DARPA Funds SabreSat: The First Air-Breathing Satellite for Ultra-Low Orbit Missions
DARPA has allocated 44 million dollars to develop SabreSat, an experimental spacecraft designed to operate in extremely low Earth orbits using atmospheric air as its propellant. The initiative represents a major step toward satellites capable of long-duration missions in orbital regions previously considered unusable due to rapid atmospheric drag.A Satellite That Breathes the Atmosphere
Instead of traditional chemical propulsion, SabreSat uses an air-breathing electric thruster. As the satellite travels through the thin upper atmosphere, a front-mounted intake collects sparse air molecules. These particles are then ionized inside a dedicated chamber and accelerated as a plasma jet, generating continuous thrust. The atmosphere becomes an effectively unlimited fuel supply, eliminating the need for onboard propellant tanks.Designed for Extremely Low Orbits
SabreSat is built to operate between 90 and 450 kilometers above Earth—altitudes known as very-low Earth orbit (VLEO). At these heights, atmospheric drag is intense enough to pull conventional satellites out of orbit within hours or days unless they use chemical fuel for constant corrections. The air-breathing propulsion allows SabreSat to maintain its altitude for up to seven years, dramatically extending mission life in a region previously off-limits to long-term operations.Advantages of Flying Close to Earth
Operating roughly twice as close to the surface as traditional satellites offers several strategic benefits. Imaging satellites gain significantly higher resolution, communication systems experience lower latency, and missions become naturally resilient to space debris, as objects at these altitudes deorbit and burn up within days. Launch costs are also reduced because missions require less energy to reach VLEO.Compact and Efficient Design
Despite its advanced propulsion system, SabreSat is compact—measuring around one meter in size. The satellite’s design focuses on energy efficiency, continuous thrust, and the ability to survive in an environment where atmospheric density fluctuates dramatically. Engineers expect the system to adapt dynamically to these variations using real-time control algorithms and optimized intake geometry.A New Frontier for Orbital Technology
DARPA’s investment highlights growing interest in using ultra-low orbits for reconnaissance, communications, and rapid-response missions. With traditional satellites operating hundreds of kilometers higher, SabreSat introduces a fundamentally different approach to orbital infrastructure. If successful, the project could enable a new class of spacecraft that blend atmospheric and orbital flight characteristics.The first launch is expected in 2027, marking the beginning of a new era in satellite propulsion and VLEO operations.
Editorial Team — CoinBotLab