Guidance methods for the atmospheric flight part of a Venus aerocapture mission are studied. A lifting entry vehicle is to be used, and in-plane atmospheric path is to be controlled through the bank angle modulation, while out-of-plane motion is left open. Three control laws for bank angle, 1) Shuttle-like law with altitude rate h´ and drag deceleration D feed-back, 2) a simple system with only D feed-back, 3) an explicit law which finds required lift-to-drag ratio from precalculated relationship as a function of D and velocity V, are considered. Numerical simulations are carried out in the presence of atmospheric modeling error and pre-encounter guidance error, and each law is evaluated in terms of final orbit apoapsis altitude dispersion or total drag deceleration dispersion.

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A wire antenna system has been installed on the 12th scientific satellite EXOS-D of the Institute of Space and Astronautical Science (ISAS) in Japan as one of 14 scientific payloads. This wire antenna system consists of four sets of the Wire Antenna Device (WAT), and each of WAT has a deployable wire of 30m with a small mass at its tip, which is wound in a reel before its deployment and is deployed with a constant speed after the satellite’s orbiting. Results of the numerical analysis made on the dynamical behavior of wires and the satellite during and after deployment of four WATs are briefly reported and compared with actual flight data obtained after EXOS-D’s successful launch on the 22nd of February, 1989.

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We have developed railgun system since 1986 for the research on hyper-velocity impacts in space. The highest projectile velocity achieved in our institute is 3.7km/sec. Railgun used for the experiment is 95cm long, and the bore is 10mm square. Projectile is polycarbonate block around its mass is 1.0-2.0g. Power supply is 6mF capacitor bank. Total maximum energy is 300kJ. The power supply is constituted by 6 stage pulse forming network. The current wave form may be controlled by varying the inductor of pulse forming network. Higher current with shorter duration of discharge results in higher projectile velocity. This is due to two reasons. One reason is that energy supplied into the railgun increases with higher current. The other reason is that efficiency of the railgun also increases with higher current. The reason of higher efficiency with higher current is that the ratio of increase rate of projectile kinetic energy to energy supplied into the railgun for a unit time increases with higher current.

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The basic technology of the tele-robotics system for extra-vehicular activity has been studied. The development started by studying a lightweight, small-size and low power-consuming actuator workable in a vacuum condition. Based on this actuator, a manipulator the size of which was as the hand of human being was developed. Then, a master manipulator was designed to operate the slave manipulator. Next, a real-time, graphic simulator was introduced into the man-machine loop of the master slave manipulator system to make task planning easier and to reduce the problem caused by time delay originating from the long distance of the communication link. To integrate these components and to research the architecture of the tele-robotics system, a multi-manipulator control network system was developed. A process for these development is detailed in this paper. The future prospect was also briefly described.

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