A reconnaissance satellite (commonly, although unofficially, referred to as a spy satellite) is an Earth observation satellite or communications satellite deployed for military or intelligence applications.
The first generation type (i.e. Corona   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 encrypted radio links.
In the United States, most information available is on programs that existed up to 1972, as this information has been declassified due to its age. Some information about programs prior to that time is still classified, and a small amount of information is available on subsequent missions.
On 16 March 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'.
There are several major types of reconnaissance satellite.
- Early warning
- Provides warning of an attack by detecting ballistic missile launches. Earliest known are Missile Defense Alarm System.
- Nuclear explosion detection
- Identifies and characterizes nuclear explosions in space. Vela (satellite) is the earliest known.
- Photo surveillance
- Provides imaging of earth from space. Images can be a survey or close-look telephoto. Corona (satellite) is the earliest known. Spectral imaging is commonplace.
- Radar imaging
- Most space-based radars use synthetic aperture radar. Can be used at night or through cloud cover. Earliest known are US-A series.
Examples of reconnaissance satellite missions:
- High resolution photography (IMINT)
- Measurement and Signature Intelligence (MASINT)
- Communications eavesdropping (SIGINT)
- Covert communications
- Monitoring of nuclear test ban compliance (see National Technical Means)
- Detection of missile launches
On 28 August 2013, it was thought that "a $1-billion high-powered spy satellite capable of snapping pictures detailed enough to distinguish the make and model of an automobile hundreds of miles below" was launched from California's Vandenberg Air Force Base using America's most powerful rocket.
...photo-reconnaissance satellites, for example, are enormously important in stabilizing world affairs and thereby make a significant contribution to the security of all nations.
During the 1950s, a Soviet hoax had led to American fears of a bomber gap. In 1968, after gaining satellite photography, the United States' intelligence agencies were able to state with certainty that "No new ICBM complexes have been established in the USSR during the past year." President Lyndon B. Johnson told a gathering in 1967:
I wouldn't want to be quoted on this ... We've spent $35 or $40 billion on the space program. And if nothing else had come out of it except the knowledge that we gained from space photography, it would be worth ten times what the whole program has cost. Because tonight we know how many missiles the enemy has and, it turned out, our guesses were way off. We were doing things we didn't need to do. We were building things we didn't need to build. We were harboring fears we didn't need to harbor.
- The OMAC Project
- Enemy of the State (film)
- Body of Lies (film)
- Ice Station Zebra
- Karlsson-on-the-Roof is Sneaking Around Again
- Defense Support Program (U.S.)
- European Union Satellite Centre
- List of intelligence gathering disciplines
- List of Kosmos satellites
- National Reconnaissance Office (U.S.)
- "Corona History". National Reconnaissance Office. Retrieved February 15, 2014.
- "Corona Program". JPL Mission and Spacecraft Library. Retrieved 16 February 2014.
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- Erickson, Mark. Into the Unknown Together - The DOD, NASA, and Early Spaceflight.
- reconnaissance satellite, Infoplease, retrieved 2014-02-17
- Hennigan, W.J. (August 27, 2013). "Monster rocket to blast off from Pacific coast, rattle Southland".
- Melissa Goldin (2014-02-17). "Fragments of Soviet-Era Satellite Burn Up in Earth's Atmosphere".
- "The State of the Union Annual Message to the Congress". 1980 State of the Union Address. The American Presidency Project. Retrieved 11 April 2014.
- """Commercial Satellite Imagery Companies Partner with the U.S. Geological Survey in Support of the International Charter "Space and Major Disasters. USGS Newsroon. United States Geological Survey. Retrieved 4 April 2014.
- ISBN 0-8239-3854-9
- ISBN 0-88730-285-8
- Norris, Pat (2008). "Spies in the Sky: Surveillance Satellites in War and Peace". Berlin; New York: Springer; Chichester, UK: In association with Praxis Publishing. Retrieved February 15, 2012.
- Israel Launches New Spy Satellite
- FAS Intelligence Resource Program - Imagery Intelligence (IMINT)
- GlobalSecurity.org: Imagery Intelligence
- Iran to Launch first spy satellite
- Egyptsat1 (MisrSat 1)
- Spaceports Around the World: Iraq's Al-Anbar Space Research Center
- Military Intelligence Satellites (NASA, remote sensing tutorial)