High-Resolution Satellite Imagery at the World’s Fingertips

A little over a hundred years ago, American explorer Hiram Bingham captured the world’s attention when his account of his expedition to Peru made the cover of National Geographic magazine in 1913. Relying on local knowledge, he visited the crumbling ruins of Machu Picchu tucked in the forests of the Andes Mountains. He used state-of-the-art photography equipment to record what was there, and returned with 250 pictures and detailed reports about the expedition. The tradition of explorers using cutting-edge technology in Peru continues today with space archaeologist and National Geographic Fellow Sarah Parcak and archaeologist and National Geographic explorer Luis Jaime Castillo.

An elevated view of about half of the city of Machu Picchu. Photograph by Hiram Bingham
An elevated view of about half of the city of Machu Picchu. Photograph by Hiram Bingham

Parcak uses remote sensing to see things hidden to the human eye. “Space archaeology is the study and the use of satellite images for mapping ancient archaeological features and environmental features by looking at different parts of the light spectrum,” says Parcak. “We see subtle changes on the Earth’s surface caused by what’s buried beneath.” The satellite imagery records frequencies outside the visible spectrum that the human eye can see: near infrared, middle infrared, thermal infrared, and radar. This imagery reveals features such as buried stone walls, geology, and vegetation changes. Enhanced imagery can help identify buried sites that archaeologists can then explore on the ground.

When most people think about archaeology, they probably imagine long days excavating in the dirt looking for bones and artifacts. But a lot has to happen for archaeologists to pinpoint the sites that are most valuable to excavate. Using remote sensing has become, Parcak says, much more of a standard first step: “An archeologist typically wouldn’t go into the field, especially if they’re doing a survey project, without having done remote-sensing work prior to that.”

A satellite image of an archaeological site in Peru. Photograph courtesy DigitalGlobe

Archaeologist Luis Jaime Castillo uses drones to take pictures and convert them into 3-D images for archeological research on the north coast of Peru. Castillo explains that archaeologists for generations have always dreamed of having a bird’s-eye view. Now, drones are affordable and allow researchers to cover huge areas in shorter amounts of time. “The more we can use technologies like drones for instance, or satellites, to actually help us in this process, the better,” Castillo says.

More and more imagery is being made available every day. “Now there are millions of satellite images of the Earth’s surface taken at different times of year,” Parcak says. “As those images become more available and new satellites get launched, costs are going to come down. It’s not just the technology, it’s accessibility. And that’s making so much more possible.”

Parcak is seizing the opportunity by inviting the public to help look through satellite imagery of Peru on GlobalXplorer°, a cutting-edge web platform. GlobalXplorer° empowers citizen scientists around the world to help reduce looting and encroachment at important archaeological sites— as well as discover and protect unknown sites— using satellite imagery. The first expedition featured on the platform is Peru. “This is a country that has so many diverse ancient cultures that the scale of what’s there is unimaginable. And that’s what the world is going to help map.”

Find out how you can become part of the GlobalXplorer° community and make a difference at GlobalXplorer.org.

Changing Planet


Meet the Author
Carolyn Barnwell has been a producer on the Science and Exploration Media team at National Geographic for over five years. She creates content to support the non-profit National Geographic Society including impact initiatives and the important work of explorers and grantees around the globe. She wrote, produced and edited for Nat Geo’s first-ever web series focused on explorers in the field: Expedition Raw and Best Job Ever. She loves yin yoga, wildlife encounters, and eating baked goods while they are still warm from the oven.