We use cookies to ensure our website operates correctly and to monitor visits to our site. This helps us to improve the way our website works, ensuring that users easily find what they are looking for. To allow us to keep doing this, click 'Accept All Cookies'. Alternatively, you can personalise your cookie settings.

Accept All Cookies Personalise settings


Pioneering QinetiQ Solar Electric Propulsion System (SEPS) to power ESA's BepiColombo mission to Mercury


A ground-breaking Solar Electric Propulsion System (SEPS) developed and manufactured by an industrial consortium led by QinetiQ, will provide the engine power behind the BepiColombo mission to Mercury, scheduled to launch on 20 October.

  • Seven-year voyage enabled by four super-efficient T6 ion engines
  • Compared to petrol engines will achieve equivalent of 17.8 million miles to the gallon

Following its launch aboard Ariane 5 from Europe’s spaceport in French Guiana, four QinetiQ T6 Gridded Ion Thrusters will propel the Mercury Composite Spacecraft along with gravity assists (Earth, Venus and Mercury) from Earth’s orbit to Mercury.

During early planning the European Space Agency (ESA) determined that BepiColombo would require electric propulsion, a first for a mission visiting one of the Solar System's inner planets. Following QinetiQ's successful development of the T5 ion thruster for ESA's GOCE (Gravity field and steady-state Ocean Circulation Explorer) satellite, which orbited Earth for 4 years, ESA selected the larger T6 thruster for BepiColombo. QinetiQ was tasked with the manufacture and qualification of a SEPS, based around the T6.

Powered by solar energy, the T6 is super-efficient, enabling the spacecraft to reach maximum velocity with minimal fuel consumption. This decreases the propellant mass needed on board by between 10 and 20 times compared to a typical chemical rocket, which is key to maximising the science payload within the constraints of the launch vehicle.

QinetiQ designed the SEPS to enable ESA to address key challenges, including those presented by the Sun’s enormous gravitational pull. The system will provide the low thrust required for the spacecraft to continuously ‘brake’ against this pull during its seven-year journey to Mercury. The thrusters are capable of withstanding the high vibration and shock levels that will be experienced during launch/separation, as well as extreme temperatures during the cruise phases ranging from around -135c to 175c.

Peter Randall, Systems Engineer Electric Propulsion, from QinetiQ says:

“It’s a source of great pride that QinetiQ is playing such a pivotal role in this voyage to investigate the secrets of Mercury. The use of solar electric propulsion has provided ESA with an extremely efficient and robust engine system, and our rigorous testing of the T6 ion thrusters we’ve delivered will ensure it achieves its mission objectives. QinetiQ has more than 50 years’ experience of researching and testing electric propulsion thrusters – and this couldn’t have resulted in a more thrilling ESA cornerstone science project.”

UK Space Agency Chief Executive, Dr Graham Turnock, said:

“UK scientists, engineers and technicians have played a vital role in developing BepiColombo and the incredibly sophisticated set of scientific instruments on board. The international collaboration involved in this mission shows how our leading role in the European Space Agency is ensuring the UK thrives in the new space age, bringing real benefits to UK companies and scientists.”

QinetiQ’s Steve Clark, Electric Propulsion Engineering Lead said:

“Thrusters are a key enabling technology for the BepiColombo mission, which is set to fascinate and inspire millions of people around the globe. This is a fantastic example of how British expertise and innovation have the potential to support European space exploration, and make significant contributions to discoveries of worldwide importance.”