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A military satellite is an
artificial satellite A satellite or artificial satellite is an object intentionally placed into orbit in outer space. Except for passive satellites, most satellites have an electricity generation system for equipment on board, such as solar panels or radioisoto ...
used for a
military A military, also known collectively as armed forces, is a heavily armed, highly organized force primarily intended for warfare. It is typically authorized and maintained by a sovereign state, with its members identifiable by their distinct ...
purpose. The most common missions are
intelligence Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can ...
gathering, navigation and military
communications Communication (from la, communicare, meaning "to share" or "to be in relation with") is usually defined as the transmission of information. The term may also refer to the message communicated through such transmissions or the field of inquir ...
. The first military satellites were photographic reconnaissance missions. Some attempts were made to develop satellite based weapons but this work was halted in 1967 following the ratification of international treaties banning the deployment of weapons of mass destruction in orbit. As of 2013, there are 950 satellites of all types in Earth orbit. It is not possible to identify the exact number of these that are military satellites partly due to secrecy and partly due to dual purpose missions such as GPS satellites that serve both civilian and military purposes. As of December 2018 there are 320 known military or dual-use satellites in the sky, half of which are owned by the US, followed by Russia, China and India (13).Why Isro's Gsat-7A launch is important for the Indian Air Force
Times of India, 19 Dec 2018.


Military reconnaissance satellites

The first military use of satellites was for reconnaissance. In the United States the first formal military satellite programs, Weapon System 117L, was developed in the mid 1950s. Within this program a number of sub-programs were developed including Corona. Satellites within the Corona program carried different code names. The first launches were code named Discoverer. This mission was a series of
reconnaissance satellite A reconnaissance satellite or intelligence satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. Th ...
s, designed to enter orbit, take high-resolution photographs and then return the payload to Earth via parachute. Discoverer 1, the first mission, was launched on 28 February 1959 although it didn't carry a payload being intended as a test flight to prove the technology.} Corona was followed by other programs including
Canyon A canyon (from ; archaic British English spelling: ''cañon''), or gorge, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to cu ...
(seven launches between 1968 and 1977), Aquacade and Orion (stated by US Government sources to be extremely large). There have also been a number of subsequent programs including Magnum and
Trumpet The trumpet is a brass instrument commonly used in classical and jazz ensembles. The trumpet group ranges from the piccolo trumpet—with the highest register in the brass family—to the bass trumpet, pitched one octave below the standard ...
, but these remain classified and therefore many details remain speculative. The
Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen nationa ...
began the
Almaz The Almaz (russian: Алмаз, lit=Diamond) program was a highly secret Soviet military space station program, begun in the early 1960s. Three crewed military reconnaissance stations were launched between 1973 and 1976: Salyut 2, Salyut 3 a ...
(russian: Алмаз) program in the early 1960s. This program involved placing space stations in Earth orbit as an alternative to satellites. Three stations were launched between 1973 and 1976: Salyut 2, Salyut 3 and
Salyut 5 Salyut 5 (russian: Салют-5 meaning ''Salute 5''), also known as OPS-3, was a Soviet space station. Launched in 1976 as part of the Salyut programme, it was the third and last Almaz space station to be launched for the Soviet military. Two Soy ...
. Following Salyut 5, the Soviet Ministry of Defence judged in 1978 that the time consumed by station maintenance outweighed the benefits relative to automatic reconnaissance satellites. In 2015, United States military space units, and commercial satellite operator
Intelsat Intelsat S.A. (formerly INTEL-SAT, INTELSAT, Intelsat) is a multinational satellite services provider with corporate headquarters in Luxembourg and administrative headquarters in Tysons Corner, Virginia, United States. Originally formed as I ...
, became concerned about apparent reconnaissance test maneuvers by Russian Luch (or Olymp) satellite which was launched in September 2014, when it maneuvered between the Intelsat 7 and Intelsat 901 satellites which are located only half a degree from one another 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 orbita ...
.


Navigation satellites

The first
satellite navigation A satellite navigation or satnav system is a system that uses satellites to provide autonomous geo-spatial positioning. It allows satellite navigation devices to determine their location ( longitude, latitude, and altitude/ elevation) to hig ...
system,
Transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...
, used by the
United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...
, was tested in 1960. It used a
constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...
of five satellites and could provide a navigational fix approximately once per hour. During the
Cold War The Cold War is a term commonly used to refer to a period of geopolitical tension between the United States and the Soviet Union and their respective allies, the Western Bloc and the Eastern Bloc. The term '' cold war'' is used because t ...
arms race An arms race occurs when two or more groups compete in military superiority. It consists of a competition between two or more states to have superior armed forces; a competition concerning production of weapons, the growth of a military, and ...
, the nuclear threat was used to justify the cost of providing a more capable system. These developments led eventually to the deployment of the
Global Positioning System The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite ...
(GPS). The US Navy required precise navigation to enable
submarine A submarine (or sub) is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely op ...
s to get an accurate fix of their positions before they launched their SLBMs. The USAF had requirements for a more accurate and reliable navigation system, as did the
United States Army The United States Army (USA) is the land service branch of the United States Armed Forces. It is one of the eight U.S. uniformed services, and is designated as the Army of the United States in the U.S. Constitution.Article II, section 2, ...
for geodetic surveying for which purpose they had developed the SECOR system. SECOR used ground-based transmitters from known locations that sent signals to satellite transponder in orbit. A fourth ground-based station, at an undetermined position, could then use those signals to fix its location precisely. The last SECOR satellite was launched in 1969. In 1978, the first experimental Block-I GPS satellite was launched and by December 1993, GPS achieved initial operational capability (IOC), indicating a full constellation (24 satellites) was available and providing the Standard Positioning Service (SPS). Full Operational Capability (FOC) was declared by Air Force Space Command (AFSPC) in April 1995, signifying full availability of the military's secure Precise Positioning Service (PPS).


Early warning systems

A number of nations have developed satellite based early warning systems designed to detect ICBMs during different flight phases. In the United States these satellites are operated by the Defense Support Program (DSP). The first launch of a DSP satellite was on 6 November 1970 with the 23rd and last launched 10 November 2007. This program has been superseded by the Space-Based Infrared System ( SBIRS).


Satellite weapons

In the United States, research into satellite based weapons was initiated by President Dwight D. Eisenhower in the 1950s. In 1958, the United States initiated Project Defender to develop an anti-
ICBM An intercontinental ballistic missile (ICBM) is a ballistic missile with a range greater than , primarily designed for nuclear weapons delivery (delivering one or more thermonuclear warheads). Conventional, chemical, and biological weapons ...
solution launched from satellites. The satellites would have deployed a huge wire mesh to disable ICBMs during their early launch phase. The project floundered due to the lack of any mechanism to protect the satellites from attack resulting in the cancellation of Defender in 1968. Since October 1967 satellite based weapons systems have been limited by international treaty to conventional weapons only. Art.IV of the Outer Space Treaty specifically prohibits signatories from installing
weapons of mass destruction A weapon of mass destruction (WMD) is a chemical, biological, radiological, nuclear, or any other weapon that can kill and bring significant harm to numerous individuals or cause great damage to artificial structures (e.g., buildings), natu ...
in Earth orbit. The treaty became effective on 10 October 1967 and, as of May 2013, 102 countries are parties to the treaty with a further 27 pending full ratification.


Military communication satellites

Communications satellites A communications satellite is an artificial satellite that relays and amplifies radio telecommunication signals via a transponder; it creates a communication channel between a source transmitter and a receiver at different locations on Earth ...
are used for
military communications Military communications or military signals involve all aspects of communications, or conveyance of information, by armed forces. Military communications span from pre-history to the present. The earliest military communications were delivered ...
applications. Typically military satellites operate in the
UHF Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300 megahertz (MHz) and 3 gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter (on ...
, SHF (also known as
X-band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxi ...
) or EHF (also known as Ka band) frequency bands. The US Armed Forces maintains international networks of satellites with ground stations located in various continents. Signal latency is a major concern in satellite communications, so geographic and meteorological factors play an important role in choosing teleports. Since some of the major military activities of the U.S. army are in foreign territories, the U.S. government needs to subcontract satellite services to foreign carriers headquartered in areas with favorable climate. Military Strategic and Tactical Relay, or Milstar, is a constellation of military satellites managed by the
United States Space Force The United States Space Force (USSF) is the space service branch of the U.S. Armed Forces, one of the eight U.S. uniformed services, and the world's only independent space force. Along with its sister branch, the U.S. Air Force, the Space ...
. Six spacecraft were launched between 1994 and 2003, of which five are operational, with the sixth lost in a launch failure. They are deployed in
geostationary orbit A geostationary orbit, also referred to as a geosynchronous equatorial orbit''Geostationary orbit'' and ''Geosynchronous (equatorial) orbit'' are used somewhat interchangeably in sources. (GEO), is a circular geosynchronous orbit in altitu ...
and provide wideband, narrowband and protected military communication systems.
Wideband In communications, a system is wideband when the message bandwidth significantly exceeds the coherence bandwidth of the channel. Some communication links have such a high data rate that they are forced to use a wide bandwidth; other links ma ...
systems support high-bandwidth transfers. Protected systems offer more sophisticated security protection like antijam features and nuclear survivability, while
narrowband Narrowband signals are signals that occupy a narrow range of frequencies or that have a small fractional bandwidth. In the audio spectrum, narrowband sounds are sounds that occupy a narrow range of frequencies. In telephony, narrowband is usua ...
systems are intended for basic communications services that do not require high bandwidth. The
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and ...
also operates military communication satellites through its Skynet system. This is currently operated with support from Astrium Services and provides near worldwide coverage with both
X band The X band is the designation for a band of frequencies in the microwave radio region of the electromagnetic spectrum. In some cases, such as in communication engineering, the frequency range of the X band is rather indefinitely set at approxi ...
and
Ultra high frequency Ultra high frequency (UHF) is the ITU designation for radio frequencies in the range between 300  megahertz (MHz) and 3  gigahertz (GHz), also known as the decimetre band as the wavelengths range from one meter to one tenth of a meter ...
services. Skynet 5 is the United Kingdom's most recent military communications satellite system. There are four Skynet satellites in orbit, with the latest launch completed in December 2012. The system is provided by a private contractor, Astrium, with the UK government paying service charges based on bandwidth consumption.


See also

* Missile Defense Alarm System *
Space warfare Space warfare is hypothetical combat in which one or more belligerents are situated in outer space. The scope of space warfare therefore includes ''ground-to-space warfare'', such as attacking satellites from the Earth; ''space-to-space warfare ...
* Spy satellite *
Strategic Defense Initiative The Strategic Defense Initiative (SDI), derisively nicknamed the "''Star Wars'' program", was a proposed missile defense system intended to protect the United States from attack by ballistic strategic nuclear weapons ( intercontinental ballist ...


References


Resources

* Squadron Leader KK Nair, "Space: The Frontiers of Modern Defence", ''Knowledge World Publishers,'' New Delhi.


External links

* N-1 For details, see
Space: The Frontiers of Modern Defence
{{Authority control Satellite, military Satellites by type