Sometimes, it takes the very newest technology to find traces of humanity's ancient past.
That's the premise that has guided Sarah Parcak in her career as an archaeologist who relies on remote sensing data gathered by airplanes, satellites and unpiloted drones. Observations from these systems can help scientists tap into visual cues that are invisible on the ground — and in turn, find long-lost traces of humans who lived millennia before we took to the skies.
In her book, Parcak pulls together an impressive collection of discoveries made using these high-tech observations and offers behind-the-scenes stories of her work. The book, "Archaeology From Space" (Henry Holt and Co., 2019), was published in July.
Space.com sat down with Parcak to learn more. This interview has been edited for length and clarity.
Space.com: For someone unfamiliar with the idea of space archaeology, could you give the summary version of how it came to be?
Sarah Parcak: The field can be defined as using any kind of space- or air-based platforms to map archaeological sites on the ground or underground, in some cases looking for patterns and shapes, in other cases looking for subtle differences in the light spectrum that we can't see, so in the near, middle and far infrared. The term space archaeology is the fun name. I could call it midtroposphere multipixel spectral analytics, and then all your readers would fall asleep. So, it's the fun name, but really, it's remote sensing for archaeology …
The field of aerial archaeology, using aerial photographs to map archaeological sites, started in the early 1900s and really picked up in World War I, when early flying aces would use their cameras to take pictures of archaeological sites in the Middle East. And their officers said, 'Wait a minute, you can take pictures from on high?' We take this for granted. But ironically, archaeology started the field of aerial reconnaissance in the military. A lot of people don't know that. Today, we benefit from military technology, so we've shared [technology] over time. But now things are shifting from space-[based] or from air-based platforms to things like UAVs [unmanned aerial vehicles] and drones, because they're much easier to control and they're much less expensive.
Space.com: This is clearly not just sort of swooping in with your satellite data and doing whatever you want. Can you talk a little bit about what that process is like?
Parcak: Before we start any archaeological work, this is science, so we start with a research question. It's not just, 'We're going to go find a lost city!' because that's super problematic and, more than ever, so slightly colonialist. Let's just say you're interested in shifting population dynamics for the Maya classic period, so between 800 and 1000 A.D. You're looking at how and why large cities may have interacted with each other and potential trading routes and where people may have lived. So, you're going in with this set of questions based on pretty serious research in the library and all the previous work that's been done in that area, no matter where you're working.
Then and only then can you say, 'What am I looking for? OK, I'm looking for features x, y and z — so I'm looking for, say, pyramids or settlements or roads.' But the challenge here is that it's beneath the rainforest, so I can't use optical satellites. I have to use this laser mapping system called LIDAR to see beneath the trees. We adapt and use technologies specific to both landscapes where we're working, but also what we're looking for …
It's kind of a detective game in that you've done all your background research and then you've got to think about the science of what you're doing, the techniques you're doing, what's worked and what hasn't worked. Then and only then do you start processing the imagery, and of course, we're collaborating closely with our colleagues in the ministries or archaeologists working in those countries. We're never working in a vacuum.
Space.com: Do you have a favorite satellite that you've used data from?
Parcak: Oh, I have so many favorite satellites. I'm partial at present to the WorldView-3 satellite. It has a resolution of between 0.3 and 0.4 meters, so that's just under a foot. It has the ability to record data in both near and middle infrared, so it allows you to visualize subtle changes to ground geology in different parts of the light spectrum, which is really helpful for archaeology. We've been using it in different parts of Egypt to visualize sites. It's an extraordinary satellite sensor system.
Space.com: Are there any upcoming satellites that are already in the works for other programs that you already have your eye on?
Parcak: The dream is to have an archaeology-specific satellite. If any billionaires are reading right now, I am taking checks — call 1-800-DONATE-PARCAK. I joke with my colleagues about it, but [I like] the idea of creating something like a space-based LIDAR system — NASA has one but it's very low resolution. There are just so many parts of the world that are beneath dense tree cover, whether it's North America, Central America, South America, Southeast Asia, central Africa. It's not feasible to collect data from a drone or an airplane, that you can only use over smaller areas, it's really expensive.
Space.com: What is your pitch to get someone interested in space excited about this particular application of space technology?
Parcak: OK, so if you're interested in space, I'm pretty sure that you're interested in the possibility of finding life on other planets. That's one of the things that's driving our space program right now. … What happens if there's civilizations on other planets? Hi, I'm an archaeologist — I know how to find them.
That's what this technology enables us to do. It enables us to find the hints of what these past civilizations look like. And I think, someday, and it's something I talk about in my book, the same techniques can be used to find structures and buildings on other planets, so I think NASA should be hiring archaeologists. We need to be planning for 100 years in the future when we're looking for these civilizations on other worlds, because astronauts aren't trained to do what we do.
Space.com: You write really compellingly about Tanis and that moment of sort of starting to see all of these structures pop up in areas of a city that seemed to have been blank.
Parcak: Tanis was Egypt's capital in the later part of the New Kingdom, this great age of empire, and this huge capital formed in the northeast Egyptian delta that lasted for 400 years. When I say this was a massive city, this was the equivalent of, say, their New York or Washington, D.C. There would have been tens of thousands of people living there. And today, there's nothing …
It's compelling to me because I think it speaks to our hubris. I don't think that the inhabitants of Tanis thought that their city would just not only disappear to dust, but that no one would even know what it looked like. That's what I thought about when we were able to map the city. I thought, 'Who are these people? Where do they live? How did they live? And then to not know anything about a capital?' When we found it and mapped it and started thinking through what the buildings were, it just evoked in my mind this idea of our impermanence.
Space.com: Are there any particular space developments in the near-term future that you think will have a really big impact on archaeology?
Parcak: With hyperspectral sensor systems, we're able to see in hundreds and hundreds of very narrow bands. Geologists have been using this technology for the last two decades to map out subtle signatures that indicate where a geological feature might be, because everything on the Earth's surface has its own distinct chemical signature [that] they're able to see across the light spectrum. Well, the same with archaeological sites, they have their own distinct chemical signature. So, the idea is that we can develop databases of archaeological sites around the world and detect them using this hyperspectral technology that's been developed by NASA.
Space.com: And you mentioned in the book that if you got to choose one place to have more space archaeology happening, it would be the Central African Republic. Can you talk a little bit about why that region's history is so interesting to you and the particular way that space technology makes archaeology more feasible?
Parcak: When we see a dense rainforest today, I think we just take it for granted, and we think, 'Oh, it's always been a dense rainforest. No one could have lived here.' If you look at the work that's coming out of a place like Brazil — and yes, the deforestation is awful — but what that deforestation has allowed archaeologists to do is find hundreds and hundreds of these archaeological sites.
My African colleagues have told me that the rainforest in central Africa touches upon eight or nine different countries. And this [is a] concept that was brought up in the movie "Black Panther," and while, yes, Wakanda, of course, doesn't exist, the idea is that there could potentially be entire civilizations there about which we know very little right now. To me, I find that very compelling, the idea that the history of the African continent could potentially be rewritten from archaeological discoveries there.
Space.com: And I can't remember if it was while you were still writing the book or if it was sort of in the publication process, but I remember seeing you tweet some statements about trying to highlight specific research and people who actually live and work in those countries and the challenges of doing all that. Can you talk a little bit about what your motivation was and how that played out during the writing process?
Parcak: I've learned over time, because I think it's a process that we all go through, the amount that colonialism still impacts the way archaeology is practiced today. And I try in all of my work very intentionally to decolonize my approaches. I can't help that the whole structure of archaeology is colonialist, so it's our system, and we need to break the system down and in some ways start from scratch. …
It's very easy with remote sensing in archaeology, and I think a lot of scientific fields, to cite white men at Western universities. And I could have done that, but that's not OK … I think it's really important for those of us that work in the West to be incredibly intentional about who we cite and how we're citing them.
Space.com: If a reader takes just one idea from reading your book, what do you hope it is?
Parcak: The past matters to them. I know it sounds trite, but I think one of the things that we're missing right now, we're dealing with climate change and unstable politicians and the world seems kind of hopeless. And I think when you understand this long framework, that we're all a part of this long trajectory, understanding where we've come from, understanding all these past civilizations and how they rose and collapsed, it gives us some perspective that we need …
I think if you're hopeless, you're stuck. You can't take action, you don't feel empowered. And if you have a little bit of hope, some measured hope, it allows you to take that deep breath and to go, 'OK, well, we've been struggling and we're going to continue to struggle, and this is how I can play a role in it.' I think it helps to unstick us a little bit if we understand where we've come from.
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