Ground demonstration of a spinning solar sail deployment concept

We describe laboratory experiments to investigate the dynamics of spin deployment of a solar sail concept, originally intended for the Interstellar Probe Mission. The spin-deployment concept is first described. A series of three experiments with increasing degrees of complexity were designed and performed and culminated in spin deploying a small-scale solar sail 2.5-μm-thin Mylar® film, 80 cm in diameter. The objectives were to explore the feasibility of the deployment concept and any related handling issues and to discover/understand possible modes of instability. To gain insight into the practicality of the deployment scheme, a tether configuration emulating the sail film was first deployed successfully in air and gravity. A 120-μm nylon film was then used for the sail deployment experiment, also in air and gravity. These two initial experiments were particularly useful for refining the experimental setup and handling procedures. Even though the influence of air drag and gravity was apparent, both of these experiments deployed without entanglements. With theexception of some handling issues, the ultrathin 2.5-μm Mylar film was successfully deployed in vacuum without entanglement. Design details and observations of these experiments are discussed. An approach to model numerically the spin-deployment dynamics is also described, and the results of simulating the dynamics of tether deployment are given.