A space mission, formerly known as GMES (Global Monitoring for Environment and Security), headed by the European Commission and the European Space Agency, to coordinate the delivery of data from thirty satellites, known as Sentinels. Sentinel-1A and -1B, launched in April 2014 and April 2016, respectively, provide all-weather day and night radar images. Sentinel-2A, launched on 23 June 2015, provides high-resolution optical images for land services. Two Sentinel-3 satellites, launched on 16 February 2016 and 25 April 2018, provide data on ocean and land. Sentinel-4 and ‐5, planned for launch in 2021, ‐4 into geostationary orbit and ‐5 into Sun-synchronous orbit, will monitor atmospheric trace gases and aerosol over Europe. Sentinel‐5P, launched on 13 October 2017 into Sun-synchronous orbit, monitors atmospheric composition and ozone. Sentinel-6, also called Jason-CS (Jason Continuity of Service), provides high-resolution radar altimetry to complement Sentinel-3 and continues the missions of Jason-2 and -3.
https://www.esa.int/Our_Activities/Observing_the_Earth/Copernicus/Overview3 Copernicus, Observing the Earth.