Verification of a Retractable Solar Sail in a Thermal-Vacuum Environment

A full-scale, 10m, flight-like, retractable solar sail prototype has recently undergone environmental deployment testing, shape surveys, deployment kinematic measurements, and structural analysis predictions in an effort to demonstrate that this payload can be qualified for flight. The large deformation, elastic strain-energy mechanics used to enforce the deterministic unfurling and refurling of the Flexible Unfurlable and Refurlable Lightweight (FURL) solar sail were predicted using finite element structural analysis techniques. These structural models were validated by comparison to shape surveys of the EDU2 system and by comparison to component level strength testing. The EDU2 system was verified to meet driving functional requirements by enduring four thermal cycles and 50 deploymentretraction lifecycles in a thermal-vacuum environment and an additional 25 hands-off cycles in an ambient environment. This testing and analysis activities have established confidence that the flight system will endure dozens of deployment-retraction cycles on-orbit. Overall these efforts have demonstrated the robustness of this FURL solar sail system to serve as a propellant-free thrust source for small satellites.