[in Japanese]

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Since the number of satellites in Earth orbit is steadily increasing, space debris will eventually pose serious problem to near-Earth space activities if left in orbit, and so effective measures to mitigate it are becoming urgent. This paper discusses an active space debris removal system, and proposes a simple light weight robot arm for capturing non-cooperative space debris.

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Experimental equipment facilities on the International Space Station (ISS) are required not to disturb the microgravity environment, and the facilities must be designed so that the generated disturbances do not violate the microgravity requirement. In order to make validation of the design, experimental or analytical verification must be performed according to the ISS program documentation. As the microgravity requirement is classified as three categories: (a) Quasi-steady Requirements (b) Vibratory Requirements (c) Transient Requirements, this study attempts several approaches for the category (b) to measure or estimate the parts level disturbance, which is required as the first step to estimate the system level disturbance. Next, system level verification is attempted based on the results of the approaches for parts level. As one of examples of experimental equipment facilities for this study, the Engineering Model (EM) of the Electrostatic Levitation Furnace (ELF) is utilized.

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[in Japanese]

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Spacecraft instruments or components that have mechanically moving part generate undesired disturbances and thus affect spacecraft performance such as pointing stability of mission payloads. With the growing demand for high pointing accuracy in observation satellites, these disturbances are now emerging as a major cause of pointing stability deterioration. In recent years, multi-axis vibration isolation systems have been required and installed in observation satellites to attenuate complex transmission of dynamic internal disturbances. In this paper, a Stewart-platform-based vibration isolation system aiming at next-generation geostationary observation satellites is proposed. This system consists of the six isolator struts which support a mission payload against a satellite main body and isolates disturbance transmission in six degrees of freedom. To design this system, the transmissibility matrix which characterizes the performance of multi-axis vibration isolation is firstly derived from a simple dynamic model. Valid physical parameters such as single isolator dynamic stiffness and geometric layout of the platform are examined and a prototype of the vibration isolation system is developed based on this result. Experimental results show that the prototype accomplished 1/10 vibration transmissibility in six degrees of freedom above 20 Hz across the board. Also, compatibility to mechanical environment was demonstrated through the vibration and shock testing under specific environmental profiles.

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[in Japanese]

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Electric sail uses natural solar wind plasma stream to generate a propulsive force and it allows a spacecraft to perform orbit transfer with small reaction mass. The aim of this paper is to investigate the performance and feasibility of electric sail kinetic impactor for asteroid deflection missions. Asteroid mitigation scenario and simulation model for electric sail are given. Through detailed studies using numerical simulations, performance of electric sail kinetic impactor is emphasized.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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The 4th-made satellite in STARS-project, "STARS-E", which is occupied in development of tethered satellite, has been developed with the aim of the orbital elevator satellite. STARS-E is an ultra-small satellite, that size is roughly 50cm cubic and weight is 50kg class, and it is considered as the mission that about 2km of tether extension and a robot to up and down the tether. Among the various mechanisms that are used in satellite, I attention to the separation mechanism that separate mother-satellite and daughter-satellite. And I proposal and study about design alternatives of retention mechanism that hold 2 satellites of mother-satellite and daughter-satellite, each mass consists of 25kg, and injection(separation) mechanism that able to extension the tether, about 2km, using a compression spring.

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Including the development of the International Space Station, space development, such as launch its own satellite in each country it is developed. Among them, ultra-small satellite than artificial satellite ever be developed and manufactured at low cost and short period of time, observations and satellite - is attracting attention as a method of a new space development by possible communication between the grounding. By space development has become familiar, in the universities and technical colleges began to research and development of ultra-small satellites are actively carried out. This time, Nohmi laboratory at the University, a member consisting Yamagiwa laboratory, to develop the ultra-small satellite "STARS-C" project was started. This project was selected in chance of being released from the Japanese Experiment Module "Kibo" of the International Space Station that Japan Aerospace Exploration Agency (JAXA) has been public offering. Stars-C to be launched this time, is composed of two satellites (2U) ultra-small satellite of each 10cm class. The mechanism, after release, two satellites which are coupled to separate between the universe, the mounted tether simultaneously to 100m extended to control the attitude. It should be noted that with such a mechanism, contained the device to the 10cm class, and it is very difficult to assemble. Or more than, I development of the above mechanism, the device rests housing of the design, and performed the evaluation. Also, we have to simulate the behavior of the universe in consideration of the attitude control of the satellite.

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[in Japanese]

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In this paper, we suggest the antenna placement optimization method for the micro-satellite in consideration of an operation condition of the satellite and its earth station using a genetic algorithm (GA) for two purposes, maximizing a margin of its link design and reducing the burden from the communication system to the other subsystems of the satellite by reducing a control of the satellite's attitude or a gimbal of the antenna for an antenna's pointing to the earth station. We defined an evaluation function that calculates the mean bit rate in its design life expressed in the follow parameter, its transmitter antenna gain in the direction of the earth station and a free space propagation loss as a weighting. For optimizing, we consider to maximize this function's value, that is equal to maximize a mean C/N0 in design life. We adapted this optimization method to an amateur band antenna of a 50kg class micro-satellite called TSUBAME as its validation example. This optimization improved the margin of its link design about 2 times than a former model, its flight model.

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[in Japanese]

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A vibrating membrane behavior induced by an impact loading is measured by photogrammetry using a grating projection method, and a spatial distribution characteristic of the displacement spectrum magnitude on the vibrating membrane surface is investigated. Three membrane models, which are a flat membrane model, a wrinkled membrane model and a miura-ori membrane model, are treated. The results show that the spatial distribution of the logarithmic magnitude of the spectra on the vibrating membrane surface has a similar distribution characteristic regardless of the existence of wrinkles and creases, while the vibration characteristics, which are a flexural wave propagation and a natural frequency, are sensitive to the membrane surface features.

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This report describes some numerical analysis by finite element method with quarter-point element. To obtain the stress intensity factor which is important physical parameter to show the stress singularity near the crack tip, by the finite element method, some finite element formulations exist. In this report, we use the quarter-point element.

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It is necessary to develop satellite with large diameter reflectors to offer high communication services, or to obtain image pictures with high resolution for radio astronomy. The purpose of this study is establishment of cable network structure integrated with compression members for 10m class deployable precise and large antenna reflectors. The cable network is a key theory to make prerace parabola surface. In this study, we propose design method for cable network structure integrated with compression members. In the design process of the cable network systems, many parameters and conditions are required to be determined such as extension rigidity of cable and compression member, cable network topologies and tie cable tensions. We suggested the new design method that introduced cable adjustment. As the result of this study, we showed the design guidelines of reduction deformation of supporting structure and reflection area loss using numerical analysis. And, it is possible to reduce the deformation of the support structure. Even when many number of facets, proposed the design method inclusive cable network compression member maintain tension balance.

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[in Japanese]

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[in Japanese]

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