Speaker
Description
The On-Ground Calibration Target (OGCT) for the Ice Cloud Imager (ICI), to be flown on the Metop-SG Satellite B, has been developed, built and sub-system tested in a joint effort by IABG mbH (thermal design, modelling & testing, thermal control sub-system manufacturing), Thomas Keating Ltd. (radio frequency & mechanical design, mechanical manufacturing), and the Institute of Applied Physics of University of Bern, IAP (radio frequency modelling & testing) under Airbus Defence and Space España (ASE) project management.
The OGCT consists of two microwave blackbodies in a wedge design, with fine temperature control achieved by liquid nitrogen cooling and electrical heaters. The challenging key requirements for thermal control include accurate knowledge of absolute temperature (better than ±0.1 K), highly stable control of target temperature (better than 0.1K / 5 min) and a uniform temperature distribution across the blackbody area (lower than 0.3 K) – all to be achieved over the full temperature range from 80 K to 335 K.
According to IABG’s heritage as a test centre, the development approach heavily relied on testing in all stages of development, combined with thermal modelling and analysis. After a successful thermal vacuum qualification test in early 2020, final acceptance of the OGCT was achieved. Since then, the OGCT has successfully performed radiometric calibration of the Ice Cloud Imager’s EM in December 2020, PFM in 2022 and FM2 in 2023. First operation of the OGCT on spacecraft level is planned for the Thermal-Vacuum test of MetOp-SG Satellite B.
The presentation gives an overview over the thermal control system of the OGCT: the evolvement of the design is presented, starting with early design concepts from 2015, with a focus on the main challenges and lessons learnt along the way, as well as the results of the thermal vacuum acceptance tests.
