Inner workings of Sentinel-5

Building on the success of the Copernicus Sentinel-5 Precursor satellite, the new Copernicus Sentinel-5 mission introduces an advanced imaging spectrometer. This cutting-edge instrument is integrated into the MetOp Second Generation A-type weather satellites, working in synergy with other onboard instruments. Sentinel-5 delivers daily global data on key air pollutants, essential climate variables, and stratospheric ozone that protects us from ultraviolet radiation. 

The animation starts with an overall view of the MetOp-SG-A satellite and then focuses on the Sentinel-5 instrument, progressively peeling off the outer shells to arrive at the core optical systems and show the instrument’s ‘optical path’. 

The progressive colour beam represents how the fan of light (representing a single 2670 x 7.5 km image of Earth’s atmosphere) enters the telescope and through the beam-splitter is directed to the various spectrometers. The first telescope serves the ultraviolet (UV) and shortwave-infrared (SWIR-1 and SWIR-3) spectrometers, while the second telescope feeds the ultraviolet/visible (UV2Vis) and near-infrared (NIR) spectrometers.  

For each of the spectrometers, the light beam travels first through its collimator optics, then to the diffracting element (the gratings or Grisms), which disperses the light into its various colours. A camera assembly then focuses the rays onto the detectors again within the focal plane assemblies. 

The animation then proceeds with the light path taken through the calibration units. For these units (one for each telescope), it either captures direct sunlight, or uses internal light sources, each of these options is selected by rotating a wheel within the assembly.