NASA SP-413 — SPACE SETTLEMENTS — A Design Study
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During acceleration the payload is tightly held in the bucket, but when lunar escape velocity is reached and the velocity is correct the payload is released. Since the bucket is constrained by the track to follow the curve of the lunar surface, the payload rises relative to the surface and proceeds into space. Each bucket then enters a 3 km region where a trackside linear synchronous motor decelerates it at over 100 g. It is returned to the loading end of the track along a track parallel to the accelerator.
TABLE 5-15 — LUNAR BASE POWER REQUIREMENTS System Power, MW Launcher 192 Mining 0.7 Compaction 7.15 Living quarters .15 Total 200
At the load end of the track the liquid helium used to cool the superconducting magnets is replenished, and a new payload loaded. Then the bucket is steered to the start of the accelerator for another circuit. Figure 5-19 shows the mass launcher schematically. More details are given in appendix F.
With a 70 percent duty cycle, this system can launch 1.1 Mt/yr. To assure this duty cycle during lunar night as well as lunar day, two complete mass launchers are necessary. A nuclear power plant rather than a solar plant is required so the operation can continue through the lunar night.
TABLE 5-13 — ANNUAL MASS IMPORTS Imports Crew consumables Maintenance supplies Crew rotation* Atmosphere leak replacement Total
Mass, t/yr 270 100 14 18 402
* The same mass is also transported from Moon to Earth.
TABLE 5-14 — LUNAR BASE EARTH-SUPPLIED MASS System Mining and conveyor system Housing and life support Technical support Launcher Power plant (200MW + 10%)
Mass, t 250 2,400 500 4,000 9,900
Total
17,050
Power and Supply Several nuclear reactor single-cycle helium-Brayton plants of 10 to 50 MW each are used instead of a single big plant because the smaller plants can be transported assembled and become ready to operate by use of space shuttle main engines. The redundancy of several smaller systems is attractive, especially since the plants need to be taken off-line for refueling every year or two. The total capacity is 220 MW and the total mass is 9900 t, including a 10 percent design factor. The mass of the power plant is estimated using the value of 45 t/MW, which is projected to be applicable to nuclear plants within the decade.1 Shielding will be provided by lunar material. 1
Austin, G., NASA-Marshall Space Flight Center, personal communication, June, 1975.
Figure 5-19 — The mass launcher.
Chapter 5 — A Tour Of The Colony