Plate Nº 41 · recorded October 10, 2026
Space & AstronomyReported finding
BepiColombo's Mercury arrival begins with 3 September separation
On 3 September 2026, BepiColombo will jettison its Mercury Transfer Module, starting a months-long sequence that places ESA's MPO and JAXA's Mio in orbit around the Sun's closest planet.
By Marcus Bennett3 min read608 words
In brief
- BepiColombo will separate from its Mercury Transfer Module on 3 September 2026, beginning the Mercury arrival phase
- Mercury orbit insertion is scheduled for November 2026, with the two science orbiters separating in December 2026
- Only NASA's MESSENGER (orbit 2011–2015) has previously orbited Mercury; Mariner 10 made three flybys in 1974–75
- ESA's Mercury Planetary Orbiter carries 11 instruments; JAXA's Mercury Magnetospheric Orbiter (Mio) carries 5
- The 31 August briefing lasted 1 hour 9 minutes and was presented by Prof. Geraint Jones, Santa Martinez, and Ignacio Tanco of ESA
On 3 September 2026, the BepiColombo spacecraft will separate from its Mercury Transfer Module, beginning the final approach to the smallest and least explored rocky planet in the inner Solar System.
The European Space Agency confirmed the schedule during a 1 hour 9 minute online press briefing on 31 August. The mission — a joint project with the Japanese space agency JAXA — will deliver Europe's and Japan's first spacecraft to orbit Mercury.
Only NASA's MESSENGER has previously orbited the planet, circling it from 2011 until a planned impact in 2015. Mariner 10 made three flybys in 1974 and 1975 without entering orbit. Once BepiColombo arrives, its two orbiters will be the second and third spacecraft ever to orbit Mercury, making the joint mission the most complex ever attempted there.
What are the upcoming milestones?
ESA laid out three sequential events in the closing months of 2026, marking the transition from cruise to Mercury arrival:
- 3 September 2026: separation of the Mercury Transfer Module (MTM), the cruise stage that supplied solar-electric propulsion during the long journey from Earth.
- November 2026: Mercury orbit insertion, a series of braking maneuvers that slow the spacecraft enough for Mercury's gravity to capture it.
- December 2026: separation of the two science orbiters, ESA's Mercury Planetary Orbiter (MPO) and JAXA's Mercury Magnetospheric Orbiter, named Mio.
After release, the MTM will drift away.
Three ESA speakers presented the briefing: Prof. Geraint Jones, Lead Project Scientist; Santa Martinez, Mission Manager; and Ignacio Tanco, Head of Inner Solar System Mission Operations.
Why does Mercury demand such a complex path?
Reaching Mercury is harder than reaching Pluto, mission planners explained during the briefing. The Sun's gravity pulls any spacecraft inward, so a direct flight would arrive too fast to brake into orbit. BepiColombo therefore used repeated planetary flybys of Earth, Venus, and Mercury itself during its cruise phase.
Heat is the other obstacle. Daytime surface temperatures on Mercury exceed 400 °C.
The MPO carried a protective sunshield through cruise, while Mio will operate farther out, tracing a highly elliptical orbit shaped to study the magnetic environment rather than the scorching surface.
What will the two orbiters actually study?
According to the briefing slides, the MPO will carry 11 instruments to map Mercury's surface composition, gravity field, internal structure, and tenuous exosphere. Mio will carry 5 instruments focused on the magnetic field, the magnetosphere, and its interaction with the solar wind.
JAXA's Mio, developed by the Institute of Space and Astronautical Science, is the first spacecraft Japan has sent toward the innermost planet. The mission targets questions MESSENGER could not fully resolve. Scientists expect the data to clarify how rocky planets form close to their host stars, and how the Sun's magnetic environment shapes small worlds without thick atmospheres.
The briefing materials describe Mercury as a 'small desert world' and the least explored of the inner Solar System's four rocky planets. Studying it, the materials argue, will shed light on the history of the entire Solar System, since the planet preserves a record of the innermost protoplanetary disk.
When does science begin?
Once the orbiters separate in December, instrument commissioning will run through early 2027. The mission is designed for at least one Earth year of nominal science operations, with extensions possible depending on fuel reserves and instrument health. ESA and JAXA teams will share data through a joint science operations center.
The arrival also opens the first sustained European and Japanese presence in the innermost Solar System. ESA has released a BepiColombo arrival media kit with explanatory infographics for readers who want to follow each milestone in detail.
via ESA Space Science News (Source)
More from Marcus Bennett
Show full bio
News editor covering regulation, policy and their impact on general science news at SciBeat.
243 articles
Nearby plates
- Eight Years in Space, and the Hard Part Starts Now
- NASA Details Its Role in Japan's Mission to Mars's Moons
- NASA and Boeing Map Starliner's Road Back to Crewed Flight
- NASA's Roman Telescope launches on mission 1,000 times faster than Hubble
- ESA's Juice Spacecraft Used Earth as a Slingshot Toward Jupiter