HAA meaning in Space Science ?

Atmospheric satellite (United States usage, abbreviated atmosat) or pseudo-satellite (British usage) is a marketing term for an aircraft that operates in the atmosphere at high altitudes for extended periods of time, in order to provide services conventionally provided by an artificial satellite orbiting in space.

Atmospheric satellites remain aloft through atmospheric lift, either aerostatic/buoyancy (e.g., balloons) or aerodynamic (e.g., airplanes). By contrast, conventional satellites in Earth orbit operate in the vacuum of space and remain in flight through centrifugal force derived from their orbital speed.

To date, all atmosats have been unmanned aerial vehicles (UAVs).