Crop Circles from space in Cornfields!

Crop Circles & Parachuting Film

Like so much that is digital, the impetus for image sensor development came from government intelligence and space programs. Cold War spy satellites monitoring the Soviet Union needed a better method of surveillance in 1960; the top-secret CIA / US Air Force Corona spy satellite program was launched. These satellites were outfitted with state-of-the-art KH-series cameras that used very long lenses and a new kind of plastic film. (Eventually, the plastic came into commercial use as "Mylar.")

To calibrate the photos for scale, shapes large enough to be seen from space were secretly mown into Midwest cornfields. (Thus, we can now understand the primary source of the mysterious crop circles that have thrilled and titillated tabloid readers for decades. And yes, they were signs from space, though entirely human in nature).

http://www.extremetech.com/article2/0,3973,15465,00.asp

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