ON-GROUND TEST CALIBRATION FOR THE MICROWAVE IMAGER (MWI) FLIGHT MODELS

D. Schobert¹, A. Graziani¹, T. Lupi², L. Salghetti Drioli¹, M. Loiselet¹, M. Belluco³, F. Tominetti³, C. Malassingne⁴, L. Peube⁴, G. Gari⁵, M. Labriola⁶, V. Mattioli⁶, F. De Angelis⁶, M. Riede⁷, M. Gotsmann⁷

¹ESA / ESTEC, ²OHB-I, ³OHB Italia, ⁴Airbus Defence and Space Toulouse, ⁵Airbus Italia, ⁶EUMETSAT, ⁷Airbus Defence and Space Friedrichshafen

The MicroWave Imager (MWI) is a conical scan total power microwave radiometer, embarked in the Satellite-B satellite series (3 satellites) of the MetOp-SG program. MetOp-SG is the space segment of the EUMETSAT Polar System Second Generation (EPS-SG), developed by the European Space Agency (ESA), aimed to provide operational meteorological observations from polar orbit.

The MWI instrument is developed by a consortium lead by OHB-Italia in collaboration with AIRBUS Toulouse and AIRBUS Italia.

MWI is one of the key innovative payload designed to deliver geolocated radiometric measurements for retrieving water vapor, clouds, and precipitation across a wide spectral range from 18.7 to 183 GHz. Its 26 channels, organized in nine receiver groups, include dual-polarization measurements from 18.7 to 89 GHz and novel channels in the oxygen absorption region (50–60 GHz and 118 GHz) to enable improved detection of light precipitation and snowfall, critical at high latitudes.

Among the three models, the Proto-flight Model (PFM) and the Flight Model 2 have completed their test campaign, while the Flight Model 3 (FM3) is in an advanced integration phase. For programmatic reasons, the FM2 will be the first flight model to fly on the MetOp-SG B1 satellite.

This abstract will present the results of the on-ground test campaign of the PFM and FM2, comparing the performances during the thermal vacuum test of the two instruments.

The data processing is performed with the Ground Prototype Processor (GPP) aimed to convert the raw instrument data into the L1b brightness temperature product and designed to support both the on-ground testing and the commissioning phase.

Results confirm compliance with the radiometric accuracy requirement of ≤ 1 K across all channels under varying scene temperatures. Radiometric sensitivity was also verified to meet requirements with margin under both ambient and vacuum conditions, confirming the high expected performance of the instrument.