The second Copernicus Sentinel-3 satellite, Sentinel-3B, lifted off on a Rockot from the Plesetsk Cosmodrome in northern Russia at 17:57 GMT (19:57 CEST) on 25 April 2018. Sentinel-3B joins its twin, Sentinel-3A, in orbit. The pairing of identical satellites provides the best coverage and data delivery for Europe’s Copernicus programme – the largest environmental monitoring programme in the world. The satellites carry the same suite of cutting-edge instruments to measure oceans, land, ice and atmosphere.