In the field of celestial or terrestrial observation, or optical inter-satellite communication that requires high pointing accuracy, it is often the issue that the microvibrations generated from internal disturbance sources such as a reaction wheel degrade the pointing accuracy of the onboard optical device. In order to satisfy the pointing accuracy requirement, it may be one effective method to install a vibration isolation system between disturbance source and payload. In this paper, a hybrid vibration isolation system with voice coil actuator and plate spring is pursued. A hybrid vibration isolation system can remove the mechanical coupling between the satellite bus and payload by controlling actuators to counteract passive elements property. This enables the vibration isolation frequency to be zero ideally (i.e., the perfect vibration isolation). Moreover, this system has the capability of active pointing control of the payload. This paper presents the outline of the precise pointing control system, and the basic control design of this system.

ASTRO-H (hitomi) was an X-ray astronomy satellite in Japan which was launched on 17 Feb. 2016. To meet its science goals, four kinds of instruments and six detectors were equipped on the satellite. The focal length of two soft X-ray telescopes was 5.6 m, and that of two hard X-ray telescopes is 12m. One of the most difficult challenges for the satellite structure was to meet the alignment requirements for instruments and detectors. Through the ground tests and observation results on orbit, it was confirmed that the performance of alignment meet the requirements. In this paper, the results of on-orbit alignment performance of the instruments and obtained techniques to control the alignment are reported.

NEXUS is a CubeSat which is developed by Miyazaki and Yamazaki Laboratory at College of Science and Technology, Nihon University and The Japan AMSAT Association. The purpose of this satellite is to demonstrate the operation of three radio devices and a camera system. We have developed these components to propose to the CubeSat developers in the future. With these components, they will be able to reduce development time and increase mission diversity. Furthermore, we have a plan to open the technical information of NEXUS to the public. By providing information, the technical threshold of developing satellite will be lowered. The summary and status of the current development of NEXUS are described in this paper.

A tape-spring can be rolled-up easily, so that it can be stored into small volume. It exerts a self-extending force when stored cylindrically and has high specific rigidity after it has extended straightly. Thus a tape-spring has excellent property as deployable space structure, and in fact it is employed as a structural member of self-deployable structure. It is known, however, that the selfextension of a tape-spring wrapped around a free-rotating hub fails if the angular velocity exceeds a certain value. The failure is caused by the detachment of the tape-spring from the hub during the rotation of the hub. This paper derives the conditions of the detachment theoretically, and compares it with the experimental results to verify the theory.

A space structure may impact with space debris, an asteroid, etc. The space structure is put to the temperature environment of a span wide from a cryogenic temperature to a high temperature by sunshine and the shade environment. It is necessary to grasp the character of material due to collision in a wide temperature range. In this research, an impact test method in a high temperature environment was studied using a simple heating system and an air-gun. Experimental results on temperature dependence of impact absorbed energy for various materials are reported.

Validity of the simplified calculation method for wrinkle amplitude using tension field theory solutions, which was proposed in past study, is discussed comparing the estimated wrinkle amplitude with the experimentally observed results. The comparative result shows that the estimated amplitude is roughly in agreement with the experiment results, while confirming the validity of the proposed method.

Cable-mesh antenna reflectors have several advantages such as ultra-lightweightness, high packaging ratio, and potential for large and high precision surface. The design point of deployable back-up structure for such cable-mesh surface is reliability during the deployment. One of the solutions of this problem is to reduce a number of actuator devices for deployment. Thus, we propose the deployable structure composed of scissors members. The structures with scissors member are usually simple and have a useful synchronized mechanical property. Any parabola shapes can be designed by finding design parameter of the scissors structure. In this paper, we investigate and propose a design method of parabolic curved surfaces by scissors structure. From the proposed design method, a model of a parabolic curved surface was made by utilizing the 3D printer. We checked the accuracy of the shape of the model by means of 3D measurement with a digital camera.

Conventionally, rotational equations of motion for rigid body is formulated using finite rotation vectors, and we can obtain an orthogonal transformation matrix that shows the attitude of rigid body. But, in fact, this formulation leads to a nonlinear mass matrix. Therefore, in this study, we derive equations of motion whose mass matrix is constant using absolute nodal coordinate formulation. In this formulation, we use the penalty potential method to the redundant degrees of freedom. It is expected that these equations have a risk of numerical instability associated with time integration. Thus, to avoid this instability, this paper derives the discrete equations of motion by energy-momentum method that provides the solution that satisfies the conservation of total energy and momentum, and examine the validity by the numerical calculation.

Characteristics of a CFRP reflector for deformable mirror systems were investigated through experiments and numerical simulations. The CFRP reflector was mounted on the actuation system and it was deformed by three actuators. In the experiments, three kinds of reflector deformation were achieved by actuating each actuator and they were measured by a photogrammetric measurement system. The deformations were analyzed and compared using Zernike polynomials. The obvious anisotropic deformations of the quasi-isotropic CFRP plate were observed and the astigmatism modes were dominant while three actuators are placed every 120 degrees. In order to investigate the effects of the actuator stiffness, some numerical simulations are performed. The results show that astigmatism modes become larger while the actuators become more flexible.

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.

The recent numerical study (Katsurayama et al. AIAA Paper 2008-4016) found that an insulating boundary in a flow is necessary to activate the electrodynamic braking effect in a rarefied flow, and it predicted that the boundary can prevents the Hall effect from dissipating the current which are necessary for the electrodynamic braking. This mechanism, however, has not been still validated experimentally. This study will measure and simulate the electrodynamic and aerodynamic force on a test model in an rarefied arc flow, of which insulating boundary—arc plume boundary—location is varied, and will validate the role of the insulating boundary in the electrodynamic braking.