European firms TransMIT GmbH and IQM have made a significant advancement in pioneering a novel type of satellite thruster: air-breathing electric propulsion (ABEP). This technology harnesses residual atmospheric gases as the working medium. Such an innovation holds the potential to prolong the operational lifespan of satellites operating in very low Earth orbits (VLEO) without needing to carry conventional propellant reserves. The system under development recently passed a crucial validation step, confirming the technical feasibility of the core concept. This project, named the Cathodeless Electric Propulsion Thruster for Air-Breathing Electric Propulsion Systems, is being executed by TransMIT GmbH, while IQM is developing the cathode-less electric thruster component under ESA’s financial backing.
Standard satellites are typically burdened with onboard fuel reserves necessary for orbital correction and maneuvering. This requirement adds to the spacecraft’s mass, limits its service duration, and escalates mission costs. This dilemma is particularly acute at lower altitudes, where atmospheric drag gradually causes the craft to lose altitude, necessitating constant thrust application to counteract the deceleration.
The ABEP concept presents an alternative strategy. At altitudes spanning approximately 180 to 250 km, trace amounts of gases still exist in Earth’s atmosphere. This type of engine captures these particles, ionizes them, and accelerates them to generate thrust. Theoretically, this permits the elimination of traditional propellant storage, offering what is essentially an unlimited source of thrust, provided the satellite remains within the region where sufficient atmospheric particles are available.
The project’s objective is to design, fabricate, and test a prototype engine capable of stable operation using mixtures of terrestrial atmospheric gases—primarily nitrogen and oxygen—while achieving an electrical efficiency of at least 50% and a specific impulse starting from 4200 seconds.
According to the developers, the new system is structurally based on the conventional design of a Radio Frequency Ion Thruster, but incorporates a critical difference: it operates without a cathode. The cathode itself is considered one of the most challenging components to integrate into ABEP systems, especially when operating within a reactive environment rich in oxygen.
The prototype is presently in the assembly stage, with testing slated to occur in vacuum facilities. If successful, this technology could form the bedrock for a new class of satellites capable of orbiting considerably closer to Earth than current assets, while maintaining their orbital positions for extended periods without depleting stored chemical fuel.
The pioneering team believes that deploying “air-breathing propulsion” could profoundly transform the satellite industry: boosting spacecraft longevity, decreasing launch mass and associated expenses, and ensuring more robust operations for satellite constellations deployed in extremely low orbits.
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