To realize a ultra-lightweight panel structure for a preliminary radar satellite with a 30-m class phased array antenna, we proposed CFRP thin plates loaded with tension to satisfy the required flatness. In actual antenna panels, a large number of patch antennas composed of a plurality of materials are mounted on the CFRP surface. Although it is assumed that thermal deformation that can not be ignored occurs due to the difference in coefficient of thermal expansion, since the patches mounted on a panel become enormous numbers and complex shapes, evaluation by numerical calculation is indispensable. Therefore, coupon specimens with antenna material mounted for CFRP thin plates are prepared and thermal deformation is measured by heating in a thermostatic oven. In this paper we describe how to measure the deformation through a window of the thermostatic oven.

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It is important to get amount of structure displacement of large spaceborne structures such like large deployment antenna reflectors to archive antenna performances, for communication and earth observation satellites with synthetic aperture radar. Recent advances of image measurement techniques make us realize on-orbit displacement measurements of large structures. In this study, based on 8-point algorithm with stereoscopic image taken by two cameras, we evaluated performances of displacement measurements with ground-based experiments. In this experiment, we developed test instrument with small manual XYZ stages and poles on another large automatic stage. With and without displacement of large automatic stage, various cases of given and measured displacement of small manual stages are compared. We confirmed that even with displacement of the large stage, displacement of small stages can be measured for horizontal and vertical directions within 1-2 pixels of the images. For deep direction, much more error can be found for every case compared to horizontal and vertical directions.

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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, measurement method for target attitude / rotating motion and proposes a simple light weight robot arm for capturing non-cooperative space debris.

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Attitude determination using earth sensors has an advantage of smaller volume compared with star trackers. The methods to determine attitude with earth sensors proposed so far are based on matching the detected known land with images or map data. Thus it can be used only in the situation some land can be seen. To resolve this problem, we have developed several methods to detect relative attitude, that is attitude shift, which does not require known land. In this paper, a new method besides suggested ones is proposed which can achieve higher accuracy. By estimating the position of unknown objects using geometrical analysis, it is possible to predict the direction to the object from the earth sensor frame, at the time after a certain period. Comparing this and actual object direction, we can calculate the relative attitude. As a result of numerical simulations, the proposed method is roughly ten times more accurate than the existing method.

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Recently, the manned moon base project is considered in Japan and some other countries as the next mission of International Space Station. Space robotics technology has played an important role in space exploration due to its advantage of low cost, safety and high performance. Therefore, humanoid robots are expected to play an important role cooperating with astronauts for lunar exploration in this project. Humanoid robot features could have many advantages, such as interacting with astronauts and the ability to perform human tasks. This research investigates the effect of gravity on bipedal robot motion, example for walking, running and jumping, from the view point of energy consumption using simulations. Gravity is an important parameter in generating a bipedal locomotion trajectory. In this research, humanoid robot motion with low moving speed used in rooms of the moon base is investigated especially. This robot mainly does physical works with astronauts in the environment with air and a flat floor as opposed to Rover.

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Because the Martian atmosphere is composed of CO₂ gas, electrochemical conversion of CO₂ to O₂ is one of the most efficient methods of extracting oxygen that is indispensable for astronauts to breathe and can be used as oxidant for rocket engines. To realize a reliable oxygen production system, a large amount of CO₂ gas must be accumulated and compressed in an electrolytic conversion system. However, dust present in the Martian atmosphere because of dust storms could damage the oxygen conversion system or cause it to malfunction. Thus, a dust removal system is necessary before CO₂ gas can be introduced into the system. To this end, we are developing an electrostatic precipitator suitable for use in the low-pressure Martian atmosphere because it has no mechanical drives and does not need any consumables such as a filter, complicated controls, and high power consumption. We constructed an improved precipitator consisting of a multi-wire and parallel-plate electrodes. The efficiency of dust removal was approximately 90% by adopting a multi-wire configuration without corona discharge in the low-pressure (700 Pa) CO₂ atmosphere that simulated the Martian atmosphere. Dust was collected on the surface of the wire electrode, contrary to the case for a pressure of 10⁵ Pa (1 atm). The deposited dust was easily cleaned by the application of vibration to the wires. An ionic pump was also developed to introduce gas into the precipitator.

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A Paddle Drive Mechanism (PDM) for a low earth orbit satellite is required to prolong its lubrication life for future missions. This paper describes that the lubrication of a strain wave gearing (SWG) is essential for extending life of a PDM. Furthermore, in order to improve the SWG life, hybrid lubrication using solid lubricants and a synthetic hydrocarbon-based grease was applied, and the PDM incorporating the SWG was tested in thermal vacuum environment. As a result, the operation of the PDM reached 16,0500 revolutions which corresponds to about 3.5 times longer life compared with the existing PDM. This hybrid lubrication was applied to the PDM of Global Change Observation Mission -Climate (GCOM-C) "SHIKISAI" launched in December 2017.

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In this paper we propose and design a miniaturized reaction wheel with magnetic bearing. In order to install much equipment into limited weight and space in a small satellite, it's required to miniaturize and reduce the weight of attitude control equipments, such as a reaction wheel. However, when a reaction wheel is miniaturized, the angular momentum decreases. This research aims to increase a wheel angular momentum with high speed rotation with magnetic bearings. In this paper the structure of reaction wheel with magnetic bearing and its control simulation is described.

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HIROGARI is a 2U size Micro-satellite jointed project by Muroran I.T. and Osaka Prefecture Univ. The mission of HIROGARI is to demonstrate the high stowage efficiency of the deployable plate with thickness, and the method to measure the structural accuracy of the deployed plate on orbit. This paper summarizes the mission feature and the system design of HIROGARI, and reports the status of the HIROGARI’s mission module development.

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In this paper, a formation planning of research and development center for multi-functional smart space systems is introduced. A smart space system is defined as a component and/ or a system with multi-function and high-performance that are also convenient for users. In the center, we will research and develop the smart space systems and provide space project support services to researchers, engineers, customers and newcomers to space activities. In a plan, we will consider, for example, a machine learning based attitude sensor, lightweight high-rigidity expansion/storage boom and array, a deployable antenna for high speed communication as smart space components, and a microsatellite system with variable shape function as a smart space system. Also, information sharing service on on-orbit observation data and processing techniques, and utilization service of testing and operation facilities will be provided. We are aiming at creating space activities such as producing not only new space engineering and science but also space venture, space business, and so on, for the contribution to society.

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The three-dimensional truss structure is a structure used in a wide range of fields including space structure. Although there seems to be no new knowledge in this report, it applies to the formulation for performing nonlinear analysis of three dimensional truss structure by introducing extensional strain and its application to the analysis of the folding process of origami structure. Furthermore, we tried to find the equilibrium position when temperature change occurred in the members of the three dimensional truss by adding the thermal strain to the extensional strain. In addition, application of analysis with thermal strain can be able to find the initial equilibrium configuration of tensegrity structure.

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Several deployable booms have been proposed and developed in order to apply deployable booms to structural elements for spacecraft. We have proposed a boom with corrugated closed section that improves the storage performance. In this research, we developed the retractable and deployable CFRP boom mechanism to examine the technical issues. The experimental model of corrugated boom was molded by inner and outer mold blocks. Two types of CFRP corrugated booms whose fiber orientations are 0/90deg and ∓45deg, were investigated. As a result, it was observed that the longitudinal crack in the boom may occur during storage depending on its fiber orientation. Finally, it was shown that fiber orientation of ± 45 ° and the designing of corrugation curvature are significant for the storage mechanics.

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Wrinkling configurations in a membrane due to wrapping fold are discussed for the effects of winding tension on interval and length through wrapping fold experiments and theoretical analysis in order to reduce wrinkles. The experiments are performed by wrapping a z-folded membrane on a cylinder with winding tension. In the experimental results, interval of wrinkle was not affected by winding tension. Length of wrinkle appeared in two modes. The shorter one was not affected by winding tension. The longer one was reduced by higher winding tension. In order to estimate the effect of winding tension on the reduction of the longer length of wrinkle, theoretical analysis was performed in consideration of the following two assumptions. One is the increase of bending moment from the unwrapped section to the wrapped section. The other is the interference between the wrinkle and the overlapped membrane. The estimated value of length of wrinkle corresponded with the experimental value of the longer one. Both results of the experiment and the theoretical analysis show wrinkles are reduced by higher winding tension.

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A whole field surface shape measurement with the grating projection method was performed in order to capture the dynamic behavior of the composite membrane subjected to impact loadings. And, a probability distribution model of the deformation behavior on the membrane was investigated. A rectangular polyimide film whose size was 0.40m x 0.40m and thickness was 25x10-6m was used. The probability distribution of the vibration response of the composite membrane does not have the theoretical model such as the lognormal distribution model, but shows a downward convex arcuate in the probability plot.

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A design of large optical system was discussed assuming a space telescope where diameter of the primary mirror exceeds 3 meters. In the case of ground telescopes, the size of telescopes becomes larger as its observation performance improves. Hence, the large scaled ground telescopes in visible and near-infrared regions in recent years adopt segmented mirror configuration to construct their primary mirrors. With regard to space telescopes, the development of James Webb Space Telescope triggered many research and technical activities for the spaceborne telescope systems. The authors currently propose an Earth observation imager from the geosynchronous orbit with ground sampling distance of 6 meters and that requires the optical aperture of 3.5 meters derived from the diffraction limit of the optical system. Considering the technical difficulty to construct a monolithic large mirror and the scalability for future missions, the authors started technical studies on the segmented mirror for the construction of the 3.5-meter primary mirror. In this paper, numerical simulations were conducted to evaluate the influence of the material selection of the segmented mirror on the deformation of the mirror due to the environmental conditions.

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Spacecraft are exposed to mechanical environment such as vibration, acoustic and shock derived from launch vehicle and are also exposed to vacuum and extremely hot and cold environment on orbit. Therefore, it is necessary to verify that the spacecraft are designed and manufactured to have enough margin to these environments. Environmental test such as sinusoidal vibration, random vibration, acoustic, shock and thermal vacuum test is one of an effective way to verify the spacecraft design and manufacturing. On the other hand, environmental test needs large parts of spacecraft development cost and duration. Therefore, environmental test should be necessary and sufficient for verification purpose. To figure out what kind of failures can be detected by each environmental test, we analyzed failures in ground tests of 15 spacecraft which have been developed by JAXA in this 30 years. As a result, the major failure modes and their occurrence rate of each environmental test have been revealed: looseness/breakage of bolt/screw (1.12 %) in sinusoidal vibration test, short/insulation due to debris (0.99 %) in random vibration test, relay chatter/reversal (0.90 %) in shock test, and parameter drift due to temperature/noise (1.74 %) in thermal vacuum test.

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When the huge structures such as a rocket or a satellite is taken for an impact test, it is difficulty to examine it in the development stage because the cost that is big to prepare an object is necessary. In this study, experimental device which has two axis of horizontal direction and vertical direction, could change those axis to slide or lock and can reappear various boundary condition was developed to operate the impact test using the cut-model for the purpose of the cost-cut. Furthermore, the object's both ends were restrained by two metal plates for minimizing a rigid change and controlled. This paper shows the result of method to simulate a pipe using by half-pipe as a cut-model.

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Numerical models for investigating penetration behavior of a metal anchor have been developed and its applicability was demonstrated. Two types of FEM mesh, triangular mesh and quadrilateral mesh were employed and some numerical simulation were carried out. These results were compared with the experimental results. It is observed from the results that the penetration behavior can be simulated properly using the triangular mesh. The effectiveness of the Johnson -Cook model with triangular mesh was demonstrated through the comparison.

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