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 The solution adopted by the team is to earmark a constant-angle wedge corridor for permanent use as a mining robot access road. A 5° angle provides a corridor width of 5 m at the perimeter of the initial 60-m radius seed—comfortably enough room for a mining robot to enter, drop off its cargo, pick up a load of waste materials, and then withdraw. The area of the constant-angle corridor increases as R2. This is the same dependence on radius exhibited by the area of the growing "seed," hence LMF mass, raw materials requirements, and waste production will increase at the same rate as the access corridor which supports interior factory systems. In other words, the expanding corridor prevents internal LMF systems from becoming "landlocked" as seed mass and radius grow exponentially in time.

The wedge corridor geometry is shown in figure 5.39. Note that as the LMF grows larger, mining robots (or any other external transport vehicle) must traverse ever greater distances, on average, to reach the entry corridor. For this reason a minimum of two such corridors should be provided, with the factory organized as two identical halves as suggested in figure 5.19. Further studies will be required to determine the optimum access and LMF configuration geometry from the standpoint of scheduling, efficiency, and access time.

Mining robots deliver raw materials to an input hopper located in the chemical processing sector, as shown in figure 5.40. Outshipments of waste materials are delivered to them in similar fashion. These hoppers serve as materials depots, able to help sustain LMF operations during periods when the supply of lunar topsoil is interrupted for any reason. Since each of the two initial seed robots makes one round trip about every eight hours, a hopper intended to serve as a one-week buffer must have a capacity of 42 mining robot loads or 76,900 kg of lunar regolith. A roughly cubical hopper constructed of 1 cm sheet aluminum and able to contain the weekly input volume of 42.7 m3 has a mass of 1650 kg.

Figure 5.40.—Raw material delivery to input hopper.

5D.5 References

Agin, Gerald J.: Real Time Control of a Robot with a Mobile Camera. SRI International Technical Note 179, February 1979.

Carrier, W. D., III: Excavation Costs for Lunar Materials. Fourth Princeton/AIAA Conference on Space Manufacturing Facilities, Princeton, New Jersey, 14 May 1979, AIAA Paper 79-1376.

Ciarcia, Steve: A Computer-Controlled Tank. Byte, vol. 6, February 1981, pp. 44-66.

Criswell, David R.: Extraterrestrial Materials Processing and Construction. NASA CR-158870, 1978.

Fickett, Arnold P.: Fuel-Cell Power Plants. Scientific American, vol. 239, December 1978, pp. 70-76.

Hart, Peter E.: Progress on a Computer-Based Consultant. SRI International, Menlo Park, January 1975.

Nichols, Herbert L., Jr.: Moving the Earth: The Workbook of Excavation. 3rd ed. North Castle Books, Greenwich, Conn., 1976.

Sacerdoti, Earl D.: Problem Solving Tactics. SRI International Technical Note 189, July 1979.

Sacerdoti, Earl D.: Plan Generation and Execution for Robotics. SRI International Technical Note 209, 15 April 1980.

Toy Robots Gaining Intelligence. Byte, vol. 5, October 1980, p. 186. See also "Inside Big Trak," Robotics Age, vol. 2, Spring 1980, pp. 38-39.

Williams, D. S.; Wilf, J. M.; Cunningham, R. T.; and Eskenazi, R.: Robotic Vision. Astronautics and Aeronautics, vol. 17, May 1979, pp. 36-41. 281