During the Cold War, accurately ascertaining the USSR's military capabilities was a top US priority—as well it should have been given that we had as many as 21,000 nuclear warheads pointed at each other during that time. And while we had plenty of spies operating in Moscow, the view from overhead provided the President and his cabinet key insights into the extent of Soviet strategic capabilities which influenced defense planning and arms control negotiations. As such, the US invested vast sums of money into high-altitude research—from early "weather balloons" to the SR-71 Blackbird and U2 Dragon Lady to orbital telescopes—and established not one but three Federal agencies—the National Reconnaissance Office (NRO), the National Security Agency (NSA), and the Central Intelligence Agency (CIA)—all in an effort to glean any speck of information that could give us an advantage.
Satellite technology is, by far, the most expensive ISR method at the US's disposal but also the most effective, its results well worth the billions of dollars spent. As President Lyndon B. Johnson famously quipped in 1967 after a Soviet hoax led to worries of a bomber gap:
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.
Of course, much of the development of our national reconnaissance capabilities is still shrouded in veils of classification. Heck, the NRO was established in 1961 and operated for three decades before the government even ever acknowledged its existence. Press reports made limited references to the agency as far back as 1971, but it wasn't until the Deputy Secretary of Defense revealed the NRO in 1992, was it ever formally discussed by the DoD. Oversight from the DoD and Congress was virtually non-existent save for the "open-checkbook" policy of the times. As long as the intelligence justified the price tag, any cost was acceptable. It wasn't until the early 1990's that any information on these devices was declassified, after the fall of the Soviet Union brought an end to the Cold War. Even now, information on the early satellites is sparse and anything after 1972 is non-existent save for a few photos taken by the KH-11 satellite which were leaked to Jane's Defence Weekly in 1985.
What we do know is that the US has been researching high-altitude reconnaissance technology since about 1946 when the RAND project, precursor to Rand Corp., began campaigning for its development. When the Army and Navy couldn't agree on who would have control over the orbital technology, it was assigned to the newly-formed USAF in 1947. It took a few years for RAND researchers working on "Project Feedback" to figure out how a satellite would even function—this was a brand new technological concept, mind you—but by 1953 they had not only devised the general characteristics and capabilities of a reconnaissance satellite but had begun to develop many of the components as well, like the television system and altimeter. The Atomic Energy Commission also began work on miniaturized nuclear power sources for the vehicles at that time. By 1954, the USAF accepted RAND's assertion that the technology was of "vital strategic interest to the United States" and officially established the US satellite program.
The Corona Program
The first such program was the Corona project, a codeword itself code named "Discoverer" for the public explanation of why the government was firing a rocket into space (a rare event in the late 1950s that would have attracted a curious public and international scrutiny). The program began in 1959 at the Onizuka Air Force Station, ran until 1972, and was declassified in 1995 by President Clinton. Its initial budget was a modest $108.2 million ($860 million adjusted to 2013), though that quickly increased following the 1960 incident in which Gary Powers' U2 was shot down over Soviet airspace. The 144-member family of Corona satellites—each designated Keyhole-#, or KH-#, depending on the spacecraft iteration—were produced and operated by the CIA in conjunction with the USAF and provided invaluable photographic surveillance of the Soviet Union as well as the People's Republic of China, and other Communist countries.
They were fed a special Eastman Kodak 70 millimeter film that produced 170 lines per mm—more than three times the 50 lines/mm resolution earlier WWII aerial photography could compose. The first Coronas carried a paltry 8,000 feet of film—per camera—though through improvements in the film chemistry and design reduced the material thickness, researchers were eventually able to double that amount. The cameras themselves underwent numerous upgrades as well, elongating to nine feet and incorporating panoramic Petzval f/3.5 lenses.
The Argon Program
The KH-5 ARGON ran in conjunction with Corona from 1961 to 1964, though never with the same degree of success. These 1150 - 1500 kg satellites manufactured by Lockheed Martin and operated by the NR used a single 76 mm focal length camera with a 140 meter resolution were operated primarily for map-making—they were the first to image Antarctica from space—and took less than a week to produce. Of the 12 flights attempted, however, only five successfully put the unit in orbit.
The Lanyard Program
The KH-6 Lanyard program was the NRO's first attempt at high definition photography but lasted just six months and three launches in 1963, two of which failed to produce images. These 1500 kg Lockheed satellites were hastily constructed using the previously-cancelled Itek "E-5" camera in order to survey a rumored anti-ballistic missile site near Tallinn, Estonia. The E-5 had a 66-inch focal length and six foot resolution covering a 9 x 46 mile area. The only successful flight returned 910 photographic frames. However, the image quality was so poor that they were virtually useless.
The Gambit Program
Outside of the Corona program, America's initial attempts at satellite photo-reconnaissance failed more often than not. The KH-7 and KH-8 series, codenamed Gambit, were a marked departure from that trend and the only other predominantly successful satellite ISR program in the 1960s. This 3,000 kg Low Altitude Surveillance Platform developed by Lockheed flew just 75 miles up (Coronas orbited at 100 miles) and operated for nearly two decades from 1964 to 1984. No fewer than 54 such satellites launched (these things only worked for three months, tops) from Vandenberg AFB aboard Titan III rockets during that time.
Eastman Kodak's A&O Division in Rochester, New York, produced the Gambit's primary strip camera system. With a focal length of 175.6 inches, a 6.3 km wide coverage area, and 3-foot resolution, the KH-8 was ideal for gathering high-resolution images of Soviet sites. Unlike conventional aperture cameras, the Gambit's slit camera reflected light off of a 48-inch mirror, through a slit aperture, and on to a moving length of Eastman Kodak Type 3404 film. It would then either drop the roll as the Coronas did or automatically develop the photographs, scan them, and transmit the images back to Earth in as little as 20 minutes through the Film Read-Out GAMBIT (FROG) feature (though after $2 billion dollars and nearly a decade of development the 1971 administration nix(on)ed it).
The HEXAGON Program
The KH-9 HEXAGON was, by all accounts, an unmitigated success with 19 of its 20 launches reaching orbit between 1971 and 1986. This $3.262 billion Lockheed-built NRO program is officially deemed a Broad Coverage Photo Reconnaissance satellite but is better known as "Big Bird." And while its existence wasn't revealed until 2011, the program dates back to the 1960s as a successor to the Corona program.
The first generation of HEXAGON employed a pair of f/3.0 folded Wright Camera cameras with a 60-inch focal length able to resolve objects down to 2 feet and carried four re-entry vehicles. The last three generations featured a pair of panoramic cameras as well as upgraded electronics, C&C systems and nitrogen-supplied re-entry canisters. They also a began surviving longer. Most spy satellites have very limited life spans—two to three months—and once they're out of film they have no further purpose. But with ever increasing film payloads, the final iteration of the KH-9 lasted 275 days in space. Between 1973 and 1980, these satellites imaged every square foot of the Earth in 29,000 pictures, much of it better quality than LANDSAT, a rival satellite mapping program. Most of these images have been declassified since 2002, though sensitive areas such as government installations and most of Israel remain tightly guarded.
The KENNAN Program
The KH-11 KENNAN is the most advanced recon satellite to be unclassified. First launched in 1976 by the NRO, it's the first US satellite to employ an EO digital sensor and charge-coupled device (CCD), which reportedly provides an Enemy of the State-style real-time observation capability. Very little is known about the satellite's hardware though many have speculated that its roughly the same size as the Hubble Space Telescope with a similar 2.4-meter mirror producing a six inch resolution. There's also wide speculation that the KH-11 is the source of images declassified in the wake of the 1998 embassy bombings, as well as others of China and Russia declassified the year prior. The images the CIA used to find Osama bin Laden's hideout were reportedly supplied by the KENNAN. Fifteen KH-11's have been launched in total—nine between 1976 and 1990 aboard Titan-3D rockets, five between 1992 and 2005 aboard Titan IVs, and the final one in 2011 aboard a Delta IV—at an estimated cost of $2.2 to 3 billion.
[Raytheon - NRO - FAS 1, 2 - Wiki 1, 2, 3, 4, 5 - Oneonta - Images: NRO, CIA, NASA]
How the US Built Its Super-Secret Spy Satellite Program