Missions · Space Codex
BepiColombo
Two orbiters travelling as one stack are about to settle around Mercury in November 2026 after an eight-year cruise with nine planetary flybys.
ESA–JAXA Mercury mission
At a glance
Key points
- Mercury orbit insertion 21 Nov 2026
- Two orbiters from ESA and JAXA
- Science operations from April 2027
The arrival sequence
The electric-propulsion transfer module that had carried the stack since 2018 was dropped on 3 September 2026. Since then MPO has provided power and thrust, starting with an 8-minute 42-second burn on 24 September. A few small corrections lead up to orbit insertion on 21 November. On 9–10 December the two orbiters part company and move to their own orbits, and full science starts in April 2027.
Who was Bepi Colombo?
Giuseppe 'Bepi' Colombo (1920–84) was an Italian mathematician and engineer. He explained why Mercury spins exactly three times for every two orbits of the Sun, and he worked out that after its first Mercury pass NASA's Mariner 10 would come back around in step with the planet. His suggestion turned one planned encounter into three, in 1974–75, and those passes supplied most of what was known about Mercury until MESSENGER.
Two spacecraft, one ride
ESA's Mercury Planetary Orbiter maps the surface and interior; JAXA's Mio studies the magnetic field and the thin exosphere. Measuring the same planet from two orbits separates what comes from inside Mercury from what the solar wind does to it.
Getting to Mercury is hard
Falling toward the Sun speeds a spacecraft up, so reaching Mercury slowly enough to be captured took one Earth, two Venus and six Mercury flybys.
What we still don't know
Why Mercury's iron core is so large, and how a planet so small still keeps a global magnetic field.
Missions
- 2018–
BepiColombo
ESA / JAXAEn routeMercury orbit insertion 21 Nov 2026; the two orbiters separate 9–10 Dec 2026 and science begins Apr 2027.
Related entries
- MercurySmallest planet · iron-heavy and airless
Sources
- ESA: Giuseppe 'Bepi' Colombo: grandfather of the fly-by (opens in a new tab)
- ESA: BepiColombo (opens in a new tab)
- ESA: BepiColombo arrival updates (opens in a new tab)
- ESA: BepiColombo factsheet (opens in a new tab)
Last reviewed against these sources. Built from public NASA, ESA and JPL data; not affiliated with or endorsed by any agency.