Analysis of Sail Deformation Based on Attitude Motion of Spinning Solar Sail

Abstract

The attitude motion of the spinning solar sail IKAROS was unique. Its behavior is highly dependent on the deformation of the flexible sail, which is easily changed by the attitude motion. Therefore, it is important to understand the relation between the sail deformation and the attitude motion in order to obtain better knowledge of sail design and management. In this study, a consideration is made about how the sail deformation varies according to the spin rate of the solar sail and how it changes the attitude motion from the view point of the structure. As a result, it was revealed that the variations of the parameters of the sail deformation and the attitude motion are proportional to the squares of the spin rate. The theory is evaluated by using the flight data of IKAROS, its sail shape is estimated, and its equivalent Young's modulus is calculated, which is an index of how much the sail with wrinkles stretches when the force is applied to it.