In current general observation scheduling of Remote-sensing satellite , the operator decides as to adoption or rejection according to priority of observation request by repeating simulation cosidering maneuver time.Therefore, in this study, we have structured algorithm of combination optimization with constraint with setting turn-around time of observation and off-nadir angle as indefinite number as method that automatically optimizes observation scheduling.The condition of optimization is to minimalize the objective function and to maximize the number of adoption.In simulation result of adjacent observation points,even if the priority of one observation point is high,there are some cases that the others with low priority are previously observed when they are combination of which objective function is minimum as optimization.

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Collisions between Asteroids and Earth sometimes occur and bring severe damage to human society. Some asteroid deflection techniques to avoid the collisions have been suggested by astronomers and scientists. We discuss these techniques, especially kinetic impactor. In this paper, we think about the improvement of the kinetic impactor by using the concept of Impact Geometry Map which visualizes the maximum change of the asteroid’s orbital energy by an impact. This report suggests a method to increase the change in the orbital energy of the asteroid by using locally optimal thrust vectoring and the Impact Geometry Map. We also use time differentiation of Impact Geometry to make an efficient spacecraft orbit. Additionally, we describe a global trajectory optimization method of spacecraft to increase Impact Geometry.

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There has been proposed the Starshade that enables direct observation of exoplanet orbiting around the host star by arranging membrane called occulter of several tens of meters radius between the space telescope and the star so that it blocks the light from the stars to the telescope. This paper derives the electric field of the diffracted light when the occulter blocks the light of the star, and calculates the optimal shape of the occulter to minimize the contrast. In the calculation, two patterns of apodization functions are employed, and the results are compared with each other. The shape of the occulter is like a flower petal, and the optimal shape and the contrast at the pupil plane are obtained by assuming the number of the petals.

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The Space Elevator is viewed as the answer to obtaining lower space transportation costs; an alternative to expendable launch vehicles. As an initial step towards realizing such a system, the Hybrid Space Elevator is undergoing consideration. In this report, the feasibility of such an Orbital Elevator utilizing the hybrid system will be analyzed, through the use of a pneumatic floating test bed for a basic two-dimensional experiment. This paper also discusses the analytical model for an Orbital Elevator, designed for use in this experiment.

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This paper describes a method to determine an attitude angular velocity of an orbiting spacecraft using a commercially available small camera and computer vision technique. Employing the earth camera has a large advantage for small / nano satellites in terms of the required volume. First of all, the spacecraft takes two pictures with specified time interval. Then, we determine “fundamental matrix”, that contains camera motion information. Finally, we calculate attitude rotation occurred during the time interval from the fundamental matrix, and derive the attitude angular velocity. Considering the case of on-orbit spacecraft, translational motion information is available using GPS or orbital parameters. Thus, we also propose a method to estimate the fundamental matrix in the case stated above. Numerical simulations are conducted with two method, usual computer vision method and the proposed one. As a result, both methods reached high accuracy, in particular, proposed method is about 20% better than conventional one.

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Space Robotics Laboratory (SRL) of Tohoku University established a ground test environment system called: MEVIμS (Model-based Environment for Verification and Integration of Micro-Satellites). The core of this system is the software simulator called: SSES (Satellite and Space Environment Simulator). SSES can perform simulations such as attitude control simulation, orbit determination simulation and power balance simulation. This paper aims to improve the results of power balance simulation by adding certain functionalities to the power supply system, which allows SSES to perform the detailed power balance simulation.

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Breakthrough technologies are needed to enhance the ability of rocket motor． In this research， the manufacturing method of conventional rocket motors has been dramatically changed by using the Multi-Segment Technology and Direct Filament Winding (DFW) Technology． These technologies enable a great increase of propellant mass ratio, Multi-Thrust and improvement in flight performance． A triple thrust pattern and 2-pulse thrust were demonstrated by static firing tests of prototype rocket motors manufactured using the Multi-Segment Technology and DFW technology． From a flight performance analysis, flight range extension by 60% and terminal velocity enhancement by 50% can be expected when these technologies are applied to a φ0.3m-class rocket．

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Hybrid rockets have been studied for space transportation. Hybrid rockets are regarded as more suitable for manned space transportation than solid fuel rockets or liquid fuel rockets because hybrid rockets are essentially safe. This study examines another means of using hybrid rockets. Our suggestion is an air-breathing type hybrid rocket booster for small aircraft. After conducting theoretical calculations, we identified the need for an axial-flow compressor for air inhalation. The use of a metalized solid fuel is expected to increase the hybrid rocket propulsion performance. Additionally, when a hybrid rocket booster is designed with general versatility, it can be installed in various aircraft. The design offering general versatility is expected to lower operating costs. And, when using cartridge type solid fuel, the hybrid rocket engine can be reused. This study yielded some knowledge related to hybrid rocket boosters.

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In this study, viscoelasticity of low-melting-point thermoplastic (LT) fuel was investigated. LT fuel has excellent mechanical and adhesive properties, as well as a high regression rate compared to conventional hybrid rocket fuel. We conducted several tensile tests, which parameter was tensile rate and temperature. It is confirmed that LT fuel has the thermorheologically simple. Therefore, we became possible to estimate mechanical behavior of the LT fuel at short to long time scale. The failure envelope of the LT fuel was also obtained; therefore, a structurally stable area of LT fuel was investegated, and found that true stress of elongation rate until 2.0 be able to approximated by the Mooney-Rivlin equation.

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Hybrid rocket motor/engine forms a boundary layer combustion in the chamber because it is composed of liquid oxidizer and solid fuel. Liquefying polymers like paraffin are recently employed as hybrid rocket fuel due to higher regression rate compared to conventional fuels. The observation studies of combustion flame on liquefying fuel surface were conducted at low oxidizer mass flux. And its combustion detailed process is still unclear. Therefore, to examine the melting fuel behavior, a two-dimensional chamber with observation window was performed at GOX 104 kg/m²s and PC 2.0 MPa. In addition, the temperature profiles near the fuel surface were measured using a thermocouple. Distance between fuel surface and flame zone affected by GOX was obtained using thermocouple technique.

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Slow regression rate of hybrid rocket fuel is a disadvantage which should be overcome. One of the solutions is usage of a solid fuel grain with a complicated geometry port. Especially, the recent development of additive manufacturing leads to promote the complication of port geometry. An engineer is required to understand a fuel regression behavior, when one designs a solid fuel grain with a complicated geometry port. Hence, in this research, the numerical tool for capturing a solid fuel surface is developed with level set method. The regression of a star-shape port with five and six slots is simulated with the developed numerical tool. The regression distance at the forward end of the port is very large in the both case of port. The fuel regression rate increases downstream, except for the forward end, in the both case of port. The oxidizer to fuel ratio of a star-shape port with five slots is larger than that of a star-shape port with six slots.

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The aerospace engineering has to apply the highest techniques in each technology field such as aerodynamics, structure, prolusion, and control. Recently, Multi-Disciplinary Optimization (MDO) design techniques is in practical use for the design of aircraft/spacecraft design, instead of the design by trial and error. In this paper, the overview of the MDO technology is discussed and several examples of authors’ study about MDO problems are reviewed.

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A new Continuous Wave (CW) laser propulsion system using porous carbon as a heat exchanger is experimentally studied. The propellant receives the heat from heated porous carbon absorbing CW laser and becomes high pressure in the chamber of the thruster. The thruster obtains propulsive force by emitting hot and high-pressure gas through its nozzle. In this experiment, we used the 4kW CW fiber laser, helium gas as propellant gas. We found that pressure in the chamber and thrust increased by laser heating and it was possible to raise the stagnation temperature to 1523K.

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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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Deployable structures are necessary for spacecraft to challenge advanced missions. It is important in designing the deployable space structures that they are easily deployable and reliably repeatable. The buckling in some cases enables external impetus to deploy the structure to be smaller, and enables stable deployment. The paper proposes a new available deployable structure “Deployable Cube”, which applies buckling actively.

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In recent years, advanced fault detection technology is indispensable in space system development. Since human judgment of various diagnostic data is limited in complex systems such as spacecraft, it is necessary to introduce an autonomous fault detection system in order to prevent serious mission failures and system damages, and it can be expected to reduce human cost. One such method is Taguchi Method (Mahalanobis Taguchi system), which has been used to date for fault detection of artificial satellites and rockets. In this research, we focus on the Taguchi Method, and apply it to the fault diagnosis of adaptive space structures with advanced functions such as shape precision control and vibration control. In this report, we apply the Taguchi Method to the self-diagnosis problem that detects abnormality occurring in the smart structure from the vibration response data, and verify its usefulness experimentally.

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Tape spring can be a lightweight structural member and is easy to roll-up into small volume, so that it is expected as member of deployable space structure. There have been proposed various kinds of members made of tape springs such as bi-convex booms consisting of two tape springs. The relation between the bending moment and the curvature of the tape is one of the research topics that attracts many researchers. They analyzed the relation numerically and/or experimentally, and some of them are applied to the design of deployable structures. In this paper, the bending moment of the tape spring is obtained as a function of the curvature and the change sate of the curvature, and the solution surface of the bending moment is shown for understanding of the characteristics of the bending moment of tape spring.

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Space structures are required for the precise and large structure. Deployable antenna is used for satellite communication and synthetic aperture radar. Especially, cable mesh antenna which is one of the deployable antenna is characterized by light weight, high packing efficiency and large size. Cable mesh antenna consists of cable network structure, metal mesh and deployable truss structures. The shape of cable network structure is formed in cable tension. In addition, surface cable network is designed as parabolic in shape by triangle flat facets. However, as the facet divisions increases, the number of cables connected to the outermost increase. As a result, the sag shape of surface cable increase to tension ratio of the cable. Therefore, the effective aperture diameter of the antenna become smaller. In addition, the weight of the deployable truss structure increases to ensure rigidity. However, it is important for cable mesh antenna to reduce the weight of deployable structure. This paper described design problem by sag shape and tension ratio. Studying on topology of cable network, tension ratio is suppressed without increasing sag shape at catenary cables. Moreover, support structure load is suppressed by reducing number of facets and increasing sag shape at inside of surface cable.

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Effects of surface modifications of a cable-network antenna on reducing grating lobe levels are investigated. Some systematic or random modifications of the node positions of the cable-network antenna are introduced and the reductions of grating lobe level are investigated through numerical simulations. The results show that the grating lobe levels are reduced by these surface modifications and the appropriate systematic modifications achieve the reduction of grating lobe level while maintaining the antenna gain. The cable network structure with the appropriate systematic modification was designed using force density method and the feasible tension distribution was achieved.

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The shape memory polymer (SMP) has shape fixability that keeps a deformed shape given in a rubber state having a glass transition temperature T_g or higher, in a glass state of T_g or lower, and a shape recovery property as an elastic body in a rubber state There. The former can be used for storage, the latter can be used for deployment and shape deformation. In this research, we propose a concept of the variable membrane structure using SMP patches. Basic experiments are performed to show its validity. , In the experiments, a three-dimensional cylinder with a number of SMP patches is demonstrated to show its capability of shape generation that can be applied to increment of the out-of-plane stiffness and an autonomous storing mechanism for membrane structures.

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Dimensional stability of space telescope structure is important to realize a highly performance observation. In particular, structures such as truss and spider arm to support optical components are required to maintain those positions with proper alignment. In order to satisfy the requirement in orbit, these structures are designed enough to be stable against thermal disturbance. In this paper, thermal displacement of truss strut was measured using built-in displacement sensor. Considering the requirement for the thermal stability, the specimens made of low thermal expansion materials (SiAlON and Super invar) were measured by the built-in sensor. The coefficient of thermal expansion (CTE) calculated from the measured thermal displacement was well matched with CTEs in test coupon. Therefore, the proposed self-sensing concept could be applicable nanometer-order displacement measurement of structural member having length over several hundred millimeters such as metering truss.

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We have worked to develop new optical surface shape measuring methods enable to grasp surface shape of large space structures with high precision and high speed on orbit for future space antenna and telescope. These methods are applicable to testing such structures on ground. In these methods, we analyze phase values of projected or painted grating patterns on the structures and perform calibration using a reference plane. It is hard to project such patterns on large structural surface on orbit, however, we must paint some grating patterns on the structures. In that case, high contrast images of grating patterns, for example white and black grating painting, are needed for precise measurement. Nevertheless, high contrast white and black patterns on surface make thermo-optical features of the structure more complex, then there is a possibility of interfering with thermal design of spacecraft. Therefore, to widen the application range of our method, we propose surface shape measuring method based on grating patterns using ultra-violet range. We use two different kinds of painting materials and cameras having sensitivity to light of ultra-violet range. Both painting materials are photographed as white in the visible range, however, one is white and one is black in the ultra-violet range. In this method, we can get high contrast grating images on the surface only in the ultra-violet range. In this study, we provide some feasibility study using commercially available ultra-violet cameras and painting materials such as titanium oxide.

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