Ballistic cycler orbits, such as the Aldrin-type Earth-Mars cycler and resonant Earth-return orbits, have long been proposed as transportation networks for sustained cargo logistics within the solar system [1, 2, 3, 4]. These trajectories rely on multi-body resonances and carefully phased gravity assists, with little flexibility beyond the highly constrained natural gravitational dynamics.

Solar sails provide continuous, propellant-free thrust that fundamentally alters this solution space and opens families of cycler orbits that either extend or do not exist under purely ballistic conditions. The existence of such solar-sail cyclers for circular-circular orbits was identified by Stevens [5] and Stevens and Ross [6], and has been extended to up to four cycles in [7]. Indeed, it is well known that solar sails can help establish non-Keplerian orbits [8] and even multi-reversal orbits [9].

Systematic approaches to designing ballistic cycler orbits [10] and solar sail stop-over cyclers [11, 12] exist. Preliminary work also exists for circular, co-planar solar sail cycler orbits [7]. However, a general framework for identifying and characterizing sail-enabled cycler geometries beyond circular-coplanar orbits is missing. To build on these works, we explore the design space of solar-sail cycler orbits between both single- and multiple bodies.

To search and characterize these cycler orbits, we start with a multi-gravity assist model with deep space maneuvers (MGA-1DSM). The gravity assists are modeled using the patched-conic approximation, neglecting the time spent inside the planet’s sphere of influence. Restricting the available ?v to solar sail achievable values reveals the existence of such cycler orbits. A direct transcription with a variable segment zero-hold parameterization is used to convert this to a solar sail model. This approach is also free to adjust the timing and parameters of each gravity assist, enabling the optimization of multiple planet-planet segments simultaneously. The solar sail is modeled with a ideal reflectivity, parametrized by its lightness number and cone and clock angles [13]. Final indirect optimization using Pontryagin’s Maximum Principle is done to optimize the multi-segment cycler to minimize relative velocity at each planetary encounter.

We apply our framework to study both self-cycler and multi-body cycler orbits in our solar system and the artificial solar system in the GTOC 13 problem [14]. Self-cyclers, where only a single gravitational body is visited multiple times, are demonstrated for Earth and Eden, whilst multi-body cyclers are shown for Earth-Venus and Eden-Yavin. Our results show that solar sail enabled cycler orbits exist across a range of practical lightness numbers and can be tuned for different frequency and relative velocity requirements, expanding the design space for both ballistic cyclers and stop-over solar sail concepts. As a representative example, in the GTOC 13 problem we identify self-cycler orbits revisiting each of Yavin and Eden every one-third of an orbital period, as well as consecutive Yavin–Eden cyclers with at least 7 consecutive visits and imperfect Yavin–Eden cyclers exhibiting sequences of at least 15 visits.