Mercury is a planet of extremes. It’s the closest planet to the Sun, but it’s not the hottest planet in the solar system. It’s a world where daytime temperatures can melt lead, but ice may still lurk in its shadowy craters. It’s also the smallest planet in the solar system and it’s likely the least understood of all the terrestrial planets in the Solar System. Now, the European Space Agency (ESA) and Japanese Space Agency (JAXA) are shedding new light on Mercury with the BepiColombo mission.
The spacecraft executed its sixth and final gravity-assist flyby of the enigmatic planet, capturing some of the most detailed images yet of Mercury’s surface. This critical maneuver, which brought the spacecraft just 295 kilometers above the planet’s surface, sets the stage for its orbital insertion in late 2026.
European Space Agency (ESA) Director General Josef Aschbacher revealed the first image during his Annual Press Briefing. Although Mercury is very hot (temperatures on Mercury soar to 750 degrees Fahrenheit or 400 degrees Celsius), the highlight of this recent flyby was cold areas. Particularly, astronomers were excited about images of the shadowed craters of Mercury’s north pole.
These craters, lying in eternal darkness, are some of the coldest places in the solar system despite Mercury’s proximity to the Sun. Craters like Prokofiev, Kandinsky, and Tolkien were captured in stunning detail by BepiColombo’s monitoring camera (M-CAM 1).
These shadowy regions are of immense scientific interest because they might contain frozen water. Mercury is a very hot place but it lacks an atmosphere, allowing surface temperatures to plunge to extreme lows in these craters. This could potentially preserve ice deposits for billions of years. BepiColombo’s future mission is expected to confirm whether these deposits are indeed water ice—a discovery that could transform our understanding of water delivery in the solar system.
The flyby also revealed vast expanses of Mercury’s northern volcanic plains, known as Borealis Planitia. Mercury’s surface is heavily cratered, much like the moon, with vast impact basins. Volcanic plains that cover large areas were formed billions of years ago when huge volumes of molten rock flooded the surface. In time, Mercury’s interior cooled and contracted, causing its crust to wrinkle. This created long, curved ridges known as lobate scarps.
What’s next for the mission?
Launched on October 20, 2018, BepiColombo represents the culmination of decades of planning and collaboration between ESA and JAXA. Named after the Italian scientist Giuseppe “Bepi” Colombo, who first proposed the use of gravity assists to explore Mercury, the mission is a fitting tribute to his legacy.
BepiColombo’s dual-orbiter design is unique. The Mercury Planetary Orbiter (MPO) will focus on mapping the planet’s surface and studying its geological features, while the Mercury Magnetospheric Orbiter (Mio) will investigate Mercury’s magnetic field and space environment. Together, they will provide a comprehensive picture of the innermost planet.
The mission will zoom in on the planet more and more in 2025. Then, in late 2026, the spacecraft will separate and the two orbiters will maneuver to their dedicated polar orbits around the planet. This will launch a new phase of the mission in 2027, where both orbiters will gather data during a one-year nominal mission, with a possible one-year extension.
Exploring Mercury is about more than understanding one planet—it’s about answering fundamental questions about our solar system. How did the planets form and evolve? What role do extreme environments play in shaping planetary bodies? And what does Mercury tell us about the Earth and other rocky planets?
With its orbit just a few years away, BepiColombo promises to transform our understanding of the solar system’s smallest and least explored planet.
