US-K

Upravlyaemy Sputnik Kontinentalny (Russian: Управляемый Спутник Континентальный meaning Continental Controllable Satellite) or US-K (Russian: УС-К) is a series of Russian, previously Soviet, satellites used to detect missile launches as part of the Oko system. It consists of a constellation of satellites, usually in molniya orbits, designated under the Kosmos system. The satellites are built by the company NPO Lavochkin and are launched on Molniya-M rockets. Oko can be directly translated as the Russian word for eye. As of June 2014, only two of the eight satellites in orbit were still functional, rendering the system inoperable.

History

US-K are the first generation of Oko satellites, the first of which was launched in 1972. The vast majority of the satellites launched (86 out of 100 as of March 2012 ) have been US-K satellites in molniya orbits. Seven first generation satellites were launched into geosynchronous orbits, called US-KS, starting in 1975. A decree of 3 September 1979 led to the creation of the second generation satellites US-KMO which had their first launch in 1991. In total, 101 satellites have been launched.