The last launch of a Russian Proton K vehicle took place on 30 March at 0549 GMT carrying the last of a long line of Oko (Eye) Early Warning satellites. The last Oko satellite is to be placed in geostationary orbit to monitor US missile launches. The Oko satellites will be replaced by a new Russian Early Warning system dubbed EKS that will have its own constellation of satellites.
According to the Ascend SpaceTrak database the Proton K vehicle has attempted 309 orbital launches and has failed 36 times. The Proton M is now the only Proton launch vehicle flying. It successfully launched the Intelsat 22 commercial communications spacecraft in an ILS marketed flight on 25 March.
The Oko satellites were first launched in 1972 and the operational constellation was intended to have four satellites in a highly elliptical Molniya orbit and two satellites in geostationary orbit to provide early warning of a US ballistic missile attack. The satellites employed infra-red telescopes to detect the heat of a missile exhaust against the cold surface of the Earth.