Shinsuke Takeuchi

The infrared space telescope SPICA, Space Infrared Telescope for Cosmology and Astrophysics, which features a 3m-class and 6K cryogenically cooled space telescope, is a next-generation astronomical project of Japan Aerospace Ex-ploration Agency (JAXA). The telescope and scientific instruments are cooled by a combination of an active (mechanical) cooling system and a passive (insulation and radiation) cooling system in the payload module. In this paper, the structural overview is described especially for the passive cooling system in the payload module and the summary of some experi-mental studies is presented.

大気球シンポジウム 平成26年度（2014年11月6-7日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県著者人数: 18名資料番号: SA6000021006レポート番号: isas14-sbs-006

We performed microgravity experiments of homogeneous nucleation of iron from the vapor phase using the sounding rocket S-520-28 on December 17, 2012. The purpose is determination of a sticking probability of iron during the nucleation from the supersaturated vapor, because the sticking probability is one of the most uncertain physical quantities to understand the formation process of cosmic dust based on nucleation theories. We prepared the specially designed MachZehnder-type interferometers with an evaporation chamber and camera recording systems to fit the space and weight limitations of the rocket. Three same systems, named DUST 1 to 3, were installed into the rocket. Iron was evaporated in an argon gas and then it was cooled and nucleated to form nanoparticles. The temperature and concentration of iron vapor at the nucleation site are determined from the movement of the interference fringe. Here, we present the brief summary of the experiments and the preliminary results of the homogeneous nucleation from iron vapor under microgravity.

平成24年度宇宙輸送シンポジウム (2013年1月17日-1月18日. 宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)), 相模原市, 神奈川県形態: カラー図版あり形態: PDF著者人数: 18名資料番号: AA0061856051レポート番号: STCP-2012-051

"Small space science Platform for Rapid INvestigation and Test", aka SPRINT - project is a new satellite series for scientific applications of Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (ISAS/JAXA). The design concept of the satellite bus is based on flexibility with alternative, and selectable options. SPRINT-A is the first satellite of the series, which aims to make scientific observations of planetary atmosphere at extreme-ultraviolet wavelength.

Our novel invention: "digital self-powered autonomous" vibration controller using a digital micro-processor is presented. The invented unit is a completely self-powered control system that does not require any external power-supply at all. Nevertheless, this digital, self-directive, and self-powered approach enables the system to be programmable and thus versatile in control scheme. The digital-autonomous controller is much more advanced and progressive than conventional analog-autonomous ones that are clumsy and awkward. This digital system can be implemented in multiple-input multiple-output systems to suppress even complicated structural vibrations. This is quite useful for various applications to energy-saving or energy-shortage systems, such as large space structures, artificial satellites, and isolated lunar bases, which all are vulnerable to long night-time without solar-power.

This paper includes evaluations of composite tanks or pressure vessels based on fracture mechanics and an improved method for tank design. Problems of exfoliation between the mouthpiece and composite in current composite pressure vessels are shown, and the simple solution by inducing a slit into the mouthpiece near the bonding interface is proposed. The effect of the slit is evaluated using a geometrically simple model as well as a pressure vessel model designed for a rocket.

Adhesive bonding structure around a metalic mouthpiece of a cryogenic composite tank was analyzed based on fracture mechanics. Energy release rate was analytically formulated considering difference in strain energies in tension and bending between before and after the crack growth based on a simplified mathematical model. The analytical results were compared with the calculated results by finite element method for five example tanks; they revealed fairly good match. This analysis gives a guideline of the initial optimal design of a cryogenic composite tank based on fracture mechanics.

In this paper, a three-dimensional analysis of launching dynamics of a sounding rocket is investigated. In the analysis, the elastic vibration of the vehicle and launcher is considered. To estimate a trajectory dispersion including the effect of elasticity of the vehicle and launcher, a three-dimensional numerical simulation of a launch is performed. The accuracy of the numerical simulation is discussed and it is concluded that the simulation can estimate the maximum value of the trajectory dispersion properly. After that, the maximum value is estimated for the actual sounding rocket and the value is shown to be within the safty margin for this particular case.

In this paper, the trajectory dispersion of the Viper rocket caused by the elastic vibration of the vehicle and rocket launcher is investigated. In order to estimate the trajectory dispersion, a three dimensional numerical simulation of the launch was carried out considering the elastical effect of the vehicle and rocket launcher. The accuracy of the numerical simulation was validated first by the comparison with the vibration data measured on actual launch, and after that the trajectory dispersion was estimated by the simulation. As the result, it is confirmed that the trajectory dispersion caused by th elastic vibration is no matter on actual launch mission.