Upravlyaemy Sputnik Kontinentalny Statsionarny ( meaning ''Stationary Continental Controllable Satellite''), or US-KS (), also known as Oko-S, was a series of

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

, and later Russian, missile detection satellites launched as part of the

Oko OKO (, obsolete Russian word for eye, also an abbreviation for Ob'yedinonnyye Kristallom Osnovaniya (, literal meaning Foundations Bound by a Crystal)) is a complex of two skyscrapers located on plot 16 in the Moscow International Business Cen ...

() programme. US-KS was a derivative of the

US-K Upravlyaemy Sputnik Kontinentalny ( meaning ''Continental Controllable Satellite'') or US-K () is a series of Russian, previously Soviet Union, Soviet, satellites used to detect missile launches as part of the Oko system. It consists of a constell ...

satellite, optimised for operations in

geosynchronous orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...

. Seven were launched between 1975 and 1997, when launches ended in favour of the modernised

US-KMO US-KMO (), an abbreviation for Upravlyaemy Sputnik - Kontinenty Morya Okeany () meaning ''Controllable Satellite - Continents, Oceans, Seas'' is a series of Russian, previously Soviet, satellites which are used to identify ballistic missile launch ...

. US-KS had the

GRAU The Main Missile and Artillery Directorate of the Ministry of Defense of the Russian Federation (), commonly referred to by its transliterated acronym GRAU (), is a department of the Russian Ministry of Defense. It is subordinate to the Chief of ...

index ''74Kh6''. As of December 2015, the entire Oko programme is being replaced by the new EKS system. Manufactured by

NPO Lavochkin NPO Lavochkin (, OKB-301, also called Lavochkin Research and Production Association or shortly Lavochkin Association, LA) is a Russian aerospace company. It is a major player in the Russian space program, being the developer and manufacturer of t ...

, US-KS satellites had a launch mass of , and a dry mass of . Built on a three-axis stabilised cylindrical bus with a diameter of and a length of , the satellites carry infrared telescopes to detect the heat of missile exhausts. US-KS satellites were launched by

Proton-K The Proton-K, also designated Proton 8K82K after its GRAU index or SL-12 after its model number, was a Russian, previously Soviet, carrier rocket derived from the earlier Proton. It was built by Khrunichev, and launched from sites 81/23, 8 ...

carrier rockets, with Blok DM and DM-2 upper stages. The first satellite to be launched was a prototype, which was followed by six operational spacecraft. With a spacecraft positioned at a longitude of 24° West, the Soviet Union could continuously monitor missile launches from the United States.

References

Oko Military satellites Military satellites of Russia {{Russia-spacecraft-stub