The calibration of the Multi-Spectral Imager on-board the EarthCARE spacecraft

The European Space Agency (ESA) is currently developing, in co-operation with the Japan Aerospace Exploration Agency (JAXA) the EarthCARE satellite mission with the basic objective of improving the understanding of the cloud-aerosols- radiation interactions within the Earth's atmosphere. As part of the EarthCARE payload, the MSI instrument will provide images of the earth in 7 spectral bands in the visible and infrared parts of the spectrum, with a spatial ground resolution of 500 m and an image width on the ground of 150 km. The radiometric accuracy of the MSI instrument is of paramount importance to accurately retrieve the physical properties of clouds and aerosols from the radiometric measurements in the different MSI spectral channels. The prelaunch calibration campaign together with the in-flight calibration facilities that the MSI instrument incorporates will ensure the fulfilment of the radiometric requirements of the mission. The overall calibration approach for the MSI instrument is described in this paper, including the pre-launch and in-flight calibration activities.