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Introduction This study focuses on how to satisfy space-based power requirements of the Strategic Defense Initiative Organization (SDIO). (Appendix A is a glossary of abbreviations used in this report.) The initial charge for this study included these tasks: ~ Evaluate the planning for the development of advanced space- based high-power technologies to determine the best combination of technology options that should be pursued. . Critique current Strategic Defense Initiative (SDI) power de- velopment plans and objectives. ~ Identify an alternate power program plan that would meet SDI requirements for space-based power. Identify technology development approaches that could lead to enabling power system capabilities for future space-based defensive systems. To examine the relevant but less demanding power needs of other U.S. space missions, the scope of the study was subsequently broadened to include consideration of military space power requirements other than those of SDIO, and of potential civil space power requirements, especially those of NASA, where power will be needed for earth- orbital, interplanetary, and lunar-surface missions. In forming the Committee on Advanced Space Based High Power 6
INTROD UCTION Technologies to conduct this study, the areas of expertise sought included nuclear, chemical, and solar energy conversion systems; space environment; materials science; thermal management; power conditioning and control systems; rotating machinery; puIsed-power generation; and system safety. Biographical sketches of the members of this committee are contained in Appendix B. The committee has had access to classified briefings and publica- tions to provide it with adequate insights regarding activities relevant to the SDI power program and to this study. However, there is no classified information in this report. The study chronology Is summarized in Appendix C. The com- mittee devoted particular attention to briefings and information sup- plied by the Independent Evaluation Group (IEG), a pane] of experts under the leadership of R. Joseph Sovie, NASA I,ewis Research Cen- ter. The lEG was established by the SDIO Power Program Office to provide it with analyses and counsel regarding its programmatic activities. The committee held a meeting in Albuquerque designed to gather up-to-date information from the lEG's Field Support Team centered at Sandia National Laboratories. That team provides the lEG with technical analyses of the ongoing power system architecture studies, and includes personnel from NASA/Lewis Research Center, Sandia National Laboratories, and the U.S. Air Force Space Technology Center. At the outset of the study, the SDIO Power Program Office made available to the committee a number of reports (listed in the Refer- ences) summarizing the results of contractor-performed studies of a variety of power-generating systems. Because of the ongoing nature of these studies, and recognizing certain shifting SDIO priorities, the committee was briefed on current SDIO thinking in October 1987 and January 1988. Military needs for space-based power for non-SD] applications were described by Air Force and Army representatives. The committee also obtained presentations relevant to projected NASA space power needs from Raymond S. ColIaday, then NASA Associate Administrator for Aeronautics and Space Technology, and J. Stuart Fordyce, Director of Aerospace Technology at NASA Lewis Research Center. The committee sought to keep abreast of relevant activities and progress in a variety of technical fields, through the contacts, ex- pertise, and efforts of its members. For example, the committee
8 ADVANCED POWER SOURCES FOR SPACE MISSIONS examined implications to space power of recent research on high- temperature superconducting materials, of progress in defining the NASA Space Station, and of the growing interest in returning to the lunar surface. The committee also took the initiative of reviewing the status and potential of a system that would provide power to space vehicles by beaming electromagnetic energy to orbit from the earth's surface. A forerunner to this study, with emphasis on space nuclear power, was conducted by the Committee on Advanced Nuclear Sys- tems of the National Research Council, under the chairmanship of John M. Deutch. That study led to the report "Advanced Nuclear Systems for Portable Power in Spacer (National Research Council 1983~. In the following chapters of this report, the committee discusses much of the information it acquired, with emphasis on those ele- ments it believes provide a basis for its findings, conclusions, and recommendations. Chapter 2 summarizes the broad space power re- quirements of SDI, other military missions, and civil missions. It also examines approaches to selecting space power technologies to satisfy SDI requirements. Chapter 3 examines available space power system options and some important safety and environmental constraints in- fluencing their selection. Chapter 4 covers the kinds of technological advances needed to meet SDI requirements, and Chapter 5 suggests approaches toward achieving such advances. Chapter 6 examines the current SDI space power R&D program and provides suggestions on how to facilitate its achieving SDI requirements.