8. 3 processing is done on the Moon itself, but the lunar mining operation is located where high concentrations of the needed materials are found in the lunar rock. Unprocessed rock is launched from the Moon by the Transport Linear Accelerator and transported to LS by the Orbital Transfer Vehicle (see Section IX.l). Table 8.1 shows the mass percentages of elements in lunar rock and soil. Steel has been chosen as the primary construction material, so an area with a high concentration of iron is used as the mining site (Apollo 15 data is, therefore, assumed to apply). Silicon is needed for the light window and solar cells, and is present in quantities far in excess of requirements. Oxygen is also available for use in the colony atmosphere. Some elements needed for the steel alloys are also present in sufficient amounts. A few alloying elements are needed from Earth, along with carbon and hydrogen for the refining process, and nitrogen for the colony atmosphere. VIII.2.2: Materials Requirements: The structure requires l.98xl0 8 kg of steel, of which 75% is AISI 4130 stee~ for the plates, and 25% is HY-100 (or similar) steel for the crack stoppers. Table 8.2 gives the steel alloy compositions. Manganese, silicon, and chromium are available in lunar rock in greater percentages (relative to iron) than needed. Alloying elements needed from Earth are Carbon: S. 45xl0 5 kg Molybdenum: 4.93xl0 5 kg Nickel: 1. 46xl0 5 kg for a total requirement of 2498 metric tons to be transported from Earth. The production of the iron required calls for l.46xl0 9 kg of unprocessed lunar rock at LS. Major by-products of the refining are l.70xlo 8 kg of oxygen, 9.9xl0 7 kg metallurgical grade silicon, and 9.89xl0 8 kg of slag. (These figures do not correspond to the percentages of elements in lunar rock, but represent the capabilities of the refining system.) Five years are allotted to build the prototype, requiring a refinery output of 1.25 kg/sec of iron, and an input of 9.23 kg/sec of unprocessed rock.
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