Unraveling the mystery behind the appearance of white crosses in a desert

Nearly 12 years ago, a pilot was flying a small plane when she saw a strange formation in a section of a desert in Arizona.

She spoke to NPR about the sighting, and said that she and a friend got a closer look at the cross-like structures she spotted.

She said they "were once part of a top-secret government program called CORONA — the nation's first reconnaissance satellite program."

Indeed, CORONA was a part of U.S. efforts to spy on the Soviet Union and other Cold War threats in the 1960s.

Americans secretly launched satellites with cameras to take photos of enemy territory -- and with this disguise, they could not be detected.

At first, the initial images were blurry, but the military tweaked its setup.

According to According to Atlas Obscura, the crosses were arranged into a 16 x 16 grid.

That way, satellites could orient themselves and focus correctly before spying on those other countries.

The location was chosen for its clear weather.

The project was successful, and helped produce more than 800,000 photos of enemy airfields and nuclear weapons sites.

CORONA ended after 12 years in 1972, and many of the concrete markers remain.

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