On-Orbit Verification of Attitude Dynamics of Satellites with Variable Shape Mechanisms using Atmospheric Drag Torque and Gravity Gradient Torque

We developed the variable shape attitude control demonstration satellite HIBARI at Tokyo Institute of Technology, and it was launched by a JAXA Epsilon rocket in November 2021. We are planning on-orbit verification of attitude dynamics using HIBARI. We will verify attitude dynamics around the equilibrium point in orbit in order to confirm the feasibility of attitude control using the change of equilibrium point due to the shape change under the disturbance torques. In this paper, we describe about the plan and preliminary simulation results for the the on-orbit experiment. We perform stability analysis to find the shapes with Lyapunov stable equilibrium points, and select the two shapes with different equilibrium points for the simulation. In addition, we decide the experimental sequence based on the operational mode of HIBARI, and simulate according to the experimental sequence for each shape under environment simulated on-orbit. It shows that the satellite attitude oscillates around the Lyapunov stable equilibrium point, and that the equilibrium point is changed due to the change of the satellite shape. The results of simulation show that the on-orbit experiment is feasible.