The innovation is a multimode chemical-electric propulsion equipped transfer stage for venture class small launch vehicles that is flexible and adaptable to meet a wide range of NASA lunar mission needs and requirements. This innovation is enabled by a novel space propulsion system that combines chemical and electric propulsion with shared propellant between the modes (multimode propulsion, MMP). Through previous efforts, we have developed technologies that enable this type of system. This includes development of our electrosprayable ‘green’ monopropellants FAM-110A and FAM-122A, demonstration of chemical and electric thrusters using these monopropellants, and development of a propellant feed system capable of supplying the three order of magnitude difference in flow rates required for operation in either mode. This project will demonstrate a 22 N chemical monopropellant thruster using our FAM-122A monopropellant, designed for inclusion as the main engine in a transfer stage capable of injecting a 25 kg small satellite payload into a TLI orbit from a small venture class launch vehicle using only chemical propulsion. The transfer stage systems, however, will also accomodate our feed system and electrospray thrusters, initially used for purposes of minor course correction, pointing, and disposal maneuvers. As electrospray technology matures, upgraded thrusters can be swapped into the vehicle to enable missions to Mars, Venus, and near Earth asteroids. This project will also perform small scale hazard classification tests, data from which will be used to assign a DOT 1.3 interim classification by the conclusion of the project in addition to investigation and development of production scale up plans.
A transfer stage with the proposed multimode propulsion system is capable of performing near term missions to the moon using near term ready technology advances, but has the capacity to grow in capability with further developments in electrospray technology. Further improvements to electrospray technology will enable the same transfer stage to accomplish missions to Mars, Venus, and unique near-Earth destinations along with the flexibility to achieve these missions without significant alteration to the propulsion hardware.
A multimode propulsion transfer stage can also function as a last-mile delivery service or on-orbit servicer for commercial and DoD applications, with the resiliency offered by the use of a shared propellant. An assembly line of the same transfer stage hardware could be created that meets the needs of a wide variety of customer missions where only the propellant allocation is altered.