Space Studies Institute Report on Space Shuttle External Tank Applications by J. Alex Gimarc 12-01-1985 copyright Space Studies Institute end and force the melt out the other end (92). It may be possible to use this furnace to form extrusions directly without the use of a press. This furnace would solve some of the mass problems inherent in handling liquid metals in a weightless environment. Dr. Andrew Cutler of CALSPACE feels that this type facility can be flyable for under 15,000 pounds mass (18, 20, 92). This furnace could use gravity gradient stabilization to help stabilize long slender extrusions. Early studies of chemical processing of the ET indicate that it is more expensive in terms of energy (30 - 40 times) and launch mass than when using a thermal (reflected solar) furnace (56). For this reason, operations that discuss chemical manipulation of the SOFI and other ET minor parts have been addressed only in a minor way in this report. Undoubtedly, this will happen in the future. However, thermal materials processing will be the starting choice of near future operations due to lower energy and launch mass requirements. The barrel of the ET has also been proposed as the base for a solar furnace (56). It is pictured below. Film deposition on the ET exterior may be used to retard SOFI outgassing. Finally, the ET itself could be used as very large diameter spool for extruded wire or cable. V. Strongback The use of the ET as a strongback takes advantage of the strength build into it as a base for construction. This has been referred to as a bedplate, a strongback, a base, or a station itself (56, 95). This concept provides mass and rigidity for operations such as space stations, satellite retrieval and repair, space antenna and reflector construction and flight, and pilot plants for goods and services. The recent evolution of the space station structural design from the Power Tower to the Dual Keel shows that structural strength and safety are very important to future planners (8). Once again, the ET can provide a very large strong object on-orbit for a minimal cost. An early proposal by General Dynamics/Convair recommends the use of the Enterprise and an ET/ACC as an initial relatively inexpensive space station (56). The rationale here is that the Enterprise will never fly without massive reconstruction. In order to get some operational use out of it, the
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