The Copernicus Sentinel-3B satellite spent six weeks at the Plesetsk cosmodrome in Russia being carefully prepared for liftoff. After being shipped from France to the launch site, the satellite was tested, joined to the rocket launch adapter, sealed from view in the fairing and taken by train to the launch pad. Sentinel-3B lifted off on 25 April 2018 at 17:57 GMT (19:57 CEST).