Half the world away, Facebook’s most ambitious connectivity project is being developed in the small industrial town of Bridgwater, three hours west of London. A sign in front of the local pub reads: “HUSBAND BABYSITTING SERVICE.” Drive 10 minutes out and you’ll reach a low brick building marked only “#11,” though everyone knows it’s Facebook. “We tried to tell people it’s a warehouse,” engineering director Andy Cox says, “but we’ve had some 10,000 parcels delivered. Everything comes in, but nothing goes out.”

Cox, 53, is in charge of Aquila, Facebook’s passenger jet–sized unmanned aerial vehicle (aka drone). He’s a professorial mechanical engineer who, earlier in his career, built Disney’s Rock ’n’ Roller Coaster. More recently, he was part of the team that set the record for keeping a solar-powered UAV aloft for two weeks. He left that project and in 2010 formed an aviation consultancy, Ascenta. In the spring of 2014, a business development guy from Facebook phoned up and offered close to $20 million to buy his group. Nine days later, Cox started working for Zuckerberg. “I brought the oldest team yet to Facebook,” he tells me, describing the aerodynamicist, the structural specialist, and others he brought along. “There were two at 74, then 65, 57, and then there was me at 51!”

I visit Cox on the day after he completed the first prototype of Aquila last July. Inside the warehouse, we climb a ladder to get a better look. We are soon nose-to-nose with Aquila, a sleek gray boomerang-shaped drone with the wingspan of a Boeing 737; it’s intended to glide slowly while staying aloft for several months at a time. The entire thing weighs less than 1,000 pounds—about one-hundredth the weight of a passenger plane.

Cox invites me to move in closer, once I remove my watch so I don’t accidentally nick the craft. I see dozens of white chalky circles drawn around areas where someone else wasn’t so careful. Later, Cox will review each with an ultrasound machine to ensure the integrity of the structure. He can’t afford to have a tiny human error derail the progress, particularly when Cox and his team are working on Zuckerberg’s clock. Normally, he says, the development process from concept to flight takes seven years. By outsourcing some of their research to universities, Cox and his team hope to be able to get that down to a little more than a year. By the end of 2016, they aim to test a system that will work like this: A ground station will transmit a radio signal to a drone, which will send that signal to other drones via lasers. The fleet will beam those lasers down to transponders within about 30 miles of each craft. These will convert the signal into Wi-Fi or 4G networks. Facebook has not yet determined the data plan or pricing for this offering.

Andy Cox, engineering lead for Facebook’s aviation team. Photo by: Art Streiber

There are many challenges to designing a plane to fly at 65,000 feet—higher than commercial planes and all but a few military aircraft. For one, the air has just 9 percent of the density it has at sea level, so a craft designed for lower altitudes won’t stay aloft. Cox devised a hot-air balloon to lift it up into the sky. The balloon will then deflate, fall to the ground with a tracking device, and be collected and recycled. The team also worked to prevent flutter—a condition that makes the drone vibrate uncontrollably.

Right now the biggest challenge Aquila faces is regulatory. Facebook has joined with Alphabet (formerly Google) to address bureaucratic obstacles. Its competitor has its own drone effort, Project Titan, incubating under its Access and Energy division. (Project Loon, which aspires to beam the Internet from high-altitude balloons and is part of the Google X lab, is further along than either UAV endeavor and will test a partnership with several carriers in Indonesia this year.) Both companies must cooperate with the Federal Aviation Administration to get permission for test flights—Facebook would prefer to conduct these closer to its headquarters. It intends to fly within an area that Maguire refers to as the “Wild West” of airspace, managed in the US by the Department of Defense in collaboration with the FAA. Google and Facebook will also need more spectrum for their projects to work. They have been lobbying the Federal Communications Commission to support an effort by the United Nations’ International Telecommunication Union to make specific radio spectrum available for drones.

Ultimately, Facebook wants to launch 10,000 Aquilas and move them around the globe to create hot spots wherever they’re needed. As with most Connectivity Lab projects, the company aims to develop the technology and then release it to outsiders to commercialize it. Facebook has a model for this in its Open Compute Project, which launched over two years ago to build more efficient, economical data centers. Once Facebook made significant progress, it open-sourced its designs.

The day after my visit, Cox and his team began to disassemble Aquila, weighing each component and testing the structure and all the motors, transistors, and propellers. Cox expected to fly Aquila last October. The date has since been pushed back several times. This month they’ve been flying a 27-foot scale model, but the stormy El Niño–influenced weather has made even these attempts slowgoing.