A high-altitude platform station also known as atmospheric satellite is a long endurance, high altitude aircraft able to offer observation or communication services similarly to artificial satellites. Mostly unmanned aerial vehicles (UAVs), they remain aloft through atmospheric lift, either aerodynamic like airplanes, or aerostatic like airships or balloons.
High-altitude long endurance (HALE) military drones can fly above 60,000 ft over 32 hours, while civil HAPS are radio stations at an altitude of 20 to 50 km above waypoints, for weeks.
Capable of flying up to 60,000 ft (18,300 m) more than 34 hours, the RQ-4 Global Hawk was put into USAF service in 2001.