chemical and traffic industries on Earth was proposed for evaluating the effect of SPS on the Earth’s environment. The simulation results indicate that the "limits to growth" in the closed Earth system which will occur in the near future can be overcome by SPS with energy investment in SPS of more than about 0.6-2.1% of the total energy used on Earth per year, if the degradation rates of solar cells are 1-3% per year or less. We hoped that this model demonstrates the effectiveness of SPS in improving the Earth’s environment in the next century, and will help to evaluate means of effective energy in investment in SPS, although the numerical values in the simulation are only approximations, and the model is still very crude. ACKNOWLEDGEMENTS The authors are grateful to Dr. Patrick Q. Collins for valuable discussions. REFERENCES [1] FORRESTER, J.W. (1973), World Dynamics, 2nd ed. (Cambridge. Wright-Allen Press, Inc.). [2] Meadows. D.H., Meadows, D.L., Randers, J. and Behrens III, W.W. (1972), The Limits to Growth (New York. Universe Books). [3] DOE/NASA REPORT (1980), "Program Assessment Report, Statement of Findings: Satellite Power Systems Concept Development and Evaluation Program," DOE.ER-0085. [4] Tajima, M. (1990) Institute of Space and Astronautical Sciences, private communication. [5] Herendeen, R.A. Kary, T. and Rebitzer, J. (1979), "Energy Analysis of the Solar Power Satellite," Science, 205, No. 4405, pp. 451-454. [6] RALPH, E.L. (1989) "Photovoltaic Space Power History," Space Power, 8, No. 1/2, pp. 3-10. [7] Mann, L.R. (1964) in R.B. Scott (Ed.), Technology and Uses of Liquid Hydrogen, (Oxford, Pergamon Press), pp. 9-37. [8] INSTITUTE OF Energy Economics (Ed.) (1984), "Concise Energy Balance Table in Fiscal 1984" (in Japanese). [9] Yamagiwa, Y. and Kuriki, K. (1990), "The Earth’s Ecological and Economic System and Lunar Resource Exploitation," Journal of the Japanese Society for Aeronautical and Space Sciences. 30. No. 441, pp. 516-523 (in Japanese).
RkJQdWJsaXNoZXIy MTU5NjU0Mg==