| Part ofa series on |
| Spaceflight |
|---|
 |
Spaceflight types |
List of space organizations |
 Spaceflight portal |
Amilitary satellite is anartificial satellite used for amilitary purpose. The most common missions areintelligence gathering, navigation and militarycommunications.
The first military satellites were photographic reconnaissance missions. Some attempts were made to developsatellite 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 asGPS 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.[1]
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.[2] Within this program a number of sub-programs were developed includingCorona.[2] Satellites within the Corona program carried different code names. The first launches were code named Discoverer. This mission was a series ofreconnaissance satellites, designed to enter orbit, take high-resolution photographs and then return the payload to Earth via parachute.[2]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.[3] Corona was followed by other programs includingCanyon (seven launches between 1968 and 1977[4]),Aquacade[5] andOrion (stated by US Government sources to be extremely large[6]). There have also been a number of subsequent programs includingMagnum andTrumpet,[7] but these remain classified and therefore many details remain speculative.
TheSoviet Union began theAlmaz (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 andSalyut 5. 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.[citation needed]
In 2015, United States military space units and commercial satellite operatorIntelsat became concerned about apparent reconnaissance test maneuvers by theRussian satelliteOlymp-K, launched in September 2014, when it maneuvered betweenIntelsat 7 andIntelsat 901, which are located only half a degree from one another ingeosynchronous orbit.[8]
The firstsatellite navigation system,Transit, used by theUnited States Navy, was tested in 1960.[9] It used aconstellation of five satellites and could provide a navigational fix approximately once per hour.
During theCold Wararms race, the nuclear threat was used to justify the cost of providing a more capable system. These developments led eventually to the deployment of theGlobal Positioning System (GPS). The US Navy required precise navigation to enablesubmarines to get an accurate fix of their positions before they launched their SLBMs.[10] The USAF had requirements for a more accurate and reliable navigation system, as did theUnited States Army for geodetic surveying[11] 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.[12]
In 1978, the first experimental Block-I GPS satellite was launched[13] 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).[14] Full Operational Capability (FOC) was declared byAir Force Space Command (AFSPC) in April 1995, signifying full availability of the military's secure Precise Positioning Service (PPS).[14]
A number of nations have developed satellite basedearly warning systems designed to detectintercontinental ballistic missile (ICBMs) during different flight phases. In the United States these satellites are operated by theDefense 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 theSpace-Based Infrared System (SBIRS).
In the United States, research into satellite based weapons was initiated by PresidentDwight D. Eisenhower in the 1950s. In 1958, the United States initiated Project Defender to develop an anti-ICBM 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.[15]
Since October 1967, satellite based weapons systems have been limited by international treaty to conventional weapons only.Art.IV of theOuter Space Treaty specifically prohibits signatories from installingweapons of mass destruction 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.[16][17]
Communications satellites are used formilitary communications applications. Typically military satellites operate in theUHF,SHF (also known asX-band) orEHF (also known asKa 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.[18]
Military Strategic and Tactical Relay, orMilstar, is a constellation of military satellites managed by theUnited States Space Force. Six spacecraft were launched between 1994 and 2003, of which five are operational, with the sixth lost in a launch failure. They are deployed ingeostationary orbit and provide wideband, narrowband and protected military communication systems.Wideband systems support high-bandwidth transfers. Protected systems offer more sophisticated security protection like antijam features and nuclear survivability, whilenarrowband systems are intended for basic communications services that do not require high bandwidth.
TheUnited Kingdom also operates military communication satellites through itsSkynet system. This is currently operated with support fromAstrium Services and provides near worldwide coverage with bothX band andUltra high frequency services.[19]
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.[20] The system is provided by a private contractor, Astrium, with the UK government paying service charges based on bandwidth consumption.[20]
| Rank | Country | Military satellites | Ref. |
|---|---|---|---|
| 1 | United States | 247 | [21][22] |
| 2 | China | 157 | [21][22] |
| 3 | Russia | 110 | [21][22] |
| 4 | France | 17 | [21][22] |
| 5 | Israel | 12 | [21][22] |
| 6 | Italy | 10 | [21][22] |
| 7 | India | 9 | [21][22] |
| 8 | Germany | 8 | [21][22] |
| 9 | United Kingdom | 6 | [21][22] |
| 10 | Spain | 4 | [21][22] |
| 11 | Turkey | 3 | [23] |
| 12 | Iran | 2 | [21][22] |
| 13 | Portugal | 1 | [24][25] |
| Africa |
| ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Americas |
| ||||||||||||
| Asia |
| ||||||||||||
| Europe |
| ||||||||||||
| Oceania | |||||||||||||
| World | |||||||||||||
| Former | |||||||||||||
| |||||||||||||
