Liquid crystalline polymers expand the capabilities of interplanetary aerobots

Abstract

Interplanetary aerobots that can provide continuing altitude control are adding a new dimension to planetary exploration. Innovative systems using reversible phase change fluids (i.e., gas to liquid and back to gas) provide the altitude control capabilities. When exploring planets such as Venus, however, especially as the aerobots approach the surface of the planet, traditional balloon envelope materials do not have the temperature capabilities to survive the 460°C environment. In addition the upper atmosphere of Venus is very corrosive, containing sulfuric acid clouds. Nontraditional balloon envelope materials are needed to provide a reliable and lightweight buoyancy lifting system for Venusian and other extraterrestrial aerobots. Foster-Miller has developed biaxially oriented PBO (polybenzoxazole) film, which can withstand these extreme high temperature requirements. These films have exceptional tensile strength, approaching 100,000 psi, and can be processed into ultra thin films (0.2 to 0.5 mils) that can be used for zero and low pressure balloon structures. With the support of NASA (JPL) Foster-Miller and Raven Industries have completed a R&D program to develop the processing protocols for fabricating Venusian balloons. During this program two earth/terrestrial PBO balloons (=4 to 5 ft in diameter and 16 ft high) were first fabricated to establish baseline fabrication protocols. Specialized high temperature seaming techniques and PBO film gold coating processes were then developed to support the fabrication of two Venusian balloons (=3 fi in diameter and 8 ft high). The following paper describes Foster-Miller’s PBO film technology, the advantages of this material and the work performed in the development and fabrication of the PBO based earth/terrestrial and Venusian balloons. Acknowledgment