Thermal Storage at -80°C for the eROSITA Telescope

eROSITA¹ is a powerful X-ray telescope currently under development for the Russian Spectrum-Roentgen-Gamma² mission. It comprises seven Wolter telescopes each equipped with its own CCD camera operating at -80±0.5°C. The cooling system for the eROSITA cameras includes passive thermal control components only: two radiators, Variable Conductance Heat Pipes (VCHP) and a newly developed Latent Cold Storage³ (LCS).

Based on the same working principle as conventional latent heat storages, a first LCS prototype was developed and used for testing different Phase Change Materials (PCM) with melting temperatures close to -80°C. The LCS proved to be almost isothermal, suggesting minimum heat losses and good thermal contact between the LCS and the PCM.