0191-9067/8(¥040375-07$02.0<y0 Copyright ® 1980 SUNSAT Energy Council RECENT DEVELOPMENTS IN THE SPACE TRANSPORTATION SYSTEM FOR THE SOLAR POWER SATELLITE HUBERT P. DAVIS, P.E. Eagle Engineering, Inc. Abstract — The transportation session of the SPS Program Review held by the U.S. Department of Energy (DOE) and NASA at Lincoln, Nebraska on April 23-25. 1980 was a good overview of the current status of the space vehicles dedicated to the SPS program. Emphasis, correctly, was upon the highest cost element of the system — the launch vehicle. A major conclusion from the session was that an improved program strategy on SPS launch vehicle development is emerging. A much smaller HLLV (100 ton payload class) can drastically reduce the present $24 billion HLLV investment to initiate placement of operational SPSs. A more advanced, much larger, HLLV can be developed during the 30-year (or more) placement interval to drastically reduce the recurring costs and thus the investment cost ($/kW) of the average SPS. Use of a near-equatorial launch site, either on shore (Kourou) or an offshore structure can also reduce Reference System transportation costs. The cargo OTV recurring costs are driven by the cost of solar cells and electric propulsion thrust units. The “magneto-plasma-dynamic” (MPD) arcjet, under development by the NASA Jet Propulsion Laboratory, is a significant opportunity to reduce the number of engines consumed and thus the Reference System costs. As a consequence of these recent developments, the SPS transportation cost spread (uncertainty) appears to be much greater than indicated in the “Comparative Assessment" of the Reference System SPS with other energy options. Further work is urgently needed in defining the operations costs, unit cost and expected life of the SPS flight vehicles in order to exploit these new opportunities and to reduce uncertainties. No new data was divulged in environmental effects of the SPS transportation operations and no environmental impact “show stoppers" have yet become evident. On April 23, NASA presented an overview of the SPS cost methodology and sensitivities. These data, relevant to the “Baseline System,” indicated that the SPS program requires an expenditure of $102.5 billion (1977 dollars) to develop and put in place the first operational 5 GW,, power plant. Almost half of these resources are devoted to the “investment phase” of the program which requires an estimated $47.5 billion. Of this investment, approximately $30 billion are required to put in place the large space transportation fleet appropriate to space deployment of 300 GW,, or more of SPS capacity. These investment phase dollars loom very large in the decision process of the SPS program and, therefore, require careful scrutiny as to the program strategy employed and the quality of the cost estimates rendered for the space transportation segment. It is the purpose of this report to summarize and provide comments upon the space transportation presentations made the afternoon of April 23, at the Lincoln,
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