Google's Satellite Revolution

More Pixels Per Pound

Satellite imagery is an invaluable tool in archaeology. Quite simply getting a satellite or aerial shot allows an archaeologist to analyze the landscape and detect features that are hard, for an observer on the ground, to find. Ancient roads, canals and buried structures can be detected, and natural features such as shorelines, topography and even soil composition can be mapped. Bring a GIS system or Google Earth into the equation and you can also compare multiple archaeological sites with each other.

Archaeologist Jason Ur, of Harvard, is one of many experts to be making full use of the technology available. He uses satellite analysis extensively in his work at Tell Brak in Syria, and told The Economist that satellite imagery offers a whole new perspective on a site.

He compares the experience to looking at a Monet: “If you were to press your nose against an Impressionist painting, you would see colour and maybe elements of form, but it’s not until you pull back that these would turn into a bridge or water lilies.”

Eye in The Sky

Long before satellites existed, archaeologists recognised the value of getting a birds-eye view of their sites. In the pre-satellite era those archaeologists who had the money would hire a pilot to shoot aerial photographs of the landscape they studied. If this wasn't possible, they would often borrow aerial photography shot for another purpose, or go for the cheaper (but perhaps more dangerous) alternative of climbing up a hill, or even a tall ladder, to get their shot.

The Nazca Lines are perhaps the most famous example of a major archaeological discovery being made without anybody getting sand in their boots. Archaeologist Toribio Majia Xesspe was the first to notice the lines, while on top of a hill in 1927. Since then, pilots have played a major role in discovering, mapping and photographing them. In fact without the ability to get a view from the air it’s likely that most of the nearly two dozen figures known today would not have been found.

Dawning of a New Era

The LANDSAT satellite program in the 1970s heralded the beginning of satellite based archaeology. Archaeologists gained the ability to purchase high-resolution shots of the earth’s surface at affordable prices. In addition the images taken could be seen in different sections of the electromagnetic band. This made it easier to do things such as analyze soil moisture (band six) identify plant species (band three) and detect water (various thermal bands) - all invaluable sources of information for shedding light on a site.

For example the Sinai Desert is not the most hospitable area for an archaeological survey. However, archaeologists Sarah Parcak and Gregory Mumford have been surveying the area for years, using satallite technology to unearth several archaeological sites. One of their discoveries was a 4,250 year old Old Kingdom fortress at Ras Budran. 
In order to narrow down the list of likely archaeological sites, Parcak has been using satellite analysis to find natural water sources in the desert. By locating these areas she can narrow down the places most likely to have been used in ancient times. Parcak has also used this technique to find sites in the East Delta and Middle Egypt.

Analyzing ancient environments

By overlaying satellite maps with detailed soil, geological and vegetation information archaeologists can learn more about the environment that ancient people lived in. The Kingdom of Aksum, which is named after its capital city, existed in Northern Ethiopia from the second to eight century A.D. The “golden period,” for this society was from the third to the sixth century, when they controlled Eritrea, southern Sudan and parts of Yeman and southern Saudi Arabia, and created the Obelisk of Axum. However, it went into a period of decline starting in the seventh century.

To better understand Aksum a team of scientists have been analyzing the soils and geology of Northern Ethiopia and comparing it to settlement patterns. To do this the team ordered a high-resolution satellite image of the area and combined it with a Thermal Emission and Reflective Radiometer (ASTER) shot. ASTER is an imaging device launched in 1999 that is capable of providing detailed geological and soil information. The combination of the images means that they could produce a colour coded map that shows the different soils used in Northern Ethiopia. They haven’t been able to draw any conclusions yet but in the future they hope to shed more light on how the people of Aksum interacted with their environment.

The Google Revolution

Ever since the launch of Google Earth 2005, archaeologists have been finding ways to incorporate it into their research. The program has several advantages. As its name suggests it includes satellite shots of just about every place on earth. It’s also very cheap (free for the basic version), which is a major plus for archaeologists, who often work on tight budgets.

Perhaps its most important advantage is the fact that the images are already processed. When an archaeologist orders a satellite photo from a government agency, or private company, they usually have to pay to have it processed. This can potentially be a time-consuming and expensive process, since the technical knowledge needed to process raw satellite footage is quite high.

Google Earth image quality varies from medium to high resolution, with the higher resolution versions allowing a detailed analysis of a landscape. Jason Ur found that Google's high-res images of Tell Brak were impressive: “At Tell Brak, where I am involved with an ongoing survey project, one can make out the square patches of bare earth where we’ve cleared off the sherds for our tent footings!”

One project has given up excavations all together, using Google Earth instead of brushes and shovels. The Archaeological Sites of Afghanistan in Google Earth (ASAGE) project detects and analyzes archaeological sites without anyone setting foot in the country. Satellite research is important in Afghanistan because the political situation means that western archaeologists can’t excavate there.  Their findings so far have been mainly from the medieval period.

Good For The Gander

One potential drawback to Google Earth, raised by Jason Ur raised in his article, is the potential for looters to learn of the precise location of unprotected archaeological sites. “In a paper publication, one can accurately plot sites on a map at a scale of 1:250,000 without necessarily providing precise location information. The scale independence of the Google Earth interface means that a Placemark (assuming it is correctly placed) is accurate at a regional level or at the street level. Thus, an unscrupulous user has access to precise geographic coordinates that can be easily uploaded into a GPS for navigation to a site,” he said.  “For some parts of the world, the unsuspecting Google Earth interface is more than happy to provide turn-by-turn driving directions, complete with estimated travel times!”

In his search on online forums he found very few instances of placemarks being placed on sites that may be unprotected. But he adds that archaeologists must be careful, when conducting research, that the precise location of sites doesn’t become publicly available. Satelite technology may have made things easier for archaeologists, but, as with most new technologies, it comes with a potential downside.
 

Image of the Nasca Lines by Vincent Marcil. Image of the Bosnian Pyramid by www.piramidasunca.ba. All rights reserved.

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About The Author

Owen Jarus

Owen Jarus is a freelance writer based in Toronto ,Canada. He has written articles on archaeology for a variety of media outlets including The Canadian Press newswire (CP), U of T Magazine, The Mississauga News and The Guelph Mercury. Education: BA from the University of Toronto in History, Geography and Near & Middle Eastern Civilizations. BJourn in Journalism from Ryerson University.

Last three pieces by this author: So You Want to go North? Ontario Archaeology Conference Will Look at the Canadian Shield, What was the Most Important Site in Ancient London? The Forum!, They’ve found an opening! Egyptologists reach end of tunnel in Seti I tomb

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