Verification of Practical Use of an Inflatable Structure in Space

Abstract

An extendible mast of a space-inflatable structure was used as a scientific probe onboard the sounding rocket S-520-23 launched in September 2007. The inflatable structure extended successfully and worked well as a scientific instrument. This was Japan's first space verification of a space-inflatable structure, and the world's first use of an inflatable structure as a practical antenna. The extendible mast as an inflatable structure is called "SPINAR" (SPace INflation Actuated Rod), and it consists of an extendible rod and inflatable extension mechanisms. The rod, which is an open section tubular member, can be stored around a spool and has the advantage of structural rigidity when extended. The principle of SPINAR is similar to that of STEM (Storable Tubular Extendible Member); however, relatively reduced weight and enlarged rigidity can be achieved in SPINAR if light and rigid composite materials replace the metallic STEM rod. In addition, an inflatable thin film tube is used as the extension actuator instead of an electrical motor for weight reduction, the extension mechanisms are simplified, and the storage and drive mechanism box are downsized. The inflatable tube does not have to be rigidized because of the virtual structural rigidization concept of the outer shell structure of the rod.

Initial Operation and Deployment Experiment of Inflatable Extension Mast in SIMPLE on JEM Exposure Platform in ISS

“…By Ken HIGUCHI 1) , Yasuyuki MIYAZAKI 2) , Kosei ISHIMURA 3) , Hiroshi FURUYA 4) , Hiroaki TSUNODA 5) , Kei SENDA 6) , Akihito WATANABE 7) , Nobuyoshi KAWABATA 7) , Takeshi KURATOMI 8) and SIMPLE Project Team…”

“…There is no ultimate solution to expand structural element in order to construct stiff space structures by inflation. The authors proposed "structural rigidization simulation system 5,6) , which does not need the controversial rigidization process. In the proposed method, the inflatable structure is not necessarily a balloon, but this can produces stiffer space inflatable structure than ever with neither elaborately-crafted mechanism nor chemical/mechanical rigidization process in space.…”

Electric field instrument onboard Japanese sounding rockets

“…Higuchi et al, 2009) was used in the S-520-23 sounding rocket experiment. For ionospheric electric field measurements to meet the scientific objectives of this sounding rocket experiment, the antenna element had non-conductive boom and the electrode only at each edge of boom, in order to have longer effective length of the dipole antenna and reduce the capacity coupling with the rocket body.…”

Achievement of Long-term On-orbit Operation of the SIMPLE Inflatable Extension Mast

“…The structure and mechanism are based on the concept of "structural rigidization simulation." [7][8][9] The IEM was successfully extended on August 17, 2012, JST (Fig. 1), and the IEM was subsequently operated in space for a remarkably long term of 845 days.…”