National Geographic : 2014 Apr
84 national geographic • april 2014 group had ever encountered anywhere. “There was no doubt in anybody’s mind that some- where nearby was the place,” Giovanelli says. A short time later, on a second scouting trip, Brown found the actual site, a wide, expansive plateau at the bottom of Cerro Chajnantor, a nearby peak. It was soon clear to all three international par- ties that by joining forces they could build a single array far more powerful than any one of them could alone. In 1999 the National Science Foun- dation and the ESO signed an agreement to work together. They settled on a plan to contribute 32 antennas apiece, each 12 meters in diameter, or about 40 feet. The Japanese agreed to provide 16 more antennas in a complementary array. Thus began an almost two-decade effort to transform one of the world’s loneliest spots into a bustling modern observatory. Land mines planted decades before by the Chilean military to deter incursions from Bolivia to the north had to be located and removed. Protracted negotiations were needed to persuade an oil company that was planning to run a pipeline through the site to reroute it. Prototype an- tennas were redesigned after testing in New Mexico. Costs mounted. Quarrels were joined and resolved. The NRAO and ESO couldn’t agree on a single antenna design, in part because each side wanted to support manufac- turers on its own shores; in the end they chose two designs and two suppliers for their share of the antennas, reduced to 25 from each of the agencies. Then there was the little town of San Pedro, which had just two telephone lines and a single gas station. “We had to assemble a little city on the mountainside in the middle of nowhere,” says the NRAO’s Al Wootten, the lead North American scientist on the project. The first of the antennas—weighing more than a hundred tons—arrived from the U.S. at the Chilean port of Antofagasta in April 2007. Escorted by a convoy of police cars, a truck hauled the gigantic dish up the mountain, its progress occasionally interrupted by herds of llamas being shepherded across the road. Over the next five years the dishes continued telescope. By the 1980s several small arrays were operating in Japan, France, and in the United States, in Hawaii and California. Soon techno- logical advances made it possible to contemplate a far larger radio array, an enormous lens with vastly more resolving power—provided a site could be found that was high and flat enough to expand the distance between antennas to whole miles. And if the dishes were portable, the distance between them could be adjusted to change the sensitivity of the tele- scope to reveal fine detail. Placed far apart, they could zoom in to focus on a small target such as a disk of dust around a star. Bunching the an- tennas together would have the effect of zooming out, which would be useful for imaging large objects such as a galaxy. Searching for an ideal setting for such a tele- scope, research groups from Europe, Japan, and the U.S. converged on the Atacama Desert. Hernán Quintana, who had pored over the military maps of the desert for weeks before the expedition in the spring of 1994, suspected that only the high ground above San Pedro de Atacama would satisfy all the requirements. But it wasn’t easy to get to. “ The trip was slow and painful, because the tires kept getting stuck in sand,” remem- bers Riccardo Giovanelli of Cornell University, who accompanied Quintana, along with Angel Otárola from the European Southern Observa- tory (ESO) and Paul Vanden Bout and Robert Brown from the National Radio Astronomy Observatory (NRAO). Halfway up the road from San Pedro, Vanden Bout and Otárola’s truck broke down. The others made it to the top of the Jama Pass. “The sky was beautiful—it was the deepest blue one can expect to see,” Giovanelli says. One of the astronomers had brought along an instrument to measure water vapor. The volume of vapor in the air was lower than the This is Yudhijit Bhattacharjee’s first story for National Geographic. Dave Yoder photographed Florence’s Duomo for the February issue.