Cycler Orbits
Mars missions can be assembled in high circular orbits far beyond the Moon, where the delta V from a high perigee launch loop ellipse is small. That delta V can be reversed to drop back to a low perigee for a rendezous with a Mars Cycler orbit.
Mars Cycler
A SYSTEMATIC METHOD FOR CONSTRUCTING EARTH-MARS CYCLERS USING DIRECT RETURN TRAJECTORIES Russell and Ocampo