TECHNOLOGY
Air-Breathing Engine Could Let Satellites Skip Onboard Fuel
A new propulsion concept that draws thrust from thin atmospheric gases has passed lab tests and computer modeling, but it still has to prove itself in orbit.
Image: Fully Assembled RF Helicon-based Plasma Thruster. Credit: F. Romano · Uploaded by IntraGoals — usage rights confirmed
Engineers are testing a satellite engine designed to run on the wisps of atmosphere found hundreds of kilometers above Earth, a concept that could let spacecraft stay aloft without carrying traditional fuel. The technology has performed well in laboratory experiments and computer simulations, though it has not yet been demonstrated on an actual mission.
The idea targets Very Low Earth Orbit, or VLEO, a band roughly 100 to 450 kilometers (62 to 280 miles) above the planet's surface. Operating in this zone offers real advantages: remote sensing cameras get sharper images, communications and radar systems can run on less power, and residual atmospheric drag naturally pulls dead satellites out of orbit rather than leaving them as long-term debris.
But that same thin atmosphere is also the zone's biggest liability. Even at these altitudes, air resistance is strong enough to steadily slow spacecraft down, forcing them to fire thrusters almost continuously just to hold their orbit. Conventional propulsion systems rely on onboard propellant, often xenon gas, which is expensive and finite. Once a satellite exhausts its fuel supply, its mission effectively ends.
The engine in development aims to sidestep that limitation by collecting and using the sparse gas molecules already present in VLEO as propellant, rather than hauling fuel from Earth. In theory, that could allow satellites to maintain orbit far longer, potentially indefinitely, without the weight and cost penalties of carrying their own propellant.
The concept remains in an early stage. While laboratory results and modeling are described as promising, engineers have not yet confirmed how the system would perform under real orbital conditions, including the variability of atmospheric density and the engineering challenges of intake and thrust generation in a near-vacuum environment. Further details on the project, including its developers, timeline, and testing partners, were not available in the source material and should be verified before publication.