Abstract: Stratospheric airship is a low-speed near space aerocraft which floats at an altitude of 18-24 km above the earth depending on the lifting gas filled in the hull envelope. The impermeability of gases in the retention layer is the key technology for the normal operation of the airship. In this article, based on an introduction to the operational principles of the airship, the requirements of envelope materials are first analyzed, especially its gas retention layer. Then, the gas permeation process is explained, and research about the permeability of helium through polymers is summarized. Finally, the article indicates that increasing the barrier property of polymer materials is the most important problem of developing stratospheric airships in China.

Key words: stratospheric airship, gas retention layer, helium, gas permeation, polymers