The Space Archaeologists

A bookish theoretician, Fletcher has a penchant for crisp polo shirts and loafers and speaks in dense, looping sentences. A colleague jokes that his landmark work on urbanism, The Limits of Settlement Growth, should be titled The Limits of Reader Tolerance. But he has a big-picture perspective rare in archaeology. The existing portrait of Angkor didn’t fit with what he knew of other early low-density cities, and he pledged to solve the puzzle. Following a talk he gave at the National Air and Space Museum, an audience member asked if he had seen the radar images of Angkor captured by the space shuttle Endeavour in 1994. He had not, and so he picked up the phone and called NASA.

The images revealed objects 100 feet across or more, crude by today’s standards. But one image, which took up the length of Fletcher’s office, offered a view of much of Angkor. He had no experience with satellite images. “It looked like crazy art,” he recalls. “Amazingly beautiful, with these incredible colors.” But he made out a long vertical groove stretching north-south—a canal—crisscrossed by a series of east-west lines that he guessed were channels. The lines extended far beyond central Angkor, suggesting that the temples were at the center of something much larger than historians had assumed. He rushed to Cambodia, where Pottier showed him the map of southern Angkor he’d traced by hand. It was exactly as Fletcher had imagined it.

The next year, Fletcher and Pottier founded the Greater Angkor Project. They made an unlikely partnership—a grizzled French expat and a highbrow British professor—but they shared each other’s determination to uncover the mysteries of the Angkorian landscape. They just didn’t agree on how.

Fletcher believed that satellite imagery and radar could help them illuminate the inaccessible north. But Pottier felt that any continuation of his work had to be done using the same painstaking (not to mention dangerous) methods he had used in the south. Although radar and satellites could detect variations in moisture and vegetation not visible to the naked eye, their resolution was inadequate, he thought, next to simple aerial photographs. “Radar—I would not say it’s worthless,” he tells me, “but it has a very limited interest.” The Endeavour image Fletcher had seen “had very, very poor resolution, so it didn’t show anything.” NASA was hyping its technology, he adds, claiming credit for discoveries that actually preceded the shuttle flight. But proof of the technology’s power was hard to deny: Using the Endeavour image, Fletcher had intuited in a few minutes what Pottier had spent half a decade uncovering.

Cracking the Data
NASA has used synthetic aperture radar to peer through the clouds of Venus and to study the folds of Saturn’s largest moon, Titan. It has also mounted a unit onto a DC-8 jet and used it to map the world closer to home. Yet an Airsar run, as it’s called, requires staffing the airplane with up to 10 people, and thus was outside an archaeological budget. Then, in 2000, NASA collaborated with the Australian government to map parts of Southeast Asia. Fletcher saw his chance. He called NASA and eventually convinced the University of Sydney and the Mekong River Commission, a water-management organization, to bankroll a detour over Angkor. Taking off from Bangkok that September, the jet veered south at the Thai-Cambodian border and traced a cross over Angkor. Fletcher received data spanning more than 10,000 square miles.

There was only one problem: No one in the University of Sydney archaeology department knew how to use it. The department was one of a handful in the world with an archaeological computing lab, but its researchers were primarily concerned with developing mapping software.