After eight years and 9.9 billion kilometres, BepiColombo finally began its arrival at Mercury on 3 September 2026, when its Mercury Transfer Module (MTM) separated from the spacecraft stack. The signal confirming the separation reached mission control at the European Space Operations Centre (ESOC) in Darmstadt, Germany, at 15:49 CEST, marking the first major step in a complex sequence that will place two orbiters around the planet in December 2026.
A Long Haul Ends With a Silent Release
The MTM was the workhorse that carried BepiColombo from Earth to Mercury, providing power and solar electric propulsion for its winding path through the inner Solar System. It completed nine planetary flybys along the way. On 3 September, after months of simulations that tested the Mission Control Team with various operational scenarios, the team gave the official "GO" for separation at 12:00 CEST. The actual separation was scheduled for 14:00 CEST, but confirmation had to travel from 200 million kilometres away, so silence fell over the control room as they waited nearly two hours.
At 14:20 CEST, a preliminary Doppler signal gave the first hint that separation had succeeded. Flight Dynamics Manager Frank Budnik heard it clearly in the voice loop, and the team could see the expected change in the spacecraft's motion.
Safe Mode and Reconfiguration Follow
After the MTM let go, the remaining spacecraft stack entered safe mode, readjusted its attitude, and reconfigured itself before sending its status back to Earth. This was a necessary step to ensure the orbiter stack was stable and ready for the next phases of the arrival sequence. The successful separation was celebrated by ESA, industry partners, and the scientific community, while thousands watched the live stream on ESA's YouTube channel.
The Mercury arrival phase is one of the most complex planetary arrival sequences ESA has ever attempted. With the MTM now out of the picture, BepiColombo is set to become the first mission to place two spacecraft in orbit around Mercury. The next steps will unfold over the coming months, leading to the December 2026 orbital insertion.
For the team in Darmstadt, the separation was the culmination of years of preparation and a quiet but critical milestone in a mission that has already travelled farther than most spacecraft ever will. The silence in the control room was broken by the confirmation that BepiColombo was finally where it needed to be, ready to begin its study of the Solar System's innermost planet.
