BepiColombo is a joint mission of the European Space Agency and the Japan Aerospace Exploration Agency to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter 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 at 01:45 UTC, with an arrival at Mercury planned for on 5 December 2025, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury. The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme; it is the last mission of the programme to be launched.