Deployment experiment for ultralarge solar sail system (ultrasail)

UltraSail is a next-generation high-payoff system with very large (kilometers-squared class) solar sails enabling high payload mass fractions for high Delta-V. One of the primary innovations is the near elimination of sail supporting structures by attaching each blade tip to a formation-flying tip satellite. To design the deployment of kilometers-long blades by centrifugal force provided by tip satellites, the peel force of the blade material must be known. In this research, an experiment to determine the force necessary to deploy a stowed film in a vacuum was designed, fabricated, and operated for various CP-1 polyimide film samples, including uncoated, aluminum-coated, and uncoated but conductive film. Results for uncoated film samples were heavily dependent on vacuum levels, with very high forces observed at low pressures due to electrostatic charge buildup. However, for the coated film and conductive film samples, the types most likely to be used on an UltraSail mission, preliminary results show that the peel forces are negligibly small. This small peel force is critical for the successful, simple, and efficient deployment f the UltraSail system. A potential problem associated with trapped air between film layers was identified by the experiment, and a future winding scheme will guard against this issue.