Understanding of what is achievable with solar-sail technology around planetary bodies is in its infancy. The seemingly simple problem of transferring from one circular orbit to another circular orbit with a solar sail around a planet is yet to be fully characterized. This work aims to start filling that gap by analyzing the coplanar patched multirevolution circular-to-circular (PMC2C) transfer. The PMC2C transfer is a continuous sequence of single-revolution circular-to-circular (SC2C) transfers, where each SC2C transfer is optimized for the achieved radius change in one orbital revolution. Then, the radius change and transfer time of a PMC2C transfer is obtained as the aggregation of the individual SC2C increments. To generalize to all initial geometries, hundreds of PMC2C transfers must be computed, which is not feasible in practice. To bypass this problem, the so-called patched method is proposed. The patched method uses a semianalytical approach to estimate the radius change and the transfer time of the PMC2C transfers, effectively removing the need for numerical optimization. Dimensionless in nature, the patched method can be used for any sail design around any planet orbiting a star. With this tool, early mission design is greatly simplified; hundreds of trajectories can be analyzed in a matter of minutes. In addition, the generalized formulation reveals the best and worst orbital geometries and initial epochs to start a PMC2C transfer, improving general knowledge of how to “sail” around planets.

The problem of how to solar sail around planets remains nearly unexplored. Most of the existing body of knowledge focuses on scape trajectories or locally optimal controls, not providing much insight into the inherent physical characteristics of the transfer problem. In this work, we present the first comprehensive study of solar-sail transfers around planetary bodies by analysing the simplest conceivable transfer, the planar Circular-to-Circular (C2C) transfer. The C2C transfer spans for only one orbital revolution, constituting the building block of more complex multi-revolution trajectories. By patching together a series of C2C transfers, a feasible initial guess for trajectory optimisation algorithms can be generated. The optimised control law maximises the orbital radius within the C2C transfer. The radius change is used as performance metric. The results suggest that the domain of the control variables can be substantially reduced, effectively enhancing convergence of the optimal control solver, and significantly reducing computational time. Furthermore, a dimensional analysis shows that the C2C performance only depends on one parameter: the ratio of the sail’s characteristic acceleration over the local gravitational acceleration. The scaled nature of the results allows 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.