阿部 琢美

欧州宇宙機関（ESA）木星探査機JUICEに搭載される電波・プラズマ波動観測器RPWI（Radio Plasma Wave Instruments）は，欧州チームにとり米土星探査機カッシーニ搭載のRPWS，日本チームにとり月探査機かぐや・ジオスペース探査衛星ERG・日欧水星探査機BepiColombo搭載の電波・プラズマ波動・レーダー観測器群からの発展展開となる．木星・衛星周回軌道への初投入となる低温電子・イオンおよびDC電場観測機能，電磁場三成分のプラズマ波動観測機能，電波の方向探知・偏波観測機能，および高度オンボード処理によるパッシブ表層・地下探査レーダー機能や波動-粒子相互作用検出機能の実現により，木星磁気圏の構造・ダイナミクスおよびガリレオ衛星群との相互作用，氷衛星の大気・電離圏および氷地殻・地下海へのアクセスを狙う．2016年7月に仙台で行なった「RPWIチーム会合」での最新状況を踏まえ，1970年代に遡る本チームの経緯・目標・展望を述べる．

Sound measurements were carried out using rocket-based propagation diagnostics in the middle and upper atmosphere via infrasonic/acoustic waves to investigate their frequency dependence. The S-310-41 sounding rocket was used, equipped with one main microphone, two sub-microphones, and a loudspeaker, to examine the sound propagation in the payload section of the rocket as a function of the ambient atmospheric pressure. The output from the loudspeaker showed a clear trend of gradual attenuation with decreasing atmospheric pressure at almost all frequencies. Acoustic wave propagation was measured, and was in good agreement with the predictions of attenuation of the sound strength of the mass spectrometer incoherent scatter model (NRLMSISE-00).

The project to verify the performance of space tether technology was successfully demonstrated by the launch of the sounding rocket S520 the 25th. The project is the space demonstration of science and engineering technologies of a bare tape electrodynamic tether (EDT) in the international campaign between Japan, USA, Europe and Australia. Method of "Inverse ORIGAMI (Tape tether folding)" was employed in order to deploy the bare tape EDT in a short period time of the suborbital flight. The deployment of tape tether was tested in a various experimental schemes on ground to show high reliability of tape tether deployment. The rocket was launched on the summer of 2010 and deployed a bare electro-dynamic tape tether with length 132.6 m, which is the world record of the length deployment of tape tether. The verification of tether technology has found a variety kind of science and technology results as the first in the humankind and will lead a large number of applications of space tether technologies.