September 12, 2007: The U.S. has successfully tested a high-altitude UAV (Zephyr) that can stay in the air for long periods, powered by solar panels on the 60 foot wing span. During the day, the solar energy powers the aircraft's two propellers, and charges a battery. At night, the battery provides all the power needed. Also called the HALE (High Altitude Long Endurance) aircraft, the UAV recently broke an endurance record by staying in the air for 54 hours. Zephyr is basically a powered glider. The ultimate goal is to have the Zephyr fly for months at a time, at high altitude (over 50,000 feet, way above the weather). Built of lightweight materials, the UAV weighs 66 pounds. The most likely job for Zephyr would be for communications relay, substituting for a communications satellite. There is growing demand for this, as comm sats are expensive and take a long time to build and get in orbit.