BepiColombo

BepiColombo is Europe’s first mission to Mercury, the smallest and least-explored terrestrial planet in the Solar System. Named after the Italian professor Giuseppe “Bepi” Colombo, the complex mission aims to unravel how planets forming close to parent stars evolve.

The mission is a joint collaboration between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). Airbus Defence and Space acted as the industrial prime contractor for ESA, leading an international consortium of over 80 companies across 12 European nations to design, manufacture, and assemble the spacecraft.

As prime contractor, Airbus led the overall system  architecture, manufacturing and spacecraft integration.

Airbus built three of the mission’s four primary module: : the Mercury Planetary Orbiter (MPO), the Mercury Transfer Module (MTM), and the JAXA’s module thermal shield (MOSIF).

While JAXA manufactured the Mio orbiter in Japan, Airbus integrated all four modules into a single 4.1-tonne composite stack. 

Because of the huge thermal and orbital challenges of reaching Mercury, the mission combines four distinct operational modules into a single launch stack :

• ESA's Mercury Planetary Orbiter (MPO): To map Mercury's surface and mineralogy.
• JAXA's Mercury Magnetospheric Orbiter (Mio): To investigate the planet's magnetosphere and exosphere.
• Mercury Transfer Module (MTM): To propel the stack along its interplanetary trajectory 
• MOSIF: Protects the Mio orbiter from intense solar radiation until stacked separation at Mercury

The MPO and Mio orbiters will perform measurements about Mercury's surface composition magnetic field, and its interactions with the Sun and solar wind.

BepiColombo launched in October 2018 aboard an Ariane 5 rocket. Following a series of nine complex planetary flybys (one of Earth, two of Venus, and six of Mercury) the spacecraft arrives at Mercury in November 2026 to begin its orbit insertion sequence. Once captured by Mercury's gravity, the stack will undergo module separation, instrument deployment, and orbital positioning. Primary science operations for the MPO and Mio orbiters are scheduled to begin in April 2027.

Once safely in their respective orbits around Mercury, the MPO and Mio orbiters will conduct a nominal one-year science mission, with the possibility of an extension depending on spacecraft health and fuel.

Orbiting as close as 46 million kilometers from the Sun at perihelion, BepiColombo experiences direct solar radiation ten times more intense than on Earth, alongside intense thermal infrared radiation emitted from Mercury’s surface, which reaches 430° Celsius. To protect the instrument and platform electronics inside, Airbus implemented an advanced thermal protection system: 

• Custom High-Temperature Multi-Layer-Insulation (HT MLI) comprising up to 50 layers, with the outermost layer serving as a heat shield made of ceramic fabric and metallic foils
• Elaborate heat pipe network and a large radiator with Titanium fins optimised to reflect Mercury infrared away from the spacecraft while continuously radiating internal heat into cold, deep space
• Extreme-heat materials: external components are protected by HT MLI or built from heat-resistant titanium covered by specialised high UV and high temperature resistant white coating, solar panels use specialised reflective glass and heat resistant sandwich structures, and exposed wiring harnesses are encased in protective tungsten-sheathed insulation

Once at the destination, the transfer module (MTM) is released. The MPO and Mio modules are captured by Mercury's gravity together. The MPO uses its thrusters to guide Mio into a high elliptical orbit. After Mio separates, the MPO ejects the protective MOSIF sunshield and descends into its own lower orbit to begin mapping.