THE PILOT DROPPED Juan Fernandez in the only jungle clearing large enough to land a helicopter, a tiny opening in an impossibly thick tropical canopy that stretched as far as the eye could see. As the sound of the rotors receded into the distance, the young University of Houston engineer followed his machete-toting survival guides deep into the shadowy Honduran rainforest. Fernandez, 40, had never been to this particular patch of jungle before that day in February 2015. But something about it felt oddly familiar. With unease, he realized it reminded him of a movie he’d seen in which scientists discover the ruins of a lost city in a remote African jungle — and are then hunted down and killed by a pack of giant gorillas.

Or was it the flick where everybody was eaten by the giant anaconda?

Regardless, the similarities between Fernandez’s present situation and the bloody scenarios spun out in a particular genre of sci-fi horror movies continued to weigh upon the young engineer as the last sunlight of the day evaporated, and he hurried to secure his hammock at the campsite. As in the movies, Fernandez reflected, he too was a member of a small science team, dropped into thick uncharted wilderness in search of a mythical lost city. He too was surrounded by towering, ancient trees, cinematic shadows, the fecund smell of wet earth and vegetation, and a tumult of unseen, wild animals hooting and cawing so loud the rainforest itself felt alive. He too had heard the warnings, weighed the jungle’s many dangers, and decided, along with the rest of his companions, to proceed with his expedition nonetheless.

It had taken Fernandez and his team many months to win the government’s permission to enter this area of western Honduras, a forlorn green spot on the map, known to harbor drug traffickers and murderous bandits, jaguars and venomous snakes. But the payoff was potentially spectacular. They had come in search of the famed La Ciudad Blanca, or “the White City,” also known as “the Lost City of the Monkey God.” The mythical ancient metropolis was said to be constructed entirely of white stone, built around a magnificent temple, capped with a towering stone sacrificial dais inhabited by a giant statue of the Monkey God. The legend of the site’s existence and the potential treasures to be found around it had tantalized westerners for centuries.

“It was a huge scream, like the movies,” recalls Fernandez excitedly, “and I thought, ‘Oh my God — this is the first one, the first casualty!”

The area’s riches were rumored to “exceed Mexico” and “equal it in the largeness of its town and villages,” the author and journalist Douglas Preston had written a few months before in The New Yorker, quoting a 16th century letter from the famed conquistador Hernán Cortés to the Spanish Emperor Charles V. Preston, a bestselling author, was in fact there that day in 2015 to further chronicle the adventures of Fernandez and the small advance team on the ground. And even his presence added to the young engineer’s sense of déjà vu. I’ve seen this film, haven’t I? That night, as the team sat down for dinner, the author excused himself momentarily from the campfire and headed to the nearby campsite to fetch an item from his pack. Several minutes later Preston’s voice pierced the jungle tumult.

“It was a huge scream, like the movies,” recalls Fernandez excitedly, “and I thought, ‘Oh my God — this is the first one, the first casualty!”

The outburst sent the mission’s government-appointed guard, a single Honduran soldier, scrambling for his machine gun, and the team’s survival experts, former members of the British Special Air Service (SAS) forces, for their machetes. Fernandez rose empty-handed and raced to the campsite with the rest of them, bracing himself for the worst. They arrived to find Preston contemplating a frightening apparition directly beneath Fernandez’s hammock: On the ground lay a coiled, six-foot-long, yellow-jawed fer-de-lance — a monstrous breed of pit viper that carries a fatal and particularly gruesome kind of hemotoxic venom.

A LiDAR rendering of Teotihuacan, another ancient city that engineers mapped usling LiDAR

“If that thing bites you, you wish you died immediately,” Fernandez says. “But you don’t. Instead it starts eating your tissues. You can lose your leg first and you die several weeks later. It’s terrible.”

Despite the perils and the paranoia, Fernandez and his team had good reason to take a calculated risk that day back in 2015. Since 2010, Fernandez, who was actually born and raised in Honduras, has worked as a technician at the UH’s National Center for Airborne Laser Mapping (NCALM), a National Science Foundation-funded research entity operated jointly with the University of California, Berkeley. NCALM, which recently moved into a newly renovated 5,000-square-foot facility Downtown in UH’s Energy Research Park, is one of the few centers in the world capable of using a revolutionary technology known as airborne LiDAR (short for light detection and ranging). LiDAR allows researchers, for the first time, to peer beneath seemingly impenetrable jungle canopies from above and produce detailed topographical maps revealing that which is hidden below.

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That night in 2015, with the pit vipers and the Hollywood-worthy horror, was only the latest chapter in a story that actually began for Fernandez in May 2012, on a previous trip to Honduras, when he squeezed himself into a battered Cessna 337 Skymaster, along with The New Yorker’s Preston and a daring pilot named Chuck. Fernandez then spent the better part of eight days personally operating a large metal box containing the center’s sophisticated machinery. LiDAR works on a principal similar to that used by radar or sonar, emitting pulses that bounce back when they hit something solid, and, thus, allowing engineers to calculate the location and shape of distant objects. Instead of beaming high-frequency electromagnetic waves or sound and measuring how long it takes them to return, LiDAR uses pulses of laser, which are so numerous and finely focused they are a capable of penetrating gaps in the jungle canopy and bouncing back off objects on the ground.

As Chuck piloted the plane back and forth over the thick jungle, “mowing the lawn,” as the UH engineer puts it, at about 2,000 feet, Fernandez beamed the laser downward through a hole in the bottom of the plane, and monitored the computer as it registered the location and timing of 125,000 laser pulses leaving and returning to the box every second. Inside, the plane, it was stifling — there was no air conditioning, or bathroom (in a pinch, you used a bottle). The flight was turbulent enough to cause motion sickness to those with weak stomachs. And more times than once, the pilot had to identify himself via radio to the Honduran military, concerned the small plane was trafficking drugs.

But, with the help of sophisticated computer analysis that began that very day, and would continue for months, the trial would pay off.

LiDAR images can be hard to interpret. But researchers are able to precisely calculate the changing coordinates in space of every single one of those millions of departing and returning laser pulses using Global Positioning Systems (GPS), and the same kind of powerful sensors used to track the spatial position of guided missiles. A visual representation of the laser impact points is then produced from this data, and different layers are then gradually stripped away from the image to reveal what lies below. The images lack the resolution of an actual photograph, so you have to know what to look for.

Thus when Fernandez and the rest of team sent their initial data on to Houston, nobody here spotted much — at first. When they passed their first batch of images on to William Carter, NACLM’s most experienced data reader, Carter quickly recognized their significance.

“l looked across this little valley and I said, ‘Oh, my gosh — there’s a plaza!’” recalls Carter, a retired National Oceanic and Atmospheric Administration scientist, and one of the center’s founding directors. “To me it was clear it was manmade. I could see these rectangular mounds down both sides and on both ends of this flat area.”

Pouring over the images, Carter also spotted multiple mounds in the valley hidden beneath the canopy, suggesting the presence of buried buildings. Once he pointed it all out to the team down in Honduras, other big finds quickly followed. Soon Fernandez spotted what had the look of terracing for agriculture. They found evidence of reservoirs and what appeared to be manmade stone quarries. And a few months later, while sitting in his office back in Houston late one night manipulating the data, Fernandez realized he was looking at what appeared to be a 30-foot-high, multi-tiered pyramid, cut into a hill opening onto the central plaza — a feature four times as big as anything yet spotted.

These were stunning discoveries in the making — and, in fact, had the potential to be watersheds in the field of archeology — if they could actually be confirmed on the ground.

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Though the team had used it for more than a decade to map geologic faults and beach erosion and perform accurate land surveys, the idea that LiDAR might be used to unearth previously hidden archeological ruins is a relatively new one. In fact, the idea that a LiDAR system could itself be mounted on airplanes and used to gather scientifically useful data from above was itself considered so novel back in the early 2000s, that when NCALM’s founders Carter, Ramesh L. Shrestha and UC Berkeley geologist William E. Dietrich first applied for NSF funding to open a center at the University of Florida, they were turned down.They finally prevailed in winning federal support for their new center in 2003 by promising to embrace a three-pronged mission: to provide the best possible LiDAR data to selected projects from across the scientific community; to develop and improve emerging LiDAR technologies; and to educate and train a workforce to produce and analyze data.

By most accounts, they have succeeded in all three goals. Since opening 13 years ago, initially at the University of Florida, the center has supported roughly 400 applications from different researchers, about half of which were then able to raise sufficient funding from the NSF and other government organizations to carry out the projects, Shrestha says. The center recently deployed a system capable of beaming 300,000 laser pulses a second. And, after moving to UH in 2010, lured by the engineering school with the promise of the resources to more than double its size, NACLM won approval from the Texas state legislature to start a graduate program. They graduated their first six Ph.Ds. this past summer.

Finding lost civilizations, however, is another level of achievement altogether — sexier and more glamorous than mapping beach erosion, salmon migration routes, or earthquake faults from the air. And it has garnered NACLM worldwide headlines.

“They were amazed after we mapped and showed them a lot of stuff that was there that they didn’t know was there,” Carter recalls, “including a lot of buildings, foundations of buildings and so on, and openings to more than 50 caves that they walked by quite often.”

NACLM did its first big archeological project in 2009, to support the work of two University of Central Florida researchers who had spent more than two decades excavating a famed Mayan archeological site at Caracol, Belize. Over the course of the previous 25 years, the two had relied on traditional techniques to map the area, and the pace had been agonizingly slow. They had succeeded in doing just 10 kilometers, and they wondered if LiDAR might speed up the process. The results exceeded even Shrestha’s expectations. Not only did the airborne LiDAR produce detailed maps of 77 kilometers in a matter of days, but the quality of the data was far superior to anything available using traditional methods.

“They were amazed after we mapped and showed them a lot of stuff that was there that they didn’t know was there,” Carter recalls, “including a lot of buildings, foundations of buildings and so on, and openings to more than 50 caves that they walked by quite often.”

The Caracol results caused a sensation in the field of archeology, a flood of press coverage, and calls from other researchers around the globe. One of the most interesting came from a nonconventional source. Steve Elkins was a successful “Hollywood guy,” recalls NCALM’s Shrestha, a former cameraman for the television show Cops, with a background in science, his own video production company and a career’s worth of connections.

Elkins had been captivated by the legend of the lost city of the Monkey God for years, even going so far as to conduct extensive research on possible locations, and launching several on-theground expeditions.

“We went downthere for a few weeks looking for this place, kind of wandering through the jungle, I think, somewhat aimlessly,” Elkins says. “We had some guides that said they knew where we were going. Obviously, we didn’t find the city. But we found some enigmatic artifacts and some art that sort of gave me an epiphany. And I said, ‘I think there’s something to this legend. Must be more here than meets the eye.’ From that moment, I got hooked.”

In 2009, Elkins called up the center to see if they might help him with his quest. For NACLM, Shrestha says, the project would prove unprecedented.

“Belize was really the first archeological job that we did strictly for archeological purposes, but in Belize the archeologists had been going in there for three decades and they knew pretty much what was there,” Shrestha recalls.

Eventually Elkins would raise and spend close to $1 million to help fund the LiDAR mapping and follow-up expeditions. Fernandez, who had first come to the States to pursue his master’s and Ph.D., was gung-ho to bring what he’d learned back to his native country and help coordinate efforts to discover what had the potential to be a national treasure. But when Shrestha asked Elkins precisely where he wanted to look for the city, he was amazed at his answer. “He said he didn’t know,” Shrestha recalls.

Shrestha suggested he take his best guess, based on what he knew. So it was then that Elkins, the reality-TV lensman and producer, chose four postage-stamp-sized spots — all valleys — on the map.

And, amazingly, when Fernandez flew over them in 2012 with LiDAR, he found exciting shapes in three of them. (The fourth had been deforested by loggers, and when the team spotted the devastation by satellite, they figured if anything had been there previously, it would have been destroyed.) There was, however, only one way to confirm there was really something there: Someone needed to travel to one of the sites and survey the situation from the ground.

Which brings us back to that harrowing night in 2015.

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There were four civilians standing in front of the snake that first night deep in the Honduran jungle: Fernandez, Preston, a photographer and the archeologist named Chris Fisher. (The rest of the crew was slated to arrive later in the week.)

The civilians left the dangerous work of managing the viper to the professionals, watching in awe as one of the SAS soldiers hunted down a seven-foot-long stick, forked at the end, pinned the snake’s head to the ground and attempted to pick it up. The soldier had agreed to try to move the snake away from Fernandez’s hammock with his bare hands, rather than kill it.

“We could eat it — it would make for good eating,” the soldier suggested. “But we need to show this to the rest of the group when they arrive, so they know what we’re getting into. Where there’s one snake, there are usually others.”

After the beast spewed venom, bared deadly oneinch fangs and tried to sink them into the soldier’s hand, however, he took out a knife and cut off the snake’s head. Not that this finished it: As the team watched in shock, the severed head continued to spit venom, and the headless snake began to slither away. Finally, the solder punctured the brain, nailing the head of the serpent to the ground with his blade, grabbed the writhing carcass and held it up like a trophy.

“We could eat it — it would make for good eating,” the soldier suggested. “But we need to show this to the rest of the group when they arrive, so they know what we’re getting into. Where there’s one snake, there are usually others.”

The group set out in search of the ruins the next morning, marching uneasily through vegetation more than thick enough to conceal another ferde- lance. Fisher the archeologist had loaded the LiDAR images Fernandez had taken from the plane into a GPS machine, which was essential given the vegetation and limited visibility around them. The camp was on a riverbank, and to get to the site of the photos, the team had to cross a small stream, wade through a swamp and ascend a slippery, 30-foothigh escarpment. Standing at the bottom, the hillside seemed impossibly steep.

“We knew we had the escarpment that we would have to climb because we had the LiDAR images,” Fernandez says. “But it’s one thing to see the thing from the computer. Once you’re actually there and look at it, you say, ‘Wow, yeah, this is going to be more challenging.’” The team had to grip branches and roots sticking out of the ground to keep from sliding down the slick, muddy slope.

It was worth the effort. At the top, Fernandez looked around and quickly noticed the terrain had changed dramatically. The light was eerily dim, almost gray, blocked out by the towering trees. The lower level of vegetation, so thick down at the riverbank, was gone. Fernandez was standing on the wide, somewhat open space, which he could see almost entirely across in the ghostly light — this was the remains of a sizeable open plaza, as much as half a football field across. This, he quickly realized, was just the beginning of a sprawling complex revealed by LiDAR to stretch some three football fields across.

And there were mounds. And as Fernandez and the rest of the team began to walk across the site, there were other discoveries, like flat stone slab sitting on top of round rocks, clearly manmade. The most exciting find came several days in. By then more than 20 people had arrived to comb the plaza and search for more evidence of civilization.

As the team headed back to the campsite, a call came from the northeast corner of the plaza. “Hey guys, I see some very interesting rocks over there,” announced one of the cameramen filming. The “rocks” were stone vessels and carved stone artifacts, decorated to depict animals.

In all, the team would find 52 artifacts half-buried in the earth, including a number of ceremonial stone seats; vessels adorned with snakes, vultures and other animals; and a spectacular giant stone head, half jaguar, half man. The cache appeared to be at the base of the pyramid Fernandez had discovered, opening onto the plaza, suggesting the head might be an offering of some sort. Fernandez had carried in a ground-based LiDAR unit that he could mount on a tripod, capable of mapping the area at a far greater resolution than from the air. And with each new finding he took careful measurements, and collected reams of data for further analysis.

Upon emerging from the jungle, local experts and anthropologists on the site suggested the artifacts likely dated to between 1000 and 1400 A.D. And they emphasized how rare it was to find such a large cache undisturbed and unlooted, and declared that, though it was impossible to know whether the team had found the mythical White City, they had certainly discovered evidence of a lost culture.

The trip was an unqualified success, the first of many. At the time the team did not have permission from the Honduran government to remove any artifacts. It would have to wait. Thus Fernandez returned for a second on-the-ground trip in February this year to document some of the excavation.

This time, the team returned with a permit to excavate, and a larger group of archeologists, funded by the Honduran government and a small grant from National Geographic, with donated time from individuals like Fernandez.

The digging revealed that, around the site of the 52 partially buried artifacts, there were actually 80 stone artifacts and a large number of ceramic fragments. Nothing so far has been discovered that might allow the team to perform accurate dating, or verify that they have indeed found the site of the White City. Fernandez documented the excavation, using LiDAR both on a tripod and a handheld device.

But the work has just begun. Fernandez and the archeologists plan to return for further excavation. And there are still two other sites spotted from the air — located in extremely hard-to-reach valleys — that they mapped, at Elkins’ behest, that seem worthy of exploration. Overall they collected 10 days’ worth of data over the three sites.).

Elkins, meanwhile, plans to release a documentary on the expedition and the search for the White City this winter, which will coincide with the Jan. 3 publication of Douglas Preston’s book, The Lost City of the Monkey God.

And for his part, Fernandez — with his personal ties to Honduras and the significance of what the expeditions have found so far — now considers the project one of the most satisfying of his young career.

“There’s definitely evidence of a society that still needs to be named and studied a lot,” he says. “But there are many, many more questions to be answered than what we were able to answer. It does show artisans with significant skill. They were an organized society. My hope is that there will be more research going into the area and, over a decade or two, we’ll be able to learn a lot more.”