Orbital Propulsion Boosters (OPBs)

The Aldrin Cycler architecture employs a dual-propellant strategy using expendable Orbital Propulsion Boosters (OPBs) mounted at opposite ends of each Mothership. High-efficiency cryogenic OPBs provide propulsion during outbound transit to Mars, while storable hypergolic OPBs perform deceleration, orbital adjustments, and Earth-return maneuvers. This approach minimizes long-term cryogenic storage challenges, eliminates the need for complex in-space propellant transfers, and improves the reliability of interplanetary transportation.