Global Observer HALE UAV

The Global Observer high-altitude long-endurance (HALE) unmanned aerial vehicle (UAV) was a liquid hydrogen-powered aircraft.

The platform was intended to operate at altitudes of 65,000 ft (19,800 m) for over a week with a flexible payload capacity of up to 1,000 lb (454 kg), according to its California-based manufacturer, AeroVironment. At such altitudes, a communications relay payload could potentially provide service for an area up to 600 mi (970 km) in diameter, or more than...