Solar sail orbital motion about asteriods and binary asteroid systems

Abstract

While SRP is often considered an undesirable effect, especially for missions to small bodies like asteroids and binary asteroid systems, this paper utilizes the SRP on a solar sail to generate artificial equilibrium points (AEPs) and displaced periodic orbits in these systems. While the solar sail dynamics for the single asteroid case are described using the Hill + SRP problem, those for the binary system are either described in the Hill four-body + SRP problem or the full bicircular + SRP problem. The results for the single asteroid case include solar sail acceleration contours to remain stationary with respect to the asteroid on either the Sun-lit or dark side of the asteroid and either in or above its orbital plane. Using a combination of analytical and numerical methods, i.e., the Lindstedt-Poincaré method and a differential corrector, orbits around these AEPs can be found. By switching to the Hill four-body problem and employing a direct multiple shooting method, these orbits can be extended to a binary system where the effect of the smaller asteroid is an oscillatory motion around the orbits found for the single asteroid case. Finally, by switching to the bi-circular + SRP problem, AEPs can once again be obtained, though their location becomes timedependent due to the changing direction of the Sun-vector. However, high above the binary system's orbital plane, the AEPs trace out a circular orbit that suggests the existence of so-called pole-sitter-like orbits. Using an analytical inverse method and a numerical differential corrector, the results indeed show families of solar sail periodic orbits above the binary system's orbital plane. Though all orbits, both in the single asteroid case and the binary system, are linearly unstable, they exist for near-term solar sail technology and for a simple steering law where the sail remains at a fixed attitude with respect to the Sun. These orbits therefore allow unique, geostationary-equivalent vantage points from where to monitor the asteroid(s) over extended periods of time.