Fashionable hats for high altitude balloons

Abstract

Aspects of the technology relate to temperature regulation for high altitude, long duration balloons, such as balloons that operate in the stratosphere for weeks, months or longer. A balloon covering overlays the balloon envelope. The material properties and configuration of the balloon covering are selected to enable it to automatically cover or expose portions of the envelope depending on environmental conditions. The covering has multiple layers of materials with different coefficients of thermal expansion (CTE). The layers are chosen to have significantly different CTEs, and flaps are created in the envelope such that depending on the temperature, the flaps will either lie flat on the envelope or curl away from the envelope. In the former case, the flaps help to retain heat in the envelope, such as during nighttime operation. Conversely, in the latter case, the flaps permit heat to escape from the envelope, such as during daytime operation.