9.24 Although space colonies date back to Konstantin Tsiolkovskiy (9.7), an electromagnetic launcher appears to be one of the few colonization features he did not think of, being popularized by Heinlein (9.8) and O'Neill (9.9). The following transport linear accelerator (TLA) details and specifications come from a report by Heppenheimer (9.10). Their use for the purposes of this project however, is not the result of an engineering evaluation by the study group of the proposed design or the feasibility of the TLA. The purpose of the lunar launch system is to transport the necessary mass of lunar ore, on the order of one million metric tons, to the assumed colony location at LS. Obviously what is needed for economical transport of such a large mass is a high efficiency, high mass flow launch system with low recurring costs. An obvious candidate in this category would be ~ny sort of catapult or high speed track launcher. The concept analyzed by Heppenheimer uses an electromagnetic suspension and acceleration system, based on a linear synchronous motor and dynamic magnetic levitation, as in proposals for magnetically"levitated and driven trains on the surface of the Earth. The launcher is configured as an oval closed track, with paraallel 15 kilometer-long straightaways. Each launch mass of 10 kilograms is carried in a passive 10 kilogram "bucket",which contains a mass restraint system and superconducting inductance coils immersed in liquid helium. The electromagnetic linear synchronous motor of the accelerator track provides the force necessary to accelerate the rock fragments to 2400 meters/second, lunar escape velocity. The acceleration track is 15 kilometers long, and consists of four segments. The first 10 kilometers of the track provide an initial acceleration of 288 meters/second 2 , with an average applied force on the bucket of 4000 N. Peak current drawn in the linear synchronous motor during this phase is 136,000 amps. Due to final velocity constraints of the system, the track along this 10 km length must be aligned to 1 mm accuracy. Accuracy of payload velocity at the exit of the initial track section is specified as 3 cm/sec, measured by laser doppler to within 2 cm/sec.
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