Field Emission Electric Propulsion: Enabling future Science and Earth Observation Missions

For over two decades, FOTEC Forschungs- und Technologietransfer GmbH, the research subsidiary of the University of Applied Sciences in Wiener Neustadt, Austria, has advanced Field Emission Electric Propulsion (FEEP) technology based on Liquid Metal Ion Sources (LMIS). In the period between 2015 and 2017, FOTEC successfully developed the IFM NANO Thruster, an integrated Electric Propulsion (EP) system for small satellites and CubeSats, later commercialized by its spin-out ENPULSION GmbH. The IFM NANO Thruster finds applications in orbit injection, drag compensation, orbit raising, formation flight, controlled de-orbiting of small satellites, and precise attitude control for larger spacecraft. Notably, it offers a dynamic thrust range from below 1 μN to 1 mN, with an adjustable Power-to-Thrust Ratio (PTR) for optimal electric power and propellant consumption efficiency. The metallic propellant, Indium, eliminates the need for pressurized components, presenting cost advantages over Xenon commonly used in similar thrust range technologies. An endurance test exceeding 50,000 hours on a single FEEP emitter has demonstrated stability and suitability for demanding missions like the ESA/NASA joint Next Generation Gravity Mission (NGGM). FOTEC's FEEP thruster underwent extensive characterization, utilizing a thrust balance and advanced plasma diagnostic tools. Recent advancements include an ion-lensing system to refine plume control and boost thrust for the same beam power.This paper provides an insightful overview of FEEP technology, emphasizing advantages and presenting recent test results. It underscores the ongoing development and qualification efforts, highlighting FOTEC's FEEP technology as a promising solution for future high-demand science and Earth observation missions.