There are three types of lidar instruments: spaceborne, aerial, and terrestrial. On earth, aerial lidar has been used in agriculture, geology, mining, tracking glaciers and ice fields for global warming, urban planning, and surveying. It had numerous classified uses in the wars in Iraq and Afghanistan. Terrestrial lidar is currently being tested in self-driving vehicles and “intelligent” cruise control, which use lidar to map the ever-shifting environment around a car moving down a roadway, as well as to make detailed three-dimensional maps of rooms, tombs, sculptures, and buildings; it can re-create digitally, in incredibly fine detail, any three-dimensional object.
The target sites of T1, T2, and T3 would be mapped with this Cessna, the same one used over Caracol. As the plane is flown in a lawnmower pattern over the jungle, the lidar device fires 125,000 infrared laser pulses a second into the jungle canopy below and records the reflections. (The laser pulses are harmless and invisible.) The time elapsed gives the exact distance from the plane to each reflection point.
The lidar beam does not actually penetrate foliage. It does not “see through” anything in fact: The beam will bounce off every tiny leaf or twig. But even in the heaviest jungle cover, there are small holes in the canopy that allow a laser pulse to reach the ground and reflect back. If you lie down in the jungle and look up, you will always see flecks of sky here and there; the vast number of laser pulses allow lidar to find and exploit those little openings.
The resulting data is what lidar engineers call a “point cloud.” These are billions of points showing the location of every reflection, arranged in 3-D space. The mapping engineer uses software to eliminate the points from leaves and branches, leaving only bounce backs from the ground. Further data crunching turns those ground points into a hill-shade picture of the terrain—revealing any archaeological features that might be present.
The resolution of the lidar image is only as good as how well you keep track of the position of the plane flying through space. This is the greatest technological challenge: In order to achieve high resolution, you need to track the plane’s position in three dimensions during every second of flight to within an inch. A standard GPS unit using satellite links can only locate the plane within about ten feet, useless for archaeological mapping. The resolution can be refined to about a foot by placing fixed GPS units on the ground underneath where the plane will be flying. But an airplane in flight is being bounced around by turbulence, subjected to roll, pitch, and yaw, which not even the finest GPS unit can track.
To solve this problem, the lidar machine contains within it a sealed instrument that looks like a coffee can. It contains a highly classified military device called an inertial measurement unit, or IMU. This is the same technology used in cruise missiles, allowing the missile to know where it is in space at all times as it heads toward its target. Because of the IMU, the lidar machine is listed as classified military hardware, which cannot leave the country without a special permit, and even then only under highly controlled conditions. (This is another reason why there was a long lag-time in the use of lidar at Third World archaeological sites; for years the government prevented the IMU from being used outside the country in civilian applications.)
Aerial lidar can achieve a resolution of about an inch, if there is no vegetative cover. But in the jungle, the canopy causes the resolution to drop precipitously, due to many fewer pulses reaching the ground. (The fewer the pulses, the lower the resolution.) The Belizean rainforest around Caracol, where the Chases had used it in 2010, is thick. But it doesn’t come anywhere near the density of Mosquitia.
The first lidar flight over T1 took off the next day, May 2, 2012, at 7:30 a.m., with Chuck Gross at the controls and Juan Carlos Fernández acting as navigator and running the lidar machine. We all went to the airport to see the plane off, watching it rise into the Caribbean skies and wink into the blue across the Gulf of Honduras, heading for the mainland. It would take three days to map the twenty square miles of T1. If all went well, we would know in four days if T1 held anything of interest. After that, the plane would shift to T2 and T3.
The plane returned from its first mission in late afternoon. By nine in the evening Sartori confirmed that the data was clean and good; the lidar machine was operating flawlessly and they were getting enough ground points through the forest canopy to map the underlying terrain. While he had no images yet, he saw no technical reason why we wouldn’t get detailed terrain maps.
After the second day of flying, on May 3, Juan Carlos came back with intriguing news. He had seen something in T1 that didn’t look natural and had tried to photograph it through the windows of the Skymaster. We gathered in his bungalow to look at the photos on his laptop.
It was my first glimpse of the valley. The photos, taken with a shaky telephoto through scratched Plexiglas, were not clear; but they showed two squarish white objects that looked like the tops of carved limestone pillars, opening into an area of low vegetation that was square in shape. The feature was on a brushy floodplain in the upper end of the valley. Everyone crowded around the laptop, squinting, pointing, and talking excitedly, trying to make sense of the pixilated images that were so tantalizingly ambiguous—they could be pillars, but then again they could be trash dropped from a plane or even the tops of two dead tree stumps.
I pleaded to accompany the third and final flight over T1, despite the logistical issues it posed. There was no room in the plane, but after some discussion, Chuck Gross agreed that he might be able to clear out a tiny space for me to crouch in. He warned me it would be mighty uncomfortable over six to seven hours of flying time.
On May 4, we arrived at the airport as the sun was just rising above the curve of the ocean, the plane throwing an Edward Hopper shadow across the tarmac. The soldiers guarding the plane greeted us sleepily. Now that I was about to be a passenger I looked at the plane more attentively, and I did not like what I saw.
“What’s with that oil streak?” I asked Chuck.
“Don’t worry about that,” he said. “I’m topping it off every day. In one flight it won’t lose enough to make a difference.”
As I crawled on board, my dismay deepened. The interior of the Cessna, once a rich velvetized fabric in burgundy, was now worn, greasy, and faded; much of the inside appeared to be held together with duct tape. It smelled of Eau de Old Car. Parts of the plane had been sealed with acrylic caulk, now peeling out in strings. As I tried to maneuver around the giant lidar box into the micro-space provided, I bumped my elbow into a panel, which fell off.
“No worries, that always happens,” said Gross, reseating it with a blow from his fist.
I marveled that a plane as unsafe and decrepit as this one looked would be used to carry a million-dollar scientific instrument. Chuck firmly disagreed. “No, sir,” he said. “This plane’s a perfect platform for the job.” He assured me the 337 Skymaster was a “classic,” and a “great little aircraft.” Unlike a King Air or a Piper Navajo, he said, this craft was ideal, with a fuel efficiency that would allow us to spend “six hours on station.” Even though it was forty years old, it was “totally dependable.”
“What if we go down?”
“Wow,” said Chuck, “what a question! First thing, I’d look for a clearing to set it down in. It’s uncharted territory: You’re out there on your own, out in the middle of nowhere, no two-way coms.” He shook his head—unthinkable.
Despite my worry, I had a lot of confidence in Chuck because I had learned of his feats of flying; at the age of eighteen, he had soloed across the Atlantic, one of the youngest pilots to do so. I hoped the aircraft’s deficiencies were mainly cosmetic. I told myself a world-class pilot like Chuck would never fly a plane that wasn’t safe.
I jammed myself behind the lidar box: no seat, my knees in my mouth. Juan Carlos was right in front of me. He was concerned about how I would fare; I sensed he was worried I might get airsick and vomit down the back of his neck. He asked if I’d had anything to eat or drink that morning. I said no.
He casually mentioned how grueling it was out there, flying low and slow over the jungle for six hours straight, banking steeply turn after turn, tossed around by thermals, sometimes dodging vultures. The A/C on the plane was broken, he said; we would be sealed in a metal tube flying in full sun. The plane had no bathroom. If you had to go, you went in your pants. I tried to assure him I would be an exemplary passenger.
Elkins gave me a GoPro video camera and a still camera with a telephoto lens and asked me to take more pictures of the mysterious white pillars and anything else of interest I spied down below.
Chuck Gross climbed into the pilot’s seat and began running down the checklist, while Juan Carlos jacked his laptop into the lidar box. He showed me the flight plan he had programmed on his computer screen, dozens of parallel lines crisscrossing the valley, designed to maximize coverage while minimizing flight time. In addition to being a lidar engineer, Juan Carlos was also a licensed pilot, enabling him to work seamlessly with Chuck.
We took off from Roatán and were soon winging over the glittering Bay of Honduras, the mainland looming up ahead. It was a gorgeous day, the sky dotted with fluffy white cumulus. Far ahead, where the blue mountains of Mosquitia rose up, we could see the cloud cover was sparse and high. As we flew inland, the settlements along the coast gave way to scattered hamlets and agricultural fields alongside slow brown rivers. The land mounted into forested foothills, where hundreds of ragged patches of clear-cutting came into view. Plumes of smoke rose from the jungle in every direction.
The logging holes eventually disappeared and we were flying about four thousand feet over unbroken, precipitous forest. Chuck maneuvered his way through the mountains as we approached T1. An hour out of Roatán, Juan Carlos pointed out the rim of the valley in the distance, a wall of green mountains with a sharp notch in them. Chuck eased the plane to a lower altitude and we cleared the rim at a thousand feet, which gave a tremendous view of the landscape. As the land dropped away beyond the rim, I was struck by the valley’s picturesque topography, the ring of mountains embracing a gentle, rolling landscape divided by two rivers. It really did look like a tropical Shangri-la.
The plane leveled off at an altitude of about 2,500 feet above ground, and Juan Carlos booted up the lidar machine, picking up where they had left off the day before. As the lidar bombarded the canopy with laser pulses, Chuck steered the Cessna in parallel lines across the valley, each four to six miles long, in a pattern that, on the computer screen, looked like a gigantic weaving. The plane was buffeted by thermals, knocked up and down, back and forth, and sometimes sliding sideways in a gut-wrenching fashion. Juan Carlos had been right; it was a brutal and scary ride. But Gross worked the controls with constant finesse and a sure hand.
“We were rocking and rolling pretty good,” Gross said later. “It’s like flying a big spiderweb. It takes incredible skill. You have to fly the middle of the line, and you can’t go sixty feet on either side of that line. You have to slide that plane around, doing all rudders. To stay on the line, in that wind, that was challenging. And you have to hold the altitude and airspeed. I had to climb with the terrain and maintain the same altitude. If the terrain starts coming up, I have to come up with it.”
Through it all, I peered out the window, transfixed. I can scarcely find words to describe the opulence of the rainforest that unrolled below us. The tree crowns were packed together like puffballs, displaying every possible hue, tint, and shade of green. Chartreuse, emerald, lime, aquamarine, teal, bottle, glaucous, asparagus, olive, celadon, jade, malachite—mere words are inadequate to express the chromatic infinities. Here and there the canopy was disrupted by a treetop smothered in enormous purple blossoms. Along the central valley floor, the heavy jungle gave way to lush meadows. Two meandering streams glittered in the sunlight, where they joined before flowing out the notch.
We were flying above a primeval Eden, looking for a lost city using advanced technology to shoot billions of laser beams into a jungle that no human beings had entered for perhaps five hundred years: a twenty-first-century assault on an ancient mystery.
“It’s coming up,” Juan Carlos said. “Right there: two white things.”
In an open area, I could see the two features that he had photographed the previous day, standing about thirty feet apart next to a large, rectangular area of darker-colored vegetation. The plane made several passes as I photographed. Again, they looked to me like two square, white pillars rising above the brush.
We got through the flight without mishap, other than the moment a few hours into the flight when I turned off the lidar machine with my knee as I tried to shift my aching legs. The machine and the pilot’s navigational system were linked, so shutting off the lidar turned off Gross’s navigation. He immediately went into a tight, stomach-sickening holding pattern while Juan Carlos booted the machine back up and I apologized profusely. “No worries,” he said, far less perturbed than I thought he would be.
We finished mapping T1 with enough fuel left over to fly a few lines over T2, twenty miles distant. The route took us over the Patuca River, Heinicke’s “most dangerous place on the planet,” a brown snake of water winding through the jungle. T2 was magnificent and dramatic, a deep, hidden valley shut in by sheer, thousand-foot limestone cliffs, draped with vines and riddled with caves. But recent deforestation—only weeks old—had reached the mouth of the T2 valley. As we flew over, I could see the freshly cut trees lying on the ground to dry out so they could be burned, leaving a hideous brown scar.
At the end of the day, we flew to La Ceiba, on the mainland, to refuel. Chuck had pushed the envelope and we landed with less than twenty gallons of aviation fuel remaining, about forty minutes of flight. But the airport had no fuel and nobody could locate the tanker bringing the resupply. Airport officials feared the tanker had been hijacked by drug smugglers. Juan Carlos called Elkins in Roatán. Elkins put Bruce Heinicke on the problem. After calling around, Bruce learned the truck was still en route, delayed by a blowout.
We couldn’t leave the Cessna unguarded, especially if the fuel didn’t arrive and the plane had to stay overnight in La Ceiba. Juan Carlos and Chuck debated sleeping in the plane, but that wasn’t ideal, since they were unarmed. They finally decided that, if fuel didn’t arrive, they would go to the US Air Force base in La Ceiba and ask the soldiers to stand guard for the night. Meanwhile, Michael Sartori was desperate to get the data and finish mapping T1, so it was agreed I’d head back to the island on my own. Fernández gave me the two hard drives with the data, and I went to the airport desk to see if I could get a commercial flight from La Ceiba to Roatán. There was a flight to Roatán that afternoon but it was already full. For $37 I was able to hitch a ride in the copilot’s seat. The plane looked even less reliable than the Cessna, and as I boarded, Juan Carlos joked about what a pity it would be to lose all that precious data in a plane crash after their hard work collecting it.
I landed in Roatán at sunset and gave the hard drives to Sartori, who snatched them up and disappeared into his bungalow, emerging only once to chow down a couple of lobster tails at dinner. He now had all the data he needed to map T1. Late that night Juan Carlos and Chuck Gross finally landed back in Roatán, exhausted but relieved. The fuel truck had arrived at the last minute.
Sartori had hours of work ahead of him. He had to merge data from several sources: the lidar machine, the GPS ground stations, the GPS data from the aircraft itself, and the data from the IMU. Together, all this would create the point cloud, forming a three-dimensional picture of the rainforest and the underlying terrain. First, he had to wait for Mango to retrieve the USB stick from the GPS unit in Culmi and bring it to Catacamas to upload to the server in Houston; Sartori then had to download the data from Houston. The lights in Sartori’s bungalow were still burning at midnight when I went to bed. Ramesh Shrestha, back at NCALM in Houston, remained awake, pressing him for updates.
This was the moment of truth: The images would show what was in the valley—if anythin
g. It was almost one in the morning when Sartori finished creating the raw images of T1; Shrestha had finally gone to bed and the Internet connection on Roatán was down. Exhausted, Sartori went to bed without even looking at the images he had just created.
The next day was Saturday, May 5. Rising early, Sartori uploaded the raw images to a server in Houston, again without examining them. Immediately on receiving them, Shrestha forwarded them to NCALM’s chief scientist, William Carter, who was at his vacation home in West Virginia. Shrestha intended to review them soon, but Carter beat him to it.
At 8:30 a.m. on that quiet Saturday morning, the terrain images of T1 arrived in Carter’s in-box just as he was about to leave the house to run errands. He needed to buy a refrigerator. He hesitated and then told his wife that he wanted to have a quick look. He downloaded the data and displayed the maps on his computer screen. He was thunderstruck. “I don’t think it took me more than five minutes to see something that looked like a pyramid,” he told me later. “I looked across the river at a plaza area with what looked like buildings—clearly man-made objects. As I looked at that river valley, I saw more, as well as alterations to the terrain. It was kind of surprising how easy it was to find them.” He e-mailed the coordinates to Sartori and Shrestha.
Sartori pulled up the images and scanned them. In his excitement Carter had mistyped the coordinates, but it took Sartori only a moment to find the cluster of features on his own. He said, “My skepticism wasn’t easily broken,” but this was clear enough to convince the most resolute doubter. Sartori was chagrined. “I was mad at myself for not seeing it first, since I was the guy producing the images!” He rushed out the door to report it to Steve Elkins, but then had second thoughts. Was it real? Maybe it was just his imagination. “I was in and out the door about six different times,” Sartori said.
I was walking back from breakfast with Steve and some others when Sartori appeared along the quay, running madly in his flip-flops, waving his arms and shouting: “There’s something in the valley!” We were startled by this sudden behavioral change, the sober-minded skeptic transformed into a raving Christopher Lloyd.
The Lost City of the Monkey God Page 9
