MERCURY — The BepiColombo mission will enter orbit around Mercury on 21 November 2026, marking the culmination of an eight-year journey to the solar system's innermost planet. This arrival will make it the first mission to deploy two independent orbiters around a different planet.

The BepiColombo mission is a joint effort between the European Space Agency and the Japan Aerospace Exploration Agency. The spacecraft launched in October 2018 on an Ariane 5 rocket from Europe’s Spaceport near Kourou, French Guiana. Since its launch, BepiColombo has traveled more than 6 billion miles (10 billion kilometers). The mission has a price tag of nearly $2 billion, and the United States contributed to the BepiColombo mission.

BepiColombo is named for Italian engineer and mathematician Giuseppe “Bepi” Colombo. Giuseppe Colombo studied Mercury’s rotation and proposed trajectories that enabled NASA’s first flybys of the planet in 1974. Only two previous missions, NASA’s Mariner 10 in 1974 and its MESSENGER mission in 2011, have visited Mercury.

Mercury is approximately 36 million miles (58 million kilometers) from the Sun on average and completes one orbit around the Sun every 88 days. Surface temperatures can reach about 800 degrees Fahrenheit (430 degrees Celsius) during the day.

Traveling to Mercury and entering orbit requires more energy, or delta-v, than sending a probe to fly by Pluto. BepiColombo used a combination of plasma propulsion and nine planetary flybys of Earth, Venus, and Mercury to adjust its velocity. The spacecraft launched with four gridded ion thrusters.

"You can go faster to Mercury if you take a direct way to it," said Frank Budnik, flight dynamics manager for the BepiColombo mission at the ESA. "But the problem is we want to insert into an orbit with respect to Mercury. You have to bring the spacecraft to the same velocity as Mercury has, and this is a very energy-demanding transfer." About six years into flight, BepiColombo's solar panels began underdelivering on power, forcing engineers to redraw the spacecraft's path, cut back on engine firings, adjust the schedule of key maneuvers, and accept a later arrival at Mercury.

The Mercury Transfer Module separated from the BepiColombo spacecraft stack on 3 September 2026. At separation from the Mercury Transfer Module, BepiColombo was about 2.1 million miles from Mercury. The Mercury Transfer Module drifted away from the BepiColombo stack at roughly 1 mph after separation.

Engineering cameras were located on three areas of the Mercury Transfer Module, which sent final snapshots of parts of the spacecraft before shutting down. The Mercury Transfer Module was responsible for generating power and providing propulsion for BepiColombo during its eight-year cruise. "Roll call completed, GO for separation," the Mission Control Team said.

"The separation of the transfer module will take place in conditions which are exceedingly challenging, and we will have to face a considerable risk that things don’t go as planned," said Ignacio Tanco, head of Inner Solar System Mission Operations at the ESA. "We are going to see for the first time systems in operation that we have not been able to fully test." A study titled "BepiColombo cruise science: overview of the mission contribution to heliophysics" was published in 2025 in Earth Planets and Space. Research titled "BepiColombo Mission Update" was published in 2025.

The European Space Agency provided the Mercury Planetary Orbiter. The Japan Aerospace Exploration Agency provided the Mercury Magnetospheric Orbiter, also known as Mio. The Mercury Planetary Orbiter and the Mercury Magnetospheric Orbiter will separate from each other on 9–10 December 2026.

Science operations for both orbiters are set to begin in April 2027. The Mercury Magnetospheric Orbiter will spin 15 times a minute. The Mercury Planetary Orbiter will position its solar array at an angle almost edge-on to the Sun to prevent solar radiation damage.

Why It Matters

The deployment of two fully independent, fully operational separate spacecrafts around a different planet represents a unique technical achievement in space exploration. The mission addresses the high energy requirements of reaching Mercury, where surface temperatures reach about 800 degrees Fahrenheit (430 degrees Celsius) and the planet orbits the Sun every 88 days. The dual-orbiter design allows for simultaneous study of the planet's surface and magnetosphere, building on the limited data returned by NASA’s Mariner 10 in 1974 and its MESSENGER mission in 2011.

The complexity of the orbital insertion required extensive trajectory adjustments using plasma propulsion and nine planetary flybys. The separation of the transfer module and subsequent orbiter deployment involves systems that have not been fully tested in these specific conditions. Science operations beginning in April 2027 will provide new data on Mercury's interior, surface structure, and magnetic field, contributing to the broader understanding of heliophysics documented in recent research publications.

Timeline

BepiColombo launched in October 2018 on an Ariane 5 rocket from Europe’s Spaceport near Kourou, French Guiana.

"Roll call completed, GO for separation." BepiColombo will enter orbit around Mercury on 21 November 2026.

What's New

"It will be the first time that a mission releases two fully independent, fully operational separate spacecrafts around a different planet." "Unlike in other missions, BepiColombo’s arrival doesn’t mean a single event."

"It’s going to be equivalent to launching a new spacecraft, only this spacecraft happens to be around a different planet."