ESA GNC Conference Papers Repository

Launched in October 2018, the ESA/JAXA BepiColombo mission to Mercury features a complex modular design, with two scientific Mercury orbiters and a cruise module with electric propulsion. A number of novel GNC challenges had to be addressed in the spacecraft design. Apart from S/C modularity and the complex electric propulsion system, a main driver for GNC were constraints on S/C attitude and solar array pointing in the mission?s harsh thermal environment, requiring sophisticated solar array guidance profiles due to power and thermal constraints. Strict attitude constraints necessitate a dedicated failure control unit to take over control in case of an outage of the on-board computer, as well as regular updates of critical spacecraft guidance. Complex default guidance settings for launch were dependent on the launch date due to S/C attitude constraints and the required accuracy of ground-provided ephemeris data. Special attitude profiles in cruise were required to achieve reasonable ground coverage while minimizing both fuel consumption for attitude control and high-gain antenna movement, deviating from the originally planned continuous rotation around the Sun line. This paper will present in-flight experience in view of the key GNC challenges of this mission.