A new design for an ion engine promises up to 10 times the fuel-efficiency of existing electric propulsion engines, according to tests by the European Space Agency. The new thruster could be used to propel craft into interstellar space, or to power a crewed mission to Mars, ESA says.

Ion engines work by using an electric field to accelerate a beam of positively charged particles – ions – away from the spacecraft, thereby providing propulsion. Existing models, such as the engine used in ESA’s Moon mission, SMART-1, extract the ions from a reservoir and expel them in a single process.

Tests on a prototype called the Dual-Stage 4-Grid (DS4G) thruster, at ESA’s Electric Propulsion Laboratory in the Netherlands showed that DS4G’s two-step process produces an ion exhaust plume that travelled at 210 kilometres per second – more than 10 times faster than possible with the engine in SMART-1, and four times faster than the latest prototype ion engine designs. This would mean a spacecraft could carry much more weight for a given amount of fuel, or it could go further, faster.

“Crewed or heavyweight robotic missions to Mars become a distinct possibility. And there’s even talk of interstellar missions,” says Orson Sutherland of the Australian National University in Canberra, who led the team that built the engine.

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