Sentinel-3A was launched at 18:57 CET on 16 February 2016 and Sentinel-3B at 19:57 CEST on 25 April 2018. Both satellites were taken into orbit on a Rockot launcher from the Plesetsk Cosmodrome in northern Russia.
The Rockot launcher is a converted SS-19 intercontinental ballistic missile, which was designed as a weapon of war during the early 1970s.
Around 150 of the SS-19 missiles were declared as excess in military terms by the Strategic Talks on Arms Reduction Treaty agreements signed by the United States and the Soviet Union in 1990 and 1991, but were permitted to be reused as civil launchers.
The adaptation of the SS-19 uses the original two lower liquid propellant stages of the ICBM in conjunction with a modern upper stage for commercial payloads called Breeze-KM – optimised for delivering up to 1950 kg into low Earth orbit.
Plesetsk is located at 63° latitude and 40° longitude, about 800 km northeast of Moscow and 200 km south of the city of Archangel. Plesetsk is Europe's only continental launch site and ideally suited to high inclination and sun-synchronous launches into low earth orbits.
Just after the launcher delivers the satellite into orbit, control is taken over by ground teams at ESOC, ESA's mission control centre, Darmstadt, Germany. The mission is handed over to Eumetsat for routine operations after commissioning. ESA and Eumetsat manage the mission jointly where ESA produces land products and Eumetsat marine products for application through the Copernicus services.