See New Detailed Photos of Mercury From a Spacecraft’s Closest Flyby Yet

A joint European-Japanese spacecraft has made its closest flyby of Mercury yet, offering new snapshots of the rocky planet’s surface.

The BepiColombo spacecraft, which launched in 2018, made its fourth pass by Mercury on September 4. At its nearest point, the vessel flew 103 miles above the planet’s surface, snapping highly detailed photos of its cratered crust along the way.

BepiColombo is a collaboration between the European Space Agency and the Japan Aerospace Exploration Agency. The spacecraft is equipped with three monitoring cameras, or M-CAMs, that captured black-and-white images of the innermost planet of the solar system. As the spacecraft approached Mercury from its so-called “night side,” the cameras took photos of its south pole and craters becoming increasingly lit by the sun.

The new images caused Johannes Benkhoff, the European Space Agency’s project scientist for the BepiColombo mission, to “shout for joy,” as he tells the New York Times’ Katrina Miller.

“It is such a relief when you find out that everything worked as planned,” he adds.

Strange, blasted little fireball. We've never seen planet Mercury better than the pictures just taken by @BepiColombo, a mere 100 miles/165 km above the distant, rocky surface, so near the Sun.
info: https://t.co/p38tUgPg28
images: @esa @JAXA_en pic.twitter.com/92tq0QXWj2

— Chris Hadfield (@Cmdr_Hadfield) September 5, 2024

BepiColombo captured some of Mercury’s craters—including Stoddart and Vivaldi—that have rings of peaks on the otherwise flat crater floor. With a ring inside the crater’s rim, the impact site looks something like a bull’s-eye. These areas are particularly intriguing to scientists—it’s not clear exactly how peak ring basins formed, but they are thought to originate with a comet or asteroid colliding with the planet. Studying these sites might also offer clues about Mercury’s past volcanic activity.

Vivaldi, which was named after Italian composer Antonio Vivaldi, measures 130 miles across. It has a “visible gap” in the ring of peaks, which scientists say formed when more recent lava flows flooded the crater, according to a statement from the European Space Agency.

Stoddart, meanwhile, measures 96 miles across. It was just recently named in August after Margaret Olrog Stoddart, a New Zealand artist who died in 1934 and was known for her paintings of flowers.

“Mercury’s peak ring basins are fascinating, because many aspects of how they formed are currently still a mystery,” David Rothery, a planetary geoscientist at the Open University in England and a member of the BepiColombo imaging team, says in the statement. “The rings of peaks are presumed to have resulted from some kind of rebound process during the impact, but the depths from which they were uplifted are still unclear.”

BepiColombo also took measurements of Mercury’s magnetic, plasma and particle environments, collecting data that will not be possible for it to get in the future, when the vessel goes into orbit around the planet. That milestone is slated for November 2026, which is roughly a year behind schedule. The delay was caused by issues with BepiColombo’s thrusters.

As one of the least-studied planets in the solar system, Mercury is still largely a mystery to scientists. They hope the BepiColombo mission will unveil new insights into the roughly 4.6-billion-year-old planet’s geology, magnetic field and composition, which might in turn shed light on its origins.

Reaching Mercury’s orbit is not easy. As the spacecraft approaches our sun, the star’s gravity makes it travel faster. To compensate, it must pass by Mercury, Venus and Earth several times to lose some speed before entering orbit around the innermost planet. BepiColombo will make two more flybys of Mercury—one in December and another in January—before flying around the sun for two years. Then, if all goes to plan, it will maneuver into Mercury’s orbit.

From there, the vessel will begin using other scientific instruments, including a high-resolution color camera, to make observations of Mercury over the course of a year or two. In total, the spacecraft contains 16 instruments between two orbiters, which will split off from each other once it’s successfully orbiting the planet, per Space.com’s Andrew Jones.

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Sarah Kuta is a writer and editor based in Longmont, Colorado. She covers history, science, travel, food and beverage, sustainability, economics and other topics.