CHEOPS instrument flight software in operation

CHEOPS, the Characterizing Exoplanets Satellite, is a Swiss-led ESA-S mission carrying out ultra-high precision photometry providing radii of transiting exoplanets. We have developed the Instrument Flight Software, which controls the instrument and processes the science data in real-time. The software implements over 100 ECSS TM/TC services and several state machines, with data processing tasks ranging from target star recognition, centroiding, on-board data reduction and compression to thermal control and FDIR. The flight hardware is based on the dual-core Leon3 processor. We present the approach that we took towards specification, design, implementation and qualification, then talk about the lessons learned especially during the commissioning.