JAXA Activities on Micro-Nano Technology Norimitsu KAMIMORI, Fumio IMAI, Junichiro ISHIZAWA， Kazuyuki　MORI Institute of Space Technology and Aeronautics (ISTA), Japan Aerospace Exploration Agency (JAXA) １）      序（はじめに） 今日は、宇宙環境利用の展望という課題で報告する機会を与えて下さいまして、有り難うございます。４０分戴いて、私の考えを述べさせていただきます。 最初に１～２分自分のことを申し上げますことをお許し下さい。私自身は長年、化学の分野、中でも有機導体、半導体で仕事をして参りました。東大理学部化学科、東大物性研、新設の岡崎の分子科学研究所にそれぞれ３分の１づつおり、４年前に宇宙環境利用の分野に参加しました。目下、懸命に勉強しつつ仕事に従事しております。 そして、現在までに学び得たことを通して宇宙環境利用の現況と将来について、私の考え方を述べてみたいと思います。

Practical Examples in JAXA Contents Introduction Practical Examples in JAXA (1) MW – CNT/Polyimide Composites (2) Carbon Nanofiber (CNF) (3) 3-D photonic crystal growth in micro-g (4) Smart material for micro-machine (5) Electrochemical Super Capacitor Summary

Introduction In Japanese Science and Technologies, Micro/Nano Technology is in major priorities (IT, Life, Environment, and Nano-Technology). In JAXA, Micro/Nano Technology is in trial phase. ISAS and ISTA researchers have taken efforts

Practical Examples in JAXA

(1) MW - CNT/Polyimide Composites R&D Item: Triple A Polyimide (Tri-A PI) . (Amorphous, Asymmetric, Addition type) Tri-A PI is expected to be an innovative polymer from its good fluidity and thermostability (Tg>573K). 　 Potential Application: Nose-Cone of reusable space launch vehicle Cf. Ogasawara, T., Ishida, Y. and Yokota, R., “Characterization of multi-walled carbon nanotube/phenylethynyl terminated polyimide -composites,” Composites, Part A, 35 pp.67-74, 2004.

MW - CNT MW-CNT was chosen because of its availability and low cost. (SW-CNT costs high for 　composite use.) 200 nm MW-CNTs (FT-grade, CNRI Inc., Japan) ・Synthesized by CVD process. ・Diameters in the range of 20-100 nm. ・Average lengths of 1-100 mm. ・Highly entangled and randomly oriented.

Properties of the MW-CNT/Tri-A PI Composites Test Result Properties of the MW-CNT/Tri-A PI Composites CNT (wt%) (vol%) Tg (K) Ｅ (GPa) σuts (MPa) εmax (%) σ0.2 Sample-A 608 2.84 115.6 7.6 69.8 Sample-B 3.3 2.3 612 3.07 99.5 4.0 80.5 Sample-C 7.7 5.4 623 3.28 97.6 3.6 84.6 Sample-D 14.3 10.3 630 3.90 95.2 2.6 92.6

(2) Carbon Nanofiber (CNF) Cup Stack Nanofiber (CSNF) by CVD Method 　　 produces by GSI Creos Corporation, JAPAN CARBERE® Schematic Illustration Large Hollow Core, Relatively Longer Portion of Open Edges

Summary of Test Results Strength of CFRP using CSNF resin(3 phases) (Normalized by CFRP using non CSNF Resin Strengths)

(3) Oversized 3-D photonic crystal growth in micro-gravity On the ground test, Convection and Strain disturb crystallization Micro-g is best environment for Colloid crystallization Colloid substance　 Nano particle (high refractive index) Particle size: ca.100nm Autonomy by means of electrostatic-repulsive force, etc. Cf. Optically Tunable Gelled Photonic Crystal Covering Almost the Entire Visible Light Wavelength Region., Y.Iwayama, J.Yamanaka, Y.Takiguchi, M. Takasaka, K.Ito, T. Shinohara, T. Sawada, and M. Yonese, Langmuir 19, 977 (2003) Fabrication of Photonic Crystal Using Colloidal Particles., K.Ito, Space material forum in Nagoya(2003)

Test Schedule Autumn, 2005 1st experiment in SM/ISS. Summer～Autumn, 2006 2nd experiment in SM/ISS. Now: Preparing experiment (developing experimental apparatus)

(4) Smart material for micro-machine Shape Memory Polymer (SMP) for space use. → High durability against space environments. High reliability of shape recovery. SMP has good processability.　→　Design flexibility 　　・molding 　　・cutting 　　・heat-sealing SMP has possibility to miniaturize and simplify actuators. Example ) Heat SMP screws are manufactured by MHI

Concept of SMP micro-machine Fix shape Transform free Mold into desired shape Recover shape Operate High Low Glass Transition Temperature （Tg） Temperature Rubbery state Glassy state Flexible Rigid To maintain precise performance and stiffness, the Tg of SMPs should be above the temperature of the SMP structure in orbit. Now, manufacturing trial models

SMPs Compared with Shape Memory Alloys Shape Memory Polymers Shape Memory Alloys Recovery volume 400~500% 7% Recovery power Small Large Density 1 g/cm3 6.5 g/cm3 Workability Good (Thermoplastic) Poor Resistance to space environment Low High Cost * $50 /kg $1000 /kg *TRC report(1995)

Resistance of FR-SMP against UV,EB,AO Changes in the storage modulus of FR-SMP Small effects of irradiation. 　　(UV,EB,AO) Irradiated samples curve closely match that of the unirradiated sample. Irradiated samples satisfy the conditions of having good shape memory properties. Change in storage modulus of FR-SMP 　　as a function of irradiation.

(5) Electrochemical Super Capacitor JAXA is developing Double Layer Capacitor. →　Long storage period. →　High cycle of charge-discharge performance. Focused on long storage period at low temperature. Mounted on MINERVA. (Robot lander carried by HAYABUSA, lunched at 2004.5) Needs to increase surface area of electrode for high electric capacity high energy density Nano technology like CNT/CNF may provide higher performance. Now

JAXA’s plan at Double Layer Capacitor 2004 – On-orbit demonstration Power Supply with high durability Nano Material Evaluate commercial technology Nano material use at Electrode Mounted on MINERVA. -50F capacitor. -Long storage period -against high/low Temp. Evaluate 5000F capacitor. Nano materials provide higher electric capacity / higher energy density.

Summary In coming 2-3years: Trial phase and evaluation Partnership with Private Company and Univ. Promotion of International Cooperation Increase actual budget in coming years