BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio. The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure. It was launched on an Ariane 5 rocket on 20 October 2018, with Mercury orbit insertion planned for November 2026, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury. The total cost of the mission was estimated in 2017 as US$2 billion.