©DigitalGlobe 2016

©DigitalGlobe 2016

©DigitalGlobe 2016

©DigitalGlobe 2016

©DigitalGlobe 2016

Design by Mondo Robot.

Design by Mondo Robot.

When archaeologists want to find lost monuments or hidden cities these days, they turn to satellite imagery. Patterns invisible to the eye on the ground become obvious from the air and help scientists decide where they should start digging. And now you can join those scientists by signing up for GlobalXplorer, a newly launched online community where members look at real satellite imagery from Peru to identify telltale patterns of ancient habitation.

GlobalXplorer is similar to other online citizen science efforts like Galaxy Zoo, where members identify galaxies from deep-field images. When you visit GlobalXplorer, you'll be shown one map tile from a satellite shot of Peru. Each tile is about 200 by 200 meters and is one of roughly 120 million such tiles in the database. After a quick tutorial on the kinds of features to look for, you'll be asked to identify whether the tile contains evidence of looting (in the tutorial, you'll learn that looting holes produce a very distinctive pattern), illegal encroachment by developers, or a possible ancient structure. The more tiles you classify, the more you can level up and gain access to new data and more difficult identification tasks.

The brainchild of University of Alabama at Birmingham archaeologist Sarah Parcak, who recently won the $1 million TED prize, GlobalXplorer is a joint effort between Parcak, National Geographic, satellite imaging company DigitalGlobe, and design firm Mondo Robot. Parcak's goal was to make archaeology accessible and fun, but also to allow ordinary people throughout the Americas to contribute to a greater understanding of the past. The site is written in both English and Spanish, and Parcak told reporters at a press conference that her goal is to "empower kids and people around the world to participate in archaeological discovery and connect them to their own history."

Everyone participating in tile identification will help scientists with actual ongoing research. Hopefully, they'll find something previously unknown.

Parcak explained that she and a team of experts will be poring over data that comes in from the GlobalXplorer participants, scoring their accuracy. People with high accuracy scores will level up to the "site discovery" tasks, which involve looking at the same tiles viewed through different filters. These "filters" are actually image-processing algorithms designed to highlight various land features that could reveal structures not obvious from a simple photograph. "My team and I are looking at features that are buried, or just under the surface, or not easy to distinguish from surrounding features," Parcak told Ars. "We process [each tile] with different algorithms to make features stand out. In Peru if there’s a wall or settlement that’s under a field, you might see on the surface that it’s affecting vegetation, making it grow a different way. You can see [vegetation patterns] by looking for different parts of the light spectrum . When users toggle through the options, they are doing exactly what we do in our sensor programs. They’ll see the imagery... we have processed but haven’t looked at yet."

But GlobalXplorer isn't just about uncovering ancient Peruvian civilizations. It's also about conserving valuable historical sites. That's why everyone who joins the site begins by looking for signs of looting and illegal use of land. Parcak wants people to understand the value of preserving clues about the past, because it's relevant to problems we face in the present, ranging from climate to war. "We've all been part of this struggle [to survive] since we became human beings... looking back, knowing humans can survive challenges, gives us hope for the future."

She has also stripped all the tiles of geolocation data, so nobody can use GlobalXplorer as a looters' guide.

Peru is the first nation that GlobalXplorer chose to focus on, but Parcak hopes there will be more to come in roughly a year. She wanted to start in Peru because the country has a rich history, spanning many ancient civilizations including the Inca and the Wari, as well as the unknown people who made the massive Nazca Lines . People arrived in Peru more than 15,000 years ago, and there is ample evidence of thriving coastal villages there going back to the early Neolithic. Parcak said that Peru's Ministry of Culture is excited about the project and has already been embracing the use of new technologies like drones for mapping.

If you've always dreamed of discovering ancient artifacts, or if your brain is just really good at recognizing patterns, you might want to give GlobalXplorer a try. Parcak says she isn't sure where the project will lead, but she hopes it will be used by teachers in the classroom, as well as citizen scientists who might someday want to volunteer to help at archaeological digs. What she does know is that she needs volunteers to look at more than a million tiles—and each tile needs to be examined by about six or seven people for accuracy. Whether you're at your desk or on the bus, you can always go to GlobalXplorer and transport yourself far away in time and space, and you'll help archaeologists in the process.

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