Propellant Management of Water-Based Microthruster for Suborbital 0G Testing

Size and power are primary limitations on nanosat missions, especially for propulsion, attitude control, or formation flight. New micropropulsion systems that are smaller, lighter, and less power expensive are required for versatile nanosats for cislunar and interplanetary missions. The Film-Evaporation MEMS Tunable Array (FEMTA) is water-based microthruster for CubeSat attitude adjustment that has been developed at Purdue University. FEMTA will provide an attitude control system for microsatellites that uses \u3c 1 W of power in \u3c 0.5 U of volume. The nozzles on FEMTA use heaters at the base of micro-capillary channels to induce film-evaporation, creating a highly controllable, low-power thrust. The novel capillary action thruster also requires a novel liquid 0G propellant management system. The FEMTA 0G propellant management system is a vapor pressure driven pump. It is self-regulating, does not rely on gravity, and does not require complex pressurization systems, making it suitable for microsatellite applications. The system uses a low vapor pressure fluid pressurant to apply a passive, constant deforming pressure upon a diaphragm that separates the pressurant from the propellant. The ratio of specific volume between the pressurant and the propellant is high enough that, as propellant is expended, the diaphragm compresses as the pressurant expands to fill the volume of the spent propellant. As part of the NASA Space Technology Research, Development, Demonstration, and Insertion (REDDI) program, the FEMTA 0G propellant management system is set to be tested during a suborbital Blue Origin New Shepard flight. In preparation for a 2023 launch, an experiment to test the propellant management system has been designed and built and engineering tests have been performed