Solar sail heliocentric elliptic displaced orbits

The orbit of a spacecraft will be a non-Keplerian orbit if forces other than the two-body Newtonian gravitational force are exerted on the spacecraft. The solar sail orbits are always non-Keplerian orbits if the solar sail is not coasting. Three free variables of the solar sail are required to make the solar sail equilibrate at a three dimensional equilibrium point because the force balance condition in the direction perpendicular to the reference plane is time varying. Usually, only two attitude angles can be adjusted for a typical solar sail. Recent advances in reflection control devices (RCD) from Japan enable the adjustment of three free variables of a solar sail. The dynamic equation is non-dimensionalized using a reference Keplerian elliptic orbit around the sun. Their local stability characteristics are investigated using Floquet theory and the results indicate that the equilibria are marginally stable if the sail attitude follows the reference attitude used to generate the equilibrium.