A military satellite can be defined as an artificial satellite that is specifically used for a military purpose. Some of the main missions of military satellites are intelligence gathering, navigation and military communications.
Photographic reconnaissance missions were the first military satellites. There are a few efforts were made to develop satellite-based weapons, but this work was halted in the year 1967 following the ratification of international treaties that ban the deployment of weapons of mass destruction in orbit. In 2013, there are 950 satellites of all types in Earth orbit. It is impossible to know the right number of these that are military satellites due to secrecy as well as partly due to dual purpose missions like GPS satellites that can serve both civilian as well as military purposes. In the year 2018, there are 320 known military satellites in the sky in which half of them are owned by the United States, followed by Russia, China, and India.
Military Reconnaissance Satellite
The first use was for reconnaissance. In the US, the first format military satellite program was Weapon System 117L that was developed in 1950. Within this program, a number of sub-programs were created like Corona. Satellite within this program consisted of several code names. The first launches were code that was named as Discovered. It was a series of reconnaissance satellite that was designed to enter an orbit that takes high-resolution photographs and return the payload to Earth through a parachute. The first mission was Discoverer 1 that was launched on 28 February 1959 although it did not include a payload being intended as a test flight in order to prove the technology.
The Corona program was there until 25 May 1972. It was uninhibited after a Soviet Navy submarine was detected. Corona was followed by other programs that include Canyon, Aquacade as well as Orion. There have been a number of programs such as Magnum and Trumpet, but these remain classified, and other details remain speculative. In the year 2015, the United States military space units as well as commercial satellite operator – Intelsat that become concerned about apparent reconnaissance test maneuvers by Russian Luch satellite that was launched in the year 2014, when it maneuvered between the Intelsat 7 as well as Intelsat 901 satellite that was located only half a degree from one another in geosynchronous orbit.
Military Communication Satellites
Military satellite communications can be used for military communications applications. Military satellites are operated in UHF, SHF, or EHF frequency bands. The United States Armed Forces maintain international networks of satellites with earth stations that are located in several continents. Signal latency is the main concern in satellite communications, so geographic, as well as metrological factors, are highly important in choosing teleports. Since some military activities of the United States army are in foreign territories, the United States government requires to subcontract satellite services to foreign carries headquartered in regions with the desired climate.
Military Strategic as well as Tactical Relay, or Milstar, is a group of military satellites that are managed by the US Air Force. There were six spacecraft launched between 1994 and 2003, of which five of them are operational, with the sixth loss in a launch failure. All of them are organized in geostationary orbit and deliver wideband, narrowband as well as protected military communication systems. Wideband systems can support high-bandwidth transfers. Protected systems provide more security protection such as antijam features and nuclear survivability, while narrowband systems are planned for simple communications services that do not need high bandwidth.
