A brief history of early surveillance satellites

A brief history of early surveillance satellites

The first surveillance satellite was launched in the early 1960s. Dubbed Corona by its developers, the spy satellite used film to take high-resolution pictures of potential threats on enemy territory. To transfer data, Corona placed exposed film in a canister, then 'de-orbited' the containers by sending them to Earth through a rapidly decaying orbit. Airplanes retrieved the canisters in mid-air, said Air Force spokeswoman Capt. Colleen Lehnee.

In 1970, the Air Force began deploying the Defense Support Program, which would eventually consist of a constellation of reconnaissance satellites in geostationary orbit. Orbiting in lockstep with the Earth's rotation 22,000 miles above the equator, the DSP satellites used infrared sensors to scan the surface for the telltale temperatures generated by the exhaust fumes of intercontinental ballistic missiles. DSP has been the linchpin of early warning programs and systems, Lehnee said.

However, with the dissolution of the Soviet Union and end to the Cold War, Defense Department scenarios shifted from large-scale incoming ICBMs to smaller missile threats arising out of theater-based conflict.

The greatest threat to U.S. deployed forces and allies will come from short-range low-altitude missiles launched by small, rogue nations, Air Force officials said. The Space Based Infrared Systems'which will eventually replace DSP'were designed specifically with that in mind, Lehnee said.

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