Weapons system 117L Also known as the "Discoverer" program, Weapons System 117L (WS-117L) was a program designed to build space-based reconnaissance satellite systems and to solve problems associated with space-based reconnaissance systems.

American Satellite Surveillance Systems

Corona - Corona was the first of a series of reconnaissance satellite systems developed through the WS-117L program. The Corona program was headed by the Central Intelligence Agency along with the Air Force. Corona satellites were used to photograph Soviet and other installations. The first successful Corona mission began on August 10, 1963. The Corona satellite system was expedited largely in part to the U-2 incident in 1960.  All of the Corona missions, with the exception of the KH-11 Kennan program, would make use of photographic film, which would have to survive re-entry through the atmosphere and be recovered.

Weapons System 117L - Weapons System 117L was the first program designed to develop space-based reconnaissance satellite systems. Several satellite systems would be developed through this program including Corona, the Satellite and Missile Observation System (SAMOS), and the Missile Detection Alarm System (MIDAS).

Keyhole - Keyhole was the designation for the initial Corona launches, which included KH-1, KH-2, KH-3, KH-4A, and KH-4B. The name was used because it is analogous to spying through the keyhole of a door.

Keyhole/Argon (KH-5) - Argon was the designation the surveillance satellites,manufactured by Lockheed, used by the United States from February 1961 to August 1964. Argon made use of photographic film in a way similar of the original Corona satellites. Of the twelve known launches, seven were not successful for varying reasons.

Keyhole/Lanyard (KH-6) - Lanyard was the designation for the first, albeit unsuccessful, attempt to establish a high resolution, optical satellite system. This program would be led by the newly established National Reconnaissance Office, and operated from March-July 1963. Because it was only able to achieve a resolution similar to that of the KH-4 satellites it was discontinued after only 3 launches.

Keyhole/Gambit (KH-7) - Gambit was the next of a series of satellites operated by the United States, by the National Reconnaissance Office, from July 1963 to June 1967. It was among the first successful Corona missions as it produced some of the first high resolution photos. These photos were typically of Soviet and Chinese missile emplacements. Gambit satellites would make use of a three camera system and missions would last typically up to eight days.

Keyhole/Gambit III (KH-8) - The Gambit III satellite system was amongst the longest serving satellite reconnaissance programs operated by the United States during the Cold War. This satellite system would operate from July 1966 to April 1984. Of the fifty-four launch attempts, only three would fail, all of which were attributed to rocket failure. The average mission time of the Gambit III satellite systems were thirty-one days. The Gambit III satellites would differ from the Gambit I satellites in that the Gambit III had a four camera system, which carried over twelve thousand feet of film, and were able to produce resolutions as small as four inches.

Keyhole/Hexagon (KH-9) - The Hexagon satellite system, commonly known as Big Bird, this satellite system was operated from 1971 and 1986. The Hexagon system was officially known as the Broad Coverage Photo Reconnaissance satellites. These satellites photographed large areas of the earth at a time with moderate resolution. These satellites were also used for mapping missions, which were used in map making. Three Hexagon missions also included electronic intelligence or ELINT gathering capabilities. These were used to eavesdrop on soviet communications and on soviet missile launches. Twenty launches were attempted, only one was unsuccessful. These satellites operated for an increasing duration of time, with the longest mission lasting 275 days.

Keyhole/Kennan (KH-11) – The KH-11 Kennan, which goes under the code name Crystal, was first launched in 1976, and missions are still ongoing to this day. According to leaked documents, this program is currently operation under the code name Evolved Enhanced Crystal. The Kennan satellite system was the first satellite system to use electro-optical imaging, which gives real time imaging capabilities. The resolution of these satellites is estimated to be as low as 2 inches. These satellites are unique in that they have been placed in sun-synchronous orbits, which allow them to use shadows to help discern ground features. These satellites became famous in 1978 when a CIA employee tried to the design of the satellite to the Soviets. He was tried and convicted of espionage.

Keyhole/Improved Crystal  (KH-12) – The later KH-11 satellites have been called KH-12 improved Crystal or Ikon satellites. These satellites also had increased download times which allowed for faster processing of photos. It is also suspected that these satellites may have stealth technology to avoid detection by other satellites.

Vela - The Vela satellite system was developed to by the United States to ensure that the Soviet Union complied with the Partial Test Ban Treaty which was ratified in 1963. The satellites were designed to monitor for nuclear explosions in space and in the atmosphere by measuring for neutrons and gamma rays. A total of twelve Vela satellites were launched during the course of the Cold War. The Vela satellites became publicly famous because of the Vela Incident which occurred on 22 September 1979. It was theorized at the time that it was a nuclear test conducted by South Africa and Israel, but new evidence does not support this theory. They have also been used in the study of Gamma-Ray Bursts.

Soviet Satellite Surveillance Systems

Zenit (Zenith) - The Zenith Satellite program, was a satellite program developed by the Soviet Union and used from 1961 to 1994. During the course of its lifespan over 500 Zenith satellites were launched, making it the most used satellite system ever. The Soviets concealed the nature of the system by giving the satellites the Kosmos designation. The Zenith satellites had an advantage over the satellites developed by the United Stated, in that they could be reused. A total of eight variants would be developed for a variety of mission types, ranging from high-resolution photography to ELINT to cartographic and topographic missions.

Yantar - The Yantar satellites, designed to replace the Zenit satellite system, are among the newest Russian satellites. Yantar satellites have been launched as recently as 2015. Two variants of the satellite have been developed for high-resolution photography and for medium-resolution broad spectrum imaging.

Weapons system 117L Also known as the "Discoverer" program, Weapons System 117L (WS-117L) was a program designed to build space-based reconnaissance satellite systems and to solve problems associated with space-based reconnaissance systems. Many satellite reconnaissance systems would be developed through the "Discoverer" program.