Fig. 8. Macrophasing of the SPS project featured by the evolution of major orbital facilities and their demonstration capability. MACROPROJECT PHASE The SPS system is quite definite and simple from the standpoint of system input and output. The input is the solar energy in space and the expected output is the electricity compatible with the present common utility facility. Thus the project objective is simply to develop such a system that can be alternate of the present energy system. The phased project planning developed by the National Aeronautics and Space Administration of the United States is a strong weapon to realize a large and complicated project with definite objectives. It divides the work involved in carrying out a project into phases designated as Phase A, B, C, and D, which include definite works for each and are separated by decision points (11). The SPS project will be also a project for which this method can be applied. Only it should be noted that there are too many factors to set definite works during the anticipated period of project which will be as long as two or three decades, from the first step of concept studies to the construction of the first operational SPS. Thus the phasing concept will be required to adapt to technical progress during long period and will have to incorporate unpredicted innovations for the next phase. For this purpose, a concept of macrophases is introduced, where each phase is featured by a main experimental facility. In other words, the macrophases will be separated by steps of the scale of demonstration of capability to solve various important problems as shown in Fig. 8.
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