2. 9 II.5: COLONY CONSTRUCTION II.5.1: Materials and Refining: The colony structure requires l.98xl0 8 kg of steel, of which 75% is AISI 4130 steel for the plates and 25% is HY-80 or HY-100 steel for stiffeners. Ninety-nine percent of this mass is available from iron, manganese, silicon, and chromium processed from l.46xl0 9 kg of lunar rock delivered unprocessed to LS. Only 2.50xl0 6 kg of alloying elements (carbon, molybdenum, and nickel) are transported from Earth. By-products of the steel production are l.70x10 8 kg of oxygen for the atmosphere and for propellant, 9.9xl0 7 kg of silicon for solar cells, and 9.9xl0 8 kg of slag suitable for radiation shielding. The refining process uses hydrogen reduction, carbon reduction, centrifuge separation, and distillation to produce the required metals. Reducing elements are recovered and recycled. The electrical power consumption of the refining process is 4.57xlo 7 watts. II.5.2: Manufacture and Fabrication: The one-ton steel ingots produced by the refinery are then manufactured into stock parts for the colony by sequences of machinery. This process is schematized in Figure 2.5. The total output of the manufacturing sequences is 600,000 lm x lm hull and bulkhead plates, 1,200,000 lm-long minor stiffeners, pieces for 3,090 major stiffener assemblies, and 3,353,000 nut-and-fastener pairs. The stock parts are then fabricated into the 20m x 20m hull sections and Sm x 20m bulkhead sections described in Section II.4.1. This procedure uses an automated layup bed which positions plates and stiffeners, electron-beam welds the plates to the minor stiffeners and the pieces of the major stiffener assemblies to~ether, drills fastener holes in the welded sections and major stiffeners, and attaches the major stiffeners to the sections. The total output of this prefabrication process is 1020 hull sections and 1050 bulkheads. The electrical power consumption of manufacture and fabrication is l.17xl0 7 watts. An automated control system regulates the production schedules of the refining, manufacture, and fabrication processes, and sets the specifications on each piece produced by the machinery.
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