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Spy satellite

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KH-4B Corona satellite
KH-4B Corona satellite
Image:Lacrosse sat.jpg
Lacrosse radar spy satellite under construction

A spy satellite (officially referred to as a reconnaissance satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications. The first generation type (i.e. Corona [1] [2] and Zenit) took photographs then ejected canisters of photographic film, which would descend to earth. Corona capsules were retrieved in mid-air as they floated down on parachutes. Later spacecraft had digital imaging systems and downloaded the images via radio links.

In the United States, most information available is on programs that existed up to 1972. Some information about programs prior to that time are still classified, and a small trickle of information is available on subsequent missions. A few up-to-date reconnaissance satellite images have been declassified on occasion, or leaked, as in the case of KH-11 photographs which were sent to Jane's Defence Weekly in 1985.

Contents

Origins

On March 16, 1955, the United States Air Force officially ordered the development of an advanced reconnaissance satellite to provide continuous surveillance of “preselected areas of the earth” in order “to determine the status of a potential enemy’s war-making capability.”[3]

Missions

Examples of reconnaissance satellite missions:

Types

United States

Time period Designation Code name or Nickname Optics Notes
1959–1962 KH-1 to KH-3 Corona Resolution: 7.5 m
Focal length: 0.6 m		 First series of US imaging spy satellites; photographs returned by film canister ejection. Each satellite carried a single panoramic camera.
1960–1962 – Samos Res: 30 to 1.5 m
Foc len: 0.7 to 1.83 m		 Most flights used radio to relay images; some film returns; probably cancelled due to poor-quality imagery.
1962-1963 KH-4 Corona Resolution: 7.5 m Film return. Two panoramic cameras.
1963-1969 KH-4A Corona Resolution: 2.75 m Film return with two reentry vehicles and two panoramic cameras. Large volume of imagery.
1967-1972 KH-4B Corona Resolution: 1.8 m Film return with two reentry vehicles and two panoramic cameras.
1961–1964 KH-5 Argon Res: 140 m
Foc len: 76 mm		 Film return. Low-resolution, high coverage-area images used for mapping.
1963 KH-6 Lanyard Res: 1.8 m
Foc len: 1.67 m		 Shortlived operation for imaging a specific site; used a camera from the Samos program; film return.
1963–1967 KH-7 Gambit Res: 0.46 m Film return with single reentry vehicle per launch.
1966–1984 KH-8 Gambit Res: 0.5 m Film return.
1971–1986 KH-9 Hexagon
"Big Bird"		 Res: 0.30 m Film return with four or five reentry vehicles per launch.
cancelled KH-10 Dorian Manned Orbital Laboratory; space station based on Gemini program.
1976–1995 KH-11 Crystal
Kennan		 Res: 0.15 m
Mirror: 2.3 m		 First known digital imaging spy satellite. Thought possibly to be similar in size and overall layout to the Hubble Space Telescope.
1990—? KH-12 Ikon
Improved Crystal		 Res: 0.15 to 0.10? m
Mirror: 2.4 to 4? m		 Digital imaging; probably incorporates low light level visible and 3 to 5 micrometre infrared imaging capabilities; possible "live" intelligence gathering.
1999—? KH-13 8X? EIS? Res: 0.10? to 0.04? m (*)
Mirror: 4? m		 Very little known; possibly includes radar imaging or maybe stealth technology.

(*) Although there is much speculation concerning imaging resolution, any optical system is limited by diffraction. For example, a satellite with a 4 m telescope at an orbit of 600 km has a diffraction limited resolution of 10 cm at 550nm (green light), so it certainly cannot read a license plate. Other effects such as an inhomogenious atmosphere further degrade resolution. The apogee of a typical filming mission would have been close to 100 km. Using the above calculation the resolution would have been less than 2 cm (<1 inch).

Soviet Union/Russia

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