Fig. 17. Basic structural element Fig. 18. Automated beam builder will need to package its construction materials in a very dense form. The need to construct very-low-density lightweight systems from high-density materials leads to a requirement for automated fabrication techniques. Such techniques will allow the payloads to be densely packaged for launch in the form of tightly wound rolls of construction materials. Since repetitive operations are more readily automated, regular uniform-crosssection structural members are planned for use in construction of the satellite. Figure 17 illustrates the basic structural element of the satellite. A process similar to the familiar roll forming of light sheet metal members has been adapted (20) to produce these structural members at a rapid pace using an automated beam builder (Fig. 18). This machine consists of roll-forming, heating and cooling, and ultrasonic welding components which function to “extrude” a finished beam. These basic structural members may be produced from rolls of aluminum strip stock or from a graphite fiber/thermoplastic-impregnated roll. The latter material has the advantages of a high modulus and a low coefficient of thermal expansion. The basic structural element of the satellite, a triangular crosssection shape, may be assembled into primary-structure triangular trusses (Fig. 19).
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