Next-generation Green Monopropellant Gas Generation

The USSF has a desire to use liquid monopropellants for high thrust propulsion (natively in chemical thrusters) and for low-thrust, very energetic missions (in electric propulsion thrusters) - so called Multimode Propulsion (MMP) capabilities - to support Dynamic Space Operations. Such MMP capabilities have a number of very favorable characteristics including high propellant density, reduced need for high pressure storage systems, continued need for chemical propulsion on DoW assets for high thrust prompt maneuver, and compatibility with future on-orbit liquid propellant refueling capabilities. One critical capability gap is an energy efficient, precision propellant feed system which efficiently converts next-generation liquid monopropellant into non-reactive vapor phase products which can be fed into the electric propulsion (EP) thruster. Key challenges arise from the fact that next-generation monopropellants have negligible vapor pressure and are extremely difficult to combust at low temperature and pressure. The desired technology should present a solution for a feed system capable of supporting sub-kW to 100 kW class EP systems: - Operation at minimum on ASCENT propellant (T) or on ASCENT and other monopropellant formulations (O) - Realtime telemetry, including mass flow rate, species composition, and temperature as inputs to the EP device - Maintain consistently characterized molecular composition (T) and extremely stable molecular composition (O) of the output vapor and support both steady-state and pulsed operation at frequencies greater than 5 Hz - Minimal SWaP with particular focus on low power consumption - Incorporate fluid/vapor facing materials that can reliably withstand long-term exposure to green monopropellants and their breakdown products over the required lifespan. Potential issues also include condensation or freezing for long-duration propellant storage in ullage and plenums if these or similar components are used - Demonstrate rapid warmup/gas generation in less than 10 minutes (T) or on-demand (O) - Ensure lifetime design consideration for future multiple refueling opportunities This work directly supports the Contested Logistics Technologies (LOG) Critical Technology Area with respect to space mobility operations.