Artificial Equilibrium Orbital Configurations by Means of Continuous Thrust

Keplerian dynamics usually dictates the orbital configuration for a space mission. The fulfillment of special requirements, however, can require that a spacecraft maintains a certain distance from the position of keplerian equilibrium. This can be true for low Earth orbits and for three-body problems. The natural equilibrium position can be occupied by another satellite or it can be simply a reference orbiting point. Such a non-keplerian configuration, also called artificial equilibrium, can be maintained only if continuous thrust – provided by low Isp motors or solar sails – is applied. In the present paper, the maps identifying the equi-thrust regions for the two- and the three-body problem are reported. Once the space regions requiring a defined value of the thrust (in module) are detected, a control strategy for passing from an artificial equilibrium to another without changing the thrust level is proposed. In such an approach, therefore, the orbital maneuver is accomplished by means of an attitude change only, allowing for a remarkable simplification of the guidance and control systems.