Clearly, evaluation of the sensitivity to refurbishment mass in future studies will require careful coupling to refurbishment periods (described above). However, this initial assessment suggests that a refurbishment time greater than 20 years will assure virtual independence of IRR to changes in refurbishment mass. Conversely, for shorter refurbishment times,
RkJQdWJsaXNoZXIy MTU5NjU0Mg==