The European and Japanese BepiColombo spacecraft have transmitted large images of the solar system’s most distant planet, flying through Mercury’s shadow to reveal craters that are constantly hiding in the shadows.
BepiColombo, consisting of two connected spacecraft, flew past Mercury for the sixth and final time on Wednesday, using the planet’s gravitational pull to adjust its trajectory for a possible orbit in 2026. The mission was launched in October 2018 as a joint venture between the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA), each of which provided its own orbiter to explore Mercury. According to ESA, during the last flyby, the twin spacecraft flew over the surface of Mercury at a distance of about 180 miles (295 kilometers).
From this close distance, BepiColombo captured images of Mercury’s cratered surface, starting with the cold, permanently dark night side of the planet near the north pole and then moving toward its sunlit northern regions.
With the help of its observation cameras (M-CAM 1), BepiColombo has obtained for the first time a close-up of the boundary separating the day and night sides of Mercury. The image above shows that the edges of the Prokofiev, Kandinsky, Tolkien, and Gordimer craters are scattered across the surface of Mercury, casting permanent shadows that may contain pockets of frozen water.
In fact, the key goal of the mission is to find out whether Mercury retains water in its shadows despite its proximity to the Sun.
The massive Caloris Basin, Mercury’s largest impact crater, stretches more than 930 miles (1,500 kilometers) across and can be seen at the bottom left of the image.
Although Mercury is a predominantly dark planet, its young features (or recent scars) appear brighter on the surface. Scientists aren’t entirely sure what Mercury is made of, but material that has been excavated from beneath the planet’s surface gradually darkens over time.
In this third image, volcanic activity and powerful collisions are the key factors behind the brighter regions of Mercury. “The bright spot near the upper edge of the planet in this image is Facula Nateir, the aftermath of the largest volcanic explosion on Mercury. At its center is a volcanic vent about 40 km [25 miles] across that has been the site of at least three major eruptions,” ESA writes.
BepiColombo is only the third spacecraft to visit Mercury; the elusive planet is difficult to reach due to the Sun’s powerful gravity. The two BepiColombo probes, consisting of ESA’s Mercury Planet Orbiter (MPO) and JAXA’s Mercury Magnetosphere Orbiter (MMO), were launched together on the same spacecraft, and each will enter its own orbit around Mercury in late 2026. The mission made its maiden flyby of the planet in October 2021 and has since been returning remarkable close-up images of the solar system’s smallest planet, as well as valuable data about the mysterious planet.
“The main phase of BepiColombo’s mission may not begin for another two years, but all six flybys of Mercury have provided us with invaluable new information about this poorly understood planet. Over the next few weeks, the BepiColombo team will be working hard to unravel as many of Mercury’s mysteries as possible with the data collected during this flyby,” said Geraint Jones, ESA’s BepiColombo Science Project Manager.
