Multifunctional Deployment Hinges Rigidified by Ultraviolet

John H. Glenn Research Center, Cleveland, Ohio

Multifunctional hinges have been developed for deploying and electrically connecting panels comprising planar arrays of thin-film solar photovoltaic cells. In the original intended application of these hinges, the panels would be facets of a 32-sided (and approximately spherical) polyhedral microsatellite (see figure), denoted a PowerSphere, that would be delivered to orbit in a compact folded configuration, then deployed by expansion of gas in inflation bladders. Once deployment was complete, the hinges would be rigidified to provide structural connections that would hold the panels in their assigned relative positions without backlash. Such hinges could also be used on Earth for electrically connecting and structurally supporting solar panels that are similarly shipped in compact form and deployed at their destinations.

A **Polyhedral Assembly of Solar Panels** would be deployed from compact stowage in two stacks, each containing ten hexagonal and six pentagonal panels. The deployment hinges between the panels would be key components that would accommodate the unfolding during deployment, hold the panels in their proper alignments after deployment, and provide electrical connections for the panels.

As shown in section A-A in the figure, a hinge of this type is partly integrated with an inflation bladder and partly integrated with the frame of a solar panel. During assembly of the hinge, strip extensions from a flexible circuit harness on the bladder are connected to corresponding thin-film conductors on the solar panel by use of laser welding and wrap-around contacts. The main structural component of the hinge is a layer of glass fiber impregnated with an ultraviolet-curable resin. After deployment, exposure to ultraviolet light from the Sun cures the resin, thereby rigidifying the hinge.

An ultraviolet-transparent polymer film is bonded to the outer surface of ultraviolet-curable layer and the adjacent surface of the solar-panel frame. The outermost surfaces of the assembly of all of the aforementioned components are coated with a layer of indium tin oxide and magnesium fluoride that has several desirable properties:

In the original intended satellite application, it would protect the underlying polymeric components against erosion by monatomic oxygen in low orbit around the Earth;
It is sufficiently ultraviolet-transmissive to enable curing of the resin by exposure to ultraviolet light from the Sun or another suitable source;
It exhibits improved (relative to prior coating materials) transmittance of visible light for collection by solar cells; and
It resists darkening under long-term exposure to ultraviolet light.

This work was done by Thomas W. Kerslake of Glenn Research Center; Edward J. Simburger, James Matusmoto, Thomas W. Giants, and Alexander Garcia of The Aerospace Corporation; Alan Perry, Suraj Rawal, and Craig Marshall of Lockheed Martin Corp.; and John Kun Hung Lin, Jonathan Robert Day, and Stephen Emerson Scarborough of ILC Dover, Inc. For further information, access the Technical Support Package (TSP) free on-line at www.techbriefs.com/tsp under the Materials category.

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