US-KS
Russian and Soviet early warning satellites
title: "US-KS" type: doc version: 1 created: 2026-02-28 author: "Wikipedia contributors" status: active scope: public tags: ["oko", "military-satellites", "military-satellites-of-russia"] description: "Russian and Soviet early warning satellites" topic_path: "history/military" source: "https://en.wikipedia.org/wiki/US-KS" license: "CC BY-SA 4.0" wikipedia_page_id: 0 wikipedia_revision_id: 0
::summary Russian and Soviet early warning satellites ::
::data[format=table title="Infobox spacecraft class"]
| Field | Value |
|---|---|
| name | US-KS |
| manufacturer | NPO Lavochkin |
| country |
| | bus | Upravlyaemy Sputnik | | applications | Missile defence | | orbits | Geosynchronous | | operator | VKS | | derivedfrom | US-K | | derivatives | US-KMO | | status | Retired | | launched | 7 | | operational | 0 | | retired | 7 | | failed | None known | | lost | 0 | | first | Kosmos 775 8 October 1975 | | last | Kosmos 2345 14 August 1997 | | mass | 2400 kg |autoconvert = off | ::
| name = US-KS | manufacturer = NPO Lavochkin | country =
| bus = Upravlyaemy Sputnik | applications = Missile defence | orbits = Geosynchronous | operator = VKS | lifetime = | derivedfrom = US-K | derivatives = US-KMO
| status = Retired | launched = 7 | operational = 0 | retired = 7 | failed = None known | lost = 0 | first = Kosmos 775 8 October 1975 | last = Kosmos 2345 14 August 1997
| mass = 2400 kg |autoconvert = off Upravlyaemy Sputnik Kontinentalny Statsionarny (US-KS; meaning Stationary Continental Controllable Satellite; ), also known as Oko-S, was a series of Soviet, and later Russian, missile detection satellites launched as part of the Oko () programme.
History
US-KS was a derivative of the US-K satellite, optimised for operations in geosynchronous orbit. Seven were launched between 1975 and 1997, when launches ended in favour of the modernised US-KMO. US-KS had the GRAU index 74Kh6. As of December 2015, the entire Oko programme is being replaced by the new EKS system.
Manufactured by NPO Lavochkin, US-KS satellites had a launch mass of 2400 kg, and a dry mass of 1250 kg. Built on a three-axis stabilised cylindrical bus with a diameter of 1.7 m and a length of 2 m, the satellites carry 50 cm infrared telescopes to detect the heat of missile exhausts.
US-KS satellites were launched by Proton-K 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
References
- Zak, Anatoly. "Oko early-warning satellite". RussianSpaceWeb.
- Krebs, Gunter. "US-KMO (71Kh6)". Gunter's Space Page.
- (17 November 2015). "Soyuz 2-1B launches EKS-1 to upgrade Russian Early Warning System".
- Krebs, Gunter. "US-KS (74Kh6)". Gunter's Space Page.
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