High altitude pseudo satellites (HAPS) are unmanned aerial vehicles (UAVs) that operate at high altitudes in the Earth's atmosphere, typically above 20 kilometers. They are also known as high altitude long endurance (HALE) aircraft, as they can fly for extended periods of time, up to several months, without the need for refueling or landing. https://www.transparencymarketresearch.com/high-altitude-pseudo-satellites-market.html