An experimental Global Positioning System (GPS) receiver based on a Commercial Off-the-Shelf (COTS) hardware and open source signal processing software modified for space applications is planed to be integrated into the PRISM Earth observation nano-satellite. This paper describes the preliminary orbit determination experiments considered to be performed as part of the PRISM missions to study the operation and performance of the COTS-based GPS receiver on a very small and low-power satellite flying in a low Earth orbit.

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To estimate accurately the impact force at landing on the moon, an experimental study considering the influences of Regolith and of lunar environment is required. By a numerical model which represents the phenomena by semi-empirical formula with experimental results, we can predict the impact force. In this paper, we introduce the experimental study to estimate the force and the numerical results with the semi-empirical formula by the Apollo ground model. Furthermore, we describe the way to predict the force by the computational analysis with smoothed particle hydrodynamics (SPH) method, and the SPH method showed good agreement with the numerical and experimental results.

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Applications of magnetohydrodynamic (MHD) accelerator for advanced propulsion has been proposed. The Magnetohydrodynamic Augmented Propulsion Experiment (MAPX) that has diagonal connected MHD accelerator is planned by NASA Marshall Space Flight Center. The diagonal accelerator with suitable electrode connections can achieve the condition that the current of flow direction is neutralized to avoid flow asymmetry and needless Joule heating. It is called the Hall current neutralized condition. In this paper, the suitable electrode connection for the neutralized condition is assessed theoretically, and it is evaluated whether the connection is able to be achieved in actual device. Although difference from ideal connection causes the difference of the current distribution, the impact is so little that variation of axial flow velocity is almost same as ideal case. We found that the actual MHD accelerator in MAPX can also attain the Hall current neutralized condition almost similar to the ideal condition.

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The Hinode (Solar-B) Optical Telescope Assembly (OTA) is sensitive to molecular contaminant deposition resulting from its organic materials outgassing on orbit. It was launched by M-V rocket on 22 September 2006 UT. The Hinode telemetry data showed that temperature of the Heat Dump Mirror (HDM) rose rapidly during first two months. This is attributed to the fact that molecular contamination deposition degrades a solar absorptance of the HDM. Each numerical analysis result for the Primary Mirror (M1) and the Secondary Mirror (M2) corresponded with a change in solar absorptance, delta alpha, converted temperature data into. The numerical analysis result for the HDM was less than delta alpha. It is necessary to take into account desorption and temperature-dependent outgassing on the numerical analyses.

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Quasi Zenith Satellite System is a satellite navigation system to serve over the whole area of the East Asia and the Oceania region. The ground trace of the satellite changes gradually due to the orbit perturbation caused by the earth gravity, moon, sun and solar radiation pressure. To study maintenance of the ground trace it was needed to know the characteristics of the orbit. In this paper we described the characteristics of the longitude of ascending node (LAN), the eccentricity (e) and the other parameters. The earth Non-Zonal term induces the harmful perturbation onto the semi major axis (a), which directly relates the longitude of ascending node (LAN) and the average longitude of the ground trace. The fluctuation of the eccentricity (e) is depend on right ascension of ascending node, and is not negligible. The orbit which has the right ascension of ascending node = 210deg is the most stable orbit. And we also suggest that it is important to control two parameters, the eccentricity and the semi major axis to maintain the ground trace. The maintenance interval should be from 6 months to 12 months.

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A Conical Shaped Charge System (CSC) is most suitable for an experimental device realizing a piece of typical debris of one gram mass and 10km /sec velocity in a low earth orbit. However, space debris is solid although the projectile discharged by a CSC is a solid-solution. Moreover, it is known that the damage situations generated by the collision with a solid and the solid-solution projectile are different. However, the difference cannot be clarified quantitatively. On the other hand, a solid one gram mass and 7 km/sec. projectile can be launched by the two staged light gas gun as the maximum performance. Then, the authors have been developing CSC which can discharge projectile of one gram mass and 7 km/sec. for the purpose of performing this comparison. This paper describes the design and development process of this CSC which can discharge a projectile with required mass and velocity successfully.

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The authors have proposed a LOX vaporization nozzle for swirling-oxidizer-flow-type hybrid rocket engines to increase engine performance. In this study, we developed the LOX vaporization nozzle for this type of a hybrid rocket engine with a 1500N-thrust. Vaporization experiments, using a LOX supply system for the nozzle to be independent of a GOX supply system for the engine, were conducted. The test runs at little oxygen mass flow rates and low combustion pressures at the design point showed that LOX could be vaporized safely through the nozzle. It was confirmed that the design of the LOX vaporization nozzle was proper. Vaporization and burning experiments using vaporized O₂ through the LOX vaporization nozzle showed that reliable and rapid ignition and stable combustion without combustion oscillation were achieved. The LOX vaporization nozzle increased the engine performance of the swirling-oxidizer- flow-type hybrid rocket engine.

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Hydrazine (N2H4) and NTO (dinitrogen tetroxide: N2O4) mixtures are used in spacecraft bipropellant systems, having the advantage, for sampling missions, of having no carbon composition. However, no reasonable combustion model of hydrazine and NTO has been developed, although an N/H/O kinetic reaction model has been investigated. To construct a hydrazine and NTO combustion model that is useful for bipropellant thruster simulation, we surveyed the literature concerned with elementary hydrazine and NTO mixture reactions for N/H/O systems. A total of 245 reactions found in 16 available studies are dealt with in the present paper.

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A conical shaped charge (CSC) system has great potential for the evaluation of the protection performance of space structures against space debris which flies in space at a hyper velocity exceeding about 10 km/s. On the other hand, in order to establish the evaluation method using a CSC system, the impact damage given by this system and another system, such as a two-staged light gas gun system, should be compared and the effectiveness of this method must be verified; moreover, the correlation of the test results obtained by the two systems must be determined. The authors have already developed a CSC system which can shoot out the jet with almost the same mass and velocity as a two-staged light gas gun system does, i.e., it could shoot one gram jet at about 7 km/s. However, since additional following jets also existed, and eliminating them remained a problem to be solved. This study devised a method of deleting the following jets for the CSC system and confirmed its validity through experiments. Moreover, the shooting performance with the mass and velocity almost equivalent to those of the two-staged light gas gun system was displayed. The correlation between damage areas produced by the CSC system and by the two-staged light gas gun system was determined on the basis of the test results.

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We propose a concept of human machine co-learning, in which the system learns the user's intention interactively, and the planner as a user learns the characteristics of the problem based on the solution represented by the system. In this paper, we propose a method to reflect the user's intention on the optimization by providing the interactive user interface connecting between "the design space", which is easier for a user to understand, and "the evaluation space", in which the system executes the optimization. We applied this idea to the NETSAT communication planning problem. NETSAT consists of existent multiple low-earth orbit satellites, and forms an ad hoc network dynamically according to the satellite position at the time when a certain communication is required. The effectiveness of our proposed method is evaluated by using the prototype system of the satellite simulator and interactive planner.

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To better understand the characteristics for preventing organic contaminants from accumulating on the critical surfaces of spacecraft, we studied on the effective prevention of molecular contaminants by using photocatalysts under ultraviolet irradiation and vacuum conditions. Squalene, tetra-methyl tetra-phenyl tri-siloxane, oleamide and diethylhexyl phthalate were used as model contaminants. TiO2 particles and TiO2-coated substrates were used as photocatalysts. TiO2 was effective in weight losses of all organics under the conditions. Transmittance of the TiO2-coated substrates increased depending on UV irradiation time.

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Analyzed in this paper are Near-Earth Asteroids sample return mission opportunities in early 2010s. The mission sequences supposed are Keplerian orbits connected with impulsive velocity changes including planetary gravity assists. The sequences are constructed by "trajectory parts connecting method", which is exploited by the author. The method enables to construct the possible sequences comprehensively under defined structure and given constraints. At the same time, it enables to assess the dynamical feasibility of the constructed sequences quantitatively by way of the total required velocity increment required to complete the sequences. Over 4000 Near-Earth Asteroids are taken into account as the candidates of the mission targets, and the mission sequences include not only the sample return from a single asteroid, but also the sample return from two asteroids. Lists of the asteroids (or their combinations) which have mission opportunities in early 2010s are provided and some example sequences are shown.

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The purpose of this paper is to analyze structural statics and dynamics of a rotating shaft with a thin-walled open cross-section having one symmetrical axis. For the shaft, flexural-torsional coupling must be considered because the centroid axis and the shear-center axis do not always coincide. After deriving the governing equations of motion for a uniform shaft rotating at a constant angular velocity, we propose methods to estimate static deflection and dynamic stability. Numerical calculations for cantilever shafts with and without internal damping indicate that the distance between the centroid and the shear-center contributes to the dynamic instability. Moreover, an application of the methods to an elastically supported model indicates that a spin-axis antenna rod for future scientific satellites under consideration is dynamically stable in the operational spin-rate.

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