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As images of charred wreckage inside the Notre Dame cathedral appeared online, engineers around the world said one observation was clear: To return the ancient structure to its glorious past, builders will likely have turn to cutting-edge technology that many associate with the future.

The rebuilding effort will likely draw upon expertise gleaned from disasters like the Fukushima Daiichi nuclear disaster in Japan and the Brazilian National Museum fire, where robots and new digital tools have been used to go places people cannot safely venture and replicate detailed artifacts lost to fire.

Throughout the rebuilding effort, experts say, engineers and preservationists will be forced to wrestle with an ever-present question.

“How do they meld brand-new 21st century technologies with ancient craftsmanship and building trades in ways that keep the cathedral preserved and alive?” said Katherine Malone-France, the interim chief preservation officer of the National Trust for Historic Preservation. “This is going to be a very interesting intersection of technology and craft, and the world will be closely watching how they pull it off.”

Some of the technology that will be used to restore Notre Dame has already been on display. As a wall of orange flames roared across the roof, high-tech machines were brought to the fight. Hovering above the cathedral, a pair of Chinese-manufactured drones equipped with HD cameras helped firefighters position their hoses to contain the blaze before it destroyed the cathedral’s two iconic belfries, said newspaper Le Parisien.

“It is thanks to these drones, to this new technique absolutely unavoidable today, that we could make tactical choices to stop this fire at a time when it was potentially occupying the two belfries,” fire brigade spokesman Gabriel Plus said.

On the ground, Colossus, a robotic fire extinguisher, blasted the nave with water, lowering the temperature of the glass-filled room, the paper said.

Some of that same technology will likely be used to return the 13th-century cathedral, which last year drew 12 million visitors, to a destination.

One way to start, the experts said, will be to bring in other drones to survey locations inside the vast cathedral that are too dangerous or damaged for engineers to reach.

Jerry Hajjar, a civil engineering professor at Northeastern University, said drones can be equipped with sensors — such as small cameras and laser scanners — that will allow engineers to document fire damage and create highly accurate three-dimensional visions of specific locations.

Hajjar said other sensors may be able to peer inside the church’s walls like an X-ray and estimate the mineralogical properties and the degree of stress the structure is under.

Another method for testing the cathedral’s integrity could involve robots, Hajjar said, pointing out that research is already underway for using climbing robots to inspect and repair steel bridges. “The value of using robots became very apparent after the Fukushima disaster,” he said. “They didn’t want to send people inside because it was too dangerous, but realized they could use crawling robots to go inside the site and get valuable images.”

It’s possible that much of the 3-D mapping work engineers will be called upon to consult already exists. In 2015, Andrew Tallon, an associate professor of art at Vassar College who died last year from brain cancer, told National Geographic that he’d completed a comprehensive laser scan of the entire cathedral. There’s only one problem: It’s not entirely clear where Tallon’s scans are currently located, the Atlantic magazine said.

A popular video game also could provide another source of digital information. In a 2014 article in the Verge, Caroline Miousse — an artist who worked on the video game Assassin’s Creed — said she devoted two years to creating a model of the church.

Gary Howes, COO of the Durable Group, a consortium of historic restoration companies, said replacing what was lost may not be the biggest challenge. Instead, he said, it will be marrying the old and the new, offering the building’s worldwide admirers a window in the past that includes upgrades and meets modern building codes.

“This project is going to be more about emotion than structure,” he said. “Everybody wants that cathedral to look like it has always looked, the way they remember it.”

Fortunately, he said, France has an advantage. “Some of the best craftsmen in the world are located in France. Whether it’s restoration or even contemporary work, they haven’t lost the historic trades like we did here in the U.S. Each year, we go there to learn from them.”