Flexible Satellites: Part I Stability” (79-193). They studied the effects of random torques on the inherent control system errors of a large satellite. They conclude that a flexible three-axis stabilized satellite can be made almost certainly asymptotically stable while the same is not true of a flexible spinning satellite. Session 23 (Symposium on Manned Operations in Space — Advanced Systems) focused on the use of extraterrestrial materials in the support of construction of large space structures and a generalized industrial economy in space and was chaired by Professors H.O. Ruppe (Technical University of Munchen) and G.K. O'Neill (Princeton University). The paper, “Cost Comparisons for Use of Nonterrestrial Materials in Space Manufacturing of Large Structures,” by E. Bock (General Dynamics, San Diego, California) was read to the session by Dr. David R. Criswell. This paper reported the results of a NASA funded systems study of the use of lunar materials for the construction of space power stations. It examined the mining and refining of lunar materials, their transport into space, the construction of SPS components and the assembly of the SPS at the rate of one per year over a 30 year period. It was found that the program size and cost could be expected to be comparable with a terrestrial based SPS program under the ground rules that all facilities would be deployed from earth. Preprint Number 79-115 was available at the meeting. Use of lunar materials to construct the space facilities should be considered in order to reduce start-up costs. David R. Criswell (Lunar and Planetary Institute, Houston, Texas) reported on detailed analysis of possible chemical engineering schemes for the production of industrial feedstocks from lunar materials. It has been established that such processes are definitely within the state-of-the-art of chemical engineering. At least one flow-sheet is available which could be tested at the bench-top scale within one year. The early use of lunar materials to support near-term lunar missions is possible following the completion of a materials development program which can be defined in complete detail on the basis of our present knowledge of lunar materials and make limited use of lunar materials for process verifications. Paper 79-116, “Chemical Processing of Lunar Materials” co-authored by R.D. Waldron, was available at the meeting. Dr. David Smith and Professor R.H. Miller (MIT) presented the paper, “Fabrication Methods for Construction from Lunar Materials” (79-F-117) which examined the systems aspects and details of the construction of components for an SPS. The work is still in progress, but several major findings are available. The space environment appears to lend itself well to the development of a space manufacturing facility, with most operations improved rather than hindered by vacuum and zero-gravity. Much of the research and development of equipment for a space manufacturing facility can be done on earth and necessary space experiments can be done on a small scale in the context of the Space Shuttle. Analysis is continuing on optimum tradeoffs in product and equipment design, production control strategies, maintenance and repair strategies and redundancy levels and more accurate manpower projections. G.K. O'Neill (Princeton University, New Jersey) reported on work with H.H. Kolm (MIT, Cambridge, MA) on “Experimental Data on High Acceleration Mass Drivers” (79-F-118). First test runs have just been started with a 2.5 m mass driver which has 13.1 cm diameter drive coils. Accelerations in excess of 100 gravities have been demonstrated with a non-superconducting bucket and tests with a superconducting bucket which is being constructed at MIT will commence this winter. Projected acceleration is 5,000 m/s2. The test program will concentrate on guidance and accel-
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