Fundamentals of circular-to-circular solar-sail transfers around planetary bodies

• Optimal one-revolution planet-centered circular-to-circular solar-sail transfer • Steppingstone for optimal multi-revolution planet-centered solar-sail transfers • Performance depends on the illumination conditions of the orbital plane and the ratio of the sail’s characteristic acceleration to the local gravitational acceleration • Two distinct regimes identified that depend on the illumination conditions of the orbital plane • Dimensionless results valid for any solar sail around a planet orbiting a star The problem of how to optimally transfer between two planet-centered orbits using solar sails remains nearly unexplored. Most of the existing body of knowledge focuses on (blended) locally optimal control laws, often considers open-ended trajectories instead of orbital transfers, or tackles specific mission scenarios, leaving insight into the general transfer problem unexplored. In this work, we present the first step in the comprehensive study of optimal solar-sail transfers around planetary bodies by analyzing the simplest conceivable transfer, the planar circular-to-circular (C2C) transfer. The considered C2C transfer spans only one orbital revolution, which may constitute the future building block of more complex multi-revolution trajectories. The optimized control law maximizes the change in orbital radius within the C2C transfer, where the achieved radius change is used as the performance metric. The results show that the C2C performance (i.e., the ability of the solar sail to transfer) depends on the illumination conditions of the orbital plane and the ratio of the sail’s characteristic acceleration to the local gravitational acceleration. Maximum performance is achieved when the orbital plane is perpendicular to the Sun-planet line, where the transfer structure resembles that of a C2C transfer conducted with an ion drive. Furthermore, by using the ratio as the scaling parameter, the results presented in this paper allow to easily compute the C2C performance for a wide range of mission scenarios around any planetary body, providing a new tool for early mission design.