Multi-directional, Multi-polarization, Multi-spectral Imager (3MI) Engineering Model (EM) On-ground calibration

The Multi-directional, Multi-polarization, Multi-spectral Imager (3M1) is one of the payloads that will be on board of the MetOp-SG "Satellite A", developed to provide information on atmospheric aerosols. 3MI is a space-based, wide field-of-view polarimeter that is designed to acquire sequential images of the same ground target, which are then combined with multiple spectral views in both un-polarized and polarized channels. This article presents the on-ground calibration approach for the 3MI payload. The calibration methodology starts from the challenging high level specifications down to the specification of adequate Key Data Parameters (KDP) introduced in an instrument model. An error budget allows to evaluate the required accuracy on each KDP and, consequently, to specify the needed Ground System Equipments for the calibration. The paper will present the facility and the developed GSE used to measure these KDP. Preliminary test results of the EM calibration campaign are also addressed.