Sentinel-3BSentinel-3B is a European Earth observation satellite dedicated to oceanography which launched on 25 April 2018. It was built as a part of the Copernicus Programme, and is the second of four planned Sentinel-3 satellites.LaunchSentinel-3B was successfully launched on 25 April 2018 at 17:57 UTC from the Plesetsk Cosmodrome aboard a Rokot launch vehicle.