User:Nanobear~enwiki/Oko

Oko (also called US-KS) (Око (УС-КС)) is a a Soviet and Russian satellite system, used to detect missile launches. It consists of a constellation of satellites, usually in molniya orbits, designated under the Kosmos (Cosmos) system.

Soviet era
The US-KS early warning system was introduced in the Soviet Union in the 1970s, and declared operational in 1982. The satellites operated in molniya orbits with the parameters 600 x 39,700 km, 63 degrees and 718 minutes, passing over the Northern Hemisphere every 12 hours. They could spot the flame of a missile launch against the stellar background within 20 to 30 seconds, leaving enough time for a counterstrike. Upper stage propellant dumps during the Oko launches were connected to several UFO detections in Uruguay, Chile and Argentina after 1977. The system requires at least 4 functioning satellites in order for it to be effective. This achieved in the 1980s, but the system often fell short of this goal.

Another early warning system, called the Prognoz, was launched in 1984 with the satellite Cosmos 2133. Prognoz was designed to use a 24-hour geosynchronous orbit to provide continuous coverage, in contrast to the 12-hour orbit used by Oko. It is unclear whether Prognoz was meant as a replacement for Oko or to supplement it. Some Oko-designated satellites were also adapted to use a 24-hour orbit.

Russian Federation
After the dissolution of the Soviet Union, the rate of launches decreased, but Russia remained committed to the program. A fully functioning constellation with 5 satellites was restored in 2001, but a fire in May 2001 in the Oko control facility at Kurilovo (Kaluga Region) 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 Cosmos 2422, was launched in July 2006.

In 2006, Russia had one operational US-KMO Prognoz (Cosmos 2379) satellite and four US-KS Oko satellites (Cosmos 2422, Cosmos 2393, Cosmos 2351, Cosmos 2368).

Satellites
There are 86 Oko spacecraft in orbit, of which four were launched into geosynchronous orbits by Proton rockets, and the remaining 84 were launched aboard Molniya-M carrier rockets into Molniya orbits. In addition, three satellites were lost during launch, all aboard Molniya-M/2BL rockets. What was believed to be the final launch of the original Oko programme, and the last flight of the Molniya-M, was launched on 23 October 2007 at 04:39 GMT, however on 2 December 2008, a further Oko launch occurred, also using a Molniya rocket.

The Oko system serves alongside the Prognoz system, which is sometimes known as Oko-1.