Design and optimization of low-thrust orbit transfers

NASA's space missions Dawn and JIMO will use low-thrust propulsion for multi-revolution orbit transfers around a central body. Here we address the problem of designing low-thrust orbit transfers between arbitrary orbits in an inverse-square gravity field by using evolutionary algorithms to drive parameter selection in a Lyapunov feedback control law (the Q-law). We develop an efficient and efficacious method to assess, with reasonable accuracy, the trade off between propellant mass and flight time (i.e., to find the Pareto front for these two quantities), and to provide the time history of the state variables and the thrust vector for any chosen point on the Pareto front.