Solar Sail Interplanetary Orbit Design for Multiple Main Belt Asteroids Exploration Mission

The most prominent advantage of the solar sail is no propellant. The thrust is continuous, small and the direction is limited by the attitude. To get the time-optimal interplanetary transfer trajectory, an optimal control model for the transfer mission is provided with the characteristic of solar sail. In the dynamic model, the force is just the gravity in the Earth influence sphere, and in the heliocentric coordinates the forces are the solar gravitation and the solar radiation pressure force. The co state initial value normalization method are proposed to avoid the problem of initial value sensitivity. The exhaustion method is used for optimal the targets and sequence. A filter method of tree structure uses the preset thresholds to reduce the computation load. At last, an orbit with flight time 6.78 years is selected and the attitude angular velocity of the huge solar sail is less than 7deg/day.