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An early warning satellite is a satellite designed to rapidly detect ballistic missile launches and thus enable defensive military action. To do this, these satellites use infrared detectors that identify the missile thanks to the heat given off by its engines during the propulsion phase.
This type of satellite was developed in the 1960s in the context of the Cold War in order to activate early warning systems in the target territories of a missile attack. It later became a component of missile defense systems, as well as regulatory control systems for nuclear tests.
The United States, Russia and China have a constellation of early warning satellites.
The objective of an early warning satellite is to detect the launch of a ballistic missile at the beginning of its trajectory, when its detection is possible since its propulsion system gives off heat.
For a typical ICBM fired from a distance of 10,000 km, this propulsive phase lasts about 3 minutes for a total flight time of about 30 minutes. After these first 3 minutes, the flight continues by inertia and the missile becomes practically undetectable by the satellite.
The early warning satellite has the advantage over a radar of being able to scan almost 50% of the Earth's surface if it is at a sufficient altitude and therefore gives the attacked country more time to react compared to a system based solely on radar.
The detection of the missile is carried out by sensors that observe infrared wavelengths corresponding to the temperature of the flames of the missile engines (greater than 1000 °C). The on-board computer that processes the signal must be able to eliminate radiation sources linked to the reflection of sunlight on the ground or in the clouds. The image is magnified by a telescope whose aperture reaches one meter on the latest US satellites.
The United States was the first country to attempt to establish a space-based early warning system. The goal was to detect Soviet ballistic missile launches and give 20 to 33 minutes notice of the missile's arrival (against 10 to 25 minutes for the BMEWS ground-based radar network).
The MIDAS satellites were launched between 1960 and 1966, and although they never entered a truly operational phase, they allowed the development of this type of satellite. DSP satellites in geostationary orbit took over in the early 1970s. Several generations of increasingly efficient DSP satellites followed one another until 2007.
Since 2011 the DSPs have been replaced by the SBIRS system, which includes dedicated satellites in geostationary orbit (SBIRS-GEO) and in low Earth orbit (SBIRS-LEO), as well as sensors on board Trumpet satellites for mixed use (wiretapping/warning) located in a Molniya orbit.
The US-K and US-KS satellites developed under the Oko program were the first generation of Soviet early warning satellites. 86 US-K satellites were placed in a Molniya orbit between 1972 and 2010 and 7 US-KS satellites, of a very similar design, were placed in geostationary orbit between 1975 and 1997, the system becoming operational in 1980.
In 1983, a design error in the on-board software of the US-KS satellites led to the so-called fall equinox incident, which consisted of a false nuclear launch warning after a confusion between the heat caused by the reflection of solar radiation in clouds and that released by the launch of a nuclear missile. [1]
Unlike their US counterparts, the US-K and US-KS only detect surface-to-surface ballistic missile launches, due to less sophisticated electronics. Later, the US-KS were replaced by the US-KMO, capable of detecting sea-to-land ballistic missile launches as well. The first of them would be placed in geostationary orbit in 1991.
In the early 1990s, after about ten years of operation, the coverage provided by these satellites was only partial, due to a reduction in the launch rate.
In 2014, the last 3 US-type satellites in service ceased their activities. [2] They have been replaced starting in 2015 by a new generation of satellites: EKS, formerly known as Tundra. [3] [4] [5]
In France, the Direction générale de l'Armement carried out preliminary tests for the development of an early warning satellite. Infrared sensors were tested on two small experimental SPIRALE satellites launched in 2009. However, an operational satellite was not expected to be launched before the end of 2020. [6]
China operates Huoyan-1 series satellites under the Tongxin Jishu Shiyan (TJS) program. [7]
Country | Series | Launch dates | Launches number / failures | Launcher | Mass | Orbit | Lifespan | Status | Comments |
---|---|---|---|---|---|---|---|---|---|
United States | MIDAS | 1960-1966 | 12/4 | Atlas- Agena | 2 tons approx. | Low Earth orbit | from some weeks to 1 year | Retired | First generation; experimental; 4 versions |
United States | DSP (phase I) | 1970-1973 | 4/1 | Titan-3C | 907 kg | Geostationary orbit | 1,25 years | Retired | |
United States | DSP (phase II) | 1975-1977 | 3/0 | Titan-3C | 1043 kg | Geostationary orbit | 2 years | Retired | |
United States | DSP (phase II MOS/PIM) | 1979-1984 | 4/0 | Titan-3C | 1170 kg | Geostationary orbit | 3 years | Retired | |
United States | DSP (phase II v2) | 1954-1987 | 2/0 | Titan-IVD Transtage | 1674 kg | Geostationary orbit | 3 years | Retired | |
United States | DSP (phase III) | 1989-2007 | 10/1 | Titan-IVD Transtage | 2386 kg | Geostationary orbit | ¿3 years? | ¿Operational? | To be replaced by SBIRS |
United States | SBIRS | 2011- | 12/0 | Atlas V 401 or Delta IV-4M+(4,2) | 4500 kg (SBIRS-GEO) 1000 kg (SBIRS-LOW) | Geostationary orbit Geostationary orbit / Low Earth orbit / Molniya orbit | 12 years (SBIRS-GEO) | Operational | Geostationary satellites (SBIRS-GEO), satellites in low orbit (SBIRS-LEO), and sensors on Trumpet satellites in Molniya orbit |
USSR/Russia | US-K | 1972-2010 | 86/3 | Molniya | 2400 kg | Molniya orbit | 1 year | Retired | Replaced by EKS |
USSR/Russia | US-KS | 1975-1997 | 7/0 | Proton-K/Bloc-DM | 2400 kg | Geostationary orbit | 1 year | Retired | Almost identical to the US-K, replaced by the US-KMO |
USSR/Russia | US-KMO | 1991-2012 | 8/0 | Proton-K/Bloc-DM-2 | 2600 kg | Geostationary orbit | 5–7 years | Retired | Replaced by EKS |
Russia | EKS | 2015- | 6/0 | Soyuz-2.1b/Fregat-M | ? | Molniya orbit | ? | Operational |
The Defense Support Program (DSP) is a program of the United States Space Force that operated the reconnaissance satellites which form the principal component of the Satellite Early Warning System used by the United States.
The Space-Based Infrared System (SBIRS) is a United States Space Force system intended to meet the United States' Department of Defense infrared space surveillance needs through the first two to three decades of the 21st century. The SBIRS program is designed to provide key capabilities in the areas of missile warning, missile defense, battlespace characterization and technical intelligence via satellites in geosynchronous Earth orbit (GEO), sensors hosted on satellites in highly elliptical orbit (HEO), and ground-based data processing and control.
Upravlyaemy Sputnik Kontinentalny or US-K 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.
The Missile Defense Alarm System, or MIDAS, was a United States Air Force Air Defense Command system of 12 early-warning satellites that provided limited notice of Soviet intercontinental ballistic missile launches between 1960 and 1966. Originally intended to serve as a complete early-warning system working in conjunction with the Ballistic Missile Early Warning System, cost and reliability concerns limited the project to a research and development role. Three of the system's 12 launches ended in failure, and the remaining nine satellites provided crude infrared early-warning coverage of the Soviet Union until the project was replaced by the Defense Support Program. MiDAS represented one element of the United States's first generation of reconnaissance satellites that also included the Corona and SAMOS series. Though MIDAS failed in its primary role as a system of infrared early-warning satellites, it pioneered the technologies needed in successor systems.
US-KMO, is a series of Russian, previously Soviet, satellites which are used to identify ballistic missile launches. They provide early warning of missile attack and give information for the Moscow A-135 anti-ballistic missile system. They were run by the Russian Space Forces and it was succeeded by the Aerospace Defence Forces.
Upravlyaemy Sputnik Kontinentalny Statsionarny, or US-KS, also known as Oko-S, was a series of Soviet, and later Russian, missile detection satellites launched as part of the Oko programme. 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.
USA-230, also known as SBIRS GEO-1, is a United States military satellite and part of the Space-Based Infrared System.
Oko is a Russian missile defence early warning programme consisting of satellites in Molniya and geosynchronous orbits. Oko satellites are used to identify launches of ballistic missiles by detection of their engines' exhaust plume in infrared light, and complement other early warning facilities such as Voronezh, Daryal and Dnepr radars. The information provided by these sensors can be used for the A-135 anti-ballistic missile system which defends Moscow. The satellites are run by the Russian Aerospace Forces, and previously the Russian Aerospace Defence Forces and Russian Space Forces. Since November 2015, it is being replaced by the new EKS system.
Kosmos 2345 is a Russian US-KS missile early warning satellite which was launched in 1997 as part of the Russian Space Forces' Oko programme. The satellite is designed to identify missile launches using optical telescopes and infrared sensors.
Kosmos 1894 is a Soviet US-KS missile early warning satellite which was launched in 1987 as part of the Oko programme. The satellite is designed to identify missile launches using optical telescopes and infrared sensors.
Kosmos 775 is a Soviet US-KS missile early warning satellite which was launched in 1975 as part of the Oko programme. The satellite is designed to identify missile launches using optical telescopes and infrared sensors.
EKSKupol is a developing programme of Russian early warning satellites as a replacement for the US-KMO and US-K satellites of the Oko programme. The satellites are designed to identify any possible future ballistic missile launches, from outer space, and complement early warning radars such as the Voronezh. This gives advance notice of a nuclear attack and would provide information to the A-135 missile defence system which protects Moscow, as well as other Russian missile defense and counterattack resources. Six satellites are planned to be initially orbited. The first of these was launched on 17 November 2015 and as of November 2022, all six of them are in service.
Serpukhov-15 is a military townlet near Kurilovo in Kaluga Oblast which is the location of the western control centre for Russia's Oko satellites. These give early warning of ballistic missile launches, mainly from the continental United States. The site is part of the Main Centre for Missile Attack Warning and information from here is processed at the Russian Aerospace Defence Forces centre in Solnechnogorsk and could be used, together with early warning radar such as the Voronezh, for launch on warning of the A-135 anti-ballistic missile system. A similar facility is located at Pivan-1 in the Russian Far East.
Pivan-1 is a military townlet near Komsomolsk-na-Amur in Khabarovsk Krai in the Russian Far East which is the location of the eastern control centre for Russia's Oko satellites. These give early warning of ballistic missile launches, mainly from the continental United States. The site is part of the Main Centre for Missile Attack Warning and information from here is processed at the Russian Aerospace Defence Forces centre in Solnechnogorsk and could be used, together with early warning radar such as the Voronezh, for launch on warning or the A-135 anti-ballistic missile system. A similar facility is located at Serpukhov-15 near Moscow.
USA-241, also known as SBIRS GEO-2, is a United States military satellite and part of the Space-Based Infrared System.
The USP, for Universal Space Platform, also known as Viktoria (Виктория), is a highly flexible satellite bus designed and manufactured by RSC Energia. It is called universal because it has been designed to be operated from LEO to GEO. It is a three axis stabilized platform with electric propulsion for station keeping, but chemical propellant is offered as an option. The bus can offer up to 3000 W of power and a payload capacity up to 1,000 kg (2,200 lb) for Low Earth orbit or HEO an up to 300 kg (660 lb) for geostationary orbit.
USA-273, also known as SBIRS GEO-3, is a United States military satellite and part of the Space-Based Infrared System (SBIRS).
USA-282, also known as SBIRS GEO-4, is a United States military satellite and part of the Space-Based Infrared System.
Tongxin Jishu Shiyan is a Chinese military satellite program operating in geostationary orbit (GEO). TJS satellites are manufactured by the Shanghai Academy of Spaceflight Technology (SAST) and launched from Xichang Satellite Launch Center (XSLC) in China's southern Sichuan Province. TJS is likely the cover name for multiple geostationary military satellite programs and should not be confused with the similarly named Shiyan satellite program.