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At a Glance

Why do we need BepiColombo?

Mercury is a mysterious, contradictory world. Despite being the closest planet to the Sun with surface temperatures of 430 degrees Celsius (800 degrees Fahrenheit), Mercury has water ice hidden in shadowed craters near its poles. The planet’s surface appears old and cratered, undisturbed by geologic activity like volcanoes. Yet it has a magnetic field, which is normally caused by a molten core that should, in turn, cause surface changes.

These apparent contradictions make Mercury as intriguing as any other planet in our solar system, yet only two missions (NASA’s Mariner 10 and MESSENGER) have ever studied it up close. MESSENGER discovered Mercury’s core makes up 85 percent of the planet’s volume—much more than Earth’s, which is just 15 percent. 

Why does Mercury have such a large core, and how does it generate the planet’s magnetic field? These are questions that BepiColombo, a joint Japanese-European Mercury mission that launched in 2018, will attempt to answer. BepiColombo will arrive in Mercury orbit in 2025. 

How did the planets form, and what was the early solar system like when life arose on Earth? To answer these questions, scientists need to understand all the diverse types of worlds around our Sun, including Mercury. By understanding how Mercury came to be and unraveling its enigmatic nature, we will be one step closer to understanding where we came from.

What’s in a name?

BepiColombo is named in honor of Giuseppe “Bepi” Colombo (1920-1984), an Italian mathematician-engineer who explained Mercury rotating 3 times for every 2 orbits around the Sun. Colombo also calculated how NASA’s Mariner 10 spacecraft could fly past Venus, using the planet’s gravity to set a course for Mercury in the 1970s. 

How BepiColombo will explore Mercury

Before BepiColombo can study Mercury, it faces a long journey. Mercury is the fastest-orbiting planet in our solar system—it blazes around the Sun at 48 kilometers per second. To reach Mercury, the spacecraft will have to perform several gravity-assist flybys to pick up speed, passing the Earth in April 2020, Venus in 2020 and 2021, and Mercury six times between 2021 and 2025 before settling into orbit. 

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BepiColombo’s journey to Mercury

On its 7-year journey to Mercury, the European-Japanese mission BepiColombo takes advantage of the gravity of Earth, Venus and Mercury to adjust its trajectory and reach its final orbit. Credit: ESA - European Space Agency, CC BY-SA 3.0 IGO

BepiColombo is actually 3 spacecraft that launched together and will travel to Mercury as a combined vehicle.

Once all 3 spacecraft arrive at Mercury in 2025, MPO and MMO will split off into two different orbits best suited to their science instruments. MPO will orbit close to the Mercury where it can observe the planet’s surface best, while MMO will stay farther back where it can study the planet’s magnetic field. 

BepiColombo (expanded view)

ESA / ATG medialab

BepiColombo (expanded view)
BepiColombo is actually 3 spacecraft, plus a sunshield, that launched together and will travel to Mercury as a combined vehicle. From bottom to top these are: the Mercury Transfer Module, the Mercury Planetary Orbiter, a sunshield, and the Mercury Magnetospheric Orbiter.

What You Can Do to Support BepiColombo

You can help us support the exploration of Mercury and other worlds by sharing the passion, beauty, and joy of space exploration:

Three ways you can be a space advocate

To follow the BepiColombo mission directly, check out these Twitter accounts:

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