AFRL Develops Solar Sails for Space Missions Published May 6, 2008 By Eva Blaylock Space Vehicles Directorate KIRTLAND AIR FORCE BASE, N.M. -- AFRL engineers developed a micro solar sail concept with unique deployment features that promote its usefulness for many new Department of Defense space missions. The concept's robust deployment scheme enables simultaneous and deterministic deployment of both masts and main sail. Rather than relying on mechanical joints typical of a planar space structure, this architecture utilizes elastic deformation to enforce deployment kinematics. The four column-loaded, cruciform-configured, self-deploying, triangular, rollable and collapsible masts support a perimeter of outer spar members that are continuously tensioned throughout deployment. This scheme enables the spars and membrane film to unfold in a deterministic manner, giving the system exceptional dynamic stiffness levels during deployment. Since the masts are self-deploying, the central actuator's only function is to control deployment rate. AFRL engineers constructed a 7.5 m2, full-scale prototype of the micro solar sail concept to demonstrate feasibility of the unique structural architecture. The prototype includes a central hub and deployment mechanism, support masts, main sail film, radial cords, and spars. This prototype completed dozens of nearly flawless deployment cycles that verified basic system functionality and demonstrated critical function and robustness of the carbon-fiber-reinforced plastic spar members. To validate the highly nonlinear finite element techniques used to analyze structural performance, the engineers took a series of photogrammetric measurements of the perimeter spars at several instances during deployment and compared this data to structural analysis predictions. Further development efforts are under way to advance the concept's readiness level.