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Developing higher level 3-axis attitude control mechanics is desired in recent satellite attitude control systems, so that we propose an innovative 3-axis attitude control for recent and future satellites by using Re ectivity Control Device, RCD, which is capable of changing its re ectance according to applied voltage. This paper shows some examples of the high accuracy and stability 3-axis attitude control method using RCD, and indicates usefulness of this method with the 3-axis attitude control simulation including the torques generated by solar radiation pressure.

University of Tokyo and Kobe University conducted a sounding rocket experiment to deploy large “Furoshiki” net in space, which is a promising candidate for the future large antenna or solar power satellites. The experimental system consisting of mother and three daughter satellites as well as a folded net was separated from S-310 sounding rocket of JAXA/ISAS at the altitude of 110km, where the daughter satellites, after separated from mother satellite with 1.2 m/s velocity, deployed a large net of 14m-sized triangle. The deployment was quire successful without any tangling and the dynamics during deployment has been captured by cameras, INS and radar distance measurement system. Retro-directive antenna micro wave transmission experiment using 4 antennae on the bottom of satellites were conducted also successfully.

University students' community of Japan, named “UNISEC (University Space Engineering Consortium)” have been organizing “Comeback Competition” annually since 2001. In this competition, a nano-satellite model of 1-2 kg with a certain control mechanism such as parafoil is, after release from a rocket in high altitude, to come back to a certain target point autonomously without human interaction, and the one which can come nearest to the target point becomes the winner. GPS is used in most cases as the primary navigation source, and guidance and control calculation is made on OBC (On Board Computer), whose output actuates the control surface of the parafoil. As the system development requires integration of many research fields such as aero-dynamic, control, structure/mechanisms, electronics and RP communication, this competition has been considered an excellent first step training for university students towards sophisticated systemdevelopment such as artificial satellite. In this paper, the objectives, rules, results, lessons learned and significance of the competition is described.

Students of University of Tokyo, ISSL (Intelligent Space Systems Laboratory), developed a nano satellite named “CubeSat-XI,” which was successfully launched by Russian Rocket “ROCKOT” on June 30, 2003. The satellite has been working well and the students have been performing various experiments using this satellite. This paper reviews the concept, significance, systems' descriptions of CubeSat-XI, and reports the post-launch flight experiment results. Especially, orbit determination and estimation of the satellite attitude will be highlighted. Earth imaging mission will also be described.

Capture of tumbling objects in space will be one of important on-orbit service technologies in future. It requires a series of technologies such as camera-image tracking of the target, target attitude motion estimation, and attitude control of the chaser to approach and grasp the target. Based on the theoretical and simulation-based research, University of Tokyo successfully performed on-orbit experiment of some of these technologies on a NASDA's (currently JAXA's) microsatellite named “µ-LABSAT.” In this paper, the objectives and procedure of these experiments, the control and estimation algorithms and the results will be described.