Thermal Vacuum Cold Target for the Metop SG MicroWave Imager

Brightness temperature values observed by satellite microwave radiometers are employed in Earth Observation (EO) mission to derive geophysical observables such as vapor and liquid integrated content, rainfall occurrence, sea surface temperature, and so on. The most common design for these radiometers is the total power scheme that requires - for the instrument calibration - targets with known and precise brightness temperature values. On board calibration relies on observations of hot and cold reference targets towards the "end to end" calibration of the receiver. Satellite-borne radiometers point at the cosmic space to mimic the cold reference target, whereas the hot reference is onboard. Additional calibration targets are generally required during the on-ground test to mimic both the scene and the cold sky in thermal vacuum chambers. This work is focused on the design, development and verification of the thermal vacuum cold target (TV-CT) for the Metop SG MicroWave Imager (MWI)