American space archaeologist Sarah Parcak uses satellites orbiting high above the Earth to find clues about what is concealed beneath our feet. Her work has been the focus of BBC documentaries on Egypt, ancient Rome and the Vikings. In 2016 she won the $1m TED prize to build a website where anyone can help make discoveries using space archaeology. Now the professor at the University of Alabama at Birmingham has a new book: Archaeology from Space: How the Future Shapes Our Past.
What is space archaeology?
It is archaeology using satellites, high-flying aircraft or any other platform that allows you to take pictures remotely of the Earth’s surface. You’re looking back on Earth to find subtle hints of ancient features buried under the ground. Sometimes things show up visually, but more often we are looking in different parts of the light spectrum that we can’t see. For example, the near infrared shows small differences in vegetation and you might expect the vegetation growing on top of buried stone to be a little less healthy. Many thousands of new Mayan sites were found recently in the Guatemalan jungle using Lidar imaging. It is a laser system, flown from an aeroplane, that bounces pulsed laser light off the ground, revealing features which would normally be hidden below the vegetation.
Do most archaeologists use space archaeology?
The field was born in the early 1980s but only took off about 15 years ago when satellites started being much more widely used. It’s become part of archaeology’s common toolkit and the number of trained archaeologists that do this kind of work is increasing.
What got you into the field?
I completed my degree at Yale in 2001 in archaeology and Egyptology – the early Indiana Jones movies helped fuel my interest. I took my first remote-sensing class while there, inspired by my grandfather. He had pioneered the use of aerial photography in forestry to map and measure tree heights, having learned about the technique as an officer in world war two. I took the class betting loads of archaeologists would use it. I found out just how new the field was.
What’s the most exciting discovery you’ve made?
Being obsessed with Indiana Jones, it has to be mapping the settlement of Tanis – this 3,000-year-old ancient Egyptian capital city [the “lost city” featured in Raiders of the Lost Ark]. It was in 2010, as part of my work on a BBC documentary project. Tanis is one of these big iconic archaeological sites, but only a tiny part of it had previously been excavated. We wondered if we could see some new features. I got satellite imagery from a very wet time of year because, compared to the sandy surroundings, the crumbling mud brick of the site absorbs water. I was zoomed in, processing the image, trying to get the small outlines of the mud brick to pop out, and when I zoomed out for the first time – boom! There was this huge map of the whole city. I almost fell off my seat. You could see clear buildings, streets, suburbs – everything. We went on to collaborate with a French team to excavate a building.
You have used space archaeology to deepen our understanding of the end of ancient Egypt’s Old Kingdom, best known for its pyramids. What did you find?
Some Egyptologists believe the Old Kingdom ended mostly for economic, social and political reasons. Others have argued its demise was caused more by drought. I used satellite imagery of the Egyptian delta and on-the-ground survey work to show that the number of settlements dropped, from the Old Kingdom to the period directly following. Smaller settlements were likely abandoned while larger settlements remained occupied. It has given more evidence to there probably having been a serious drought that lasted for a lengthy period of time and played a more major role in the decline than previously assumed. That has ramifications for today with our civilisation facing climate change, in that more rural areas will be abandoned for cities.
We can all now try to spot things from space with GlobalXplorer, which you launched in 2017. How does it work?
It allows anyone in the world to look at high-resolution images to help find and protect archaeological sites. After a short tutorial, you start searching images we give you. You begin looking for evidence of looting – the diggings can be easy to spot – and then you can advance to finding new archaeological sites. We’ve essentially made it a game. As people use it, they get better. So far, our images have been from Peru. We’ve had about 90,000 users find almost 20,000 previously unrecorded potential sites there, 700 of which we think are of major archaeological importance. People have a 90% success rate at identifying genuine archaeological features.
You have mapped looting across Egypt over time, showing that it got exponentially worse following the 2009 global recession, with another spike after the 2011 revolution. How does mapping looting from space stop people doing it?
Aside from getting western collectors to stop buying antiquities, the first step to stopping looting is identifying where it’s happening. In 2014, I shared the results of the project with the US state department. My testimony, along with those of my colleagues, helped get restrictions to stop Egyptian antiquities being imported into the US. The state department needed proof that there was looting and that this was an ongoing problem.
How will technology further shape archaeology in the future?
The highest resolution satellite imagery we have right now is 0.3 metres. In the next five to 10 years, I’m expecting that to get down to about 0.1 metres. Imagine being able to zoom in from space and see a pottery shard! There are also more archaeologists using drones which allow you to see at a resolution of a couple of centimetres, though they can’t map hundreds of square kilometres and they are banned in some places like Egypt. In the book I imagine a future where robots do the actual digging and collection. I am expecting a lot of eye-rolling from my colleagues. But look at how much surgery is done robotically. Why wouldn’t archaeology adopt it too?
Where are you hoping to apply space archaeology next?
Later this year I will be going back to an ancient Egyptian site at Lisht to carry on with our excavation work there. The Egyptian government asked our team to work on a specific tomb to secure it from looters. I want to apply some of the highest resolution satellite imagery, as well as thermal infrared imaging, to see whether we can find additional buried tombs nearby. Also, we know Egypt’s capital in the Middle Kingdom, Itj-Tawy, was situated around there, but the city has never been found. It beckons! Beyond that, I am keen to experiment with new sensor systems on drones. And it would be amazing to design an archaeology-specific satellite. We don’t have one of those yet. Any billionaire funders – do call!