ESA-JAXA BepiColombo spacecraft begins intricate Mercury insertion after eight‑year cruise

After an eight‑year voyage through deep space, the joint European Space Agency‑Japan Aerospace Exploration Agency mission BepiColombo has entered the most demanding phase of its journey, beginning a months‑long series of maneuvers to slip into orbit around Mercury.

The spacecraft, launched in October 2018, carries two distinct scientific probes: the Mercury Planetary Orbiter built by Europe and the Mercury Magnetospheric Orbiter, also known as Mio, contributed by Japan. Their combined payload is designed to investigate the innermost planet’s surface, interior, and magnetic environment.

Approaching Mercury is notoriously difficult. The planet orbits just 0.39 astronomical units from the Sun, exposing any incoming craft to extreme thermal radiation and a powerful solar gravity well. Engineers must execute a precise sequence of engine burns and trajectory corrections to reduce speed without overheating the spacecraft, a process described by mission managers as "tricky" and high‑risk.

BepiColombo follows a lineage of Mercury explorers that includes NASA’s Mariner 10 in the 1970s and the MESSENGER orbiter, which concluded its mission in 2015. Those missions provided the first close‑up images and magnetic field data, but many fundamental questions remain unanswered, such as why Mercury’s core is proportionally larger than Earth’s and how its weak magnetic field interacts with the solar wind.

The European MPO will map the planet’s topography, composition and exosphere, while Mio will focus on measuring the magnetic field and plasma environment. Together, the probes aim to clarify Mercury’s geological history and its role in the broader narrative of planetary formation in the solar system.

The current approach began on Thursday, marking the start of a carefully choreographed series of deep‑space burns that will gradually lower the spacecraft’s orbit. The plan calls for several weeks of fine‑tuning before the final orbital insertion, slated for early 2025, when the probes will separate and commence independent operations around the planet.

Scientists worldwide are watching closely, as the data expected from BepiColombo could reshape models of planetary cores and magnetic dynamo processes. The mission also serves as a testbed for future missions to the Sun’s vicinity, where thermal and radiation challenges are even more severe.

Looking ahead, the mission team will continue to monitor spacecraft health and adjust the flight path as needed, while preparing the scientific community for the influx of high‑resolution measurements. Success will not only deepen our understanding of Mercury but also demonstrate the viability of complex, multi‑probe missions to harsh environments.