Cryogenic Cooling for Spacecraft Payload

This thesis investigates the implementation of a cryocooler for the THESEUS (Transient High Energy Sky and Early Universe Surveyor) mission, one of the three candidate missions for the European Space Agency's (ESA) seventh medium-class scientific mission (M7), currently in its preliminary study phase (Phase A) since September 2023. The primary objective of THESEUS is to study gamma-ray bursts to enhance our understanding of the early evolution of the universe. Additionally, the mission includes monitoring X-ray transients and conducting infrared observations in response to external signals detected by dedicated sensors. To meet the stringent thermal requirements of the infrared observation sensor, the implementation of a cryogenic cooling system, either active or passive, is essential. Maintaining low operating temperatures is crucial for detecting faint signals from deep space, shielding it from potential disturbances, such as the infrared radiation emitted by the Sun and the Earth, while minimizing interference to have a clear signal while limiting background noises. In this context, thermal analysis plays a fundamental role in accurately modeling and simulating the satellite’s operational environment, including conductive and radiative heat exchanges. To this end, ESATAN-TMS, the ESA-standard software for thermal analysis, was employed. The study focused on refining the thermal model previously developed during the M5 mission phase to enable the integration of the active cryogenic system. A key aspect of this work involved developing and incorporating a thermal mathematical model to simulate the operation of the ESA-proposed cryocooler. This allowed for the assessment of its performance and verification of its compliance with the temperature requirements of the infrared telescope camera. The analysis led to a redefinition of the payload module’s thermal architecture, optimizing the cooling of the five onboard instruments, ensuring the required thermal stability, and minimizing both the area and mass of the radiators. Furthermore, the satellite’s service module design was optimized to meet the thermal requirements of its internal electronic units. This optimization resulted in a reduction of the effective radiating area, therefore decreasing heater power consumption during the cold phases of the mission. This thesis was conducted at Thales Alenia Space – Italy in Turin, under the supervision of Engineer Savino De Palo, head of the thermal analysis and aerothermodynamics unit, and the professor at the Polytechnic of Turin Manuela Battipede.