Satellite Archaeology

Archaeology is a messy business. Digging holes—in the dirt, in the sand, and in the rain forest—is essential. Now there’s a new way to search, with no shovels needed. Some 400 miles up in space, satellites collect images that are used to identify buried landscapes with astonishing precision. Like medical scans that let doctors examine parts of the body they couldn’t otherwise see, satellite images help scientists find and map long-lost rivers, roads, and cities, and discern archaeological features in conflict zones too dangerous to visit. “There is much we miss on the ground,” emphasizes University of Alabama at Birmingham archaeologist Sarah Parcak, a pioneer in using satellite imagery in Egypt. “We’ve only discovered a fraction of one percent of archaeological sites all over the world.”

Parcak is nudging that fraction up. Through “thousands of hours” of trial and error she has perceived what the human eye can’t. Hard-won successes have taught her what works: combining and processing images so she can peer into the infrared part of the light spectrum, which is invisible to the naked eye. The images allow her to detect subtle surface changes caused by objects like mud bricks a foot or less underground. In 2011, relying on infrared satellite pictures, Parcak and her team identified 17 potential buried pyramids, some 3,000 settlements, and 1,000 tombs across Egypt. At the 3,000-year-old city of Tanis, once a capital in the Nile Delta, she found evidence of hundreds of dwellings. “Above ground, you can’t see anything,” she says. “It’s a silty mound with brown, muddy earth covering everything.” After a few days of processing and peering at the images, “this amazing map popped out,” she recalls.

Using laborious, low-tech excavation, it might have taken a century to assemble a similar city plan. But old-fashioned digging is exactly what’s needed to confirm these high-tech finds. A French team has made a start, excavating a single Tanis house. When it comes to archaeology, distance provides crucial perspective, but there’s no substitute for being up close. —Hannah Bloch

Graphics: 5W Infographics. Sources: Sarah Parcak and Gregory Mumford,
University of Alabama at Birmingham; DigitalGlobe