U.S. Centennial of Flight Commission home page

Patch from canceled Manned Orbiting Laboratory program

Insignia from canceled Air Force Manned Orbiting Laboratory.

CORONA image showing transport vehicles and bombers

CORONA image showing transport vehicles and bombers.

First imagery taken by CORONA - Mys Shmidta Air Field, USSR 18 Aug 1960.

First imagery taken by CORONA - Mys Shmidta Air Field, USSR 18 Aug 1960.

CORONA cameras

The CORONA cameras.

CORONA recovery sequence

CORONA recovery sequence.

KH-11 photo of the Shifa Pharmaceutical Plant, Sudan

KH-11 photo of the Shifa Pharmaceutical Plant, Sudan.

Reconnaissance and Signals Intelligence Satellites


From the beginning of warfare, commanders have always sought a better view of the battlefield. They climbed nearby mountains or built towers to enable them to look down on their enemies, conducting reconnaissance. They soon pressed balloons and airplanes into the reconnaissance role when these became available. During the Cold War, the United States and the Soviet Union used satellites to spy on each other, taking pictures (called imagery intelligence or reconnaissance) and intercepting communications and other electronic transmissions (called signals intelligence). Today several other countries have also developed “spy satellites,” and these activities are the most secret activities carried out in space.


The U.S. Air Force started its first military space program in 1956. Known as Weapons System 117L (or more simply, WS-117L), it was an effort to develop a television-based reconnaissance satellite for spying on the Soviet Union. The program limped along underfunded until after the Soviet launch of Sputnik, in October 1957, when it shifted into high gear. At this point, the U.S. Air Force began developing two types of satellites. One was a system, soon named Samos, that would take a picture on film and develop it in orbit, scanning it like a computer scanner and relaying the data to the ground over a radio link. This system was slow, and the satellites could transmit only a few dozen images a day, which was too little to have any value. The Samos readout system was canceled in the early 1960s.


The other system, which was led by the Central Intelligence Agency (CIA) with substantial Air Force participation, was named CORONA in February 1958 (the names of U.S. intelligence satellites are always written in all upper-case letters). This system used a panoramic camera on a stabilized satellite to take a long, thin image on a 70-millimeter strip of film. The film wound on a reel inside a small bucket-shaped reentry vehicle and reentered the atmosphere, where it was snatched out of the air by a passing airplane while hanging from its parachute. CORONA could see objects as small as six to nine feet (two to three meters) on a side. Only the film was saved; each satellite was used for only a single mission. The first successful mission was in August 1960 and more than 120 satellites were launched until the early 1970s, when the system was replaced by a much more massive satellite commonly referred to as the “Big Bird,” but actually named the KH-9 HEXAGON.


Beginning in 1960, the Air Force began developing a new, high-resolution satellite system called the KH-7 GAMBIT. This satellite could take very powerful images of a small area on the ground, allowing an intelligence analyst to look at targets as small as 1.5 feet (0.5 meters) across. By 1967, an even more powerful version entered service, allowing experts to see objects as small as about three inches. This was the most powerful satellite ever operated by any nation, but it did not allow operators to read license plates, like Hollywood satellites could.


The Soviet Union also started its own reconnaissance satellite program in the late 1950s. This effort, known as Zenit, used a modified version of the Vostok piloted spacecraft, equipped with several cameras that took still images. The entire large reentry vehicle would return to Earth with both film and cameras, allowing the cameras to be reused. The Soviets also developed a higher-resolution system called Yantar, versions of which are still in use today.


After Sputnik, the U.S. Navy began developing a small satellite for intercepting Soviet radar transmissions. Several of these satellites, named GRAB, and later DYNO, were launched starting in 1960 and followed by a better series of satellites named POPPY. They intercepted the electronic signals emitted by ground-based aircraft search radars, allowing the Navy and the Air Force Strategic Air Command to locate the radar positions and develop ways of avoiding or jamming them. A more capable system, called PARCAE, used groups of small satellites. It could locate ships at sea based upon their radar and radio transmissions by triangulating their position.


Starting in 1961, all of these intelligence collection satellites were operated by a highly secret agency within the Department of Defense called the National Reconnaissance Office, or NRO. The NRO was not even publicly acknowledged until 1992.


Throughout the 1960s, the United States and the Soviet Union operated much bigger and better versions of their film-return satellites and signals intelligence satellites. In the late 1960s the U.S. Air Force began operating a communications intelligence satellite named CANYON that intercepted Soviet telephone transmissions. Follow-on versions of this satellite, named VORTEX and MERCURY, continued to operate into the 21st century. In the early 1970s, the CIA deployed a satellite named AQUACADE for intercepting the faint radio signals from Soviet missile tests, using a giant mesh dish for detecting the electronic whispers. Modern versions named MERCURY and ORION were launched in the 1980s, and even more upgraded versions were launched in the 1990s. These satellites are believed to have truly massive antennas that unfurl in geosynchronous orbit.


The one major limitation of the film-return satellites like CORONA, HEXAGON, GAMBIT and Zenit and Yantar is that it could take days for their images to reach the eyes of an intelligence expert. Both countries investigated whether piloted reconnaissance satellites could partly fulfill this role. The U.S. Air Force's Manned Orbiting Laboratory (MOL) was designed to assess the capabilities and potential of military operations in space but was abandoned in 1969, before it ever flew. The Soviet Union launched several Almaz military space stations during the 1970s before abandoning its effort. Both countries realized that humans and sensitive optics were a bad combination.


Throughout the 1960s both the U.S. Air Force and the CIA sought to develop a “real-time” imaging satellite system that could transmit its images to the ground as fast as it took them. The CIA sponsored the development of what became the Charge Coupled Device, or CCD, like that used in modern digital cameras. In December 1976, the NRO launched the first satellite using this new technology, called the KH-11 KENNAN. The KH-11 allowed images to reach an intelligence expert, or the desk of the President of the United States, within minutes. It too revolutionized intelligence collection and by the 1980s the United States no longer launched film-return satellites. These satellites look much like NASA's Hubble Space Telescope, with a large mirror inside a long tube, except they point at the Earth rather than the stars. They can probably see objects about the size of a softball. Versions of the KH-11 equipped with some infrared capability (later called CRYSTAL and now called by some highly-secret code name) continue to operate today and their images are vital to U.S. military operations.


The Soviet Union continued to lag behind the United States and did not orbit its own real-time reconnaissance satellite until the 1980s. After the Cold War ended, Russian military space launches diminished to a trickle and they launched fewer reconnaissance satellites. Surprisingly, the Russians still launch the occasional film-return satellite, possibly because their real-time satellite, although fast, cannot take high-quality photos.


The final major limitation to imaging satellites was clouds. In the 1960s, the U.S. Air Force launched a radar satellite named QUILL, capable of peering through clouds, but it could not see much detail. In the late 1980s, the NRO launched the first of a new class of large imaging satellites, named LACROSSE (and later ONYX). These satellites probably see images on the ground about three feet (one meter) across.


China also developed film-return satellites starting in the 1980s, and may have a real-time reconnaissance satellite today. France led a consortium of European countries during the 1990s and orbited its Helios reconnaissance satellite. France has also sought to develop small signals intelligence satellites as well. In the late 1980s, Israel launched its first imaging satellite, called Ofeq, and has since followed with others. Other countries, such as India, have also sought to develop a satellite reconnaissance capability. But the emergence of commercial imaging satellites in the late 1990s, capable of taking images of objects as small as two feet (0.61 meter) across, means that a capability once available only to the superpowers is now available to any country—or person—with a credit card.


-Dwayne Day


Sources and Further Reading:


Burrows, William E. Deep Black. New York: Berkley Pub Group, 1988.

Clark, Phillip S. “Development of China's Recoverable Satellites.” Quest, Summer 1998, 36-43.

Coolbaugh, James S. “Genesis of the USAF's First Satellite Programme.” Journal of the British Interplanetary Society 51 (August 1998): 283-300.

Day, Dwayne, et al. Eye in the Sky: The Story of the CORONA Spy Satellites. Washington, D.C.: Smithsonian Institution Press, 1998.

Day, Dwayne. “Listening From Above: The First Signals Intelligence Satellite.” Spaceflight, August 1999, 339-347.

Gorin, Peter. “Zenit-The First Soviet Photo-Reconnaissance Satellite.” Journal of the British Interplanetary Society 50 (November 1997): 441-448.

Gorin, Peter. “Black ‘Amber': Russian Yantar-Class Optical Reconnaissance Satellites.” Journal of the British Interplanetary Society 51 (August 1998): 309-320.

Hhua-Bao Lin and Gui-Rong Min. “The Chinese Recoverable Satellite Program.” IAF paper, 89-426 (1989).

___________________ “Aspects of the China's Recoverable Satellite Platform.” IAF paper, IAF-93-U.2.522 (1993).

Klass, Phillip. Secret Sentries in Space. New York: Random House, 1971.

Lewis, Jonathan. Spy Capitalism: Itek and the CIA. Princeton, N.J.: Yale University Press, 2002.

Madden, Frank. “The CORONA Camera System: Itek's Contribution to World Security.” Journal of the British Interplanetary Society 52 (November/December 1999): 379-396.

McDonald, Robert A., ed. CORONA: Between the Sun & the Earth. Baltimore, Md.: American Society for Photogrammetry and Remote Sensing, 1997.

Pike, Christopher Anson. “CANYON, RHYOLITE, and Aquacade: U.S. Signals Intelligence Satellites in the 1970s.” Spaceflight, November 1995, 381-383.

Richelson, Jeffrey. America's Secret Eyes in Space. New York: Harper & Row, 1990.

____________. The Wizards of Langley: Inside the CIA's Directorate of Science and Technology. Boulder, Colo.: Westview Press, 2001.


“Military Space Programs.” Federation of American Scientists. http://www.fas.org/spp/military/program/imint/

National Reconnaissance Office. http://www.nro.gov

“The National Security Archive.” The George Washington University. http://www.gwu.edu/~nsarchiv.

Richelson, Jeffrey T. “U.S. Satellite Imagery, 1960-1999.” April 14, 1999. http://www.gwu.edu/~nsarchiv/NSAEBB/NSAEBB13/

“Showcase Corona.” Central Intelligence Agency Directorate of Science and Technology. http://www.cia.gov/cia/dst/showcase.html


Educational Organization

Standard Designation  (where applicable

Content of Standard

National Council for Geographic Education

Standard 1

How to use maps and other geographic representations to acquire and process information.

International Technology Education Association

Standard 3

Students will develop an understanding of the relationships among technologies and the connections between technology and other fields of study.

International Technology Education Association

Standard 4

Students will develop an understanding of the cultural, social, economic, and political effects of technology.