World First Air-Breathing Space Engine Could Fly Satellites Around Mars

The European Space Agency (ESA) has built and fired an engine that runs on air. This world-first electric thruster could allow satellites to operate in very low Earth orbits for extended periods of time.

The atmosphere-munching engine could one day propel satellites skirting around other planets like Mars, the Agency reported.

3_7_Air-breathing Thruster The air-breathing thruster creates a purple plume. Sitael/ESA

Air molecules replace propellents

Satellites use electric thrusters to compensate for air drag at very low orbits. Their operating lifespans, however, are cut short by a limited onboard propellant supply.

An engine that runs on air could theoretically sustain itself far longer by mooching molecules from the edges of a planet's atmosphere.  

Developed by space technology companies Sitael and QuinteScience under the ESA’s Technology Research Programme, the new dual-stage thruster catches and compresses air molecules before charging them.

3_7_Thruster concept This diagram explains the thruster concept. A Di Giacomo/ESA

First, a novel intake system captures the molecules instead of letting them bounce away. Then, the thruster charges them with electricity. Accelerated by this charge, the air molecules flow out of the engine, thrusting it forward.

The team tested their device in a vacuum chamber designed to mimic the environment 125 miles above sea level. To begin with, they made sure the engine could fire repeatedly with a propellant called xenon. This successfully produced a blue plume.

Next, the team replaced some xenon with a nitrogen-oxygen air mixture. Igniting the thruster again with both xenon and air, the engineers noticed the pume change color.

3_7_Thruster Plume Xenon When fueled by xenon, the engine plume glows blue. Sitael/ESA

“When the xenon-based blue colour of the engine plume changed to purple, we knew we’d succeeded,” ESA engineer Louis Walpot explained.

The team then successfully fired up the engine using just the air mixture. Again and again, the air mixture worked, proving the thruster's feasibility.

“Air-breathing electric propulsion is no longer simply a theory but a tangible, working concept, ready to be developed," Walpot said. One day it could serve as the basis of "a new class of missions,” he added.

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