In 2026, the joint European Space Agency (ESA) and Japanese Aerospace Exploration Agency (JAXA) mission, BepiColombo, will finally enter orbit around Mercury, marking the start of a long-awaited period of intensive scientific investigation. This mission isn’t just another flyby; it’s designed to fully unpick the mysteries of the solar system’s innermost planet.
A Two-Part Approach
BepiColombo comprises two main orbiters: the Mercury Planetary Orbiter (MPO) and the Mercury Magnetospheric Orbiter (Mio). Both are currently attached to the Mercury Transfer Module (MTM), which has been guiding the spacecraft since its launch in 2018. The MTM uses a clever gravity assist technique, pioneered by physicist Giuseppe “Bepi” Colombo, to gradually slow the spacecraft down for a controlled orbital insertion.
Why Now?
For years, BepiColombo has gathered preliminary data, including insights into the solar wind and high-resolution surface images. However, its most potent tools – such as the MPO’s X-ray spectrometers – have been obscured by the MTM. In September 2026, the MPO and Mio will detach from the MTM and begin their descent into orbit. By November, these instruments will have an unobstructed view, allowing for detailed analysis.
What Will We Learn?
This mission is expected to deliver unprecedented data about Mercury’s magnetic environment, surface composition, and internal structure.
- The MPO will take the first-ever X-ray images of a planetary surface, helping explain the unexpectedly high X-ray emissions from Mercury’s dark side.
- Spectrometers will analyze the planet’s sunlit side, revealing its surface composition and providing clues to its evolution.
- The Mio will study Mercury’s magnetosphere, the area of space dominated by the planet’s magnetic field.
“If you can understand how the different planets have come to be as they are, you can understand the dynamics of the whole solar system,” says Charly Feldman, an instrument scientist at the University of Leicester.
The Wait and the Risk
While the anticipation is high, the mission team acknowledges the risk. Instruments have been in transit for years, and there’s no guarantee they’ll function perfectly upon activation. As Feldman notes, “There’s nothing we can do if it’s broken.”
Mercury’s anomalies have long puzzled scientists. The planet’s unusually large iron core, weak magnetic field, and high surface temperatures pose fundamental questions about planetary formation and evolution. BepiColombo is poised to provide the answers.
The mission represents a major step forward in our understanding of the solar system’s innermost world. By combining cutting-edge instruments with a well-planned orbital trajectory, BepiColombo is set to rewrite our knowledge of Mercury and, by extension, the forces that shape all rocky planets.
