BepiColombo separates from its Mercury Transfer Module today, 3 September 2026, at 14:00 CEST (12:00 UTC). ESA’s live coverage from the European Space Operations Centre in Darmstadt begins at 13:45 CEST. Here is the full timeline, where to watch, and what to expect during the long wait that follows.
Today’s schedule
All times CEST (UTC+2).
- 13:45 — ESA live coverage begins from ESOC, Darmstadt, on the agency’s YouTube and LinkedIn channels
- 14:00 (12:00 UTC) — Mercury Transfer Module separation
- 14:30 — Scheduled break in ESA’s broadcast
- 15:30 — Coverage resumes
- ~15:53 — Expected signal acquisition and first spacecraft health checks
The broadcast gap between 14:30 and 15:30 is not a technical problem. It is built into the schedule because there will be nothing new to report during it.
What happens at 14:00
The Mercury Transfer Module is released from the two science orbiters and left to drift on its own trajectory around the Sun. Nothing about the manoeuvre is reversible.
What continues towards Mercury is the composite: ESA’s Mercury Planetary Orbiter, carrying eleven science instruments, with JAXA’s Mio magnetospheric orbiter attached. From this afternoon they fly on the MPO’s chemical propulsion alone — the system that has to perform the Mercury orbit insertion burn on 21 November. There is no backup engine and no second attempt.
The module is being discarded because of mass. The insertion burn can deliver a fixed amount of velocity change, and dragging more than a tonne of spent hardware through it is simply not affordable in propellant terms. The transfer module’s own propulsion — four QinetiQ T6 ion thrusters running on xenon — was switched off permanently on 15 June 2026, and it has been dead weight ever since.
We covered the engineering behind all of this in detail in our full explainer on the MTM separation and BepiColombo’s Mercury arrival.
The two hours of silence
The part of today that flight controllers like least is not the separation. It is what comes after.
Releasing the module changes the spacecraft’s mass, its balance and its antenna geometry, all in the same instant. The composite then has to stabilise its attitude and re-establish a clean radio link with Earth before anyone on the ground can confirm its condition. That is why signal acquisition is not expected until around 15:53 CEST, close to two hours after the event.
During that window, silence is the expected outcome, not a warning sign. Confirmation that separation occurred and that the spacecraft is healthy should come in the second half of ESA’s broadcast.
What we will know by this evening
Three things, in order: that the module released cleanly; that the composite recovered its attitude and pointing; and that the MPO’s systems came through the transition in good shape. If all three hold, BepiColombo’s arrival sequence stays on track for 21 November.
After that, the calendar runs to early December for Mio’s separation from the MPO, March 2027 for the MPO’s final science orbit, and April 2027 for the start of full science operations. BepiColombo will be only the second spacecraft ever to orbit Mercury, after NASA’s MESSENGER — and the first to observe the planet from two orbits at once.
Watch our breakdown
We are covering the separation on the SpaceInfo Club YouTube channel, with a walkthrough of today’s timeline, what the transfer module actually did over eight years, and what to listen for during ESA’s commentary.
More mission coverage is collected in our full article archive.
