BepiColombo is an international exploration mission to Mercury, jointly undertaken by the Japan Aerospace Exploration Agency (JAXA) and the European Space Agency (ESA). The spacecraft was launched in October 2018.

In May 2024, during the journey to Mercury, ESA reported that a malfunction had occurred in the power system of BepiColombo's Mercury Transfer Module (MTM) that prevented the ion engine from using maximum power.
Glitch on BepiColombo: work ongoing to restore spacecraft to full thrust （ESA）

As a result of efforts to investigate the cause of this issue and identify countermeasures, it was decided that the MTM ion engine could operate at a lower power output than originally planned. However, this level of thrust would not allow the originally planned Mercury orbit insertion in December 2025, and new trajectories were therefore considered. A new trajectory that would allow the spacecraft to reach Mercury under reduced ion engine power but without changing the scientific observations after arrival was announced on September 2 (see below). On this new trajectory, BepiColombo will arrive at Mercury in November 2026, approximately one year later than the original plan.
Fourth Mercury flyby begins BepiColombo's new trajectory （ESA）

BepiColombo will change trajectory from the fourth Mercury swing-by on September 5 (JST). During the fourth swing-by, the altitude over the planet will be lower than originally planned in order to conserve the ion engine power, and after the sixth and final Mercury swing-by, the spacecraft will head to Mercury on the new trajectory.

Despite the delay of approximately one year, there will be no disruption to the operation of the Mercury Magnetospheric Orbiter (MMO/Mio) developed by JAXA, or to the Mercury Planetary Orbiter (MPO) developed by ESA. Both orbiters are scheduled to carry out their scientific observations as originally planned.

During swing-by, beautiful close-ups of Mercury will be captured using the monitoring cameras (M-CAM) onboard the MTM and will be publicly released, so please look out for these!