simple, economical manner, and over which some inexpensive protective layer is positioned, having no moving parts and using no exotic materials, cannot be made for a few dollars a square meter rather than the thousands of dollars per square meter experienced in the space program... ” b. Space Transportation System Space transportation costs projected for an operational SSPS system are based upon the extensive studies of advanced transportation systems, conducted by NASA and Grumman, prior to the selection of the current space shuttle system. In addition, the results of technology development programs related to advanced propulsion techniques (e.g., ion/electric propulsion) were used to expand the base of potential transportation options that might be considered for an SSPS program. The foundation for transportation cost projections for an operational SSPS are therefore based upon an extensive advanced transportation system “data bank” that has been developed over the past few years. We are therefore confident that the cost projections represent realistic estimates of technically-achievable goals in the 1985-1990 time period. Three basic phases lead to an operational SSPS program; they are: • Technology Development/Verification, « Prototype System Development, and • Operational System Development. As regards space transportation aspects related to these phases, it has been assumed that ground-to-low Earth orbit (LEO) transport of payloads would be accomplished by the space shuttle system presently under development by NASA for the technology development and prototype phases only. For the operational SSPS system, it is assumed that a new low-operating cost transportation system would be developed, compatible with the high traffic volume needs. It is expected that this new transportation system would be an evolutionary growth of the present space shuttle, and that its development costs would be amortized over the quantity of operational SSPS platforms expected to be operating in space in the future. Projected delivery costs for an operational SSPS were developed by examining several alternative combinations of space transportation elements for delivery of payloads to synchronous orbit where final assembly of the SSPS was assumed to take place. The transportation elements examined included all-chemical and mixed chemical-ion transportation systems: (1) The fully reuseable (booster and orbiter) two-stage Earth orbital shuttle studied by NASA during 1971 and 1972, generally referred to as the ‘Phase B Shuttle.” The operational costs of payload delivery to LEO of this system are less than half those of the partially reuseable shuttle currently under development by NASA. (2) The chemical propulsion stage (CPS), a large space-based reuseable “space tug” that launches itself into orbit after staging from the reuseable booster.
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