After eight years of travel through the inner solar system, the BepiColombo mission has started its final run toward Mercury. The European Space Agency and the Japan Aerospace Exploration Agency built and operate the spacecraft together.
ESA reported that the arrival phase formally began on September 3, 2026, when the Mercury Transfer Module separated from the rest of the spacecraft stack. Two ESA deep-space tracking antennas, in Spain and Argentina, picked up the signals that confirmed the separation. Telemetry showed all systems working normally.
Transfer module drops away
The transfer module provided the propulsion and solar-electric power that carried the stack on its long, looping route. With that job complete, it is no longer needed. The remaining composite spacecraft now flies on its own toward the planet.
Orbit insertion is set for November 21, 2026. At that point BepiColombo becomes the first mission to orbit Mercury with two spacecraft at the same time.
Two orbiters, two different jobs
ESA's Mercury Planetary Orbiter, known as MPO, will study the surface and the interior. JAXA's Mercury Magnetospheric Orbiter, called Mio, will focus on the planet's magnetic field and the particles around it. The two will separate from each other on December 9 and 10, 2026, then settle into different orbits.
Mercury is the smallest planet and the closest to the sun. Its surface swings between extreme heat and extreme cold, and it has almost no atmosphere to protect it from solar radiation. Working there requires shielding and careful thermal design.
Science phase starts in 2027
Commissioning of the instruments will take several months. The science phase is scheduled to begin in April 2027. Researchers expect the data to help explain how a planet that formed so close to the sun still ended up with a magnetic field and a surprisingly large iron core.
A long road to the smallest planet
Getting to Mercury is harder than it looks. The planet sits deep in the sun's gravity well, so a spacecraft that flies straight at it speeds up and overshoots. BepiColombo instead used a series of flybys of Earth, Venus and Mercury itself, bending its path and slowing down just enough to be captured. The journey took about 7.2 years. Mission planners say the wait buys a longer, more stable orbit once the spacecraft settles in.