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“ If the electrophoretic potential is positive or negative, a particle moves towards one of the electrodes in the system. The direction of movement depends on the relative charge signs of the particle and the electrode, and the velocity is a function of the magnitude of the electrophoretic potential. If the potential of a particle is zero (the isoelectric point) , particles remain stationary and suspended. Electrophoretic separation depends on differential migration rates for particles in the bulk suspension medium (although electrode-reaction electrophoresis is employed for electroplating) . ”

“ The first alternative is impractical, as large structures contrived to reduce tensile stresses on basalt components would be difficult to design and of limited utility. Compound basalts could be prepared by sintering basalt-sodium flux materials and imbedding the melt with a cross-hatched pattern of basalt filaments to increase tensile and shear strength without sacrificing rigidity. (The sodium flux reduces the fusion point of the mixture so that the basalt filaments do not themselves melt.) ”

“ As on Earth, a continuing tradeoff between availability of primary materials, processing options, and substitution of materials can be expected. Systems designed for the Moon might not be appropriate for Mars, an iron asteroid, or Titan. Still, most of this section describes silicate minerals processing as these are the dominant components of lunar soil and seem likely to be representative of the composition of many asteroids, Mercury, and the moons of Mars. ”

“ The compressional strength and elastic modulus are quite high; that is, basalt as a construction material is far more rigid than other substances listed, a quality of some importance in large space structures. One drawback is tensile strength, roughly an order Of magnitude lower for basalt than other typical construction materials. This problem can be overcome either by designing structures such that basalt components are not exposed to high tensile or extensional stress states or by producing a compound basalt reinforced with fibers. ”

“ One technique - high-voltage zone electrophoresis -- is particularly well-suited to lunar soil separation because it is a one-step, self-automated separation method. Typically, a tank is filled with suspension medium into which two electrodes are inserted. Filter paper is mounted on both electrodes. When an electric field is applied, mineral particles move toward the filter paper and are trapped in various positions along its length. Each mineral phase migrates to a discrete area depending on the magnitude and sign of the electrophoretic mobility. ”

“ Electrophoretic separation appears highly adaptable to automation. The process itself is largely self-regulating and the collection of separated minerals appears to be a trivial robotics task. An automated biological electrophoresis system already has been designed and is under construction (Bartels and Bier, 1977) .
An automated high-voltage zone electrophoretic separation system for lunar materials might require a large tank with two electrodes and filter paper (perhaps comprised of spun basalt fibers) suspended between them. ”

“ The team concludes that significant multiplication of resources at LEO is attainable if part of the propellant required to run the system is drawn from the Moon. Lunar oxygen production allows 4.82 kg of raw material to be brought to LEO from the Moon for every kilogram of hydrogen lifted from Earth. If the OTV is removed, this multiplier factor rises to 4.92. Production of silanes as well as oxygen may allow 7.74 kg of raw material to be brought to LEO from the Moon for every kilogram of Earth-supplied hydrogen. ”

“ Lunar soil is introduced via the input port into the suspension tank. Lunar soil goes into suspension and begins to separate and move towards the electrodes. Individual mineral species move towards the electrodes along paths and with velocities which are a function of their electrophoretic potential. Various mineral species are trapped and plated onto a bond of filter paper continuously rolled through the suspension tank. ”

“ Early work in France involved substituting melted basalt for glass and was not directed toward improving.the product over the raw material. German researchers advanced another step by evolving a technology for recrystallizing the melt and casting it into simple shapes. The Soviet Union began experimentation with basalt in the 1930s at the Moscow Rock Foundry Works. Processed basalt currently is being manufactured either on a pilot or factory scale in Czechoslovakia, Poland, Sweden, Italy, and the United States. ”

“ Even more revolutionary is the concept of an impulse launcher to lift cargo off the surface of the Earth (Mongeau et al., 1981) . If payloads are of sufficient size and are projected almost vertically, atmospheric resistance reduces velocity by only about 15% (see Kolm in Grey, 1977) . Since the launch must be nearly perpendicular to minimize atmospheric drag, it is not feasible to supply a LEO station directly. (About 7 km/sec of horizontal velocity would have to be added after launch, so there would be no advantage in using an impulse launcher.) ”

“ Both continuous and staple fibers can be made from basalt. Continuous fibers are produced using standard glass fiber production equipment. After the feedstock is fused in an electric furnace, the melt is fed to electrically heated platinum.rhodium bushings containing 200-300 perforations. As shown in figure 4.7 (Subramanian et al., 1975) , a drum winding pulls the fibers from the platinum.rhodium bushing perforations. Fiber diameter is a function of melt temperature and drum or centrifugal nozzle speed. ”

“ There will be only moderate initial supply from Earth and very limited resupply thereafter. A LEO facility able to accept raw lunar stock and a very small factory able to extract oxygen from and load lunar soil into arriving spacecraft for Moon-to-LEO transport are assumed already to exist. ”

“ Figure 4.8.- Tensile strength of epoxy resin composite DGEBA reinforced by untreated and silane A-1100 treated basalt fibers. Figure 4.9.- Tensile modulus of epoxy resin composite (DGEBA) reinforced by untreated and silane A-1100 treated basalt fibers. Processed or machined basalt has been suggested as a logical construction material with which to produce the component parts Of large space and lunar structures. The strength of this basalt and of other construction materials must be compared. ”

“ In addition, the material must be fine-grained, homogeneous, unweathered, nonporphyritic, and uncontaminated. A melting temperature range of 1500-1600 K must be associated with a relatively low viscosity (100-1000 poises) in order to cast well. ”

“ BH = 1/9 a = B = 0.038 δV1 = 3.2244 km/sec δV2 = 0.84303 km/sec δV3 = 1.69147 km/sec δV4 = 2.51872 km/sec X = 0.39718 dMHlift/dP = 0.2075, so the multiplier is (0.2075) -1 = 4.82 kg of extra payload gained for every kilogram lifted to LEO from Earth. ”