laboratory; larger-scale tests which should demonstrate realistic thruster efficiencies are planned for the next few months. Although there is considerable development work to be done, no major advances in physics or technology are needed to build a launch system using CO2 lasers; large FELs offer even more possibilities in a slightly longer term. In either case, beamed laser energy and the uniquely simple flat-plate thruster offer the first real near-term competition to rockets for getting into space. ACKNOWLEDGEMENTS The author gratefully acknowledges extensive discussions with Arthur Kantrowitz, Dennis Reilly, Lowell Wood and numerous laser propulsion researchers. This work is supported by the Directed Energy Office of the Strategic Defense Initiative Organization, and performed by the Lawrence Livermore National Laboratory under the auspices of the US Department of Energy, contract No. W-7405-ENG-48. REFERENCES [1] Kantrowitz, A. (1972) Propulsion to orbit by ground-based lasers, Astronautics and Aeronautics, 10, May, pp. 74-76. [2] Jones, L.W. & Keefer, D.R. (1982) NASA’s laser-propulsion project, Astronautics and Aeronautics, 20, September, pp. 66-73. [3] Frisbee, R. H., Horvath, J.C. & Sercel, J.C. (1984) Space-Based Laser Propulsion for Orbital Transfer, JPL D-1919, Jet Propulsion Laboratory, December. [4] Details of the double thruster, and additional background information on laser propulsion, are included in: J. T. Kare, (Ed.) (1987) Proceedings of the 1986 SDIO/DARPA Workshop on Laser Propulsion, LLNL CONF-860778, Lawrence Livermore National Laboratory, August, Vols 1 and 2. [5] Nelson, J.E., Mast, T.S. & Faber, S.M. (Eds) (1985) The Design of the Keck Observatory and Telescope, Keck Observatory Report No. 90, University of California and Californial Institute of Technology, January. [6] US Congress, Office of Technology Assessment (1988) Launch Options for the Future: a Buyer’s Guide, OTA-ISC-383, July, p. 20 (Washington, DC, US Government Printing Office). [7] Redd, F.J. (Ed.) (1988) Proceedings of the Second Annual AIAA/Utah State University Conference on Small Satellites, Utah State University, September 1988.
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