METimage Cryogenic Sub-System STM thermal vacuum test campaign



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2020 International Conference on Environmental Systems


METimage (Meteorological Imager) is a passive imaging spectro-radiometer on board MetOp-SG satellite A, which provides moderate resolution optical imaging of clouds, aerosols, and surface variables in 20 spectral channels ranging from the visible to the infrared. The central subsystem of the METimage instrument accommodating the Visible and Infra Red Focal planes, ensuring their thermo-mechanical stability is the Cryogenic subsystem (CGSS). This paper describes the STM thermal vacuum and thermal balance test campaign of the CGSS. The design features the combination of a high conductive decoupling and radiative insulation of the internal optics with respect to the external environment to guarantee cryogenic temperature of these components. The temperature is obtained by one cryocooler. The CGSS Assembly ensures a proper positioning, alignment and thermos-mechanical stability of the cold optics with respect to the cryostat reference frame. Micro-vibrations export is minimized as well by the CGSS concept. To verify all, a detailed STM thermal balance and thermal vacuum test campaign has been carried out at Airbus Friedrichshafen. Function and operation of the TMU under flight-representative conditions have been successfully validated. The required cryogenic temperatures have been achieved at detectors levels. Besides, one of the challenges of this test was the confluence of different engineering disciplines: thermal, mechanical, optical and alignment. Besides being a thermal test campaign, measurements of different areas have also been carried out to verify the functional performance of the subsystem i.e:. alignment measurements at different temperatures levels, micro-vibration measurements considering different boundary conditions or thermo-elastic displacements of the cold optics during cool down using an interferometer. Details about the STM test campaign in vacuum are presented in the paper, as well as the main lessons learnt. The consolidation and confirmation of Structural, Thermal and Optical Performance analysis and budgets parameters with the multidisciplinary test results are highlighted as well.


Heiko Joos, Airbus Defence and Space GmbH, DE
Marta Bello-Escribano, Airbus Defence and Space GmbH, DE
ICES108: Thermal Control of Cryogenic Instruments and Optical Systems
The proceedings for the 2020 International Conference on Environmental Systems were published from July 31, 2020. The technical papers were not presented in person due to the inability to hold the event as scheduled in Lisbon, Portugal because of the COVID-19 global pandemic.


Cryogenics, Testing, Optics