BepiColombo's Twin Orbiters Set to Separate as Mercury Arrival Phase Begins

BepiColombo, the joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), is entering the arrival phase of its journey to Mercury. The spacecraft launched in October 2018 and has spent years on a long, looping route to the solar system's innermost planet. On September 3, 2026, its two science orbiters are scheduled to separate from the mission's propulsion module, marking the start of that arrival phase.

ESA's Mercury Planetary Orbiter (MPO) and JAXA's Mercury Magnetospheric Orbiter (MMO), known as Mio, will separate from the Mercury Transfer Module at around 8 a.m. EDT (1200 Greenwich Mean Time, or GMT). According to ESA, communication links with the newly free-flying orbiters are expected to be established no earlier than 9:53 a.m. EDT (1353 GMT), after which ground teams will carry out spacecraft status checks.

The two orbiters will remain attached to each other after separation. Mercury's gravity is expected to capture them on November 21, 2026. MPO will then release Mio into its final orbit, an ellipse ranging from 590 to 11,640 kilometers above Mercury, around December 9 or 10; a week later, MPO will move toward its own orbit. MPO is scheduled to reach its final orbit, ranging from 480 to 1,500 kilometers in altitude, on March 10, 2027.

The mission's science phase, lasting at least one Earth year, is set to begin on April 6, 2027. ESA says MPO will map Mercury at different wavelengths and chart its mineralogy and elemental composition, while Mio studies the planet's magnetosphere, the region of space shaped by its magnetic field. The mission is named after Italian mathematician and engineer Giuseppe "Bepi" Colombo.