on design and technique options are recommended, as are evaluations to determine productivity rates in space. Reference E5, the NASA forecast for 1980-2000, states that considerable effort will be required to learn how to assemble and control huge structures, and that this will undoubtedly require considerable advancement in our abilities to carry out human EVAs. This document further states that a program to meet these requirements can be laid out with confidence. The requirement for automated, or robot/teleoperator construction mechanisms was considered in Ref. A9. This document proposes a movable, orbital construction facility. Support equipment would include a traveling crane, a movable manipulator crane with a manned, end-effector and teleoperator arms. The manipulator is described in some detail, and reference is made to NASA's remote manipulator simulation facility. In addition, Ref. E5 forecasts advances in the areas of robots and teleoperators . Other requirements and considerations that will play a role in the space assembly/construction of an SPS include the atmospheric drag that will occur in LEO (Ref. A4, E9). Some type of propulsion system for orbit adjustment will probably be required to maintain this altitude. Also, ground station contact for a LEO-based activity is mentioned in Ref. E9. The coverage per pass must be considered for any such approach. Thermal stresses at eclipse, possibly causing vibration of large structures (Ref. A2) are expected to occur throughout the life-cycle of the SPS. The effect of this on manufacturing activities would have to be considered. Another factor concerns the control of surface flatness, especially for the relay satellite. Reference A4 states that for reflectors, this must be held to 40 mils (1 mm) over a 0.4 square mile 2 (1 km ) surface. Reference A13 (JSC) discusses the trade-offs between deployable structures and space-construeted structures and states that for low density payloads, foldable, deployable elements would have advantages. Reference A4 points out that to meet structural requirements, a "spider web" type structure is attractive and could be deployable.
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