The European Space Agency (ESA) has announced that its newest satellite, called BepiColombo, will travel to Mercury using ion-electric thrusters developed by U.K. company QinetiQ.

An artist's impression of BepiColombo. Credit: ESA

The space agency already uses a smaller version of the same system--made of T5 ion thrusters--aboard its GOCE satellite, which launched earlier this year to measure Earth's gravitational field. BepiColombo, which is scheduled to launch in 2014, will use four T6 ion thrusters. The company says the thrusters used in both spacecraft are 10 times more efficient than traditional chemical ones. ESA awarded QinetiQ a contract worth $37.4 million to build the electric propulsion system.

While chemical propulsion systems are most commonly used in space, they are inefficient for deep-space missions to planets like Mercury because they require large amounts of fuel. Electric propulsion systems produce less thrust, but they are very efficient, making them ideal for long-distance missions.

Ion propulsion works by electrically charging, or ionizing, a gas and accelerating the resulting ions to propel a spacecraft. The concept was conceived more than 50 years ago, and the first spacecraft to use the technology was Deep Space 1(DS1) in 1998. Since then, aside from GOCE, there have only been a few other noncommercial spacecrafts that have used ion propulsion: NASA's Dawn mission to the outer solar system, launched in 2007; the Japanese deep-space asteroid-sample-return mission called Hayabusa, launched in 2003; and ESA's SMART-1 spacecraft, which launched in 2003 and crashed on the moon in 2006. (There are many commercial communication satellites that use ion thrusters.) NASA recently finished testing a new ion propulsion system for Earth-orbiting and interplanetary spacecraft that could be ready for launch by 2013.

While the technology still needs some fine-tuning, to make these engines even more efficient, compact, and economical, many experts say that for complex planetary missions that require lots of energy, ion-electric thrusters are definitely the answer.