In 2006, Darpa, the Department of Defense’s R&D arm, commissioned AeroVironment, a company specializing in remote aircraft, to create an unmanned aerial vehicle (UAV) small enough to fly through an open window. AeroVironment had already built the 4.5-foot-wingspan Raven, which first saw combat over Afghanistan in 2003, but making a UAV so much smaller took five years and 300 different wing designs.