A solar power sail demonstrator “IKAROS” deployed its square large membrane successfully by centrifugal force. The deployment consisted of two stages. The flight data suggest that the membrane deployment in the second stage was remarkably non-synchronous. This paper reproduces the non-synchronous deployment behavior using a small experimental model deployed in a vacuum chamber. Then, two kinds of finite-element analyses are conducted to show that the effect of membrane creases may have caused the non-synchronous deployment.
