ESA has built an ion engine that uses air for propulsion in space

The European Space Agency (ESA) has built an engine that can provide propulsion in space in the upper layers of the atmosphere by sucking in limited air molecules. According to ESA, this is the first time that this concept has been proven.

ESA explains that the engine actually works by replacing entrained fuel with atmospheric molecules. According to the space agency, this could lead to a new class of satellites that are able to operate for long periods in very low Earth orbits, for example at an altitude of about 250 km.

The motor is a fairly simple, passive design and works by drawing in atmospheric air molecules, which are compressed by a compressor. These molecules are then given an electrical charge so that they can be accelerated and repelled, which provides the drive. Electricity is only needed for the transformers and the electrodes.

ESA’s GOCE satellite, which has been deployed for several years to measure Earth’s gravity, has already flown at altitudes of 235km using a similar engine. At these altitudes, such a motor is necessary to be able to continuously compensate for the air resistance, which would otherwise cause the satellites to drift too much off course in the long run. However, this engine still ran with 40kg of xenon as fuel, which meant that the powertrain was at an end in 2013 when the gas ran out.

The concept based on air molecules has been tested in a vacuum chamber simulating the conditions of the atmosphere at an altitude of 200 km and speeds of 7.8 km/s. To that end, ESA built a full test engine where the challenge was to design the intake vent to capture the air molecules as much as possible, while avoiding bouncing off too often. ESA describes it as a dual-stage thruster, where the intake and thruster are combined.

In the end, the concept proved to work, whereby the test system could be ignited several times and there was actually propulsion based on the ‘atmospheric fuel’. According to ESA, this means that ‘air-breathing electric propulsion’ is no longer just a theory, but an actual working concept ready to be developed. In the future, for example, it could be used to keep satellites in relatively low Earth orbit operational for longer.