Construction Ways of a Space Solar Power System with Gravity Gradient Stabilization under Disturbance Torque

Abstract

A Space Solar Power System (SSPS) has been proposed at the Institute for Unmanned Space Experiment Free Flyer and ISAS/JAXA. The objective of this paper is to evaluate the attitude stability of the SSPS under construction. At first, we investigate "line construction", where the modules are arranged in the shape of line. Through approximate estimation, it is shown that the roll and yaw angular frequencies of attitude motion are twice and once of the orbital angular velocity in the first step of construction, respectively. Furthermore, through dynamical analysis, roll and yaw angles tend to divergence in first step. To avoid such a divergence, we consider another construction way, "construction with similarity", where satellite is constructed keeping similar configuration. From the analysis, it is shown that divergences in the roll and yaw angles can be avoided in the construction with similarity. However, the resorting torques around the pitch and yaw axes are weak in the first step when the SSPS is constructed with similarity. In particular, maximum amplitude around the yaw axis becomes about 29 degrees. Therefore, for both construction ways, active attitude control is desired in first step of the constructions.