Speaker
Description
The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is a collaborative effort between the European Space Agency (ESA) and the Chinese Academy of Sciences (CAS). The primary objective is to better understand the interaction between the solar wind and the Earth’s Magnetosphere. The primary payload is the Soft-Xray Imager (SXI) instrument, which is an x-ray telescope build by the University of Leicester, UK and funded primarily by the UKSA. The telescope will image the motion of x-rays with the Earth’s magnetic boundaries including the bow shock, magnetopause, and cusps.
The telescope features two CCD detectors which are passively cooled to 155K by three staged radiators: a telescope radiator at 180K, a baffle radiator at 170K and, a detector radiator at 145K.
During the instrument STM in 2021, significant temperature discrepancies up to 40K were seen between the test data and the thermal model predictions in the balance phases. Due to limited time before the next level STM test, a systematic root cause analysis was performed to ‘debug’ the main issues. This was carried out via ad-hoc test phases, thermal sensitivity analysis and test article inspection. Estimates of each root cause were quantified using heat balances and equivalent parasitic heat loads. Finally, the main root causes producing > 10% of the total parasitic were corrected with design solutions and modifications to the test setup.
The main root causes were identified as test harness, detector flexi radiation, decreased MLI efficiencies and facility / test-setup. These were subsequently corrected at the PLM level STM and the SXI PFM and detector temperatures of 145K were achieved. The presentation will focus on the lessons learned from the root-cause analysis and is particularly relevant for thermal designs with 'very cold' zones that might not get the same level of attention as cryogenic thermal designs.
