The European Space Agency, ESA, Copernicus programme has six missions, as of present:
SENTINEL-1 Radar satellite, which provides the ability to see at night, through clouds, and provide millimetre accuracy on measuring elevation.
SENTINEL-2 Optical satellite with multiple wavelength detectors, primarily for monitoring changes on land.
SENTINEL-3 Like S-2, this is another optical satellite which is highly versatile and can monitor both land and sea.
SENTINEL-4 A high orbit (36,000km) environmental monitoring platform, measuring pollutants in the atmosphere.
SENTINEL-5 Like S-4, focused on monitoring the environment and measuring pollutants, but this is a low orbit of just over 820KM.
SENTINEL-6 An ocean altimetry satellite to provide ocean topography measurements.