Design and evaluation of an ultra-light extendible mast as an inflatable structure

Space inflatable actuated rod (SPINAR) has been developed as an ultra-light one-dimensional extendible structure driven by an inflatable actuator. SPINAR satisfies ever-intensifying requirements such as lightweight, high rigidity, high strength, high packaging efficiency, favorable antenna performance and simple extension mechanisms. Performed were the analysis of the requirements for structural design of one-dimensional extendible antenna structure and the detailed conceptual design for a scientific mission under consideration in ISAS/JAXA, and the advantages of the inflatable-assisted structure were evaluated. The rod of SPINAR consists of tri-axially woven fiber composite materials and thin inflatable tube. The extension tests were successful at any direction with respect to the gravity. Spin extension tests on a turntable also showed smooth extension. Spin extension test of SPINAR on a turntable under micro-gravity environment using airplane parabolic flight was performed in August 2005, and the test showed that SPINAR would satisfy the requirements for the science mission. The composite rod was tested as an antenna in radio wave environment, and the material was selected to use as a dipole antenna for a high-resolution electric-field sensor. SPINAR is expected not only to use as an antenna rod, but also to explore a broad range of application opportunities as an excellent substitute for conventional mechanical deployable structures.