US-K

Oko

Manufacturer	TsNII Kometa NPO Lavochkin
Country of origin	Soviet Union Russia
Applications	Early warning of missile attack
Specifications
Regime	Molniya
Production
Status	Operational
Built	86+
Launched	85
Operational	2
Lost	6
First launch	Kosmos 775 8 October 1975
Last launch	Kosmos 2469 30 August 2010

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.

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.

After the dissolution of the Soviet Union, the rate of launches decreased, but Russia remained committed to the programme. A fully functioning constellation with 5 satellites was restored in 2001, but a fire in May 2001 in the Oko control facility at Serpukhov-15 near Kurilovo outside Moscow reduced the number of operational satellites to 2. A further satellite was launched in the same year. Between 2002 and 2006, there were no Oko launches, until another Oko satellite, designated Kosmos 2422, was launched in July 2006.

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