Design and Fabrication of a Low-Cost Composite Spaceframe Spacecraft Structure

As part of an internally funded research program at Southwest Research Institute a low cost composite spaceframe structure, suitable for use in small satellite applications, has been designed and fabricated. For reasons of low mass, high strength, and dimensional stability composite material was investigated for use as the spacecraft load bearing structure. A design concept was developed that allowed for the use of composite material while minimizing the high cost and long lead times generally associated with fabrication. A large portion of the high cost of using composites is due to the investment in producing a mold. Typically, the high non-recurring engineering (NRE) cost of the mold would be offset by a large production run. When fabricating a single structure, as is common for spacecraft, most of the mold investment is lost. In order to overcome this difficulty, the design concept was an octagonal spaceframe consisting of eight individual wedges bonded together. This allows a single, small, simple mold for the individual wedges to be used repeatedly (at least eight times). In order to prove the concept Texas Composite, Inc. has fabricated a first prototype unit. A second unit has been ordered for a thorough structural and materials test program to be conducted by Marshall Space Flight Center.