BepiColombo: ESA and JAXA mission to Mercury

Spacecraft and instruments

BepiColombo consists of separate modules built to perform complementary measurements. The European-built Mercury Planetary Orbiter (MPO) carries instruments for high-resolution imaging, geochemistry and geodesy. The Japanese-built Mercury Magnetospheric Orbiter (also called Mio or MMO) studies the planet’s magnetosphere and plasma environment. A transfer module provides propulsion and power during the cruise phase and delivers the orbiters to Mercury. Together the payload includes cameras, spectrometers, magnetometers, a laser altimeter and particle detectors.

Propulsion and trajectory

To reach Mercury with manageable fuel requirements, BepiColombo used a long interplanetary cruise with solar electric propulsion and gravity-assist maneuvers. This approach slows the spacecraft relative to the Sun so it can be captured by Mercury’s gravity when the cruise ends. The mission launched in October 2018 and is expected to enter Mercury orbit in late 2025, after several planetary flybys and a dedicated braking phase.

Scientific goals and methods

The mission aims to answer fundamental questions about Mercury’s origin and evolution: How is the planet’s large metallic core structured? What are the composition and formation history of surface materials? How does a weak, intrinsic magnetic field interact with the solar wind? BepiColombo’s twin-orbiter architecture allows near-simultaneous observations from different vantage points, linking surface properties with surrounding space environment measurements.

Importance and context

• Second dedicated Mercury survey following NASA’s MESSENGER mission, providing new instrumentation and orbital strategies.
• Improves knowledge about planetary differentiation and the effects of intense solar radiation on a close-in planet.
• Provides precise tracking data useful for studies of Mercury’s gravity field and tests of relativistic gravity.

For mission updates and data releases see the agencies’ pages: mission information and agency portals. BepiColombo is expected to operate in Mercury orbit through a multi-year science phase, returning measurements that will refine models of terrestrial planet formation and near-Sun space physics.