0191 -9067/81 /010033-10$02.00/0 Copyright ' 1981 SUNSAT Energy Council SPS TRANSPORTATION REQUIREMENTS — ECONOMICAL AND TECHNICAL DIETRICH E. KOELLE Advanced Programs and Technology Development MBB Space Division Ottobrunn, Federal Republic of Germany Abstract — The SPS launch operations require a new heavy lift launch vehicle with more than 200 Mg (tons) in geosynchronous orbit. The specific transportation cost have to be two orders of magnitude lower than the specific launch cost of the Shuttle + IUS, in order to make the SPS launch economically feasible. This requirement can only be fulfilled by a fully reusable heavy lift cargo vehicle. However, even in this case the present range of cost for the launch of a 5 GW power satellite is 2 to 6 billion US dollars (50 to 150 $/kg to GEO). The paper will discuss the major transportation cost criteria, as there are launch vehicle type, size (payload), launch rate per year, recovery mode, reusability, operations and refurbishment cost. The cost trends are shown graphically and a resulting transportation system with minimum cost is presented. Finally, a possible implementation scheme is shown for an international effort to meet this space transportation challenge. THE TRANSPORTATION PROBLEM The transportation of 50,000 tons (Mg) mass to GEO — as presently estimated for a 5 GW SPS — poses a great challenge to system design and technology of future launch systems. The present situation and the future goal in this business are shown in Fig. 1. The specific costs are expressed in MY (man-years) per Mg (megagram or metric ton). Indicating the effort in MY makes more sense than giving the present value of this effort which increases year by year. In 1980 the value of one MY is about 92,000 US dollars or 70,000 AU. The diagram shows the cost reduction for larger vehicles with larger payloads as a principle trend for all transportation systems (airplanes, ships). However, the reduction in specific cost for larger expendable vehicles is by far not sufficient for an SPS-program. What we need is a cost reduction by two orders of magnitude to the range of 0.5 to 1.5 MY/Mg [or 50 to 150 dollar/kg (1981)} to GEO, in order to make the SPS economically feasible! The Space Shuttle as a partially reusable system means only a modest reduction in launch cost (factor 2). It seems feasible, however, to realize the goal indicated above with an unmanned, fully reusable large ballistic cargo launch vehicle. The prime requirement in this case is economic optimization (and not performance optimization, as in the past!). 33
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