Mission MeRcury


  • The European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) successfully sent two probes on a joint mission to Mercury, the closest planet to the Sun.


  • An Ariane 5 rocket, launched from French Guyana, lifted an unmanned spacecraft, BepiColombo, which is carrying the two probes. The spacecraft separated and went into orbit for the 7-year trip to Mercury.


  • It is the first European mission to Mercury, and the first to send two spacecraft to make complementary measurements of the planet and its environment at the same time. The orbiters are ESA’s Mercury Planetary Orbiter (MPO) and JAXA’s Mercury Magnetospheric Orbiter (MMO, or ‘Mio’). The ESA-built Mercury Transfer Module (MTM) will carry the orbiters to Mercury using a combination of solar electric propulsion and gravity assist flybys, with one flyby of Earth, two at Venus, and six at Mercury, before entering orbit at Mercury in late 2025.


  • The two orbiters will be able to operate some of their instruments during the cruise phase, to try and collect data at Venus. Moreover, some of the instruments designed to study Mercury in a particular way can be used in a completely different way at Venus, which has a thicker atmosphere.


  • A few months before reaching Mercury, the transfer module will be jettisoned, leaving the two science orbiters to be captured by Mercury’s gravity. MPO will separate and descend to its own orbit. Together the orbiters will make measurements (see graphic).


  • The Sun’s enormous gravity makes it difficult to place a spacecraft into a stable orbit around Mercury. The mission will have to ensure a controlled fall. The spacecraft has been specially designed for extreme temperatures.


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