The European Space Agency (ESA) announced on 19 August 2026 that it had scheduled a briefing on the next planned milestones for BepiColombo, the joint ESA–JAXA mission preparing to operate around Mercury. ESA said the mission was scheduled to separate its Mercury Transfer Module on 3 September, carry out the planned Mercury orbit insertion in November and separate its two science orbiters in December.
The announcement was a pre-event media invitation. It did not report that any of these milestones had already occurred, and it included no new measurements, spacecraft-health data or scientific results.
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What ESA announced
ESA scheduled the online briefing for 14:00–15:00 CEST on 31 August 2026. The session was to be held in English and was intended to discuss BepiColombo’s mission status, operational challenges and the scientific opportunities expected as the spacecraft prepares to begin operations around Mercury.
The milestone sequence identified by ESA was:
- 3 September 2026: planned separation of the Mercury Transfer Module.
- November 2026: planned Mercury orbit insertion.
- December 2026: planned separation of the two science orbiters.
The listed speakers were Geraint Jones, ESA Lead Project Scientist; Santa Martinez, Mission Manager; and Ignacio Tanco, Head of Inner Solar System Mission Operations.
BepiColombo is a collaboration between ESA and the Japan Aerospace Exploration Agency (JAXA). JAXA provides the Mercury Magnetospheric Orbiter, named Mio. The mission includes a Mercury Transfer Module and two science orbiters intended to carry out observations around the planet.
Why the arrival phase matters
A spacecraft’s arrival phase is the part of a mission in which it carries out the operations needed to move from its interplanetary journey into the target planet’s operational environment. For BepiColombo, ESA identifies the separation of the Mercury Transfer Module as a critical milestone marking the start of this phase.
Separating a transfer module from science orbiters is a mission-operations step that allows the scientific spacecraft to proceed towards their intended operational configuration. The subsequent orbit-insertion operation is intended to place the mission into orbit around Mercury.
An orbiter can pass repeatedly around a planetary body, allowing instruments to observe the planet, its surrounding environment and changes across different orbital positions. This is important for a mission designed to study Mercury over time rather than make a single brief encounter.
ESA describes BepiColombo as Europe’s first mission to Mercury and says its orbiters will be only the second and third spacecraft to orbit the planet. ESA also identifies Mercury as the least explored planet of the inner Solar System. The agency says studying the planet can help improve understanding of Mercury itself and of the history of the Solar System more broadly.
However, the invitation provided no spacecraft specifications, orbit parameters, instrument details or new observations. Its immediate significance was operational: it documented the planned sequence leading towards the mission’s science phase.
What remained uncertain
The dates in ESA’s announcement were planned milestones, not confirmed outcomes. The invitation did not establish whether Mercury Transfer Module separation would occur as scheduled on 3 September, nor did it provide a precise date for orbit insertion in November or science-orbiter separation in December.
It also did not specify the operational challenges facing the mission, the spacecraft’s detailed health status or the criteria required to proceed from one milestone to the next. No scientific measurements or instrument results were reported.
The ESA invitation does not report the outcome of the 31 August briefing or confirm whether any milestone occurred. Later mission updates would be needed to assess the status of the separation and orbit-insertion operations, as well as the science orbiters’ readiness to begin observations.