Mercury-bound spacecraft with Leicester-built instrument set to fly by Earth

Space scientists at the University of Leicester are preparing to bid a final farewell to the BepiColombo spacecraft on Friday as it passes close to Earth on its way to Mercury, carrying equipment designed and built at the University.

Like many interplanetary spacecraft, BepiColombo is taking a circuitous route to its destination. Swinging past other planets in a carefully planned trajectory greatly reduces the fuel required on the mission and reduces the spacecraft’s velocity. This is known as a gravity assist manoeuvre or slingshot effect.

BepiColombo will make its closest approach to Earth at 4.25am GMT on Friday morning when it will be just 12,700km above the South Atlantic, which is actually within the orbits of some satellites. It will not be visible from the Northern hemisphere but will be tracked by the European Space Agency’s European Space Operations Centre (ESOC) in Darmstadt, Germany where a limited number of ESA staff are practising social distancing. BepiColombo is a joint project between ESA and the Japanese space agency JAXA which carries cutting-edge instruments provided by teams of scientists funded by national agencies.

The Earth fly-by provides an opportunity to test and calibrate some of the instruments aboard the spacecraft. In addition, three externally-mounted cameras on BepiColombo are expected to take some amazing pictures of the Earth and the Moon as the craft hurtles past.

Launched on 20 October 2018, BepiColombo is now approximately 1.3 billion km into its journey, with about 7.3 billion km still to go. It will make two fly-bys of Venus and six fly-bys of Mercury itself, slowing down each time, before the two probes it carries settle into orbit in December 2025. Only two other spacecraft have ever visited the innermost planet.

One of the key instruments aboard BepiColombo is the Mercury Imaging X-ray Spectrometer (MIXS) which was built by a Leicester-led international team and principally funded by the UK Space Agency. This will work with a second spectrometer called SIXS to analyse the surface composition of Mercury by collecting fluorescent X-rays, emitted by rocks after stimulation by high energy solar X-rays or electrons from Mercury’s environment.

Professor Emma Bunce, Professor of Planetary Plasma Physics and Head of the University’s School of Physics and Astronomy, is leading the MIXS team. She said: “This is an important milestone for the mission, and hence for our instrument on board. We will not be talking to our instrument during the flyby, but some others will be operating and we look forward to some beautiful pictures of the Earth and Moon. Following this flyby the spacecraft will be slung in the direction of Venus for the next gravity assist later in 2020. Each planetary encounter over the next few years gently slows BepiColombo down, so that we can eventually achieve orbit around Mercury in 2025.”