MetOp-SG Satellite-B Thermal Design and Thermal Vacuum Test

The MetOp-SG (Meteorological Operational Satellite - Second Generation) programme comprises a series of meteorological satellites developed by ESA in collaboration with EUMETSAT and with the support of a European industrial consortium led by Airbus Defence and Space as the prime contractor. MetOp-SG is designed to provide crucial data for operational weather forecasting, climate monitoring, and atmospheric research. These satellites are equipped with a range of advanced instruments that collect data related to atmospheric temperature, humidity, wind, cloud cover, and various other parameters, to better understand weather patterns, track severe weather events, and improve long-term climate predictions. MetOp-SG satellites are constructed in two series: spacecraft A, carrying visible, infrared, and microwave imagers and sounders, and spacecraft B, carrying microwave imagers and a radar. Each series includes three identical satellites. The first A-series satellite is foreseen to be launched in 2025, while the first B-series satellite will be launched in 2026. MetOp-SG satellites will fly in a Sun-synchronous orbit at 832km altitude. MetOp-SG satellite B benefits from the common platform developed for both series, with thermal control managed by cavities, including various subsystems and units. They feature a set of radiators, heaters and multi-layer insulation. The four instruments, which three of them include deployment or ration mechanisms, have a more complex thermal control to meet their thermal requirements in a varying thermal environment. The verification of MetOp-SG satellite B Proto-Flight Model started in 2024 and underwent an exhaustive Thermal Balance and Thermal Vacuum test. This paper presents an overview of the satellite B thermal design and the thermal vacuum test definition and preliminary results, including the lessons learned from this crucial phase of the spacecraft verification.