BepiColombo Captures the Enigmatic Charms of Mercury’s Shadowy Craters and Fiery Landscapes

The latest visuals of Mercury’s cratered terrain are the final ones we will observe prior to the BepiColombo mission commencing its orbit around the solar system’s innermost planet by late 2026.

Since its launch in 2018, the collaborative European-Japanese BepiColombo spacecraft has conducted six flybys of Mercury, utilizing each encounter to lower its velocity and modify its trajectory for easier orbital insertion. Although the principal scientific instruments of the mission are yet to be activated, the monitoring cameras aboard have provided us with some of the clearest observations we’ve ever captured of the Swift Planet.

The European Space Agency (ESA) has just unveiled three of the most striking images from BepiColombo’s recent flyby on January 8, taken from approximately 300 kilometers above the surface of Mercury while passing over its north pole and northern regions.

“Waking up at 5:30 am was necessary, but once the close-up images started appearing in our shared folder, it was definitely worthwhile,” remarks David Rothery from the Open University in the UK. “We had analyzed some simulated visuals in advance and leveraged those to formulate our imaging strategy, but the actual views exceeded our expectations.”

The image displayed above, taken over the planet’s north pole, illustrates the distinct boundary between sunlight and darkness on Mercury, referred to by researchers as the terminator line. Mercury experiences some of the highest temperatures in the solar system where sunlight hits its scorched surface, but it also has extremely low temperatures in craters that are perpetually shrouded in shadow due to their edges.

Some of these shadowed crater areas can be seen along the terminator line in the image. “Observing from above Mercury’s north pole was incredible, and even spotting the sunlit peak of the central mountain within the crater Tolkien, whose floor remains in eternal shadow, was remarkable,” shares Rothery.

Researchers have uncovered some indications that these cratered areas may harbor frozen water. One of BepiColombo’s primary mission goals is to ascertain whether that water truly exists and quantify its amount.

Mercury is also home to extensive volcanic fields, collectively referred to as Borealis Planitia, which BepiColombo observed during its flyby. Scientists believe that these fields were created from massive lava flows more than 3 billion years ago that inundated pre-existing craters, some of which are visible in the image above. Most of these inundated plains are flat, with a few impact craters that likely formed more recently.

The Caloris Basin, which spans 1500 kilometers wide and is Mercury’s largest crater, can be observed towards the lower left of the image. Researchers are eager to discover more about how this crater, along with Borealis Planitia and the solidified lava flows in between, are interrelated once BepiColombo begins its orbit around the planet.

The luminous area located near the top of the planet in this image is referred to as Nathair Facula, and researchers suspect it is the leftover of Mercury’s greatest volcanic eruption ever. At the center of this region lies a 40-kilometre-wide volcanic vent, which seems to have been the origin of at least three significant eruptions that ejected volcanic materials for hundreds of kilometers.

“[Nathair Facula] was precisely at the threshold of what we anticipated to discern, but after having published findings based on images from the earlier NASA mission to Mercury, it was thrilling to see it once more,” states Rothery. “It stands as a crucial scientific target for several instruments aboard BepiColombo when we commence orbiting, because it provides our best opportunity to decipher what aspect of Mercury’s composition has made it possible for explosive volcanic eruptions to persist throughout much of the planet’s history.”