Cycler Paths

A cycler path (aka Aldrin-Cyler Oath, Cyclers) is a trajectory that encounters two or more bodies regularly. Once the orbit is established, no propulsion is required to shuttle between the two, although some minor corrections may be necessary due to small perturbations in the orbit.
Cyclers are used for transporting people or materials between those bodies using minimal propellant (relying on gravity-assist flybys for most trajectory changes) and can carry heavy radiation shielding to protect people in transit from cosmic rays and solar storms.
Long-distance haulers (aka Space Truckers), Cruise Ships, and some large military surveillance crafts also use these cycler orbits to stay an energye efficient perpetual motion around 2 or more points in a solar system.

Type

Planetary Orbit