A Spanish startup called Kreios Space has secured backing from NATO for a plasma engine designed to keep satellites flying at altitudes where the atmosphere would normally drag them down within weeks. The alliance’s support, channeled through its innovation pipeline, targets a propulsion concept known as air-breathing electric propulsion, or ABEP, which collects wisps of residual atmosphere near 200 kilometers above Earth and converts them into thrust.
If the technology matures, it could hand Western defense planners a tool they do not currently have: persistent surveillance and communications satellites orbiting far closer to Earth’s surface than today’s constellations, without the constant need to refuel.
Why 200 kilometers matters
Most Earth-observation satellites orbit between 500 and 2,000 kilometers up. At those altitudes, atmospheric drag is negligible and spacecraft can stay aloft for years. But the distance limits how sharp their images can be and how strong their signals are when they reach the ground.
Drop a satellite to 200 kilometers and the physics change dramatically. Sensors can resolve finer detail with smaller, cheaper optics. Communications links strengthen. The catch is that traces of atmosphere at that altitude, thin by any terrestrial standard but thick enough to matter at orbital speeds, create relentless drag. An unpowered satellite there loses altitude fast, typically reentering within days to weeks depending on its size, shape, and solar conditions.
Conventional electric thrusters can fight that drag, but they burn through finite supplies of xenon or krypton. Once the tank is empty, the mission is over. An air-breathing engine sidesteps that limit by scooping up the very gas molecules causing the drag and ionizing them to generate thrust. In principle, the satellite never runs out of propellant. Its operational life becomes a question of component durability and available solar power, not fuel reserves.
The science that already works
The core physics behind ABEP were validated in 2018, when the European Space Agency successfully fired an air-breathing electric thruster in a ground facility simulating conditions at roughly 200 kilometers. That test proved a spacecraft could, in principle, collect thin atmospheric molecules and turn them into usable thrust. It was a physics demonstration, not a flight-ready product, but it removed the most fundamental question mark: whether the mechanism works at all.
Since then, academic research has mapped both the promise and the obstacles. A 2022 peer-reviewed paper in the Journal of Electric Propulsion offers the most thorough independent survey of the field. It traces ABEP development from early mission studies through technology verification and identifies four persistent engineering challenges that no group has fully solved:
- Intake efficiency: Capturing enough rarefied gas at orbital speed to sustain meaningful thrust.
- Mixed-gas ionization: The atmosphere at 200 kilometers is a shifting blend of molecular nitrogen and atomic oxygen, harder to ionize cleanly than the pure noble gases conventional thrusters use.
- Erosion: Atomic oxygen at those altitudes is highly reactive and eats away at thruster components over time.
- Ground-testing fidelity: Replicating the extreme low-density conditions of 200-kilometer altitude inside a vacuum chamber is expensive and imperfect, meaning lab results may not translate directly to orbit.
Together, ESA’s demonstration and the peer-reviewed literature form the strongest public evidence base for evaluating any company’s ABEP claims. The physics are proven. The engineering is not.
What NATO sees in Kreios Space
NATO has been expanding its investment in dual-use space technologies through programs like the DIANA accelerator and the NATO Innovation Fund, both launched to connect allied startups with defense needs. Kreios Space, based in Spain, has emerged from that pipeline with a plasma engine tailored specifically for sustained VLEO flight.
The strategic logic is direct. Satellites that loiter at 200 kilometers rather than 500 or more can deliver sharper intelligence imagery and stronger signals for communications or electronic surveillance, all with smaller, less expensive hardware. For an alliance that increasingly views space as a contested domain, the ability to field cheap, replaceable, high-resolution satellites closer to Earth is operationally attractive.
Backing a European startup whose underlying technology has already been validated at the physics level by ESA also reduces risk compared with funding a completely unproven concept. It keeps a strategically relevant capability within allied industrial networks and signals to the broader defense sector that VLEO missions are moving from theoretical interest toward concrete planning.
What is still unproven
Several critical details about the Kreios program remain undisclosed. The exact size of NATO’s financial commitment, the timeline for any in-orbit demonstration, and the specific technical specifications of the Kreios engine have not been confirmed by publicly available primary sources. It is also unclear whether Kreios has conducted its own thruster firings or whether its design differs meaningfully from ESA’s earlier demonstration hardware beyond being optimized for a different mission profile.
The engineering gaps identified in the peer-reviewed literature remain open. No published test, from any group, has demonstrated the thousands of hours of continuous ABEP operation that a persistent surveillance satellite would demand. Erosion from atomic oxygen is a particular concern: components that perform well in short lab runs may degrade unacceptably over months of continuous exposure. And the gap between a successful ground firing and a working spacecraft is wide, spanning power management, thermal control, intake geometry, and long-term materials behavior.
Whether NATO’s support will push Kreios past these barriers depends on factors that are not publicly documented: the maturity of the company’s intake design, the materials chosen to resist atomic oxygen erosion, and the power budget available from whatever satellite bus the engine is paired with.
Where ABEP fits in the VLEO race
Kreios is not working in isolation. ESA’s own DISCOVERER program spent years studying VLEO satellite design, including aerodynamic shaping and propulsion options. Several research groups in Europe and Asia have published ABEP results, and other startups are exploring alternative approaches to sustained low-altitude flight, from high-efficiency Hall thrusters burning stored propellant to hybrid designs.
What distinguishes the air-breathing approach is its theoretical endurance. A satellite that manufactures its own propellant from the surrounding atmosphere could, if the thruster holds up, operate indefinitely at altitudes where any fuel-dependent competitor would eventually go dark. That advantage is what makes ABEP strategically compelling and why NATO is willing to place an early bet on it, even before a full orbital demonstration exists.
For now, the most defensible reading of the evidence is that air-breathing electric propulsion has moved well beyond theory but has not yet crossed into routine application. ESA proved the physics. The academic literature outlines a credible engineering path. NATO’s backing of Kreios Space shows that defense institutions see enough promise to invest. What remains missing is the hardest part: a flight-proven engine running continuously in the corrosive, ultra-thin atmosphere 200 kilometers above Earth, month after month, delivering the performance that the physics says is possible.
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*This article was researched with the help of AI, with human editors creating the final content.
