It may be a white disk hovering in the sky, but it’s not a UFO. It’s a flying robot called Cypher, and in its first full-scale test last January it went gliding down the streets of Fort Benning, Georgia, peering around corners, hovering in front of windows, delivering packages, [CK: what exactly did it do and how? Does it have hands?] and perching on roofs. Cypher is a six-foot-wide, 250-pound doughnut, with a pair of propellers in its middle. The propellers spin in opposite directions so they cancel each other’s torque—otherwise the contraption would twist out of control—but the blades are pitched so that both provide upward and forward thrust. The robot has a computer smart enough to follow general commands such as fly down Main Street, without having to be told to avoid each lamppost, and it has a Global Positioning System receiver to keep it from getting lost. The U.S. Army is considering using Cypher chiefly as a military scout. It can track a person through woods, scan an area for underground bunkers, sniff out chemicals, or transmit battlefield images back to base. The way we look at it is, Cypher is really a flying truck, says James Cycon, aerospace engineer and Cypher project manager at Sikorsky Aircraft Corporation in Stratford, Connecticut, which developed the robot. We can put different instruments on it for whatever we want to do with it.