Spacecraft Headed to Mercury Will Take Unexpected Detour Due to Thruster Glitch
The European Space Agency (ESA) has announced that its BepiColombo mission to Mercury will experience a significant delay due to a propulsion system glitch. Originally scheduled to enter orbit around Mercury in December 2025, the spacecraft will now arrive in November 2026. The delay is a result of a malfunction that prevented the spacecraft from operating at full thrust.
Details of the Glitch
The issue was identified in the spacecraft’s Transfer Module, which is responsible for generating the necessary thrust for its journey. The malfunction was traced to unexpected electrical currents between BepiColombo’s solar array and the power distribution unit. This problem has led to reduced thrust capabilities, forcing the spacecraft to adjust its trajectory.
To compensate for the reduced thrust, ESA engineers have developed a workaround. BepiColombo will follow a revised trajectory that takes it closer to Mercury’s surface than initially planned. This change will involve a flyby of Mercury on Thursday, which is crucial for reducing the spacecraft’s speed and altering its path toward the planet.
During this flyby, BepiColombo will pass approximately 56 miles (35 kilometers) closer to Mercury than originally intended and will also make its first pass over the planet’s poles.
Mission Adjustments and Scientific Opportunities
Despite the setback, the mission team is optimistic about the scientific opportunities presented by the new trajectory. Johannes Benkhoff, BepiColombo project scientist, expressed enthusiasm about the flyby, stating that it will allow the spacecraft to gather valuable data from previously unexplored parts of Mercury’s environment. The close approach will also provide the first images of Mercury’s south pole.
BepiColombo was launched in October 2018 as a joint mission between ESA and the Japan Aerospace Exploration Agency (JAXA). The mission includes two orbiters: ESA’s Mercury Planet Orbiter (MPO) and JAXA’s Mercury Magnetosphere Orbiter (MMO). Each orbiter is designed to study different aspects of Mercury, including its surface, interior, and magnetic field.
The spacecraft will perform a total of nine gravity assist maneuvers—one around Earth, two around Venus, and six around Mercury. It has already completed its first Mercury flyby in October 2021, returning detailed images of the planet.
Impact on the Mission
The unexpected delay means that BepiColombo will not enter Mercury’s orbit until November 2026, nearly a year later than planned. However, the new trajectory and additional flybys will still contribute valuable data to our understanding of the solar system’s smallest planet. Mercury remains one of the least explored planets due to its proximity to the Sun and the challenges associated with reaching it.
The BepiColombo mission aims to uncover secrets about Mercury’s composition, magnetic field, and evolutionary history, providing insights that could enhance our understanding of planetary processes in our solar system.