Northrop Grumman is experimenting with providing the Global Hawk UAV with autonomous aerial refueling. The trick? The UAV with the gas will fly behind the aircraft its fueling. According to N-G, this will reduce the cost of the modification by limiting changes to only the Global Hawks that will do the refueling. The ultimate goal is to reduce the number of aircraft equipped with rare, and expensive, sensors by allowing aircraft to stay on station much longer.