The Boeing Phantom Eye unmanned aerial vehicle (UAV) completed its first autonomous flight last month at the NASA Dryden Flight Research Center at Edwards Air Force Base, Calif. The liquid-hydrogen powered aircraft's flight lasted 28 minutes. The Phantom Eye reached an altitude of 4,080 feet and a cruising speed of 62 knots. After touching down, the vehicle sustained damage when the landing gear dug into the lake bed and broke. The Phantom Eye is a high-altitude, long-endurance, hydrogen-powered UAV with a liquid-hydrogen propulsion system that enables the aircraft to stay on station for as long as four days.