This Land Art Was Used For Secret Cold War-Era Surveillance

Large concrete crosses that dot the Sonoran desert landscape were once used to calibrate satellite cameras.

Today’s imaging satellites are sophisticated enough to take stunning high-resolution images of Earth from deep in outer space. But when CORONA, the first imaging reconnaissance satellite, launched in the late 1950s, the cameras at the time had trouble focusing their lenses from so far out. For that, they needed a physical counterpart on the Earth’s surface: a series of large optical targets that lay flush with the land to be used to focus and calibrate the secret aerial cameras used for spying during the Cold War.


Calibration Mark AC48 with Satellites. [Photo: courtesy Julie Anand/Damon Sauer/Ground Truth]
In many cases, these relics of early surveillance technology can still be found intact today. In China’s Gobi desert, they are enormous zigzag patterns etched into the arid ground. Near Edwards Air Force Base in California, they look like giant parking lots painted with hatch marks. And in the Sonoran desert in Arizona, where photographers Julie Anand and Damon Sauer have been working on their series Ground Truth, they are 60-foot concrete crosses plodded systematically along a 16-square-mile grid.

The targets documented in Ground Truth were built specifically for CORONA, which at the time of its launch was a top-secret spy satellite the U.S. used to monitor Russia and China. In 1995, an executive order signed by President Clinton declassified the CORONA project and released some 800,000 images—or 2.1 million feet of film—to the public.

The process for gathering this film sounds precarious, to say the least: when the cameras orbiting the earth from 100 miles above ground were through with a round of film, it was ejected from the satellite and floated down by parachute before being intercepted by a passing airplane.

Calibration Mark AK46 with Satellites. [Photo: courtesy Julie Anand/Damon Sauer/Ground Truth]
Surprisingly, the only snag to this elaborate process was that the first spy photos came out blurry. That’s what the concrete crosses were for—the Corps of Engineers built the grid in the Sonoran desert to calibrate the cameras on board the spacecraft.

Even after the CORONA mission was declassified, however, the crosses remained largely forgotten until 2004 when an amateur photographer spotted them from her plane. Where there were once more than 250, now only a little over 100 remain, as much of the property went from government to privately owned. Some are covered up by sand and shrub, and all are difficult to spot on the flat desert landscape until you’re only a few feet away.

Anand and Sauer read about the concrete crosses located about an hour south of their home in Phoenix, Arizona, and decided to track them down. They spotted their first one driving down Highway 8, and began tracking the others, which are all spaced an even 1 mile apart from each other. They take multiple images of the large structures at varying angles, then stitch them together in Photoshop to get one high-resolution image. In their latest evolution of the three-year project, they’ve also started mapping the satellites in the sky using an Apple tool called SkySafari. When they plug in the GPS coordinates, and the date and time the photo was taken, the software gives a list of the orbiting satellites and Anand and Sauer map the web of satellite trajectories in the image.


Though it’s hard to see on the computer, the printed versions of their images show the individual satellite names. “We think that’s really important since that’s part of how the images end up functioning as data-rich maps,” Anand writes in an email. “The names often either allude to country of origin, satellite function (for example “GPS,” “DirectTV,” etc.), or just evoke space itself (example: names like “Globalstar”).”

They also allude to the invisible flow of information all around us, which isn’t so unusual to imagine today, but would have been in the ’50s, ’60s, and ’70s when CORONA was gathering its intelligence. On the Arizona desert floor, the remaining of the slowly disappearing concrete crosses serve as physical relics of Cold War-era surveillance technology.




About the author

Meg Miller is an associate editor at Co.Design covering art, technology, and design.