The BepiColombo mission has reached a pivotal moment in its eight-year journey to Mercury the solar system’s enigmatic innermost planet. This ambitious endeavor, led by the European Space Agency (ESA) with contributions from Japan and the United States aims to unravel the mysteries of Mercury’s origins and its unique environment.
The mission’s journey has been nothing short of extraordinary. Launched in 2018, BepiColombo has utilized a combination of plasma propulsion and nine planetary flybys to navigate the complex gravitational landscape of the inner solar system. This intricate dance with Earth, Venus, and Mercury has allowed the spacecraft to gradually adjust its trajectory, setting the stage for its historic arrival.
The final stretch: separating the Mercury Transfer Module
On September 3, 2026, BepiColombo successfully jettisoned its Mercury Transfer Module (MTM) a critical component that provided propulsion and power throughout the mission’s journey. This maneuver, executed 39 million miles from the Sun, marked a significant milestone in the mission’s timeline.
The separation of the MTM was a high-stakes operation, described by Ignacio Tanco head of inner Solar System mission operations at ESA, as “equivalent to launching a new spacecraft.” The operation required precise coordination and presented considerable risks, given the extreme temperatures and intense solar radiation near Mercury.
With the MTM successfully detached, the mission’s two science orbiters—the Mercury Planetary Orbiter (MPO) built by Europe and the Mercury Magnetospheric Orbiter (Mio) from Japan—are now poised to begin their scientific observations. The MPO will focus on studying Mercury’s surface and interior, while Mio will investigate the planet’s magnetosphere and magnetic field.
Overcoming challenges: a journey of resilience
The path to Mercury has not been without its obstacles. In late 2024, BepiColombo’s ion thrusters experienced a partial power loss, necessitating an extension of the mission’s cruise by a year. Despite this setback, the mission has covered more than 6 billion miles (10 billion kilometers) and is now on track to maneuver into orbit around Mercury on November 21, 2026.
The mission’s resilience is a testament to the ingenuity and dedication of the teams involved. Elsa Montagnon BepiColombo’s spacecraft operations manager at ESA, highlighted the successful activation of the MPO’s solar arrays, confirming that the spacecraft’s power margins are positive. This critical verification ensures that the orbiters are ready to commence their scientific missions.
Unveiling Mercury’s secrets: scientific objectives and expectations
BepiColombo’s arrival at Mercury promises to shed new light on the planet’s origins and its unique characteristics. The mission aims to map Mercury’s surface in high resolution, providing insights into its composition and geological history. One of the most intriguing aspects of Mercury is the presence of water ice in the dark floors of its polar craters, a phenomenon that BepiColombo will investigate in detail.
The European-built orbiter will fly closer to Mercury, equipped with cameras and instruments to study the planet’s surface. Meanwhile, Japan’s smaller orbiter will fly in a higher orbit, with sensors tuned to detect magnetic fields, plasma, and dust. Routine science observations are set to begin in April, assuming the rest of the arrival sequence goes according to plan.
Santa Martinez ESA’s mission manager for BepiColombo, emphasized the mission’s ambition: “Mercury is a challenging destination. It’s very difficult to reach. It’s very difficult to operate at because of the extreme environment so close to the Sun. But what makes this mission really unique is that for the first time in space exploration, we are bringing two spacecraft to the vicinity of the planet, and we are going to put them in orbit around this mysterious body.”
The mission’s success will not only expand our understanding of Mercury but also contribute to our broader knowledge of the solar system’s formation and evolution. As Geraint Jones ESA’s project scientist for BepiColombo, noted, “Having two spacecraft there is groundbreaking. It makes an enormous difference in understanding the effects that the solar wind has on planets like Mercury, so, fundamentally, we want to learn about the origins of this planet and how it came to be like it is.”
