[5] The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure.

[8] On 15 May 2024, ESA reported that a "glitch" prevented the spacecraft's thrusters from operating at full power during a scheduled manoeuvre on 26 April.

[9] On 2 September, ESA reported that to compensate for the reduced available thrust, a revised trajectory had been developed that would add 11 months to the cruise, delaying the expected arrival date from 5 December 2025 to November 2026.

[10] BepiColombo is named after Giuseppe "Bepi" Colombo (1920–1984), a scientist, mathematician and engineer at the University of Padua, Italy, who first proposed the interplanetary gravity assist manoeuvre used by the 1974 Mariner 10 mission, a technique now used frequently by planetary probes.

In Japanese, Mio means a waterway, and according to JAXA, it symbolizes the research and development milestones reached thus far, and wishes for safe travel ahead.

[1] Although originally expected to enter orbit in December 2025, thruster issues discovered in September 2024 before its 4th flyby resulted in a delayed arrival of November 2026.

Mercury is too small and hot for its gravity to retain any significant atmosphere over long periods of time, but it has a "tenuous surface-bounded exosphere"[24] containing hydrogen, helium, oxygen, sodium, calcium, potassium and other trace elements.

During this time it will use solar-electric propulsion and nine gravity assists, flying past the Earth and Moon in April 2020, Venus in 2020 and 2021, and six Mercury flybys between 2021 and 2025.

Four final thrust arcs reduce the relative velocity to the point where Mercury will "weakly" capture the spacecraft in November 2026 into polar orbit.

[30] The initial target launch of July 2014 was postponed several times, mostly because of delays on the development of the solar electric propulsion system.

This leads to a flight profile with months-long continuous low-thrust braking phases, interrupted by planetary gravity assists, to gradually reduce the velocity of the spacecraft.

The solar array requires continuous rotation keeping the Sun at a low incidence angle in order to generate adequate power while at the same time limiting the temperature.

[50] The MPO will carry a payload of 11 instruments, comprising cameras, spectrometers (IR, UV, X-ray, γ-ray, neutron), a radiometer, a laser altimeter, a magnetometer, particle analysers, a Ka-band transponder, and an accelerometer.

The payload components are mounted on the nadir side of the spacecraft to achieve low detector temperatures, apart from the MERTIS and PHEBUS spectrometers located directly at the main radiator to provide a better field of view.

[8] At the time of cancellation, MSE was meant to be a small, 44 kg (97 lb), lander designed to operate for about one week on the surface of Mercury.

The MSE would have carried a 7 kg (15 lb) payload consisting of an imaging system (a descent camera and a surface camera), a heat flow and physical properties package, an alpha particle X-ray spectrometer, a magnetometer, a seismometer, a soil penetrating device (mole), and a micro-rover.