High-Performance, Refuelable, “Green” Propulsion System for Multi-Object Removal/Retrieval System

Flight Works is proposing to address the issue of Active Debris Removal, Technical Need Area 2023-3, by modifying the high delta-V ldquo;greenrdquo; propulsion system of its Lunar Transfer Stage (a.k.a. Small Orbital Maneuvering Vehicle, S-OMV) for use in an active orbital debris removal/object retrieval system. This system relies on pump-fed ASCENT propulsion which drastically decreases inert mass fraction and allows operating the thrusters at their maximum Isp regardless of tank pressure. With the high density-Isp of ASCENT, the pump-fed system performance rivals with that of conventional bipropellant systems. With the bidirectional pump, the system can refuel itself from simple, low-cost tankers launched on demand or stored in space. ASCENT systems have yet to be designed for Rendezvous and Proximity Operations (RPO), however. Typically, the higher thruster duty cycle and preheat requirements needed with ASCENT (when compared with hydrazine) leads to larger impulse bit, hence coarser control, and increased power consumption. With the use of a pump, the control limitation can be circumvented, allowing the system to operate at different pressure points to best match thruster duty cycle for optimum system output depending on mission needs. Similarly, thrusters can be packaged for optimum thermal management to reduce preheat power. nbsp; As a result, the upgraded propulsion system has precise and efficient RPO capabilities. When integrated into a retrieval or disposal system, it is able to de-orbit multiple 100 kg-sized objects, or up to a single 3,000 kg object initially orbiting at 500 km, or 1,200 kg at 1,000 km, before re-boosting itself into orbit for refueling. Refueling can be accomplished at low cost with Flight Worksrsquo; Medium-OMV-based simple tankers, and thus increase the total disposal capacity to over ten metric tons. nbsp; As a first step toward commercial operations, Flight Works plans to supply the system to a private firm for retrieval of a historical space artifact.