Analysis of a class of Earth-Mars cycler trajectories

Sun-orbiting spacecraft trajectories that repeatedly encounter Earth and Mars may play a central role in a future Earth-Mars transportation system. Such orbits are known as Earth-Mars cycler trajectories (cyclers). By using gravity-assist maneuvers at Earth or Mars, many cyclers can avoid using large amounts of propellant. The known cyclers were found using heuristics or numerical searches. We describe a new, systematic method for constructing and evaluating cyclers. Our method reveals that previously known cyclers, such as the Aldrin cycler and the Versatile International Station for Interplanetary Transport cyclers, belong to a larger family of cyclers. Our cycler construction method also reveals some previously unknown cyclers. For example, we identify a new cycler that repeats every two synodic periods and has a low V-infinity at Earth and Mars (5.65 and 3.05 km/s, respectively).