著者

Takanao SAIKI Osamu MORI Jun'ichiro KAWAGUCHI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.14, no.ists30, pp.Pd_127-Pd_132, 2016 (Released:2016-11-26)

---

JAXA has developed a Jovian Trojan asteroid sample return mission using a solar power sail. Jovian Trojan asteroids are among the few remaining frontiers in our solar system and may hold clues to its formation and evolution. However, visiting Jovian Trojans is much more difficult than reaching near-Earth objects because of the large amount of fuel required to reach them. Moreover, large distance from the sun makes power generation difficult. Solar power sails offer an effective way of realizing such challenging exploration. This paper outlines a solar power sail spacecraft and discusses the design of a trajectory for a sample return mission to a Jovian Trojan asteroid. The time of flight is long, but a large payload can be delivered to the asteroid by using a solar power sail. Reducing the duration of a sample return mission is difficult, but it is possible for a one-way mission. This paper presents a trajectory design for such a one-way mission.

著者

Jun KIMURA Hauke HUSSMANN Shunichi KAMATA Koji MATSUMOTO Jürgen OBERST Gregor STEINBRÜGGE Alexander STARK Klaus GWINNER Shoko OSHIGAMI Noriyuki NAMIKI Kay LINGENAUBER Keigo ENYA Kiyoshi KURAMOTO Sho SASAKI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.2, pp.234-243, 2019 (Released:2019-03-04)

参考文献数

50

被引用文献数

4

---

Laser altimetry is a powerful tool for addressing the major objectives of planetary physics and geodesy. Through measurements of distances between a spacecraft and the surface of the planetary bodies, it can be used to determine the global shape and radius: global, regional, and local topography: tidal deformation: and rotational states including physical librations. Laser altimeters have been applied in planetary explorations of the Moon, Mars, Mercury, and the asteroids Eros, and Itokawa. The JUpiter Icy Moons Explorer (JUICE), led by European Space Agency (ESA), has started development to explore the emergence of habitable worlds around gas giants. The Ganymede Laser Altimeter (GALA) will be the first laser altimeter for icy bodies, and will measure the shape and topography of the large icy moons of Jupiter, (globally for Ganymede, and using flyby ground-tracks for Europa and Callisto). Such information is crucial for understanding the formation of surface features and can tremendously improve our understanding of the icy tectonics. In addition, the GALA will infer the presence or absence of a subsurface ocean by measuring the tidal and rotational responses. Furthermore, it also improves the accuracy of gravity field measurements reflecting the interior structure, collaborating with the radio science experiment. In addition to range measurements, the signal strength and the waveform of the laser pulses reflected from the moon's surface contain information about surface reflectance at the laser wavelength and small scale roughness. Therefore we can infer the degrees of chemical and physical alterations, e.g., erosion, space weathering, compaction and deposition of exogenous materials, through GALA measurements without being affected by illumination conditions. JUICE spacecraft carries ten science payloads including GALA. They work closely together in a synergistic way with GALA being one of the key instruments for understanding the evolution of the icy satellites Ganymede, Europa, and Callisto.

著者

Takane IMADA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.8, no.ists27, pp.Tg_1-Tg_10, 2010 (Released:2010-11-23)

被引用文献数

1 1

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This year will be a major milestone for JAXA with the launching of the new heavy rocket H-IIB and HTV (H-II Transfer Vehicle). Together they will form an important infrastructure for transporting supplies, equipment, and experiment modules to the LEO (Low Earth Orbit) station and will be the basic design of a manned spacecraft in the future. In the previous paper in ISTS in 2008, a preliminary study focusing upon the LES (Launch Escape System) and parametric analyses for its abort system was reported. The missing parts of a manned flight utilizing the combination of HTV and H-IIB are selected as the main structure in this paper. In addition, the progress made in spacecraft design is included along with its development plan in which important development items that have not yet been investigated enough in Japan are identified.

著者

Naoko OGAWA Yuichi TSUDA Yuto TAKEI Hiroka INOUE Shota TAKAHASHI Yasuhiro KAWAKATSU

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.3, pp.398-403, 2019 (Released:2019-05-04)

参考文献数

3

被引用文献数

3 4

---

The Martian Moons eXploration (MMX) mission is now under study by the Japan Aerospace Exploration Agency (JAXA). Its scope includes the world's first landing on one of the Martian moons, collecting samples from the surface, and returning to Earth. This paper describes the orbit design for MMX. Nominal and backup trajectories for launch in 2024 and 2026 are discussed. The Mars orbit insertion (MOI) sequence using 3-impulse maneuvers is introduced. A new scheme, the robust MOI, is also proposed as a contingency to enhance the robustness of the mission sequence. A method to design a robust MOI trajectory and examples are presented.

著者

Alperen PALA Toshinori KUWAHARA Takumi SAITOU Hiroki UTO Yoshihiko SHIBUYA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.20, pp.65-72, 2022 (Released:2022-12-21)

参考文献数

18

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Many satellites are currently in orbit around the Earth and will remain so for years, even though they have completed their intended missions owing to their long natural de-orbiting times. Many methods have been proposed to increase the de-orbiting speed of such satellites, of which one uses atmospheric drag sails. The micro-satellite ALE-1 is equipped with a drag sail that is deployed at a distance from the satellite through the use of a boom element to ensure continuous communication and solar charging. The drag sail is also capable of separating itself from the micro-satellite if necessary to decrease the de-orbiting speed. This paper discusses an in-orbit demonstration where the aforementioned boom element is extended, as well as the deployment of the aforementioned drag sail and com-pares the space and ground experiment results.

著者

Hyun-Ung OH Hye-In KIM Jeong-Ki KIM Jae-Seop CHOI Su-Hyeon KIM

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.62, no.5, pp.256-264, 2019 (Released:2019-09-04)

参考文献数

29

被引用文献数

3

---

This paper reports the Smart Call from the Sky (SCSky) Can Satellite (CanSat) platform developed by Chosun University, South Korea, with a focus on a smart material of shape memory alloy actuator applications. The primary objective of this study is to verify the effectiveness of a remote screen touch system using shape memory alloy wires. The system is currently being utilized to operate the on-board smartphone of a CanSat by telecommands from a ground station. It provides real-time streaming video showing the internal and external states of CanSat through video calls during actual flight. The secondary objective of the mission is to acquire a wide-scan image from the on-board USB cameras, whose elevation angles are actuated using shape memory alloy springs. The effectiveness of the design proposed was validated experimentally through actual flight tests using model rockets.

著者

Jun KIMURA Hauke HUSSMANN Shunichi KAMATA Koji MATSUMOTO Jürgen OBERST Gregor STEINBRÜGGE Alexander STARK Klaus GWINNER Shoko OSHIGAMI Noriyuki NAMIKI Kay LINGENAUBER Keigo ENYA Kiyoshi KURAMOTO Sho SASAKI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

pp.17.234, (Released:2019-01-31)

参考文献数

50

被引用文献数

4

---

Laser altimetry is a powerful tool for addressing the major objectives of planetary physics and geodesy. Through measurements of distances between a spacecraft and the surface of the planetary bodies, it can be used to determine the global shape and radius: global, regional, and local topography: tidal deformation: and rotational states including physical librations. Laser altimeters have been applied in planetary explorations of the Moon, Mars, Mercury, and the asteroids Eros, and Itokawa. The JUpiter Icy Moons Explorer (JUICE), led by European Space Agency (ESA), has started development to explore the emergence of habitable worlds around gas giants. The Ganymede Laser Altimeter (GALA) will be the first laser altimeter for icy bodies, and will measure the shape and topography of the large icy moons of Jupiter, (globally for Ganymede, and using flyby ground-tracks for Europa and Callisto). Such information is crucial for understanding the formation of surface features and can tremendously improve our understanding of the icy tectonics. In addition, the GALA will infer the presence or absence of a subsurface ocean by measuring the tidal and rotational responses. Furthermore, it also improves the accuracy of gravity field measurements reflecting the interior structure, collaborating with the radio science experiment. In addition to range measurements, the signal strength and the waveform of the laser pulses reflected from the moon's surface contain information about surface reflectance at the laser wavelength and small scale roughness. Therefore we can infer the degrees of chemical and physical alterations, e.g., erosion, space weathering, compaction and deposition of exogenous materials, through GALA measurements without being affected by illumination conditions. JUICE spacecraft carries ten science payloads including GALA. They work closely together in a synergistic way with GALA being one of the key instruments for understanding the evolution of the icy satellites Ganymede, Europa, and Callisto.

著者

Mohamed Yahia EDRIES Atomu TANAKA HORYU-IV Team Mengu CHO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.14, no.ists30, pp.Pf_7-Pf_16, 2016 (Released:2016-02-13)

被引用文献数

3 3

---

HORYU-IV is a lean satellite weighing 10 kg or less designed at the Kyushu Institute of Technology. It is planned to be launched with the ASTRO-H in FY2015 as a piggyback on an H-IIA rocket. The main mission of HORYU-IV is to acquire on-orbit data of discharge phenomena occurring on high-voltage solar arrays. An electrical power subsystem (EPS) is one of the HORYU-IV bus subsystems. The function of the EPS is to provide uninterrupted power to all subsystems during the satellite's lifetime. High reliability, high efficiency and simplicity are the main requirements to be considered in the design of an EPS. Generally, an EPS consists of solar arrays, rechargeable batteries, and a power control and distribution unit (PCDU). A peak power tracking topology is preferred to extract the maximum power generated by the solar arrays. The extra energy is stored in nickel-metal hydride batteries. The simple design and usage of available commercial-off-the-shelf components are the main features of the PCDU which controls the battery charging and load voltage regulation. Functional tests under different operating conditions were carried out on the designed EPS to qualify its performance. The aim of this paper is to explain the design of the EPS, and to present and analyze the test results.

著者

Hiroki UTO Toshinori KUWAHARA Tomoyuki HONDA

出版者

The Japan Society for Aeronautical and Space Sciences

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.3, pp.295-300, 2019

被引用文献数

7

著者

Yuri MATSUSHITA Yasuhiro YOSHIMURA Toshiya HANADA Yuki ITAYA Tadanori FUKUSHIMA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.20, pp.10-15, 2022 (Released:2022-02-05)

参考文献数

11

被引用文献数

2

---

This paper aims to assess the risk of mission termination for a large constellation of satellites in a low-Earth orbit. Many large constellations will be deployed to provide broadband network services using thousands of satellites. There is concern that such large constellations will have a serious impact on the long-term sustainability of outer space activities due to the rapid increase in population. First, therefore, the authors conducted an assessment under nominal activities (referred to as “business-as-usual”) on the basis of a prediction by ESA’s MASTER-2009 and NASA standard breakup model 2001 revision. The assessment found that nearly one catastrophic collision may happen in a large constellation, generating more than two million fragments as small as 1 mm in size. Second, the authors conducted a further assessment assuming a hypothetical collision of a satellite in a large constellation using the NASA standard breakup model and a spherical finite element model adopted in ESA’s MASTER-2009. In consequence, another catastrophic collision may happen to a large constellation, generating approximately a half-million fragments as small as 1 mm in size. Therefore, such catastrophic collisions and resulting secondary collisions should be prevented for large constellations.

著者

Hideki UCHIYAMA Takeshi MACHI Michitaro NAKAMURA Yoshiyuki GUNJI Satoshi NOZAWA Masahiro NOHMI Mami SAITO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.19, no.4, pp.616-620, 2021 (Released:2021-07-04)

参考文献数

4

---

We propose a new educational use of a nanosatellite for high school and junior high school students, and not making a nanosatellite but using it. We held a workshop in which high school and junior high school students made observation plans using Stars-AO, which is a CubeSat equipped with a high-sensitivity visible-light camera. We evaluated the educational effects of the workshop by analyzing the response writings of the students and their replies to questionnaires. The participants' abilities and interest in science and space engineering increased because of the workshop. In this study, we report the workshop details and evaluation of its educational effects.

著者

Hiroshi ARAKI Ko ISHIBASHI Noriyuki NAMIKI Hirotomo NODA Masanori KOBAYASHI Keigo ENYA Masanobu OZAKI Takahide MIZUNO Yoshifumi SAITO Kazuyuki TOUHARA Shoko OSHIGAMI Shingo KASHIMA Jun KIMURA Shingo KOBAYASHI Gregor STEINBRUEGGE Alexander STARK Christian ALTHAUS Simone Del TOGNO Kay LINGENAUBER Hauke HUSSMANN

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.2, pp.150-154, 2019 (Released:2019-03-04)

参考文献数

10

被引用文献数

1

---

GALA (GAnymede Laser Altimeter) is one of the payload instruments of the JUICE (JUpiter ICy moons Explorer) project to be launched in 2022 to the Jovian icy moons Ganymede, Europa, and Callisto. GALA is developed through an international collaboration between Germany, Japan, Switzerland, and Spain. With the performance model of GALA, we have sought to create the interface conditions that satisfy the science requirements on the probability of false detection (PFD) and the range accuracy. The science requirements on GALA performance can be summarized as involving the following four criteria: [1] for Europa fly-by, PFD is less than 0.2 from an altitude of 1300 km or lower, [2] under the worst observation condition for albedo and surface slope of GCO500 (Ganymede Circular Orbit whose height is 500 km), the accuracy of ranging is less than 10 m and PFD is less than 0.2, [3] under the nominal observation condition of GCO500, the accuracy of ranging is less than 2 m and PFD is less than 0.1, and [4] under the best observation condition of GCO500, the accuracy of ranging is less than 1 m and PFD is less than 0.1. For the assessment, however, we had used literature data as the characteristics of the laser detector of GALA, avalanche photodiode (APD), which should be degraded due to the severe radiation environment around Jupiter. Then we carried out a more realistic model simulation of GALA by incorporating these degradation effects of APD. Characteristics of APD, such as gain, quantum efficiency, excess noise index, surface dark current, and bulk dark current, were re-evaluated through radiation tests using the data of dark and photo current of the APD irradiated with 2-MeV-electron and 50-MeV-proton beams, which are the radiation conditions assumed for JUICEGALA around Jupiter. These degraded characteristics of APD by radiation were introduced to our performance model of GALA. As a result, our performance simulation of GALA showed again that the science requirements are satisfied even after taking into account the degraded characteristics of APD. The remaining matter is the effect of noise or digitization in the Analog Electronics Module (AEM), which must be taken into account for the final specifications of GALA.

著者

Takeshi KANDA Masaki SATO Toshiya KIMURA Hiroya ASAKAWA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.61, no.3, pp.106-118, 2018 (Released:2018-05-04)

参考文献数

37

被引用文献数

5 5

---

This paper describes the characteristics of methane-fueled rocket engines and compares these characteristics with those of hydrogen-fueled engines in terms of both expander and coolant-bleed cycles. Methane vaporizes in a cooling jacket under low-pressure operating conditions, whereas it liquefies in the turbine in the coolant-bleed cycle. The thermodynamic property of methane limits the operating range of methane-fueled engines. When the coolant-bleed cycle is used, the specific impulse degradation of methane-fueled engines becomes larger compared to that of hydrogen-fueled engines. This is due to methane having a lower specific heat and temperature after regenerative cooling. Even though the heat absorbing ability of methane is much lower than that of hydrogen, methane-fueled engines can operate with higher chamber pressures using the expander cycle. This is due to the larger density and the higher temperature after the regenerative cooling of liquid methane. Throttling of the methane-fueled engines does not have a great impact on the pump exit pressure in the expander cycle, whereas it increases the bleed ratio and degrades the specific impulse in the coolant bleed cycle of methane-fueled engines.

著者

Shota TAKAHASHI Naoko OGAWA Yasuhiro KAWAKATSU

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.17, no.3, pp.404-411, 2019 (Released:2019-05-04)

参考文献数

9

被引用文献数

1 2

---

Failure of the orbit insertion maneuver has a significant impact on the entire mission, for the trajectory of a spacecraft is largely deflected by swing-by. The risk can be reduced by targeting a point on the B-plane where the spacecraft reaches the free-return (FR) trajectory with the target body in the case of insertion failure. The backup orbit must also satisfy conditions suitable for the mission. We investigated the type of orbit insertion that is both robust to failure and reasonable for the mission requirements. We call this method FR ensured orbit insertion. Among various failure modes of the orbit insertion maneuver, we focus on the complete maneuver failure. The impact parameters on the B-plane to achieve the orbit insertion are formulated based on the geometry of velocity vectors at swing-by. The necessary deflection angle αFR at swing-by must be smaller than the possible maximum deflection angle αmax for the target body. When we introduce proper scaling factors, the relation of αmax and αFR is characterized by a single parameter λ. Using polar orbit insertion as an example, maps which show the reachability of FR trajectory after the insertion failure for each approaching condition are presented. The derived maps can be used as a tool to assess the applicability of the method in the mission design. Finally, as an application to practical mission design, we demonstrate the use of FR ensured orbit insertion in JAXA's MMX mission.

著者

Yuichi TSUDA Takanao SAIKI Fuyuto TERUI Satoru NAKAZAWA Makoto YOSHIKAWA Seiichiro WATANABE Hayabusa2 Project Team

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.4, pp.115-123, 2020 (Released:2020-07-04)

参考文献数

8

被引用文献数

2

---

Hayabusa2 arrived at the asteroid Ryugu in June 2018, and as of April 2019, the mission succeeded in conducting two rovers landing, one lander landing, one spacecraft touchdown/sample collection and one kinetic impact operation. This paper describes the initial nine months of the asteroid proximity operation activity of the Hayabusa2 mission, and gives an overview of the achievements thus far. Some important engineering and scientific activities conducted synchronously with spacecraft operations in order to complete all planned operations in time against unexpectedly harsh environment of Ryugu are also described.

著者

Keiyu HANDA Masato FUNATSU Kenji SHIBUSAWA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.18, no.5, pp.209-215, 2020 (Released:2020-09-04)

参考文献数

14

被引用文献数

1

---

Recently, various unmanned and manned Mars exploration programs have been proposed. To send a space vehicle safely to the ground of Mars, the vehicle needs to be protected from the aerodynamic heating. The accurate prediction of the aerodynamic heating is important for the design of safe and light-weight thermal protection system. For the accurate prediction, it is necessary to simulate the plasma generated behind the shock wave and to clarify its internal state. To investigate the state of the plasma, spectroscopic measurement is useful. We performed the spectroscopic measurements of carbon dioxide (CO2) plasma generated using microwave discharge under the pressure condition during Mars entry. To investigate the basic characteristics of microwave-discharged CO2 plasma, the spectra of the radiation were obtained in the wavelength region of 200 to 800 nm. As a result, carbon monoxide (CO) fourth positive bands, CO third positive bands, CO Ångström bands, and atomic oxygen lines were observed. Electronic excitation temperature was also estimated by the Boltzmann plot method for the atomic oxygen lines.

著者

Ryodo HEMMI Hideaki MIYAMOTO

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.63, no.4, pp.124-131, 2020 (Released:2020-07-04)

参考文献数

30

被引用文献数

5

---

Estimating the regolith properties of Phobos’ surface is of critical importance for the landing and performance of the Martian Moons eXploration (MMX) sample return mission. Regolith physical properties such as strength, regolith thickness, and the presence of regolith layers are related to morphologies of superposing impact craters. However, the accurate depths of Phobos’ sub-kilometer-diameter craters including irregularly shaped craters have not yet been fully characterized. Here, by using our high-resolution (20 m/pixel) digital elevation model of the nearside (or the sub-Mars side) of Phobos, we investigate the topographic profiles of the sub-kilometer craters. We confirm the presence of crater rims, and bowl-shaped, central-mound, and flat-floored crater geometries. The topography of one flat-floored crater is consistent with a boundary of regolith layers at a depth of ~160–180 meters. Morphometric measurements of 35 sub-kilometer craters show that their depth-to-diameter (d/D) ratios are in the range of 0.037 and 0.174 (mean value = 0.089, median value = 0.093). This suggests either a surface layer composed of rocky debris that effectively dissipates impact energy and causes a reduction in crater depth, or subsequent resurfacing events changed the original crater topography.

著者

Yoshiki YAMAGIWA Koki TAO Shoji SATO Kiyotoshi OTSUKA Yoji ISHIKAWA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.16, no.2, pp.165-171, 2018 (Released:2018-03-04)

参考文献数

12

---

The understanding of cable dynamics is one of the most important issues for the design and construction of a space elevator. We propose a new method for constructing the space elevator by simultaneously deploying cables upward and downward from the main space station maintained in GEO and balancing both cables. The analysis is performed using our originally developed cable dynamics model. The model is a two-dimensional lamped mass model. In the model, the tether is modelled by mass points, which are connected to each other by a spring and a damper, and are pulled out per assumed length. In this study, we first analyze the cable dynamics and stress for assumed deployment conditions of the cables. We then obtain the total impulse necessary to keep the main station in GEO and control the cable speed during deployment so that it does not exceed the maximum stress of the cable. The results are also compared with the preceding method for the same conditions. The initial result shows that with the proposed cable-deployment method, the total propellant mass necessary to control cable dynamics while maintaining the station in GEO can be decreased by about one-third compared with that necessary to raise the main station to higher orbit and to control cable dynamics as in the preceding cable-deployment method.

著者

Kengo IKEMA Anna V. GUBAREVICH Osamu ODAWARA

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN (ISSN:18840485)

巻号頁・発行日

vol.8, no.ists27, pp.Pp_1-Pp_5, 2010 (Released:2010-12-28)

参考文献数

1

被引用文献数

1 1

---

Toward future exploration programs on planetary surface, a study on flexibility of joint structure of space suit has been carried out with the aid of an origami technology. Since space suits are pressurized inside, it is necessary to design a pneumatic fabric tube which is able to bend easily. A new joint structure, Membrane-Beam Folding Structure (MBFS), is proposed in the present work to give flexibility to pneumatic tubes. MBFS represents a fabric tube with metal beams attached according to the Yoshimura folding pattern. In order to investigate structural characteristics of MBFS, axial elongation and bending tests are carried out for examining effects of pressurization and external bending moment, respectively. The axial elongation test shows spring-like behavior of MBFS that is explained by restoring force which metal beams produce. The results of bending test show that large deformation of MBFS starts even by initial loading although a 15 kPa-pressurized fabric tube requires 50 N to start large bending deformation. It is confirmed that prestress induced by internal pressure has been mostly counterbalanced with equivalent restoring force. The value of restoring force necessary for starting an immediate bending has been estimated by a numerical analysis based on applied Euler-Bernoulli beam theory.

著者

Kazuki ISHIHARA Kentaro YONEYAMA Tomoki SATO Hiroaki WATANABE Noboru ITOUYAMA Akira KAWASAKI Ken MATSUOKA Jiro KASAHARA Akiko MATSUO Ikkoh FUNAKI

出版者

THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES

雑誌

TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES (ISSN:05493811)

巻号頁・発行日

vol.66, no.2, pp.46-58, 2023 (Released:2023-03-04)

参考文献数

57

被引用文献数

4

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Rotating detonation combustors (RDCs) are among the combustors that use supersonic combustion waves known as detonation waves, and are expected to simplify engine systems and improve thermal efficiency due to their supersonic combustion and compression performance using shock waves. Research is also being actively conducted worldwide on a cylindrical RDC; a RDC without an inner cylinder, which is expected to simplify and downsize the combustor. However, most of the research was performed using gas propellants, and liquid propellants were rarely used. Since liquid propellants are used in many combustors, it is important to evaluate the performance of RDCs with liquid propellants. In this study, a cylindrical RDC with a liquid ethanol–gas oxygen mixture was constructed and tested at a flow rate of 31.5 ± 5.0 g/s, an equivalence ratio of 0.46–1.39, and a back pressure of 14.5 ± 2.5 kPa. The thrust was shown to depend strongly on the combustor bottom pressure history. In addition, the start-up process of the cylindrical RDC with liquid fuel was clarified by self-luminous and CH* radical visualizations. It was found that the detonation wavefront propagated at a distance of 2–3 mm from the combustor bottom, and the main combustion region was 10–15 mm in height.