Air-Breathing Thruster Paves Way for Never-Ending Space Missions at Earth and Mars

[Judi Lynn]

By Tereza Pultarova, Space.com Contributor | March 23, 2018 12:45pm ET

For the first time, the European Space Agency (ESA) has tested a novel air-breathing electric thruster that could allow near-Earth orbiting satellites to stay in space almost indefinitely. The thruster, designed to harvest atmospheric molecules and use them instead of onboard propellant, could also make future Mars exploration easier, ESA officials said.

Satellites need propulsion to hold their position or move around in space. Conventionally, satellites use rocket-like chemical propulsion, but electrical thrusters are becoming increasingly popular due to their better efficiency. However, current electrical propulsion systems still need to use a propellant, such as xenon, and their mission lengths are therefore limited by how much propellant they can carry. Due to weight constraints, satellites can carry only a limited amount. Those orbiting close to the Earth, in the range of a few hundred kilometers (about 125 miles), consume it at a higher rate, as they need to compensate for the atmospheric drag that slows them down and pulls toward the Earth.

Instead of carrying its own propellant, a satellite using ESA's new system would skim air molecules from the top of Earth's atmosphere. The molecules turn into plasma when compressed. An electric field is then used to accelerate the stream of plasma to provide thrust for the satellite.

"Providing atmospheric drag compensation without the use of carry-on propellant, this kind of electric propulsion would let satellites orbit at very low altitudes around Earth for very long operational time," Louis Walpot, who leads the project at ESA, told Space.com in an email.

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