MERCURY ARRIVAL AND SCIENCE

Two months before Mercury orbit insertion, BepiColombo will jettison MTM, its work complete; BepiColombo will use a chemical thruster system for the rest of the mission. Orbit insertion will start with a rocket firing on 5 December 2025. We will command 14 more maneuvers over a period of 100 days to bring first MMO and then MPO into their targeted scientific orbits. The two spacecraft will separate once they have reached the planned MMO orbit, and then MPO will continue to descend. Shortly after MMO separation, MOSIF will be jettisoned.

This phase is operationally very intense. The first 6 weeks, from the first maneuver to reaching the MMO orbit, are mission critical. The spacecraft must reach MMO’s orbit before Mercury reaches aphelion, a period when the BepiColombo orbits will spend periods of every orbit eclipsed by Mercury’s shadow. Five maneuvers are required to reach the MMO orbit, spaced by only a few days. Because this period is so critical, we in flight operations will run this part of the sequence in a mode very similar to that of launch and early operations, with a fully capable backup ground station available for tracking and command uplink in case of adverse events at ESOC. All of ESA’s 35-meter deep space ground stations will be used, and NASA’s Deep Space Network will be asked to support us as well.

After a 30-day commissioning phase, scientific operations will finally start in April 2026. The nominal science mission duration is 1 Earth year, with a built-in extension capability of another year. Operations will remain critical and very intense due to the short orbital period of the spacecraft (2.3 hours), the need to continuously operate the 11 MPO instruments in order to maximize scientific coverage of the planet, and the scorching thermal environment where external surfaces of the spacecraft are expected to experience temperatures up to 350 degrees Celsius (660 degrees Fahrenheit). As during cruise, the MPO solar array needs to be kept angled away from the Sun at all times. A substantial portion of our work in flight operations is to command the spacecraft’s attitude profile (how the spacecraft and solar arrays point) during the normal operations mode and in any backup or safe modes. The spacecraft needs attitude updates no less frequently than every 20 days; the nominal plan foresees weekly updates.

Approved in 2000, the ESA/JAXA BepiColombo mission to Mercury is finally getting ready for launch. The spacecraft has been undergoing its final integration and test activities at Kourou in French Guiana since the beginning of May. At ESOC, the simulation campaign for the launch phase has started. The countdown is running…