Archaeologists are finding more ancient cities and lost human settlements than ever before. And it's all thanks to new imaging technologies commonly used in surveillance. With highly-accurate measurements from satellites, drones, LiDAR, and more, archaeologists are making discoveries that were once impossible.
Patricia Murrieta-Flores, an archaeologist at Lancaster University in the U.K., told io9 that archeologists have long been early adopters of new technology: "Since very early on, archaeology has learned and adapted theories, methods and techniques from other disciplines, such as geology, geography and chemistry, among many others." Though a previous generation's archeologists might have carried trowels, dustpans and maps, these days they're more likely to be using radar.
Over the past thirty years, the field has rapidly evolved, and now makes use of satellite imagery, ground-penetrating radar, computed tomography (CT scans) and even robotic drones. Here are some of the discoveries these spy technologies have made possible.
Before archaeologists can excavate a new discovery, they need to find it first. In the past, this could involve poring over historical records and maps. Nowadays, archaeologists have added another tool to help them locate areas of interest: Satellite imagery.
In fact, researchers have made important discoveries just by looking at Google Earth images. In 2011, archaeologists used the popular 3-D map program to see what archaeological secrets are buried in Saudi Arabia — they found that large portions of the country are rich in archaeological remains that may be several thousands of years old. And last year, satellite archaeologist Angela Micol made waves when she reported that she found Google Earth anomalies that may be pyramids buried in Egypt (her claim drew a lot of criticism from other scientists, but Micol and others are working to determine what the structures in the images really are).
Other archaeologists are using satellites equipped with infrared cameras, which are able to peer beneath the ground. "Space archaeologist" Sarah Parcak is a pioneer in using infrared satellite imagery for archaeology. A couple of years ago, Parcak and her team used the technology to identify more than 1,000 tombs, 3,000 settlements and up to 17 potential buried pyramids. Parcak's work also revealed buried city streets and houses in Tanis, the famous ancient Egyptian city featured in "Raiders of the Lost Ark." In an interview with the BBC, she said, "Indiana Jones is old school, we've moved on from Indy. Sorry, Harrison Ford."
Last year, scientists found a new way to use satellites to identify buried settlements — by searching for anthrosol, a type of soil resulting from long-term human activity. Archaeologists have used anthrosol detection on the ground level for years, so researchers at Harvard and MIT developed an automated system to seek out anthrosol in multi-spectral satellite images. With the technique, they mapped about 14,000 Mesopotamian settlement sites, which span some 8,000 years.
Archaeologists can also use satellite imagery for more than finding sites to investigate. Elizabeth Stone, an anthropologist at Stony Brook University, uses satellite-based monitoring to assess the levels of looting and destruction of archaeological sites in Mesopotamia (modern-day Iraq). Recently, other scientists have used the technique to investigate archaeological looting in Peru.
Though satellite imagery is important to archaeologists, they may be trumped by another aerial imaging technique. Arlen Chase, an anthropological archaeologist with the University of Central Florida, thinks LiDAR (Light Detection and Ranging) is a "paradigm changer" for archaeology. "What LiDAR has done is given us control of space, the way radio carbon dating has given us control of time," Chase told io9.
With LiDAR, researchers use low-flying planes to send out laser pulses to the ground — by analyzing the pulses reflected off the ground and the vegetation, they can then create 3-D topographical maps of the ground surface. For over two decades, Chase and archaeologist Diane Chase (his wife) conducted countless ground expeditions to map out the ruins at Caracol, an ancient Mayan city just outside Belize. When the couple used LiDAR on the region a couple years ago, they were able to map around 80 square miles of the ruins in just a few days — about 10 times the area they previously mapped in their 20 years of work.
Other scientists are also catching on to the usefulness of LiDAR for archaeology. Earlier this year, archaeologists used the technique on the rain forests of Honduras in Central America, and discovered what may be the legendary La Ciudad Blanca, "the White City."
"Nothing recent has been as impactful as LiDAR," Arlen Chase said. "It has just moved us forward by leaps and bounds."
Murrieta-Flores added that LiDAR is enhanced by geographic information systems (GIS). These are software systems for arranging geographic data in layers — for example, you might have a layer of LiDAR data on top of a map showing local water systems, which could help you track where ancient communities were most likely to build in order to be in areas fed by streams. She explained:
These technologies make a huge difference for archaeologists today because they allow you to integrate very large volumes of data, which was previously impossible. They also enable the integration of very disparate sources, such as historical maps with modern data, archaeological data and others. They help you to not only visualize and integrate all this in a very efficient way, but also to analyze and therefore identify in a quick and expedited way the patterns underlying such data. In addition, you can also retrieve information about your data with simple queries. Before the development of GIS, the traditional way of recording findings at a landscape scale was to just draw points on a paper map. This would only allow you to see the distribution of sites or findings but nothing else. Nowadays GIS projects integrate huge amounts of attributed information that makes it possible to do spatial analysis to identify trends and patterns.
In 2010, University of California Los Angeles archaeologist Michael Harrower used GIS technology to investigate the origins of irrigation in Yemen. And when GIS is combined with 3D-modeling technologies, scientists can create a kind of virtual copy of entire sites.
A major concern in archaeology has always been the potential damage caused by excavation — Indiana Jones may have trampled through ruins without a care in the world, but real-life archaeologists try their best to preserve the remnants of the past as best they can. In recent years, scientists have begun testing out quite a few different non-invasive techniques to analyze archaeological sites.
Ground-penetrating radar, or GPR, allows archaeologists to see what's underground without ever needing to dig. Back in 2002, researchers successfully used GPR in Petra, Jordan to locate underground structures and guide later excavations. People have also used the technique extensively for the Duffy's Cut Project, which seeks to learn more about the lives of Irish immigrants who were buried in Duffy's Cut, Pennsylvania almost 200 years ago. And recently, scientists used GPR to try to map undiscovered ruins in Pompeii — they believe the technique could be used to provide detailed maps of the subsurface ruins, which will probably never be excavated.
Last year, archaeologists found that they could pinpoint and distinguish areas devoted to prehistoric middens (trash dumps) and plazas by measuring the varying levels of phosphorous in the soil. At their study site in Pickaway County, Ohio, where a village once stood around 700 years ago, the researchers identified a U-shaped ring of high phosphorus concentrations, which indicates a village midden, enclosed by an area of low phosphorous concentrations, which signifies a plaza where ceremonies took place. In their paper, the authors note that such noninvasive techniques are important because excavation is often "expensive, time-consuming, and may run counter to conservation ethics" (though other scientists have stressed that noninvasive techniques can never replace excavation).
The use of robots has also found its way into archaeology. Most notably, scientists have sent tiny robots into Egyptian pyramids to check out chambers they could never get to themselves. In 2011, the robotic explorer Djedi captured the first images of enigmatic markings on the wall of a small chamber in the Great Pyramid of Giza. Last year, archaeologists used another robot to build 3-D maps of ancient Rome's largest sewer system (called Cloaca Maxima). A few months ago, another team guided robots underneath the Temple of the Feathered Serpent, an ancient pyramid in pre-Hispanic city of Teotihuacan, and discovered hundreds of mysterious spheres — nobody knows what the purpose of the orbs are yet.
Of course, to really learn about ancient cultures, you need to study the remains of people from those cultures, not just the locales. As we discussed in this piece about how scientists study mummies, there are number of non-destructive techniques archaeologists are now using to learn about human (and animal) remains, including CT scans, mass spectrometry, DNA analysis and protein analysis. And earlier this month, a conservator at the University of Stavanger's Archaeological Museum in Norway devised a way to determine if ancient bone contains any DNA, a technique that could help scientists avoid wasting time and money carrying out DNA analyses on remains that contain no genetic material.
As scientists and engineers develop new technologies, archaeologists will no doubt be quick to adopt them. So what's in store for archaeology in the near future?
Chase is excited to see where LiDAR goes from here. "It's still expensive to use," he said. "But there will be newer discoveries that eliminate certain less-complex models that we have been using to interpret the data." He also thinks new techniques to better see things buried underground will come along.
Murrieta-Flores noted a couple of interesting tools that are currently in the works, such as Reflectance Transformation Imaging (RTI). The method essentially enables you to re-light an imaged object from any angle and enhance its surface attributes. Researchers are currently using RTI to try to decode the world's oldest undeciphered text. "One of the most important aspects of RTI so far is that it is very easy to implement and everything has been developed as open source so countries with less resources can easily adopt it," she said.
Murrieta-Flores is also excited about the use of "Tangible User Interfaces" in archaeology, in which people manipulate digital information through physical environments. For instance, researchers designed ArcheoTUI (video below) to help archaeologists piece together fragments of fractured archaeological objects.