Benefits of the In-Orbit Thermal Correlation of the Solar Orbiter Spacecraft

Solar Orbiter, an ESA/NASA spacecraft launched in 2020, was designed to explore the Sun and heliosphere and investigate key questions about our star. To answer these questions, the spacecraft will fly within 0.28AU of the Sun, with a suite of remote and in-situ payloads, measuring solar wind, electromagnetic fields and energetic particles, as well as taking the nearest pictures of the Sun ever taken. This mission comes with a set of demanding thermal challenges that the spacecraft must overcome. In order to understand the thermal performance of Solar Orbiter in space, a set of in-flight thermal correlations were performed at several different distances from the Sun. The correlated thermal model was then used to simulate and predict an accurate thermal performance over the entire mission timeframe. This analysis proved very useful, and led to uncovering potential issues much earlier in the mission than would otherwise be possible with conventional operational monitoring. This allowed for detailed discussions and analysis by the involved parties, leading to a much deeper understanding of the potential problem, and ultimately much more informed decisions taken by the operations team, avoiding significant spacecraft risks. Further, the increased confidence in the thermal model enabled its use in predicting and justifying other thermal configuration changes on the spacecraft, significantly lowering operational risk. This paper is a presentation of the in-fight thermal correlations that were performed, as well as a discussion about the benefits of the process — including real in-flight examples.