AN OPTIMIZATION OF A SOLAR SAILCRAFT TRAJECTORY IN AN EARTH-MARS TRANSFER CONSIDERING THE ATTITUDE DYNAMICS

Resumo

The goal of this work was to optimize the trajectory of a solar sailcraft in an Earth-Mars transfer. Solar sailcraft is propulsion system with great interest in space engineering, since it uses solar radiation to propulsion. So there is no need for propellant to be used, thus it can remains active throughout the entire transfer maneuver. This type of propulsion system opens the possibility to reduce the cost of exploration missions in the solar system. In its simplest configuration, a Flat Solar Sail (FSS) consists of a large and thin structure generally composed by a film fixed to flexible rods. The performance of these vehicles depends largely on the sails attitude relative to the Sun. Using a FSS as propulsion, an Earth-Mars transfer optimization problem was tackled by the GEO real algorithm (Generalized Extremal Optimization with real codification). This algorithm is an Evolutionary Algorithm (AE) based on the theory of Self-Organized Criticality. The FSS was able to perform up to 10 maneuvers
until reach Mars. Two angles values are necessary to characterize the FSS film normal vector. Therefore, the GEO real algorithm had to optimize up to 20 design variables in order to minimize the transfer time from Earth to Mars. Once the optimized control law and the FSS trajectory were obtained, the attitude equations of motion were considered. Finally, the impact of this consideration in the FSS control law performance was evaluated. Keywords: Solar sailcraft, Trajectory optimization, Evolutionary algorithm, Attitude dynamics, Generalized Extremal Optimization.