A space observatory is expected to be placed far from the ecliptic plane. A Ulysses-type solar polar orbit is a promising candidate, This paper investigates what spacecraft can be injected into this orbit by the 2-ton-version H-IIA launch vehicle. Three injection methods are studied, (1) going to Jupiter directly using the solid motor upper stages, (2) utilizing an Earth swingby after injection into an intermediate orbit by the solid motor, and (3) utilizing the EΔV-EGA by an electric propulsion system.

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It is essentially important for space manipulators to avoid autonomously collision with insufficient prior information. Decentralized autonomous control is one of the more feasible approaches for adapting to uncertain environments using limited calculation resources. This paper describes a decentralized autonomous control algorithm for space manipulators that uses the local distance information between the arms of the manipulator and obstacles to avoid collisions. The adaptability of the algorithm was assessed by computer simulation.

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In order to establish automatic landing technologies for space planes, the Automatic Landing Flight Experiment (ALFLEX) was planned and 13 flights were carried out from July to August in 1996. As one of the research items of ALFLEX, we developed the pseudolite differential Global Positioning System (GPS) System for ALFLEX to acquire the differential GPS (DGPS) navigation technique for automatic landing. We chose a pseudolite method for the DGPS system of ALFLEX designed because the pseudolite method simplified the onboard system and improved the geometrical dilution of precision (GDOP) at landing. Although the pseudolite had these advantages, the method had some technical challenges and had many newly developed elements, and we encountered some difficulties during the development of the pseudolite DGPS System. However finally the pseudolite DGPS system worked well with good accuracy at the automatic flight experiment. This paper outlines the pseudolite DGPS System for ALFLEX and the results of its development. Then this paper presents the evaluation results of navigations; DGPS navigation, carrier smoothing DGPS navigation, IMU-DGPS-RA integrated navigation and IMU-DGPS integrated navigation. Finally this paper discusses the evaluation results of multipath effect on the pseudolite signal and the comparison of the GDOP between the pseudolite method and the datalink method.

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