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By Abbie MacKinnon on

11 things you might not know about BepiColombo

A new spacecraft has landed at the Science Museum: the Structural Thermal Model of BepiColombo, developed to test the strength of the spacecraft when on its mission to Mercury. Here are some interesting facts you might not know about this challenging mission...


A joint mission between the European Space Agency and the Japan Aerospace Exploration Agency, BepiColombo is the first ever two-spacecraft mission to Mercury. The two satellites will go into separate orbits around Mercury. This is a unique aspect of the mission. These synchronised satellite orbits will provide scientists with detailed sets of data which will give them a fuller picture of the planet.


It is only the third ever mission to Mercury. NASA has sent two spacecraft to Mercury: Mariner 10 passed the planet three times in the 1970s and MESSENGER orbited it from 2011-2015. Scientists are still analysing MESSENGER data today.

Image of Mercury taken by Mariner 10
Image of Mercury taken by Mariner 10 © NASA/JPL


BepiColombo is named after mathematician and engineer, Professor Giuseppe ‘Bepi’ Colombo. Colombo studied Mercury and calculated how to get a spacecraft into a successful orbit around the planet. His contribution to our understanding of Mercury led the European Space Agency to name their cornerstone mission after him.

Giuseppe 'Bepi' Colombo
Giuseppe ‘Bepi’ Colombo © ESA


Around 1200 engineers and scientists from 16 different countries have worked on this mission since 2000, and the flight model will launch on an Ariane 5 rocket from French Guiana in South America.


The BepiColombo on display is a twin of the flight model and is called a Structural Thermal Model. It was used to test the structure of the spacecraft and is vital to the success of the Mission. It was tested in the Multishaker and the Acoustic Chamber to make sure it could withstand the vibrations of launch. It was also tested in the Large Space Simulator which checked it could manage the temperature extremes during the journey.

BepiColombo Structural Thermal Model (full-scale)
BepiColombo Structural Thermal Model (full-scale)


BepiColombo will experience Mercury’s dramatic temperature changes, reaching 400°C on the sun side and -190°C on the night side. Everything on the spacecraft is designed to protect it from the heat and radiation.


Part of this protection is a special space blanket which is made up of 97 layers of aluminium, plastic and glass ceramic fabrics. This insulation blanket was specially developed for the Mission and helps to keep the onboard instruments as close to room temperature as possible.

Engineers hand-stitching the space blanket onto the sun shield
Engineers hand-stitching the space blanket onto the sun shield


BepiColombo also has a special radiator which moves the heat from inside the spacecraft out into deep space. The flight model has ‘fins’ covering the radiator which look like venetian blinds and help to protect BepiColombo from radiation. The test model on display in the Science Museum is missing its ‘fins’ because they will be flying to Mercury on the flight model!

Mercury Planetary Orbiter radiator panel
Mercury Planetary Orbiter radiator panel and instruments © ESA


It will take BepiColombo more than seven years to get to Mercury. It will have to take a very complex route there which involves coming back past Earth nearly two years after it launches in 2018. It will also fly past Venus twice and Mercury six times before settling into its orbits in late 2025.


After launching, BepiColombo will be travelling too quickly to be able to put the two scientific satellites into their Mercury orbits. To help slow down, BepiColombo is fitted with four solar-electric ion thrusters. These thrusters use xenon for fuel and solar power for electricity. They are designed to fire in the opposite direction of travel and act as a brake, slowing BepiColombo down.

Artist’s impression of the BepiColombo spacecraft in cruise configuration, flying past Earth. The Mercury Transfer Module is shown with two ion thrusters firing
Artist’s impression of the BepiColombo spacecraft in cruise configuration, flying past Earth. The Mercury Transfer Module is shown with two ion thrusters firing © ESA


BepiColombo had key contributions from UK industries. The British made solar-electric ion thrusters for example, were made by the UK-based company, QinetiQ. This type of electric propulsion is a first for a mission to an inner planet.

BepiColombo also carries 16 instruments on board that will gather data about the surface and interior of Mercury as well as its magnetic field. Some of the instruments were developed by British scientists. The Mercury Imaging X-Ray Spectrometer, or MIXS, was developed by scientists from the University of Leicester and the University of Helsinki.

The University of Helsinki also developed the Solar Intensity X-ray Spectrometer, or SIXS, along with scientists from Aberystwyth. (MIXS is Finnish for ‘Why’? and SIXS is Finnish for ‘That’s Why’!) These two instruments work closely together to provide data on Mercury’s magnetosphere.

Come face-to-face with a full-size engineering model of BepiColombo at our free exhibit Mission to Mercury: BepiColombo and learn more about this integral part of a space mission’s development programme.