View source for US-K

{{short description|Series of Soviet/Russian missile warning satellites, 1975-2010}}
{{Infobox Spacecraft class
|name = Oko
|manufacturer = [[TsNII Kometa]]<br/>[[NPO Lavochkin]]
|country = Soviet Union<br/>Russia
|applications = Early warning of missile attack
|orbits = [[Molniya orbit|Molniya]]
|status = Inoperable
|built = 86+
|orders = 
|launched = 85
|operational = 2
|failed = 
|lost = 6
|first = [[Kosmos 775]]<br/>8 October 1975
|last = [[Kosmos 2469]]<br/>30 August 2010
|retired = 
}}
'''Upravlyaemy Sputnik Kontinentalny''' ({{langx|ru|Управляемый Спутник Континентальный}} meaning ''Continental Controllable Satellite'') or '''US-K''' ({{langx|ru|УС-К}}) is a series of Russian, previously [[Soviet Union|Soviet]], [[satellite]]s used to detect [[missile]] launches as part of the [[Oko]] system.<ref name="cato"/> It consists of a constellation of satellites, usually in [[molniya orbit]]s, designated under the [[Kosmos (satellite)|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.<ref>{{cite web |url=https://themoscowtimes.com/articles/russia-blinded-by-loss-of-missile-detection-satellite-36742 |title=Russia blinded by loss of missile detection satellite |publisher=Moscow Times |date=26 June 2014 |access-date=22 May 2018 |archive-date=30 December 2018 |archive-url=https://web.archive.org/web/20181230233452/https://themoscowtimes.com/articles/russia-blinded-by-loss-of-missile-detection-satellite-36742 |url-status=live }}</ref>

== 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 <ref name="gunther-usk"/>) have been US-K satellites in [[molniya orbit]]s. Seven first generation satellites were launched into [[geosynchronous orbit]]s, called [[US-KS]], starting in 1975.<ref name="gunther-us"/> A decree of 3 September 1979 led to the creation of the second generation satellites [[US-KMO]] which had their first launch in 1991.<ref name="Podvig-History"/> In total, [[List of Oko satellites|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, Kaluga Oblast|Kurilovo]] outside Moscow reduced the number of operational satellites to 2.<ref name="Kommersant"/> 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.<ref name="harvey_military"/>

In 2006, Russia had one operational [[US-KMO]] ([[Kosmos 2379]]) satellite and four US-K satellites ([[Kosmos 2422]], [[Kosmos 2393]], [[Kosmos 2351]], [[Kosmos 2368]]).<ref name="harvey_military"/> In June 2011, [[Kosmos 2422]], [[Kosmos 2430]], [[Kosmos 2446]] and [[Kosmos 2469]] were reported to be the only operational satellites.
[[File:Kosmos 2469 ground track.jpg|thumb|right|[[Ground track]] of Kosmos 2469]]

== Satellites ==
The Oko satellites are drum-shaped, 2 metres long and with a diameter of 1.7&nbsp;m. They weigh 1,250 kilograms without fuel and 2,400 kilograms when fully loaded. They have a 350&nbsp;kg infrared telescope pointing toward Earth, with a 4&nbsp;m conical sunshield and an instrument bus. The telescope, which is the satellites' main instrument, is able to detect radiation from ascending missiles. Two solar panels provide a total of 2.8&nbsp;kW of power. There are also several smaller, wider-angle telescopes to supplement the main instrument. The satellites have 16 liquid fuel engines for [[Spacecraft attitude control|attitude control]] and 4 for maneuvering.<ref name="harvey_military"/>

The system requires at least 4 satellites to be fully functional. The danger of false alarms increases when there are fewer than 4 satellites in orbit, due to the inability to double-check a detection.<ref name="harvey_military"/> However, this risk is reduced by the presence of the US-KMO geosynchronous satellites.

The satellites are built by [[NPO Lavochkin]] and launched with [[Molniya-M]] rockets. The advantages of Oko include that the system is reliable and well-established, and that it uses the relatively inexpensive (but now discontinued) Molniya launcher.<ref name="harvey_military"/>

The last US-K satellite ([[Kosmos 2469]]) was launched on 30 September 2010.<ref name="lastHEO"/> As of December 2015, the entire Oko programme is being replaced by the new [[EKS (satellite)|EKS]] system.<ref name="eks-launch2">{{cite web|url=http://www.nasaspaceflight.com/2015/11/soyuz-2-1b-eks-1-russian-early-warning-system/|title=Soyuz 2-1B launches EKS-1 to upgrade Russian Early Warning System|date=17 November 2015|access-date=2015-12-17|archive-date=2015-12-20|archive-url=https://web.archive.org/web/20151220074647/http://www.nasaspaceflight.com/2015/11/soyuz-2-1b-eks-1-russian-early-warning-system/|url-status=live}}</ref>

==References==

<references>
<ref name="harvey_military">{{cite book|last=Harvey|first=Brian|title=The Rebirth of the Russian Space Program|publisher=Springer|location=Germany|year=2007|edition=1st|chapter=Military programs|isbn=978-0-387-71354-0}}</ref>
<ref name="cato">{{cite journal
| title = Reducing a Common Danger: Improving Russia's Early-Warning System
| journal = Cato Policy Analysis No. 399
| date = May 3, 2001
| first = Geoffrey
| last = Forden
| publisher = [[Cato Institute]]
| url = http://www.cato.org/pubs/pas/pa399.pdf
| access-date = May 5, 2012
| archive-date = October 10, 2012
| archive-url = https://web.archive.org/web/20121010012819/http://www.cato.org/pubs/pas/pa399.pdf
| url-status = live
}}</ref>

<ref name="Podvig-History">
{{Cite journal
 |first       = Pavel
 |last        = Podvig
 |year        = 2002
 |title       = History and the Current Status of the Russian Early-Warning System
 |journal     = Science and Global Security
 |volume      = 10
 |issue = 1
 |pages       = 21–60
 |issn        = 0892-9882
 |doi         = 10.1080/08929880212328
 |bibcode = 2002S&GS...10...21P
 |url         = http://iis-db.stanford.edu/pubs/20734/Podvig-S&GS.pdf
 |url-status=dead
 |archive-url  = https://web.archive.org/web/20120315024323/http://iis-db.stanford.edu/pubs/20734/Podvig-S%26GS.pdf
 |archive-date = 2012-03-15
|citeseerx        = 10.1.1.692.6127
 |s2cid = 122901563
 }}</ref>

<ref name="gunther-usk">{{cite web|url=http://space.skyrocket.de/doc_sdat/us-k.htm|title=US-K (73D6)|first=Gunter|last=Krebs|work=Gunter's Space Page|access-date=5 March 2012|archive-date=11 May 2013|archive-url=https://web.archive.org/web/20130511170555/http://space.skyrocket.de/doc_sdat/us-k.htm|url-status=live}}</ref>
<ref name="gunther-us">{{cite web|url=http://space.skyrocket.de/doc_sdat/us-ks.htm|title=US-KS (74Kh6)|first=Gunter|last=Krebs|work=Gunter's Space Page|access-date=5 March 2012|archive-date=17 January 2012|archive-url=https://web.archive.org/web/20120117160244/http://space.skyrocket.de/doc_sdat/us-ks.htm|url-status=live}}</ref>
<ref name="lastHEO">{{cite journal|url=http://russianforces.org/blog/2010/09/cosmos-2469_might_be_the_last.shtml|title=Cosmos-2469 might be the last HEO early-warning satellite|journal=Russian Strategic Nuclear Forces|first=Podvig|last=Pavel|date=2010-09-30|access-date=2012-04-22|archive-date=2012-03-09|archive-url=https://web.archive.org/web/20120309043643/http://russianforces.org/blog/2010/09/cosmos-2469_might_be_the_last.shtml|url-status=live}}</ref>

<ref name="Kommersant">{{Cite web
| url = http://www.kommersant.ru/doc/264323
| title = У России проблемы с ПРО: Она сгорела
| trans-title = Russia has an ABM problem: it burnt down
| access-date = 2012-04-23
| date = 11 May 2001
| first1 = Sergey
| last1 = Topol
| first2 = Ivan
| last2 = Safranov
| author-link2 = Ivan Safranov
| publisher = [[Kommersant]]
| archive-date = 2014-10-20
| archive-url = https://web.archive.org/web/20141020130918/http://www.kommersant.ru/doc/264323
| url-status = live
}}</ref>
</references>
{{Oko}}
{{Russian Reconnaissance Satellites}}

[[Category:1973 in spaceflight]]
[[Category:Oko]]
[[Category:Military satellites]]
[[Category:Military satellites of Russia]]
[[Category:Satellites in Molniya orbit]]