took this real world ‘limit-to-growth’ into account. Increases in station resources to accommodate the mission needs were limited by the lift capability provided by several transportation models. The most conservative model assumes only five NSTS flights a year are available to SSF. On the more aggressive end of the range, NSTS capability is augmented by multiple expendable vehicle (ELV) launches to provide over 600000 pounds mass per year to station for crew and payload logistics and growth element delivery. ELVs contained within the transportation models include commercially provided Titan 4, Ariane V and H-II from the European and Japanese partners, respectively, and a heavy-lift Shuttle C available during the evolutionary phases of space station. Figure 1 shows the lift to orbit as a function of station operating year (post-phase I) for two of the transportation models defined for this analysis. The moderate capability of Fig. 1(a) begins with five NSTS launches and is augmented in years three and four with one Ariane, one H-II and one Titan 4 and an additional NSTS. In years five and beyond, the number of ELV launches is doubled to provide over 400 klbs of lift. The more aggressive model of 1(b) assumes eight NSTS launches beginning in year three and introduces the Shuttle C in year five. It should be
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