If Indiana Jones had only had a satellite … The many wonders of space archaeology

 

Probably the most famous pyramids in the world… those at Giza, near Cairo, shown here in a high resolution satellite image. By studying such images, archaeologists can be very precise about on-the-ground research, saving both time and money.

Strange as it may seem, archaeologists often look to the sky to discover sites buried deep beneath the earth. Space archaeology, as it’s called, refers to the use of high-resolution satellite imaging and lasers to map and model everything from hidden Mayan ruins in Central America to specific features on the ancient Silk Road trade route in Central Asia. The process saves research teams years it would have taken to do the same work using ground-based survey techniques.

Archaeologist, Egyptologist, University of Alabama at Birmingham professor and TED Fellow Sarah Parcak makes extensive use of this technology in her work, and she has done much to popularize space archaeology. She wrote the world’s first overview book on the subject, and gave a riveting talk at TED2012 to explain how borrowing the tools of space exploration helped her identify an ancient Egyptian city that had been hidden for thousands of years. Here, she tells the TED Blog more about how it all works — and how she applies it to her on-the-ground explorations.

How long has space archaeology been around? Who figured out that this could work?
Archaeologists have used aerial photographs to map archaeological sites since the 1920s, while the use of infrared photography started in the 1960s, and satellite imagery was first used in the 1970s. But it wasn’t until a seminal conference held at NASA in 1984 by my friend Dr. Tom Sever, whom I call the father of space archaeology, that we started to see more peer-reviewed papers on the topic. Tom introduced the field to a number of influential archaeologists — and then things really started developing when those archaeologists trained their graduate students, and those students started getting positions ten years ago.

Today, space archaeology is fairly standard practice. Conventional excavation and survey are crucial to confirm any satellite imagery findings, but analyzing the images saves time and money and allows projects to focus on specific locations at archaeological sites.

How do these technologies help to identify objects buried in the ground?
The only technology that can “see” beneath the ground is radar imagery. But satellite imagery also allows scientists to map short- and long-term changes to the Earth’s surface. Buried archaeological remains affect the overlying vegetation, soils and even water in different ways, depending on the landscapes you’re examining. So, for example, buried features in desert environments appear different from buried features in floodplains. When a wall is slowly covered over by earth, the materials it’s made from decay and become part of the soils around and above it, sometimes causing vegetation above and next to the wall to grow faster or slower. Satellite imagery helps archaeologists to pick up these subtle changes.

If you find a series of linear shapes in the same alignment as known archaeological features, and they match excavated examples, you still need to excavate to confirm, but you can be fairly sure that the imagery is accurate. Often discrepancies are much more readily apparent in the infrared part of the light spectrum, since vegetation and other changes to soils appear more strongly in infrared.

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