New Mercury Images from BepiColombo’s Flyby – Sky & Telescope

This is a year for flybys, and the very first one occurred this week: The BepiColombo mission has made its final flyby past Mercury, ahead of orbital insertion in late 2026.

The flyby was the sixth for the mission, and saw the spacecraft come as close as 295 kilometers (183 miles) to the world’s nighttime surface. It then made a close outbound pass over the sunlit northern pole of the planet. The flyby occurred at 5:59 Universal Time (UT) on January 8th.

“Based on our preliminary assessment, everything proceeded smoothly and flawlessly,” says Frank Budnik (ESA), the mission’s flight dynamics manager.

The mission, named for Italian scientist Giuseppe “Bepi” Colombo, was originally slated to arrive at Mercury in 2025, but a thruster anomaly in early 2024 caused ESA controllers to opt for an extra flyby and a later orbital insertion. When it comes to gravitational slingshot assists, bleeding off enough momentum to get captured around Mercury close to the Sun is actually as difficult as getting to the outer solar system.

BepiColombo is actually a pair of stacked spacecraft: The European Space Agency’s Mercury Planetary Orbiter and Japan’s Mercury Magnetospheric Orbiter, both of them attached to the Mercury Transfer Orbiter. The flyby’s newest images come courtesy of the M-CAM imagers on the transfer module, selfie cameras that are meant to help monitor the mission. This flyby marks the last closeup views of Mercury for thesee cameras. The European and Japanese orbiters will take over the imaging after that, after they separate prior to orbital insertion.

The new images give us tantalizing views of permanently shadowed craters, including Tolkien, Kandinsky, and Prokofiev. Although the rims of these craters are subject to the blazing Sun, the dark floors are suspected of harboring water ice.

The receding spacecraft also snapped views of the broad volcanic plains of Borealis Planitia, which includes the Rustaveli and Fonteyn Crater. The smooth plains appear in stark contrast against Mercury’s cratered surface and are thought to have formed 3.7 billion years ago.

Another image captures a view of a region that includes the enormous Caloris Basin. Spanning 1,500 kilometers — and so a good portion of the planet’s surface — the basin shows signs of the cataclysmic impact event that nearly shattered the planet, with rippling troughs radiating from the impact site.

These preliminary images tease the questions that the BepiColombo mission aims to answer, starting up where NASA’s world-mapping Messenger mission left off in 2015: Is there water ice on Mercury? What’s the planet’s geological history? What does Mercury’s story tell us about the formation of the early solar system?

The real science phase of BepiColombo’s operations won’t start until early 2027, after the spacecraft has become the second mission to orbit Mercury. This exciting last preview of the mission’s final destination will have to hold us over until then.