Recently, products and service have become more and more complex, and have been desired to be released rapidly. Therefore, not only national projects but also small team projects have become to need system thinking and system engineering (SE) process. However, it is difficult to introduce conventional SE processes into the small team project such as university-led nanosatellite projects, because the SE process is far different from their present process. This research aims to develop a web application including its methodology to realize open model-based collaboration (Open MBC), which is a framework to support efficient and collaborative development of complex systems. This paper describes the concept of Open MBC, concrete processes, and the features of the web application. Open MBC is a fusion of a system model, a collaborative work flow, and an open engineering platform. The system model graphically represents the relationships among elements. The collaborative work flow provides efficient collaboration and further functions as a platform for promoting the re-discovery and reuse of knowledge. Open MBC holds communication among engineers in great account. It provides communication on system models, same as GitHub provides communication on codes. We believe that feedbacks and lessens learned from experienced engineers should improve low motivation of young engineers. Our application is called BALUS (browser-based assisted library universal system design application), and runs on a web browser, such as Google Chrome. Users are not requested to install software on their own computer, and can use the application even with a smart phone or a tablet. We conducted design education programs using BALUS. It revealed that BALUS was useful for the MBSE education and activities of students and engineers of small and medium-sized enterprises where no SE professionals are employed. The result of questionnaire from students showed that the feature to create requirement diagrams rapidly and concurrently helped beginners to learn “System Thinking.”

Along with the improved accuracy of MEMS gyroscopes and accelerometers in recent years, JAXA has been studying a navigation-grade Inertial Measurement Unit (IMU) using MEMS gyroscopes and accelerometers for launch vehicles. One issue regarding application of the MEMS IMU for launch vehicles is how to maintain measurement accuracy under high vibration environment during the launch phase. We thus developed a trial model of high accuracy MEMS IMU and evaluated its measurement accuracy under a high vibration environment by conducting random vibration tests. This paper presents the issues of the MEMS IMU for launch vehicles, trial model of the MEMS IMU, and evaluation results of the MEMS IMU under a high vibration environment.

In this study, the momentum of the target when collided with a projectile at hypervelocity was measured. Pendulum targets were used in the experiments. The momentums of the target were calculated based on the maximum swing angle of the pendulum. The target material is comparable to aluminum alloy which was used for the rocket body. It is confirmed that, as the impact velocity increases, the ratio of momentum of the projectile before impact and the momentum of the target after impact changes. Furthermore, as the thickness of the target changes, the ratio of momentum of the projectile before impact and the momentum of the target after impact changes.

We examined the effects of impact angle on the penetration depth and hole size of two kinds of ultra-high molecular weight polyethylene fiber fabrics when spherical projectiles with a diameter of 1 mm made of aluminum alloy 2017-T4 obliquely struck the fiber fabrics. Impact velocities were 2 km/s and 5 km/s. In the case of fiber fabrics with high fabric density, the absorbed energy per penetration depth at the impact angle of 45 deg. was greater than that at the impact angle of 0 deg. On the other hand, the absorbed energy per penetration depth of fiber fabrics with low fabric density at the impact angles of 30 deg. and 45 deg. was smaller than that at the impact angle of 0 deg. The impact angle clearly affected the hole size of projectile penetration and its tendency. The penetration mechanism was also discussed.

It is known that aerodynamic characteristics of a slender body vary substantially at high angles-of-attack (AoAs), and then, will have strong impacts on its flight. For, example, the yaw force makes flight unstable. In this study, we investigated the relation between the yaw force and the configuration, and details of flowfield around the slender-bodied-vehicle numerically. The configuration consisting of “nose cone” and “square aftbody” parts was employed as the baseline, and then, compared with other three configurations having different fineness ratios. According to our computed results, in the case of 50 degrees of AoA, the longer the model became, the more asymmetry appeared: yaw force and asymmetry were found to be attributed not only to the length of the body, but also to the nose bluntness. On the contrary, in the case of 140 degrees, the shorter the model became, the more asymmetry appeared. Furthermore, the large nose bluntness increased C_Y. Interestingly, this trend is totally opposite to that observed at 50 degrees. It had been considered that the large nose bluntness and the small fineness ratio can reduce asymmetry and C_Y, however, this study showed that it is not true in the case over 90 degrees, due to complex wake flow structure discovered in the present numerical simulations.

This paper proposes static attitude and rate feedback controllers with an observer-based disturbance estimation technique for the attitude control of spacecraft inertial pointing, using only magnetic torquers. Disturbances widely exist in real-world control systems and bring adverse effects to the performance of control systems. Since the disturbances cannot be measured directly, a modified nonlinear disturbance observer was applied to estimate the system uncertainty including unknown moments of inertia and external disturbances, and then to introduce feedforward compensation to cancel it. The numerical simulation results demonstrate that the proposed new control approach allows faster convergence of the closed-loop system to the desired equilibrium and better control efficiency under the lumped uncertainty.

This paper discusses a transfer system between the Earth and Mars orbit using electric propulsion under the assumption of launching the H-IIA launch vehicle on a one-way trip. The spacecraft was assumed to be launched into the geocentric orbit, then transferred to the Earth's heliocentric orbit using electric propulsion or a kick motor, and further transferred to Mars revolving orbit using electric propulsion. The dependency of the payload mass on the specific impulse of the propulsion and launch system were investigated by performing orbit optimization based on the direct collocation method. As a result, the most suitable transfer method to Mars orbit was the combination of a kick motor from the geostationary transfer orbit to the Earth's heliocentric orbit, and subsequently the use of electric propulsion to transverse to Mars orbit with C₃ = 9 km²/s². The maximum payload mass was 1,500 kg for a specific impulse of 3,000s.

The coking phenomenon within a lightweight carbon-phenolic ablator exposed to the heating environment of air is investigated. The existing one-dimensional charring ablation analysis code is modified so that the coking behavior of the ablator can be calculated as well as the thermal response behavior within a lightweight carbon-phenolic ablator. The mass conservation equations for a pyrolysis gas and carbon in the gas are given. The energy equation including the coking process is also presented. The measured density distributions of some arc-heated CFRP ablator samples are compared with those calculated by the ablation analysis code, from which good agreement is obtained. The density profiles with and without coking are compared. The effect of temperature dependency of carbon mass fraction in a pyrolysis gas in the coking equation upon the density profile is examined. The effect of heating rate upon the density distribution in an ablator is also examined. The effect of coking upon the surface recession is studied analytically and experimentally.

The objective of this paper is to study the effect of observation by Angle Only Navigation to plan non-cooperative Active Debris Removal approach for debris mitigation, and to have a concept of criteria for safe operation and mission assurance.

We have been developing a microsatellite based on our concept of a satellite to meet the potential needs of challenging space-science missions that only a microsatellite can accomplish. A binary black hole (BBH) is a state in which two black holes at the center of their respective galaxies are closing the orbital distance around each other. Observations using conventional large satellites have obtained insufficient results for BBH exploration because the satellites cannot be engaged in the long-term and concentrated observation of astral body such as BBH which is not established the existence. Microsatellites have two advantages; namely, they can be occupied with long-term observation, and they have a low-cost and short-term development compared with large satellites. Thus, we can possibly program a challenging mission for a microsatellite, even with a certain risk. We implemented two key technologies on our microsatellite named ORbiting Binary black-hole Investigation Satellite (ORBIS), namely, a Distributed Architecture with a Common Signboard System and mission-equipment space for astronomical observation equipment. The specifications and progress of each subsystem are reported in this paper, along with an outline and the current status of the ORBIS development.

This paper proposes a novel passive sun-oriented control using the solar radiation pressure torque. Satellites that solar array panels are allocated as an umbrella is assumed. The top of the umbrella is oriented to the sun direction by the sun pressure and its weathercock stability. In order to dump the oscillation, a reflectance control device is attached on the solar array panels. The method realizes the sun-oriented without any other attitude control devises in the satellite. The availability of the method is evaluated in case of a solar-sail type spacecraft, a 50cm-class LEO satellite, and a 1U CubeSat by numerical simulations. Furthermore, a combination of the proposed control and the other passive attitude control is discussed.

We propose a method that enables a satellite to decide its operation mode by using a distributed architecture with a common signboard subsystem, where each subsystem is regarded as an independent player in a game; we then simulate the operation mode and its transition in the satellite, based on game theory. The status of the satellite is expressed with the remaining-battery ratio and data-accumulation ratio on two axes, and we define two thresholds for each axis. By adopting a dynamic cooperative game model, in which the thresholds are determined dynamically, the mode transition was adjusted depending on the satellite status, and the time efficiency of the mission mode was improved.

OMOTENASHI is a 6U CubeSat that will be launched in 2019 by the Space Launch System (SLS) with the objective of landing on the Moon. The CubeSat is planned to perform two deterministic maneuvers. The first maneuver (DV1) by gas jet propulsion system transfers the probe from the nominal SLS trajectory to a lunar targeted trajectory. The second maneuver (DV2) is applied by the solid rocket motor before landing to counteract the vertical component of the S/C velocity. The high approach speed at the Moon, combined with large errors induced by the solid motor, requires the probe to approach the Moon with a shallow Flight Path Angle (FPA). If the angle is too steep, expected errors in the DV2 may cause the probe to crash. However, a shallow FPA increases the probability of a Moon-flyby or collision with the local topography. In this paper, we present a design method for Earth-Moon transfer trajectory robust to orbit determination (OD) and DV1 execution errors. First step consists of a grid search to determine the nominal DV1 vector with four candidates obtained. Subsequent error analysis suggests the need for a Trajectory Correction Maneuver (TCM). For the two scenarios of OD error provided by the navigation team, an error analysis was conducted including the TCM. Two realistic OD error scenarios were considered: 30 min or 3 hours of two-way Doppler and range measurement. Error analysis conducted considering TCM shows the need for 3 hours of OD to achieve nearly 100% of transfer success rate.

JAXA offers a program called “Aerospace School” to high school students as a form of informal education. Participants are divided into teams and work together to come up with a theme for their mission at various JAXA facilities. They also allocate roles and responsibilities among themselves. The goal is not only to provide Science, Technology, Engineering and Mathematics (STEM) knowledge, but also to build their confidence. We hope this experience will help young adults think about their future career paths, and we strive to actively help them realize their potential. This paper presents the methods, specific examples of, and changes to the Aerospace School program that occurred between 2014 and 2017.

Airplanes are paid attention as a new platform for Mars exploration. A high-altitude flight test using balloon was conducted in June 2016 by Japanese working group for Mars exploration aircraft. This paper reports a method of control gain tuning for the flight test using evolutionary computation approach. This method can find optimal robust control gains efficiently and automatically. The combination of the control gains are evaluated by the simulations of a finite number of the dispersion conditions defined by the sensitivity analysis. A summary of a flight test, a control law, an optimization method, a flight simulation method, an evaluation function setting, and an optimization result are described.

This paper describes the error and uncertainty analysis of the CAMUI hybrid rocket regression simulator. Simulation errors compared to test firings are described and followed by an analysis of the potential uncertainties causing this error. For each uncertainty identified, a sensitivity analysis is then performed with the help of a custom-built simulator to evaluate its impact on the simulator accuracy. It was found that uncertainties in LOX travel time, Reynolds number grouping and model assumptions for the first upstream burning surface have the largest impact on the simulator accuracy and are identified as the main focus points for further research.

To analyze the effects of a magnetic-field distribution and an ambient pressure on the axial, lateral, and angular impulses of a microwave rocket sustained by an external magnetic field, a shock wave propagation was numerically reproduced by solving a compressible fluid dynamics equation. This equation involved an energy source evaluated based on a fully kinetic simulation coupled with an electromagnetic wave propagation. The external magnetic field having a lateral offset against the vehicle axis was applied to the microwave-rocket nozzle to induce the asymmetric shock wave for obtaining the postural control force. Negative impulses in the lateral and angular directions were obtained when the magnetic field with a lateral offset of 3.0 cm was applied to the discharge region at ambient pressures of 0.003 atm. However, the directions of the lateral and angular impulses reversed when the ambient pressure was changed from 0.003 atm to 0.006 atm, despite maintaining the lateral offset of the magnetic field at 3.0 cm because the decay timing of the shock wave inside the rocket nozzle was changed. It is necessary to increase the vehicle radius or decrease the energy absorbed by the plasma to obtain the same direction impulse, regardless of the ambient pressure, because postural control is difficult when the impulse direction depends on the ambient pressure.

Thrust-generation processes were numerically reproduced using a computational fluid dynamics code in a microwave-rocket system. The nozzle-shape dependence of the thrust performance was evaluated when an external magnetic field satisfying electron cyclotron resonance heating condition was applied to the rocket nozzle to enhance shock waves induced by the microwave irradiation. A larger-radius nozzle could not cancel out a negative thrust after a positive thrust because compression waves reflected from an open end of the rocket nozzle became weaker. Utilizing the smaller-radius nozzle is better to achieve the higher thrust performance because the faster and stronger pressure restoration is obtained from the open end of the rocket nozzle.

On-board orbit determination (OD) using directions of celestial bodies, planets and asteroids, in the Solar System for the Autonomous Navigation (AutoNav) is introduced in this paper. For deep space missions, OD has been performed by Range and Range Rate (RARR), which is a traditional ground tracking approach by radio waves. RARR enables the higher accuracy of OD than other methods. However, such radio navigation has the inevitable problems, such as strength reduction of radio waves and the transmitter limitation. Furthermore, people must stay and operate the spacecraft on the ground station, which makes the operating cost and burden considerable. Therefore, there has been a growing interest in the autonomy of the spacecraft in recent years to avoid the above-mentioned problems. This paper considers on-board OD using directions of celestial bodies from spacecraft. In particular, the selection of target bodies to observe is focused on because it's important that the selection of such target bodies leads to the satisfaction of mission requirements or increment of scientific observation. Then, this paper presents the method for the target selection, which is computationally cheap and makes the target selection easy.

A new performance parameter titled “tubular equivalent regression rate” is introduced to evaluate burning rates in hybrid rockets with geometrically complex solid propellant grains. Tubular equivalent regression rates are calculated for eight previously reported CAMUI-type hybrid rocket firing tests and compared with extrapolations of previously reported empirical correlations for classic, swirl and vortex hybrid rockets. A non-dimensional number titled “CAMUI Number” is introduced to evaluate how CAMUI-like a solid propellant grain is. The CAMUI Number ranges from 0-1: 0 means no CAMUI-type blocks are used, 1 means only CAMUI-type blocks are used. The results show that the tubular equivalent regression rate increases logarithmically with CAMUI Number, and approaches a value of around 3 [mm/s] for a CAMUI Number of 1. This increase in tubular equivalent regression rate is shown to correspond to an increase in performance range from a classic (tubular) hybrid rocket at low CAMUI Numbers (0.1) to surpassing a vortex hybrid rocket for high CAMUI Numbers (>0.7). Furthermore, through the block-by-block analysis of tubular equivalent regression rate in a fuel grain with a CAMUI Number of 0.71, it is shown that maximum burning rates were achieved in blocks under slightly oxidizer rich conditions.

To realize indoor location based services, indoor positioning function is the main function. However, available solutions such as Google Maps are not provided yet. In most cases, it is necessary for the service provider to develop the positioning environment themselves. We consider that this point is one of the reasons why indoor positioning technology has not spread significantly. In this study, we defined “the simplification of developing indoor positioning environment” as “to realize the development of an indoor positioning environment by a user,” and proposed a method for process optimization to solve the indoor positioning environment issue using a design structure matrix. Moreover, we verified the effectiveness of the proposed method by applying it to an existing use case of developing an indoor positioning environment and validated that the proposed method can create an optimized process.