INVOLVEMENT IN SPS John Richardson National Academy of Science To amplify what you have just heard concerning the NAS reasons for participating in the assessment of the SPS concept: the ultimate commitment of effort and resources on this program is truly staggering and, by the same token, even the next step of investigation will mean a considerable expenditure of public funds. The Academy believes that it should, along with many others, speak to what, if anything, should be done next in the R&D. It has been shown that the assessment of SPS technology may contain many lessons about the assessments of other large scale technologies that our country will be called upon to make in the future. The Academy report will be completed in June of 1981, hopefully in time for use in connection with the DOE submission to 0MB for the fiscal 1983 budget in September 1981. I would also like to pay tribute to the responsiveness and excellence both in DOE and NASA and in other groups in providing information to the Academy during the beginning phases of its investigation. Turning to the substance of some of our impressions, I can't give you any conclusions but I can tell you some of the striking features of SPS that are occurring to us and certainly have occurred to others. The tremendous extrapolation of scale from our present capabilities permeates the concept. Example: the Heavy Lift Launch Vehicle and the Electric Orbit Transfer Vehicle contain extrapolations in space transportation systems both in physical performance and in cost to a huge extent, in particular, I believe that no ion-engine flight from LEO to GEO has yet occurred and we are extrapolating that. The solar cell technology has to be extrapolated from current achievements of square centimeters of area to the integration of square kilometers of solar cells, a factor of ten to the tenth, and at the same time this has to be scaled down by a factor of one hundred in cost. In terms of the population of space workers, the world has seen perhaps fifty astronauts operating in orbit but the space worker population of the SPS would be many tens of thousands. The reliability of the parts and the subsystems has to be high; while we might not have to achieve the ideal reliability of a computer system where a complete shut-down is preferrable to even a small impairment, we do want something like the reliability of our telephone system in which minor impairments are preferrable to a complete shut-down. Although it is not a feature of the SPS reference system, some have proposed and the NSF is bound to investigate through our work, the eventual space manufacture of SPS components and, in part, the manufacture of these components from nonterrestrial materials -- also an extrapolation of capacity and capability. Turning to the economic area, in the absence of any fatal flaw to this system -- perhaps a good rule might be that if the SPS costs are found to be high and firm then it should be scrubbed, but if the costs are high and soft then we should do some R&D. As of now I think the costs are high and not firm. The R&D for this project must extend over long periods of time and will come to huge amounts of money; one estimate is that by the time the first SPS is built some $68 billion will have been spent over a period of some 16 years. The financing of such amounts on such a time scale is not in the usual horizon of Wall Street and that will be a difficulty to overcome. Some members of our group reason that the unit costs of an SPS will certainly vary somewhat with its economic lifetime. The reference system has a lifetime assumption of 30 years but as far as we can see that lifetime is not uniquely set by any estimates of wear and tear on the system or by any estimates of technological change. It seems that the factors that set the economic lifetime of SPS need to be more sharply determined and the sensi-
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