Space mission to Mercury: How an ion engine works

[Richard Pascoe]

The solar electric propulsion systems – or ion engines - which will power the next generation of spacecraft to Mercury and beyond are ten times more efficient than conventional rocket engines.
In an ion engine the gas xenon is pumped through a chamber where xenon atoms are stripped of an electron, becoming electrically charged ions, and drift towards two grids a millimetre apart.
The grids are fed with two thousand volts – in space this power will come from paper-thin solar panels spanning 26m. As the ions pass through the electrified grids they accelerate to up to 50km a second and shoot from the rear in a parallel beam.
On Earth, at sea level, the thrust would be just enough to lift a pound coin. In space, however, the same thrust will create a much much bigger lift.
The SEPS will be attached to the back of the BepiColombo spacecraft and launched into space inside an Arian 5 rocket in 2014.
Once in orbit, the engine will push the BepiColombo away in an everwidening spiral, glancing by the Moon and on into an orbit of the Sun. It will slingshot around Venus and spiral into line behind the rapid orbit of Mercury.

“Mercury has a magnetic field which is quite unusual,” said Neil Wallace, the project's chief engineer. “It seems to have a molten iron core, like Earth. That makes it an odd planet. We want to understand how it formed, and why, and why it is where it is. That should help us understand more about the Earth.”

Source: http://www.telegraph.co.uk/science/science-news/6125451/Space-missi...