Carrying a multispectral imager, the Sentinel-2 mission offers ‘colour vision’ for Europe’s Copernicus programme to monitor Earth’s changing lands in unprecedented detail. The multispectral imager is the most advanced of its kind – in fact, it is the first optical Earth observation mission of its kind to include three bands in the ‘red edge’, which provide key information on vegetation state. This advanced imager uses a push-broom concept and its design has been driven by the large 290 km-swath requirements together with the high geometrical and spectral performance required of the measurements. Two kinds of detectors integrate high-quality filters to isolate the spectral bands perfectly. The instrument’s opto-mechanical stability is extremely high, which has meant the use of silicon carbide ceramic for its three mirrors and focal plane, and for the telescope structure itself.

The animation shows how light from the visible and near-infrared range propagate inside the instrument cavity. It bounces off the three mirrors before reaching the two visible near-infrared and shortwave infrared detectors.