BepiColombo mission will start to unpick Mercury’s secrets in 2026

We will finally begin to unravel the mysteries of Mercury in 2026, as the BepiColombo spacecraft descends into orbit around the solar system’s innermost planet.

BepiColombo consists of a pair of spacecraft from the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). The Mercury Planetary Orbiter (MPO) and Mercury Magnetospheric Orbiter (Mio) are attached to a parent spacecraft, the Mercury Transfer Module (MTM).

Since its launch in 2018, the MTM has flown by Mercury six times, using the planet’s gravity to slow its descent until it could easily go into orbit, a technique invented by the mission’s namesake, physicist Giuseppe “Bepi” Colombo.

The mission collected important scientific data, such as clues about the solar wind and high-resolution images of Mercury’s surface. But its most powerful instruments, like a pair of X-ray spectrometers on ESA’s MPO, have not yet been used because their view has been obscured by the MTM.

In September 2026, MPO and Mio will detach from the MTM and begin their descent into orbit, which is expected to be completed by November, allowing them to finally lay eyes on the planet.

Charly Feldman of the University of Leicester, UK, worked on one of the MPO instruments. “There is this anticipation: is our instrument still working and is it going to work as expected? » she said. “There’s nothing we can do if it’s broken. It’s been building for a very long time, so while it’s incredibly exciting, it’s also a little nerve-wracking.”

In addition to imaging Mercury’s magnetic environment in far greater detail than any previous mission, Mercury’s surface will also be mapped and analyzed extensively, using tools such as DFO’s spectrometers. “These will be the first X-ray images of the surface of another planetary body,” says Feldman.

This could help us solve mysteries such as the surprisingly high amount of X-rays coming from the sun-facing night side of the planet as measured by previous missions. It can also measure X-rays coming from the sun-facing side of the planet, which will allow scientists to determine what Mercury’s surface is made of, which can then tell us about the planet’s evolution. “If you can understand how different planets came to be the way they are, you can understand the dynamics of the entire solar system,” says Feldman.

Stargazing and space science in the Land of the Rising Sun, Japan

Discover Japan through the lens of astronomy, from advanced research centers to skies that inspire both science and tradition. Visit world-class facilities including JAXA’s Tsukuba Space Center, Nobeyama Radio Observatory, and Tanegashima Space Center, then stargaze under the pristine skies of the Japanese Alps and Yakushima Island.