Post by larryc1 on Feb 27, 2019 0:15:34 GMT
Between 1959 and 1972 the USAF/ CIA ran a spy satellite program called 'Corona'. In order to calibrate the cameras involved a 16 x16 grid of concrete maltese crosses, each 18.3 meters (60 feet) in width was laid out at Casa Grande, AZ. (The targets are 1.6 km (1 mile) apart). Many of these objects are extant in the desert. I have found many of them in a slightly obsessive 'Where's Waldo' search. Many have been lost to development and the desert sands. Land subsidence eventually made the grid unusable.
en.wikipedia.org/wiki/Corona_Satellite_Calibration_Targets
www.google.com/maps/d/u/0/viewer?mid=1CkeC8CvojF3V_89o9_C9DL9OFfY&ll=32.78280478038547%2C-111.58987615593128&z=11
Detailed account of the 'Corona' program.
en.wikipedia.org/wiki/Corona_(satellite)
en.wikipedia.org/wiki/Corona_Satellite_Calibration_Targets
www.google.com/maps/d/u/0/viewer?mid=1CkeC8CvojF3V_89o9_C9DL9OFfY&ll=32.78280478038547%2C-111.58987615593128&z=11
Detailed account of the 'Corona' program.
en.wikipedia.org/wiki/Corona_(satellite)