Heliogyro Orbital Control Authority

Solar sailing is an elegant form of space propulsion that reflects solar photons to produce thrust. Different sail configurations exist, including a traditional flat sail (either square- or disc-shaped) and a heliogyro, which divides the sail membrane into a number of long, slender blades, analogous to a helicopter rotor. The magnitude and direction of the induced thrust force depends on the sail’s attitude with respect to the Sun, i.e. on the cone angle. At each cone angle, a flat sail can only generate force of particular magnitude and direction, while this paper demonstrates that a heliogyro can arbitrarily reduce the magnitude of the thrust vector through the additional control of pitching the blades. This gives the heliogyro more force control authority, which is exploited in this paper for orbital control. A linear-quadratic regulator feedback controller is used to quantify the maximum error in the injection state vector of a solar sail Sun-Earth sub-L1 halo orbit from which the nominal orbit can still be recovered. The conclusion is that approximately an order of magnitude larger error in position and velocity can be accommodated, demonstrating superior capabilities of the heliogyro over a flat sail for orbital control.