This is an ion thruster, and along with three others it will propel one of the largest missions ever undertaken to Mercury.
Its pale blue exhaust is unlike anything you will have seen and that’s because this revolutionary new space engine isn’t powered by conventional chemical propellant.
What makes ion thrusters special is that for the same amount of conventional rocket fuel, one of these can help a spacecraft reach a speed 15 times faster than a conventional chemical thruster.
The only downside is that they’re very weak, which means that acceleration can take a very long time.
While acceleration is key on Earth in space the most important task is to reach the highest speed and that’s what these thrusters can do.
Just 22cm in diameter, four of these British-developed ion thrusters will propel the European Space Agency’s BepiColombo spacecraft all the way to Mercury.