Research balloon

They are usually unmanned, filled with a lighter-than-air gas like helium, and fly at high altitudes.

Research balloons usually study a single aspect of science, such as air pollution, air temperature, or wind currents, although sometimes several experiments or equipment are flown together.

Because of the altitude reached by most research balloons, the air is too thin and too cold for humans to survive, therefore most research balloons are unmanned and operated remotely.

There have been some balloons equipped with pressurized cabins, beginning with professor Auguste Piccard in the 1930s.

With the help of a research balloon, the upper atmosphere of Venus was examined by the Vega program.