Displaced Solar Sail Orbits Around Asteroids with Free Angular Velocity

This paper investigates displaced solar sail orbits around an asteroid, characterized by free angular velocity and the orbital plane that is always perpendicular to the direction of solar illumination. It enables precise control of orbit shape and spatial orientation, as well as improving coverage to the asteroid under varying sunlight directions. It is found that the angular velocity must be constrained within certain bounds to ensure controllability, which can lead to full orbit circles or orbit arcs in the inertial frame. A nonlinear controller is designed to track real-time-required attitude angles [Formula: see text], incorporating a [Formula: see text]-switching strategy to ensure bounded angular velocity. A novel mission concept of long-term displaced orbit around 433 Eros throughout its heliocentric orbit using available solar sail technology is proposed based on the preceding studies.