One of the crosses today

These are not grave crosses, but horizontally placed concrete elements in the shape of a Maltese cross, which were once used to set up optical devices carried by spies or satellites.

One of the crosses today

Photo: Google Maps

Mysterious calibration targets, visible from space, are located in a 26×26-kilometer square grid. They were 18 meters each, and there were exactly 272 of them near the town of Casa Grande in Arizona. The targets were used between 1959 and 1972. It is so certain that the bronze plaques placed on them bear the name of the cartography service of the U.S. Army, but their exact purpose is still disputed.

The targets were built on a leased area, which was transferred to other tenants when the program ended. If the owners stipulated in the contract, the army removed the concrete elements, but in most cases this was not the case – 143 crosses still stand in the desert.

During the Cold War, the United States worked with great force on its spy satellite program. It was the Corona program, which was surrounded by strict secrecy until 1995, and its main mission was to explore the military facilities of the Soviet Union, especially its nuclear weapons. The resolution of the first devices was twelve meters — that was the size of the smallest recognizable feature in his images. From 1963 onwards, technical progress made it possible for the KH-2 and KH-3 cameras keyhole, ie keyhole abbreviation) to take images with a resolution of up to three meters.

As mentioned, the targets are assumed to have played a role in the Corona program, but are not specifically mentioned in the decrypted documents of the program. The XXI. In the 16th century, due to an investigation by tourists wandering into the area, U.S. Army historians began to visit those still involved in the program, but to this day they have not been able to reach the end of the story. So either none of the participants are alive anymore, or it could be a particularly secret part of the story that they can’t even talk about today. The latter is unlikely for two reasons: one is that the calibration targets used by the Corona program are known, and these are strange objects consisting of three rows of monoscopically variable-width stripes.

The other reason is that the thing was not so secret. In 1978, President Jimmy Carter himself praised the spy satellite program as an important means of securing world peace and balance of power, which they certainly intend to pursue.

It is against secrecy, and it may be a mystery that local newspapers also wrote in 1967, without mentioning espionage, mysterious concrete objects inhabiting their surroundings, which are used to “dynamically test low and high altitude aerial photographs as an extremely accurate point of reference.” Based on the latter, it can be assumed that the crosses may also have been used for spy-photo calibration by aircraft scouts undertaking more agile and dangerous operations than the satellites of the era.

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