Herschel Heaters Control Modeling and Correlation

Herschel and Planck satellites have recently undergone the thermal vacuum and thermal balance (TVTB) test which was performed in the ESA-ESTEC Large Space Simulator for Herschel and in Centre Spatial de Liège (CSL) for Planck. One of the specific targets of the Herschel test was the verification of the thermal stability of two HIFI units (required to be better than 3.10⁻⁴ °C/s) and of the Star Tracker mounting plate (required to be better than 2.5.10⁻³ °C/s), with particular attention on the performance of the relevant feedback control loops. Control system design and model predictions are presented and compared against the test results. Further discussion on the requirement verification is provided.