One sweltering tuesday this summer, I found myself standing on the vast aluminum roof of an East Coast government building, staring at a slim metal rod with a microphone and a metal box bolted to it. The contraption stared back, impassive as a Buckingham Palace guard. I took its picture. I wondered aloud whether we would all have something like it on our homes one day. It did not respond. It was listening for one specific threat, and that threat wasn’t me.
From the outside, this appeared to be the most boring building in America: beige cement blocks surrounded by a lazy river of asphalt parking lots. But below my feet was a Homeland Security office, and its occupants were concerned about the ways terrorists or mischief makers might use small, off-the-shelf drones to conduct video surveillance or deliver unwanted packages.
The contraption, called DroneShield, was designed to detect the sound of an approaching drone and warn of its impending arrival. On this particular day, DroneShield’s inventors, Brian Hearing and John Franklin, were demonstrating the device for a representative from the office. After they completed the installation, we climbed a ladder down to the ground. Their white polo shirts peppered with soot, they offered the client a cookie. (He declined.) Then they fired up a drone about the size of a biology textbook, and we all watched as it whirred effortlessly up, up, up into the sky.
Having invented flying robots that can go places we’d rather not, how will we prevent them from going too far?
The drone, a white, four-propeller rig, emitted a buzzing hum—sort of like a hive of bees trapped in a mailbox. Comparing it against a library of common drone sounds, DroneShield correctly identified the model—a DJI Phantom—in about three seconds and dispatched a text-message alert that, if this hadn’t been a drill, would have sent security guards running.
The client nodded. Then, mostly for dramatic effect, the DroneShield guys illustrated how one might capture such a drone with a net gun, a tool normally used to catch feral animals. While Franklin leveled the drone above us, Hearing charged the gun with a compressed-air cartridge, took aim, and fired. The net sprawled out on the grass, having missed its target. A second shot also failed. The drone hovered patiently, like a butler waiting on his drunken master. On the third try, the net swaddled the drone in mesh and brought it down to the ground, undamaged. We all cheered. It was strangely exhilarating to see the drone finally tangled in white threads. Man had triumphed over machine, for now. The DroneShield guys retired to Ruby Tuesday for beers.
