equivalent of a factory to be flown in orbit. The energy for this factory will likely be from a solar reflector (15). Other sources require additional mass to be launched to the factory and are therefore more expensive. A. Melting Facilities There are several proposed facilities for the melting and processing of the ET. Three different types will be described in the following sections. They are a tether based facility proposed by Dr. Joe Carroll of CALSPACE (15), a combination ET storage rack and melting facility proposed by Tom Taylor (25), and the materials processing facility proposed by Dave Christensen of Wyle Labs (17). The Carroll facility sections the ET by the use of an Electron beam gun and then uses a 30 - 40 meter (about 115 feet) diameter solar mirror to melt them into a graphite crucible for storage or future use (14, 15). The A-Frame is used for structural strength of the facility. The tether is used for tank storage and the stabilization of the crucible. If the melt (on the order of five tons) is heated sufficiently in the graphite crucible and stored with either a layer of slag or a lid, keeping it molten will not be a large problem. The way that this particular system works is that once the melt is up to temperature, the total energy contained in the melt is so high and the surface area is so small that the losses due to radiation are not significant. The liquid can be drawn off and fabricated to any desired form such as metal flakes or powder for propulsion, metal vapor deposition for thin reflective surfaces, metal for extrusions, metals for metal crystal growth experiments, and metal rope or braided metal rope for tether or construction purposes (56). The Carroll facility is very attractive in that it is relatively simple to set up and operate and does not require a large amount of heavy industrial equipment to be flown. A second type facility would be the combination ET storage rack and melting facility (25). The illustration above proposes a large diameter thin mirror working on an ET. The concept is to melt the entire ET into a molten ball. This would enhance the drag characteristics of the ET on-orbit. For example, 36 ETs could be stored in a ball of about 27 feet in diameter (25). This ball would have two layers. The outer layer would be a crust of slag which includes the remaining SOFI and the miscellaneous metallic portions.
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