by Philip K. Chapman
From L5 News, December 1981
In 1977, the Department of Energy initiated a three-year program (the Concept Development and Evaluation Program, or CDEP) which was to evaluate the potential of Solar Power Satellites (SPS) and to provide recommendations about whether they should be taken seriously as a future energy option. The total funding for this effort was set at $15.5 million, and on-going work by NASA on the SPS was integrated with it. At the time, many space advocates believed the CDEP was an attempt to delay if not kill the SPS, and there is no doubt that DOE management was and is hostile to the concept. In practice, however, the DOE and NASA staff undertook a serious and honest study of the system and its ramifications. They deserve to be commended: the CDEP could serve as a model for careful technology assessment.
The first step in the study was to specify a “strawman” design called the Baseline Reference System (BRS), which assumed solar power conversion by single-crystal silicon photovoltaic cells (with gallium-arsenide cells as an alternate) and a microwave beam to transmit power to Earth. The design chosen was deliberately very conservative, and therefore heavier and more expensive than an actual SPS would be. The explicit purpose of the BRS was not to suggest an optimal approach, hut merely to provide a common starting point for investigations of the societal, environmental and other implications of the SPS.
The CDEP findings were presented at a meeting of the participants in Lincoln, Nebraska, in April 1980. The overwhelming consensus was that there were no technical impediments to building the SPS, but that much more work was needed to determine whether the system could be economically competitive, to establish optimal designs, and to ensure minimal environmental impact. Despite the strongly positive tone of this meeting, DOE requested no funds for further work, and the final report carefully omitted any recommendations about the system.
When it became clear in 1979 that the CDEP was producing results favorable to the SPS, the National Research Council of the National Academy of Sciences was asked to set up a Committee on Satellite Power Systems to provide a critique of the study. In early July of this year, the Executive Summary of the NRC report was released to the press (other interested parties were told that no copies were available). The result was a flurry of negative headlines. For example, on July 4 there was a story in the Washington Post headed “$3 Trillion Space Power Plant Opposed,” and on July 17 one in Science headed “Solar Power Satellite Research Called Premature.”
The L-5 News has now obtained a complete copy of the NRC report (Electric Power from Orbit: A Critique of a Satellite Power System, National Academy Press, Washington, DC), as well as some of the supporting documents. In subtle but crucial ways, the report misrepresents the findings of the Committee, and the summary given to the press further misrepresents what the report says. If these distortions were corrected, there would be very little in the report with which any proponent of the SPS could disagree. As a matter of fact, the detailed findings are quite similar to those reported at the CDEP meeting in Lincoln.
One major distortion is that conclusions based on the BRS (which nobody regards as a practical design) are used to denigrate the overall concept. For example, the summary says that “based on an examination of cost estimates for the reference SPS…an SPS will not become a cost-competitive source of electrical energy in the next 20 years” (emphasis added). It is these estimates which lead to the $3 trillion cost for an installed SPS capacity of 300 GW (i.e., $10,000/kW). If this is what an operational SPS system would actually cost, it would never be built. However, there do exist other conceptual designs which may offer costs below $1500/kW, which would make the SPS the cheapest available source of power. It is obviously important to continue research until these estimates can be confirmed or denied.
The Committee agreed that it would be premature to make a commitment now to development and deployment of the SPS, a conclusion with which I entirely concur. This does not constitute a recommendation that SPS studies be terminated. For example, the report of the Working Group on Space Systems (Appendix C) states: “While we believe that the reference system should now be abandoned, we recommend that NASA continue conceptual studies on promising new SPS concepts” (emphasis added). The summary, however, says “…a specific program of research justified in terms of the SPS would not now be warranted.” To quote one of the Committee members, “somehow the recommendation that no development be undertaken on SPS has now been distorted…into a recommendation or assumption that there shall be no research program.”
As originally written, the report of the Working Group on Space Systems (chaired by Dr. Thomas 0. Paine, President, Northrup Corporation) contains many quotes from eminent authorities which illustrate the folly of denying technical possibilities. An example is Lord Rutherford in 1933: “Anyone who expects a source of power from the transformation of atoms is talking moonshine.” These quotes were all deleted from the NRC report, changing the emphasis significantly.
One of the valuable aspects of the report is that it points out that much of the technology needed for SPS is also needed for other space programs. These basic elements include: economical transportation to low Earth orbit (LEO); deployment of a LEO operations center, with automated facilities for construction of large structures; economical transportation between LEO and geosynchronous orbit (GEO); improved solar cells; and an eventual staffed base in GEO. A vigorous space program aimed at achieving these objectives could have a highly desirable synergistic effect, enhancing capabilities in many areas other than the SPS: monitoring and management of terrestrial resources, development of space industrialization, the space sciences (including planetary exploration), exploitation of extraterrestrial resources, human habitats off Earth, and space technology for national security. It is to be hoped that the various diverse interests in the pro-space movement will follow the lead provided by the NRC Committee on Satellite Power Systems and join together in support of such a program.
If the United States undertook this core space program, major advances in particular areas could be achieved with quite modest additional funding. For the SPS, the needed supplemental program would have three components: (i) study of SPS system concepts to determine optimal designs and provide realistic preliminary cost estimates; (ii) research in long-lead areas such as the possible effects on biota of exposure to low-level microwave radiation; and (iii) coordination with other research programs to ensure that SPS needs are taken into account (for example, development of photovoltaic cells should consider their mass as well as their cost and efficiency). An SPS research project organized in this fashion, as an adjunct to a primary space program, would allow orderly investigation of the promise of power from space, without developing vested interests which might impede termination of the effort if the SPS proved infeasible.
A careful reading of the NRC Report suggests that most members of the Committee on Satellite Power Systems would approve this approach. It is quite unfortunate that this fundamentally constructive study has been damaged by biased editing and misleading publicity. If the misrepresentations remain uncorrected, the report will have little credibility or utility, and the work of the Committee will be largely wasted.