A Deployable Stiffened Biconvex Mast

Deployable structures are a common spacecraft configuration feature. Deployables are used to configure spacecraft inertia properties, provide expanded antenna aperture and solar array area, or to provide separation between spacecraft components. Lightsat design would be especially enhanced by small size lightweight deployable structures. A review of the state of the art of deployable structures has been conducted and shows that these devices can be divided into two categories: one, rollable mast of the stem, bistem, or stacer types; and two, folding trusses. The rollable masts are generally of open section and susceptible to thermal excitation. Folding trusses are not available in small size. To address these design challenges, a rollable closed section biconvex mast was design, constructed, and experimentally evaluated. The mast was constructed of composites to obtain high stiffness and low weight and to exploit the relative ease with which a shaped cross section can be fabricated. The mast has a lenticular cross section that can be flattened to allow it to be stowed around a drum. Once on orbit, the mast is unrolled and opens up to the lenticular cross section. A novel stiffener has also been developed which increases the capability of the section. Design characteristics and test results are presented.