An overview of a sounding rocket, S-520-25th, project on space tether technology experiment is presented. The project is prepared by an international research group consisting of Japanese, European, American, and Australian researchers. The sounding rocket will be assembled by the ISAS/JAXA and will be launched in the summer of 2009. The sounding rocket mission includes two engineering experiments and two scientific experiments. These experiments consist of the deployment of bare electrodynamic tape tether in space, a quick ignition test of hollow cathode system in space, the demonstration of bare electrodynamic tether system in space, and the test of the OML (orbital-motion-limit) current collection theory.

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Drag-free control systems have been studied to detect gravitational waves by measuring distortions in the fabric of space-time. The purpose of drag-free control is to counteract nongravitational forces such as residual aerodynamic drag or solar radiation pressure. The objective of this study is to use miniature microwave discharge ion thruster, 1, for this propulsion system. In this experiment, the thrust dynamic range was between 7-100 %, and the thrust noise was less than 0.02 N/Hz 1/2 in the frequency range of 0.1-1.0 Hz. Although the design of 1 thruster has not yet been optimized, we can expect that the 1 thruster will be feasible for DPF thruster after optimization. Nomenclature= ion acceleration voltage, V m i = mass of xenon atom, 2.18x10 -25 kg S y = output power spectrum density S x = input power spectrum density H r = frequency response function of rth input H p = frequency response function of the microwave power input H v = frequency response function of the ion acceleration voltage input H f = frequency response function of the propellant flow input

Atmospheric pressure CO2 plasma was generated by a laser driven plasma wind tunnel. At an ambient pressure of 0.38 MPa, a stable plasma was maintained by a laser power of 1000 W for more than 20 min. The translational temperature was measured using laser absorption spectroscopy with the atomic oxygen line at 777.19 nm. The measured absorption profiles were analyzed by a Voigt function considering Doppler, Stark, and pressure-broadening effects. Under the assumption of thermochemical equilibrium, all broadening effects were consistent with each other. The measured temperature ranged from 8500 K to 8900 K.

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