Ion-driven air motor

Іонний двигун, що працює на повітрі

The ESA has created an ion engine propellant with air. A satellite equipped with such an engine may fly in the upper atmosphere for years on end without refueling.

The European Space Agency has developed new ion motor that uses gas molecules, substantial number of which is contained in envelope of air around the Earth.

This type of electric motors has already been developed before, including in the ESA, but this is the first time when air became motor’s working body.

As a reminder, ion-driven motor was already installed on ESA’s GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) satellite launched in 2009. However, it used xenon — inert gas — as propellant, and once that was exhausted, the mission was over. Continuously-operating motor was needed to maintain high speed on orbit because GOCE had to struggle with expanded air resistance at the altitude of about 250 km. When satellite ran out of all 40 kg of propellant, space mission was interrupted and satellite has burnt upon entrance to the dense layers of the atmosphere.

Innovative ESA’s motor will have no restrictions as to the propellant, since it will take it from the ambient environment – directly from the atmosphere, where satellite will be located. The air-breathing thruster was initially run with xenon propellant. Engineers were progressively replacing it with a mixture of nitrogen and oxygen and eventually managed to make it operational without any xenon at all. This system allows the thruster to eject the charged air molecules at a typical speed of 7.8 km/s at an altitude of about 200 km. Following a series of improvements and modifications, the ESA announced that device works on a simple, passive basis and has no valves or complex parts.

The only visual difference between motors running on xenon and nitrogen-oxygen mixture is the color of thruster plume: unlike the blue color of xenon-based motor, the color of ion-driven air motor is purple.

Developers say that as soon as this motor is adjusted in the proper way, it will be able to work in Martian atmosphere. There is much tension now around the issue of satellites suitable for Mars colonization projects, since several companies and countries are simultaneously working hard to colonize the Red Planet.