A series of Earth-observing satellites developed by the European Space Agency for the Copernicus programme. The first two satellites (Sentinel-1A and Sentinel-1B) launched in April 2014 and April 2016, respectively, and carry advanced radar to monitor the Earth’s surface no matter what the weather; they form a constellation of two satellites orbiting 180 degrees apart, allowing the mission to image the entire Earth every six days. Sentinel-3A launched on 16 February 2016 and monitors wildfires and the state of vegetation, maps the way land is used, and measures the height of rivers and lakes. Sentinel-5P launched on 13 October 2017 from the Plesetsk Cosmodrome aboard a Rokot booster; it is the first Copernicus mission dedicate to monitoring Earth’s atmosphere.

Sentinel-5 Precursor is the forerunner of Sentinel-5 to provide timely data for air-quality monitoring services through Europe's Copernicus programme.

Credit: ESA/ATG medialab