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There are some tethered-systems. The range of a tension is expected to become micro level in 10(exp -2) N in micro power to control the structure in space. The SSPS (Space Solar Power System) Project is as an example to control the vibration of the structure by using the tether technology. This is a system that generates electricity, converts the electric power into the microwave in space, and transmits it to the earth from space, and tether is used to control the vibration of the solar panel. The tether moves in accordance with the panel vibration and the speed resulting in the tether. A contact less measurement device is expected in order to measure the micro order tether tension and speed from the point of the observation. The method of measuring the tether tension and the speed without touching tether is studied in this paper as a contact less measurement method. The tether tension can be measured without any disturbance in this method. This paper examines experimentally the method to measure the tether tension and speed without contact by employing a laser displacement sensor., 資料番号: AA0063965021

In order to construct SPSes (Space Power Station) and space stations, much cheaper method to bring material for construction is necessary. Here, the space tugboat is suggested for this purpose, which uses the JxB arc-jet propeller, solar energy and solid propellant. Basic experiment of the JxB arc jet propeller is carried out to obtain large thrust density and stability of the arc-jet. By controlling the magnetic filed, arc gap, electrode length, discharge current, etc., we could obtain high thrust density. In this propeller, carbon and aluminum can be used as propellant., 資料番号: AA0063965025

Japan Aerospace Exploration Agency (JAXA) has been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. JAXA is proposing a roadmap that consists of a stepwise approach to achieve commercial SSPS in 20-30 years. Current SSPS study undertaken by JAXA consists of three main subjects. SSPS concepts and architectures study, technology flight demonstration and major technology development. In SSPS concepts and architectures study, special committee and working groups which include 180 or more persons participate from industrial, administrative and academic sectors are organized. And some configurations of SSPS has been studied. This paper presents the results of these study effort in 2007., 資料番号: AA0063965027

This paper studies attitude and vibration control of tethered Space Solar Power Satellite (SSPS), which is the concept of a manned lunar landing to establish the lunar base. The purpose is to launch SSPS on the moon circular orbit and to build a system for supplying electric power. The large flexible panel is excited on its vibration according to change of attitude. The input torque for changing attitude is analyzed by Optimal-Control Theory and secondly, excited vibration of the panel is analyzed and then, control algorithm is studied for the system. The method of control uses the tether tension of the Mission-Function Control algorithm., 資料番号: AA0063965020

SSPS (Space Solar Power Station) transmits power to Ground by using 5.8 GHz microwave. This microwave has the possibility to cause discharge on solar arrays of SSPS by leaks and diffractions. Satellites that pass under SSPS also have the same possibility, because they are momentarily irradiated by microwave. Therefore, we carried out on experiment to irradiate solar cells with microwave, and analyze the discharge occurrence. We used 20 mm x 40 mm solar cells and 35 mm x 70 mm solar cells in the experiment, and used a microwave of 400 W. Discharges occurred only with the 20 mm x 40 mm solar cell, and the 35 mm x 70 mm solar cell had no discharges even for the 400 W irradiation. Points of discharge were concentrated on the inter-connector and the N electrode of the solar cell. So we concluded that the discharges involved the shape of the solar cell electrode. It seems that electric field concentrates on the electrode. Both the influence of the electric field concentration and the outgas in the experiment using real solar cell are closely related. Therefore we made samples that imitated the electrodes of a solar cell on a polyimide film. We then irradiated the samples with the microwave, but we could not confirm a discharge on the samples. For this reason, we considered that the discharges didn't generate by the influence of the electrode shapes. We considered the influence of the gas that was generated from the adhesive, and we made the sample that is nearest to a real solar cell. As a result, we irradiated the sample with the microwave, and we confirmed a discharge on the sample. For this reason, we considered that outgas from the adhesive and the concentration of the electric field by the electrode shapes is necessary., 資料番号: AA0063965013

Space solar power station needs an energetic and efficient laser as the energy transfer device from a broadband solar light to a coherent laser light. The concept of active-mirror amplifier with transparent Nd/Cr:YAG (Yttrium Aluminum Garnet) ceramics is proposed under consideration how to convert a wide spectrum of sun light to a monochromatic laser light. New ceramic material pumped by an arc-metal-halide lamp has been implemented experimentally as a fundamental prototype for the space solar power station. CW (Continuous Wave) laser light generated in a LD (Laser Dye)-pumped 1,064-nm Nd:YAG rod laser oscillator was amplified so that a spatial mode of laser output has been improved to Gaussian mode. The saturated amplification of output laser power was observed at around 40 W/sq cm in output power density when the diameter of input laser profile was 18 mm. The maximum output laser power obtained was up to 180 W (about 60 W/sq cm) with keeping spatial beam quality when Nd:YAG ceramics doped Cr ions density of 3 percent was used., 資料番号: AA0063965018

本研究では、2006年度にUSEF(Institute for Unmanned Space Experiment Free Flyer)で提案された太陽発電衛星(SPS: Solar Power Satellite)の設計点の安定性を評価している。このSPSは、発送電パネル部、バス部、それらを繋ぐテザーから成る。原案システムと派生型の静的釣合システムに対して、最小ポテンシャルエネルギの原理とシミュレータの2つの方法で、平衡点を求め、安定性を評価する。解析の結果、原案システムはパネルが撓むが安定な平衡点を持ち、静的釣合システムの1つはパネルの撓まない安定な平衡点を持つことが示される。次に、静的釣合システムを柔軟多体系でモデル化してシミュレーションを行う。柔軟多体系でモデル化した場合、パネル弾性変形が現れると剛体多体系での解析結果と異なる解析結果が得られる場合があることが示される。, This study evaluates stability of the design points of Solar Power Satellites (SPS's) proposed by USEF (Institute for Unmanned Space Experiment Free Flyer) in 2006. The SPS consists of the power generation and transmission panel part, the distributed bus part, and tethers connecting them. For the original system and three types of static balance systems, the equilibrium points are found and their stabilities are evaluated by using the principle of minimum potential energy and the numerical simulations. The original system has the stable equilibrium point whereas the panel part is bent. One of the static balance systems has the stable equilibrium point at the design point where the panel part is flat. Then the static balance system is analyzed again as a flexible multi-body system by numerical simulation. The analysis using a flexible body is slightly different from that of rigid body when the elastic deformation becomes remarkable., 資料番号: AA0063718044

資料番号: AA0063585018, レポート番号: JAXA-SP-06-035

Electric double layer capacitors (EDLCs) which have been developed for terrestrial applications are energy storage devices without electrochemical reaction. EDLCs are interesting energy storage candidate in space applications, for example, Space Solar Power Systems (SSPS), where long-life electrical power sub-system is required. In this study, cycle life performance of EDLCs under different satellite operating conditions was tested. In order to realize performance of EDLC modules, circuits that equalize voltages of individual cells in modules are necessary. Equalization circuits were designed with a simple configuration utilizing only electric switches. The effectiveness of the equalization circuit for EDLC modules was successfully demonstrated., 資料番号: AA0049500059, レポート番号: JAXA-SP-06-006

Our modern life is supported by massive energy consumption. At present, oil and gas have become the main energy sources. When these fossil fuels are wasted, a massive amount of CO2 is generated. Therefore, this problem becomes a hot topic. In order to develop power generation from a clean energy source such as the solar power, the SSPS has been studied since end of the 60th. Many groups have been established to develop make and promote the specialized technology for SSPS. One of them has taken charge of the development of the spacetenna (the transmitting antenna of the SSPS system). Key task of the development of the spacetenna is realization of a light and multi-functional antenna and transmitter system. One of promising candidates to satisfy the requirement of the spacetenna is the technique of an active integrated antenna (AIA) that consists of a planar antenna and an integrated circuit. Utilizing nature of the AIA, the authors have fabricated the prototype AIAs, and have developed a thin, light, high-power and functional transmitting antenna for the spacetenna. For instance, the configuration of the active integrated antenna was proposed in the functional-layer fashion, which consists of the amplification circuit layer, the coupling layer, the radiation layer and so on. To realize the two-dimensional array using the fundamental structure mentioned above, the combination of an FET amplifier and a directional coupler in the circuit layer was adopted to provide the equi-phase as well as the equi-amplitude to each antenna element. In this report, a design, a trial production, and evaluation of 5.8 GHz antenna array, or a phase shifter and an amplifier are shown by making the information acquired from the made prototype into a source. AIA with more sufficient electric power efficiency than the last prototype was able to be made by this., 資料番号: AA0049121016

2-D development of the panel antenna using smart actuators has been studied. This actuator that employs a shape memory alloy (SMA) has several advantages as; (1) Simple and light-weight structure as compared with motor system. (2) Deployment speed is well controlled to minimize the effect on the attitude of the system and to suppress the shock when the panel is fully deployed. (3) The shape of the antenna panels can be controlled using two types of SMA actuators, (this function can be used to compensate the thermal deformation of the panels). (4) Oscillation of the panels can be suppressed using super elastic state of the SMA actuator. We have fabricated the two dimensional unfolded panel that consisted of 4 x 8 sub-panels with the SMA hinges, batteries and control circuits. The size of the sub-panel is around 12 x 24 cm. SMA generates heat when electric power is provided. Temperature of the SMA can be controlled by switching electric power on and off. The demonstration model is equipped with a latch mechanism using the magnet. In the laboratory test, it is confirmed that the hinge with the SMA coils work well as expected. Control of the shape of the panel surface using angle sensor and smart actuator is still remained for future work., 資料番号: AA0049121013

先ず、軌道上の太陽発電衛星のダイナミックスを解くために、数値シミュレータを開発している。シミュレータでは、系の構造柔軟性をバネで接続された多剛体により近似し、ニュートン・オイラー法に基づき定式を行なっている。また、重力傾斜、J(sub 2)項による摂動、太陽輻射、空気抵抗の効果を考慮して、軌道運動、姿勢運動、構造柔軟性を同時に解いている。次に、発電部をモジュール化し、テザーにより連結する太陽発電衛星のシステムコンセプトを提案する。本システムは、建築時および建築後の軌道運用において、重力傾斜安定を保ち、系が安定であるという特徴を有す。当初、衛星の前後方向に非対称な設計を行ったが、太陽輻射トルクにより姿勢の安定性が損なわれることが明らかになり、対称な設計に変更した。結果的に、開発したシミュレータを用いた設計の必要性が明らかになった。, We firstly construct a numerical simulator to calculate the behavior of Solar Power Satellites in orbit. In the simulator, the structural flexibility of the system is approximated by rigid bodies connected with springs, and the equations of motion of the system are formulated by Newton-Euler equations. As the external force acting on the system, we consider gravity, J(sub 2) term perturbation, solar radiation pressure, and atmospheric force. This numerical simulator calculates the orbital motion, the attitude motion, and the structural flexibility simultaneously. Secondly, we propose a system concept of solar power satellites. In the system, the power generation part is modularized and each module is connected with tethers. The feature of the system is that the passive gravity gradient stability is maintained during construction as well as in the completed system. The initially designed model was unstable because of asymmetric configuration and solar radiation pressure torque. We have redesigned it into the symmetric configuration and successfully obtained a stable configuration. Therefore, the usefulness of the developed simulator is clarified., 資料番号: AA0063480038

To raise the economics of Space Solar Power System (SSPS) that is to supply large energy from space to the ground and is expected for practical application in 20-30 years, weight reduction and improvement of the life-span need to be sought to reduce transportation costs and life cycle costs. In relation to the SSPS research that has been conducted by JAXA, present report suggests a new vision for material development applying the Japan-developed FGMS concept and proposes some concepts of innovative materials in which the advantages of FGMS are fully utilized., 資料番号: AA0049057005, レポート番号: JAXA-SP-05-011

We have been conducting studies on Space Solar Power Systems (SSPS) using microwave and laser beams for years since FY1998 organizing a special committee and working groups. In the study, some configurations of both microwave based SSPS and laser based SSPS has been studied. This paper presents a summary of SSPS concepts and architectures study., 資料番号: AA0049057002, レポート番号: JAXA-SP-05-011

宇宙太陽発電衛星(SPS: Solar Power Satellite)はkmクラスの巨大な送電アンテナを衛星軌道上に構築し、地上においてマイクロ波として電力を受電するシステムである。送電距離が36,000kmにおよび極めて高い精度でのビーム制御が要求される。SPSのためのビーム制御に関する基礎実験に関して報告する。, 資料番号: AA0063353043

資料番号: AA0049122087

The Solar Power Satellite (SPS) and the Space Solar Power System (SSPS) have been studied for years as future alternative energy sources when fossil fuel becomes scarce. An SPS collects solar energy in orbit and transmits the energy to various destinations. An SSPS is a total system that includes an SPS and ground facilities to utilize power from the SPS. JAXA is presently conducting system-level studies of a microwave-based SSPS (M-SSPS) and laser-based SSPS (L-SSPS). The M-SSPS is comprised of solar energy collection mirrors, power generators (PV arrays), and power transmitters (amplifiers and antennas). The size of the primary mirror will be 7 sq km, and the total mass will be 10 thousand tons to receive 1 gigawatt of electrical power on Earth. The other major SSPS concept is a laser-based system SSPS (L-SSPS), which uses a laser to transmit power. The M-SSPS requires the use of high voltage to transmit electrical power from the power generator (PV arrays) to the power transmitter to reduce the mass of cables and electrical loss at the cables. The power transmission tube (e.g., a magnetron) also must use high voltage. These high voltage devices may generate electrical charge and discharge. This is one of many technical challenges to be overcome before an SSPS is realized., 資料番号: AA0049206004, レポート番号: JAXA-SP-05-001E

As satellite power levels of advanced spacecraft climb above 20-50 kW, higher solar array operating voltages become attractive. For Solar Power Satellites, voltages well above 1,000 V have been suggested. However, micrometeoroid impacts on such high voltage arrays may have catastrophic results. To assess these effects, contemporary GaAs modules and samples of the Stretched Lens Array (SLA) modules were exposed to hypervelocity impact with 100 micrometer diameter soda lime glass spheres at velocities up to 12 km/sec. The two strings of GaAs cells were held at differential voltages above 60 V and bias voltages near - 200 V. A plasma environment typical of Low Earth Orbit (LEO) was also present. The SLA was held at bias voltages up to - 1,000 V. Several types of arcs were observed in the GaAs strings. Higher bias voltages were limited by lack of cover glass overhang, but in the case of the SLA no arcing occurred., 資料番号: AA0049206009, レポート番号: JAXA-SP-05-001E

Space solar power station needs an energetic-effective lasers as an energy transfer device from partially coherent solar light to coherent laser light. A concept of active-mirror amplifier with transparent Nd/Cr:YAG ceramics is proposed under consideration how to convert a wide spectrum of sun-light to monochromatic laser light. New ceramic material pumped by an arc-metal-halide lamp has been implemented experimentally as a fundamental prototype for the space solar power station. CW laser light generated in a 1,064 nm Nd:YAG master laser oscillator was amplified so that a spatial mode of laser output has been improved to a quasi-single mode. The maximum output laser power obtained was up to 3 W with an input lamp power of 9 W resulting in an optical-optical conversion efficiency of 33 percent that was close to the theoretical prediction of 40 percent with keeping spatial beam quality., 資料番号: AA0049121018

High RF-DC conversion efficiency of a Rectenna, which consists of an antenna and a rectifying circuit is one of the key problems for realization of Solar Power Station/Satellite and Wireless Power Space System. The objective of the present study is a development of a high-efficiency rectifying circuit. In this paper, we conduct the optimization of circuit parameters to realize high-efficiency rectifying circuits by investigating diode parameters, an electrical length of microstripline between diodes and an output capacitor, and parameters of a microwave substrate. At first, we calculate the relation between diode parameters and RF-DC conversion efficiency. The results show that the optimal value of input power is decided by junction capacitance of a diode. Next, we estimate the optimal electric length of a microstripline between diodes and an output capacitor by the investigation of circuit design. The results show that capacitance connected with diodes in parallel is the most sensitive factor to the optimization of the electrical length between diodes and an output capacitor. And we clarify the relation between the capacitance and the electrical length with theoretical analysis., 資料番号: AA0049120026

Increase of energy consumption with an increase of global population has brought out change of climate, plant and ecological system all over the world. It is said that the exhaustion of petroleum will come near future. One of the best measures for this energy crisis was the construction of the solar power satellites (SPS) which supply electric power through microwave to the ground in a high efficiency. It is anxious for this ultra-big project that a vast heat and propellant should be discharged in each launch of scalar array segments, sub-structures and materials and makes remarkable influences on the global environment surrounding human lives. If most of the space power stations could be made on the moon by using lunar resources and transported to the geostationary orbit, energy consumption for the transportation and the influence on the global environment would be much reduced. An initial fundamental equipment, facilities and chemical media or materials should be carried from the ground to the moon. There are many processes to produce solar cell and structures. All technologies of production and transportation seem to be realized with great difficulties. However, a launch system on the moon like a linear motor on the ground and the transportation systems are already partially utilized. Each production process needs much energy and power. Robots in various shapes suitable for performing the processes play important roles. They need no food and can work to construct production plant, power station and factory by feeding electric energy. At first, regolith should be gathered and put into a special reactor with reducing agent, for example, hydrogen. If water could found on the moon pole, it would play an important role, of course, for the life support as well as the production of scalar cell, structure materials, etc. Furthermore, if a robot could produce another robot as well as many other facilities, devices and materials, production system would grow in both its system and production scale. None of such automatic production methods has been studied, but these production system can be realized after a century or so by continuous research and developments in cooperation of many scientific and technical fields all over Japan and the world., 資料番号: AA0049120009

For the demonstration and verification of solar power satellite's functions, a small demonstration solar power satellite has been examined by USEF and ISAS/JAXA. Structural characteristics and attitude motion in steady operation have already been studied. In this paper, deployment sequence for the stable and fast deployment is investigated. The deployment sequence consists of two-stage truss extension and two-stage panel deployment. At first, attitude motion in the deployment is analyzed through numerical simulations. From the result, it is shown that nonlinear effect can not be negligible when pitch angle exceeds about 0.6 rad. In such a case, because independency of the pitch angle does not hold true for the nonlinearity, pitch motion leads to the large roll and yaw motions. Next, to realize stable and fast deployment, optimization of the deployment is carried out by changing each deployment time, interval and acceleration of the deployment. As an objective function, weighted sum of deployment times, maximum amplitudes of attitude angles and residual amplitudes of attitude angles is used. The optimization is carried out by Powell's method. From the result it is shown that maximum amplitudes of attitude angles are kept within 0.08 rad, and residual amplitudes of attitude angles are kept within 0.01 rad without any active control if about five orbital periods (about eight hours) can be spent for the total deployment., 資料番号: AA0049120010

In recent years, global warming and environmental pollution raise a problem along with the increase in the carbon dioxide radiation by use of a fossil fuel. An SSPS (Space Solar Power Satellite) plan has been proposed as one of the solutions of these problems. Namely, a huge solar cell is carried on a geostationary orbit, electric power obtains from the sun, it changes and transmits to microwave, and there is a plan to use it again as electric power on the earth. Clean energy can be supplied without any weather conditions in a whole night and day. Lightweight, small, and beam control are demanded for SSPS realization. It is most important to generate the exact a microwave beam to the pilot signal transmitted from the receiving antenna side on the earth. In this research, Active Integrated Antenna (AIA) with a mixing system retrodirective function in a SSPS power transmission part, was demonstrated. It becomes the promising solution of the microwave beam control by uniting AIA with retrodirective technology. In this paper, examination of AIA with a mixing system retrodirective in SSPS is reported. The design and fabrication of a loop oscillator by mixing for the retrodirective function were performed. The output at 5.80 GHz was obtained with well-worked antenna patterns by mixing with the local oscillation frequency of 8.70 GHz and the pilot signal of 2.90 GHz., 資料番号: AA0049120024

In the tethered-type solar power satellite, a large panel structure for the power generation and transmission is adopted. A huge number of actuators are required to deploy the large panel in orbit. In our research, a deployment mechanism using coils of shape memory alloy (SMA) has been studied. When the SMA coil is heated by applying an electric current, it works to deploy the folded panels if the coil has a memory for rotation. This mechanism has several advantages as: (1) Simple and light-weight as compared with motor activation, (2) Deployment speed is well controlled to minimize the effect on the attitude of the system during deployment and to suppress the shock when the panel is fully deployed, (3) The shape of the unfolded panels can be controlled using two types of SMA coils (this function can be used to compensate the thermal deformation of the panels), and (4) The oscillation of the panels can be suppressed by heating the SMA coils to the super-elastic state. We have fabricated the hinges containing the SMA coils as shown in this report and integrated them to a test panel composed of 4 x 8 sub-panels. The size of the sub-panel is 12 x 24 cm. The test model is equipped with a latch mechanism using the permanent magnet. In the laboratory test, it is confirmed that the hinge with the SMA coils work well as expected, but it is found that the life of the SMA coils is unexpectedly limited by the metal fatigue. Further study is required to redesign the SMA coils to eliminate the fatigue effect., 資料番号: AA0049120012

This paper is devoted to analyze dynamical characteristics of a tethered Space Solar Power Satellite (SSPS) system proposed by the Japan Aerospace Exploration Agency (JAXA). The system consists of large, thin, flexible rectangle plates connected to a bus system through tethers. Attitude of the tethered SSPS is gravity-gradient stabilized with employment of tether technology. The control method is studied for the solar panel, which is directed toward solar light in order to improve the efficient generation of electric power. The controlled performance is analyzed by numerical simulation. The results show efficient performance of the tethered SSPS for the generation of sufficient electric power., 資料番号: AA0049120011

資料番号: AA0047900020

編隊飛行する太陽発電衛星システム(FF-SSPS)は、静止軌道上にあって地球指向する発送電部と、太陽輻射圧を揚力として利用して赤道面から一定の距離に保たれつつ太陽指向する反射鏡によって構成される。本稿では、まず、円軌道近傍におけるHill方程式で表される系に対してLQRを適用し、反射鏡の発送電部に対する相対軌道制御則を導く。続いて、静止軌道上で想定される摂動源を組み込んだ軌道制御シミュレーションを実施し、制御則の有効性を検証する。, A space solar power satellite system using a formation-flying reflector (FF-SSPS) consists of the main body and two formation-flying reflectors. The main body is located on geostationary orbit. Two reflectors are located north and south of the main body. Their orbital planes are parallel to the main body's orbital plane. First set is the control law to maintain the relative position of the reflector for the main body, which is an applied linear quadratic regulator (LQR) for the system expressed in Hill's equation around a circular orbit. Then the efficiency of the control law is confirmed using an orbit control simulation that incorporates the perturbations that are assumed on geostationary orbit., 資料番号: AA0047897011

資料番号: AA0047900014

資料番号: AA0047900015

This paper presents a new concept of a solar power satellite system configured by formation flying (Formation-Flying Solar Power Satellite: FF-SPS). In this concept, the solar power satellite system consists of sunlight reflectors and an Earth-pointing segment. The Earth-pointing segment is on a common GEO, and the reflectors are placed on the north and south by using solar pressure to raise their orbits from GEO. Therefore, the orbits of the reflectors and that of the Earth-pointing segment make three parallel GEOs. The feasibility is also discussed focusing on the orbital and attitude mechanics of the reflector. Through some analyses, it is shown that the required propellant for the control of the formation flying SPS is about a few 10 percent larger than that for previous concepts. The structural feasibility is also discussed through FEM analyses. It is revealed that it is possible to assemble the lightweight reflector structure with sufficient stiffness using deployable structures based on current technologies. Although FF-SPS requires more control propellant than previous concepts, its feasibility is technologically equivalent to previous ones. FF-SPS is the first concept that has both Earth-pointing and Sun-pointing segments without any single point of failure., 資料番号: AA0048129002, レポート番号: JAXA-RM-04-011

The concept of Space Solar Power System (SSPS) is of supplying solar energy to the earth by concentrating energy into a huge sunlight concentrator placed on stationary orbit and sending it in forms of electric power or laser. Sunlight concentration technique is used to control the amount of energy coming into an energy conversion device. It is one of the most important techniques in the SSPS concept. Sunlight concentration technique complexly relates to other techniques such as energy conversion and transmission techniques and is not appropriate to and should not be studied individually. It is being planned to come to a result and put SSPS on a commercial basis in the year of 2030 or around. To do so, it was determined what were to be innovative technologies required for the sunlight concentration technique. Also made were investigations and researches to solve problems and achieve the goal through committee activities. Last year, studied were wave length selection technique and properties capable of enduring space environments from a point of incoming energy control. From that study, it is known that controlling wave length through dielectric multi layers is effective to control incoming energy., 資料番号: AA0048129004, レポート番号: JAXA-RM-04-011

On study of Space Solar Power System (SSPS) in JAXA (NASDA), two types of SSPS are now being studied. The one is the microwave based power transmission system (M-SPS), and the other is the laser based power transmission system (L-SPS). On this paper, the MPT status and feature of the M-SPS are described., 資料番号: AA0048129003, レポート番号: JAXA-RM-04-011

資料番号: AA0047899044

A prototype model of high efficient Active Integrated Antenna (AIA) has been developed, as a candidate of a transmission unit in SSPS (Space Solar Power System). The developed AIA consists of three layers, Receiving part, Phaseshifting part, and Transmitting part. Size is 360 mm x 360 mm x 70 mm. Receiving part has the function to receive an external standard signal with 9 receiving antennas, and adjusts the received signal power level and phase. Phaseshifting part has the function to control the phase of the microwave signal outputted from Receiving part by phase shifter according to the phase control command sent from an external phase control equipment. Transmitting part amplifies the microwave signal outputted from Phaseshifting part with the pre-amplifier and high power amplifier of a semiconductor. And Transmitting part has the phased array antenna composed of 9 microstrip antennas of 3 by 3. Moreover, amplified microwave is transmitted from 9 antennas and a power transmission microwave beam is formed. Fundamental characteristic verification test of the prototype AIA has been also performed to acquire characteristic data. The result shows that the AIA will be an applicable candidate for the microwave power transmission unit of SSPS. This paper describes an outline of the prototype model of AIA., 資料番号: AA0047275027

As growth in electric power of spacecraft, development of less-expensive and lighter space power system is required. Especially, for future high power spacecraft such as the hybrid solar sail that has the potential to explore the Jupiter and asteroids, or Solar Power Satellite, very light weight photovoltaic solar array system with specific power exceeding 1 kW/kg will be required. It is expected to reduce the mass of the solar array system dramatically utilizing the thin-film solar cells. Recently, as low-cost solar cell, amorphous silicon (a-Si) solar cells and CIGS solar cells are developed for the terrestrial commercial product conducted by New Energy and Industrial Technology Development Organization. In addition, high radiation tolerant of CIGS and a-Si solar cells was reported. In this paper, possibility of the terrestrial thin-film solar cell 's technologies for space applications is described., 資料番号: AA0047275005

Large-structured, high-performance spacecraft for scientific observation in space have recently been operated, so that large amount of primary power with solar cells is required to achieve their mission objectives. To resolve such a requirement, the asteroid sample return mission spacecraft, MUSES-C, which carried multijunction solar cells with a high efficiency of 26 percent and was launched at Kagoshima Space Center (KSC) in May, 2003, has paved the way for the application of the multijunction solar cells. Their widespread spectral response to the extraterrestrial sunlight, the so-called air mass zero (AM0) sunlight, can range from ultraviolet to infrared rays. In general, solar cells under development are required to withstand the AM0 sunlight during a long duration in order to be qualified as space solar cells. That's what is called aging. At their practical stage, power generation capability of solar cell panels must be evaluated by means of the AM0 sunlight after the installation of the solar cells in the panels. However, there is not a solar simulator with three kinds of lamp and the AM0 spectral characteristic for the multijunction solar cells in the world yet. It is thought that such a simulator is essential to the evaluation of future multijunction solar cells. Thus, first of all, it is described how to design a new multi-solar simulator with the three kinds of lamp: Hg lamps with high brightness in the UV region, Xe lamps in the visible region, and halogen lamps in the IR region. In its performance, it is possible to achieve an illumination intensity of 1.4 kW/sq m a projection area of 2.5 x 2.5 sq m, and a uniformity of +/- 15 percent. In addition, a spectrometer of 250 to 1,850 nm in wavelength is required to maintain a precise simulator performance specified for more than hundreds of hours., 資料番号: AA0047275007

In Japan, plans for a demonstration SPS experiments were proposed from the Ministry of Education, Culture, Sports, Science and Technology (MEXT), and the Ministry of Economy, Trade and Industry (METI). In the METI's plan assumes that existing launch technology will be used for an early actual proof. In this demonstration satellite, due to the limit of transmitting antenna size and generation of power, power flux density on the ground (PFD) becomes about 0.3 W/sq m. This satellite assumes a subrecurrent orbit and its altitude is 370 km. For this reason, it is considered that the rectenna site is constructed in the place where the satellite passes the zenith. The lowest operation power density of conventional rectenna was about 100 W/sq m, so, present power density is not the sufficient strength so that rectenna may operate. So, receiving power can be increased by using parabola antenna, however, the power reception time from the satellite drastically decreases, since the beam profile becomes pencil beam. In order to lengthen the power reception time, an elliptical beam with wide-angle directivity in the satellite's direction of movement, and narrow directivity perpendicular to it is desired. A rectangular parabola rectenna with an elliptical beam was proposed, which can be formed by changing the reflector's rectangular shape and the directivity of the primary feed. A theoretical analysis was performed by the PO method and confirmed its validity using experiment. The target antenna gain was set to 32 dBi, and it is a condition for applying sufficient input power to the rectifying circuits. The - 3 dB beam width was designed +/- 4 degrees for the major-axis direction. The calculated antenna gain and the aperture efficiency were 32.0 dBi, 48 percent, respectively. Since, this value changed to 31.8 dBi and 46 percent in the experiment, respectively. For low input power flux density, good low input power characteristic rectifying circuits were adopted. The maximum value of the present rectifying circuit efficiency was 75 percent for a 350-mW input. From these data, it was proven that the efficiency of rectenna could be expected to about 33 percent. It is considered that this value is an enough practicable value, when the power density is low with 0.3 W/sq m is considered., 資料番号: AA0047275028

In order to acquire the fundamental data for economic study on Space Solar Power Systems (SSPS), the awareness survey of SSPS was carried out to general adults. The survey aimed at the fundamental data collection relevant to general adult's concerns about space development and utilization, the consciousness about future energy and environmental problems, the view about future energy, and the respondent's attribute. The findings are listed below. 1) 80 percent of adults consider necessity of transmitting the space solar energy to the earth and use it. 2) For the necessity of further research and development of SSPS, 52 percent consider it should be greatly promoted, and 29 percent consider it should be promoted. Therefore, 80 percent or more of adults recognize needs for promotion of research and development of SSPS. 3) On the other hand, for the recognition of SSPS, 2/3 of the whole adults replied that they do not know at all. The recognition is still low. 4) People who have high concerns on space development and energy problems tend to feel strong necessity for SSPS. Although same results are shown to the concern on the environmental problems and the necessity of SSPS, the correlation is higher in the space development and energy problems. 5) The rate of those who accept the 500 to 1,000 yen expenditure per person per year for realization of SSPS was 32 percent which is the highest. 6) The rate of people who considers environment and safety as important for future power generation is very high (eco friendly (89 percent), safety (91 percent)). On the other hand, 70 percent of people expect to keep the charge level at the present condition or below the condition. 7) As a major power generation in the future, terrestrial solar power occupied 44 percent following SSPS (21 percent). Although there are many people who learned about SSPS in this questionnaire, the rate of those who expect SSPS as the primary power system of the next generation is high, and it can be said that the expectation is large., 資料番号: AA0047275024

In recent years, as the solar power satellite, the spacecraft is enlarged and requires much higher voltage. However, there are some technical problems as using high voltage in the solar power system. In the space environment, electric discharges occur on the solar cell arrays and the discharges cause damage to the arrays and the efficiency falls. Therefore, it is important to work out to these problems for developing the application in the space. There are two causes in the electric discharges at the solar arrays. One is electric charging phenomenon at a coverglass surface of the solar cell by interaction between the solar cell and the space plasma. The other one is electric field emphasis at a triple junction point that consists of the coverglass and interconnector in the space plasma. In this paper, the charging phenomena of the coverglass on the solar cell under Low Earth Orbit space plasma environment is discussed. So, the charging experiments are carried out using a sample that consists of Acrylic insulator and Aluminum conductor in simulated LEO plasma environment. In the experiments, distributions of electric charges are measured to time on the insulator surface of the sample. As a result, it is clarified that the electric charging of the insulator surface is based on positive ions in the space, and the charging depends on the strength of the electric field on its surface. Therefore, electric discharges occur when the potential difference between the object of the solar system and plasma space increases., 資料番号: AA0047275012

A SPS (Solar Power Satellite) which is a part of the Space Solar System (SSPS) project has been studied at the USEF. Quasi-static analysis had been carried out for the practical SPS. The present purpose is to evaluate the attitude stability of the SPS under construction. During construction, it is assumed that the modules of 100 x 95 sq m are arranged in the shape of line. As the result of quasi-static analysis, it is shown that the roll and yaw angular frequencies of attitude motion are twice and once as large as orbital angular velocity in first step of the construction, respectively. Furthermore, as the result of dynamical analysis, amplitudes of the roll and yaw angles tend to divergence in first step. To avoid such a divergence, another model was proposed which is constructed keeping similar configuration. The construction way is called construction with similarity. From the result of simulations, it is shown that divergences in the roll and yaw angles can be avoided in the construction with similarity. However, the stability around the pitch and yaw axes are weak in first step for construction with similarity. In particular, maximum amplitude around the pitch axis is 5 deg. Therefore, both constructions need active attitude control because there are problems in first step of the constructions., 資料番号: AA0047275019

The space solar power system (SSPS) is required for clean power source in the near future. The SSPS consists of not only conventional spacecraft technologies but also newly developed technologies. In development of the SSPS the new technologies should be inspected both on orbit experiment and on the terrestrial experiment. However the experiment cost on orbit is high, attention should be paid to developing simulation method as alternative to experiment on orbit to cut the cost down. In this paper described is development of a novel simulation method for analyzing microwave beam propagation characteristics from an SSPS orbit to ground beam detection point. Several studies for microwave beam propagation in space plasma important for SSPS had been done. These studies were focused on the nonlinear effects appeared in the extremely high power microwave propagation in the space plasma. In contrast with these studies, overall propagation analysis was focused on from the orbit to the ground. The simulation method developed is based on the beam propagation method (BPM) on a conventional PC platform. To overcome the increasing calculation error in long distance propagation with beam size expansion, alternative direction implicit method (ADI) is introduced. The databases IRI, COSPER, and IGRF are used to take account of space environment (ionosphere) and the atmosphere on the microwave propagation path. Simulated are microwave beam propagation characteristics of 5 m of beam radius from altitude 570 km through ionosphere and atmosphere. Good agreement was obtained with the theoretical expectation but the simulation took 6 days CPU time on PC platform. As the code with ADI method suited for parallel computing, the calculation time could be shortened to 2 days with 4 CPU through 570 km propagation., 資料番号: AA0047275025

Shape memory alloy (SMA) has attractive characteristics such as shape memory effect, super elasticity and hysteresis of stress-strain relationship. By utilizing SMA for actuators of large deployable panels, it is expected to realize controlled and low-shock deployment, sequential deployment, shape control during deployment, also shape control and vibration absorption after deployment, and so on. Generally, expected functions of actuators for deployment, shape control, and vibration suppression for panel-like huge space structures are small attitude deviation during deployment, low shock at latching, good structural accuracy, controllability of static shape such as thermal deformation compensation, large vibration damping, capability of folding panels with a certain quantity of thickness. A multi-functional actuator utilizing SMA may be able to satisfy the requirements. In this paper, proposed is a conceptual design of a multi-functional SMA actuator, which is applicable to a unified panel of power generation and transmission of a solar power satellite. The basic principles and possibilities of deployment, latch mechanism, shape control and vibration absorption are presented. A hinge for two-way angle control effect can be realized by making a pair of SMA coils, each of which undergoes one-way shape memory treatment at different aperture angle. One of the pair of SMA coils is conducted to heat up to the reverse transformation temperature in order to activate the shape recovery effect one way. In the case that both of the pair of SMA coils are conducted at the same time to heat up, the hysteresis loop of stress-strain relationship at the high temperature phase of SMA can be used to damp the vibration of a large amplitude. The hinge with two-way shape memory effect requires a latching mechanism that can latch and release at any hinge angle between the two panel units. The latch can be designed by combining permanent magnet and electromagnet, and a tongue of magnetic material. Demonstration model of the function has also been made. Instead of thick panel unit with actual thickness, a thin rigid panel represents the mid-surface of the thick panel unit. Spacers with height of half of the thickness of a thick panel unit are attached to the both sides of the mid-surface panel in order to demonstrate the thick panel unit. The SMA hinges and magnetic latches combine 8 x 4 panel units. Some functions of the multi-functional hinge of the panel have been proved., 資料番号: AA0047275020

For realization of Space Solar Power System (SSPS), it's essential to develop Microwave Power Transmission (MPT) System with high DC-RF conversion efficiency and light weight. MPT system for SSPS requires very accurate beam control (less than 0.001 degree) with huge phased arrays whose diameter is over 1.0 km. It also requires total efficiency of more than 80 percent (excluding conversion efficiency of solar cells) to work as a space system. To satisfy these requirements, a Phase Controlled Magnetron (PCM) is suitable for microwave transmitter. The PCM takes advantage of high power, high DC-RF conversion efficiency, low cost, and light weight of a magnetron. Typical output power from the PCM is 300 W, while output power from one antenna element is less than 1 W. Therefore insertion of power divider and phase shifters after PCM output is required to satisfy SSPS parameters and it leads to disadvantage. Because the power dividers and the phase shifters are inserted after high power microwave output, insertion loss in these elements is very critical. The loss after the PCMs must be reduced to realize the PCM-based MPT system. Slot-coupled Active Integrated Antenna (AIA) system is proposed as one of the solution of this Final Stage problem. This system uses waveguide slot antenna as a power divider and AIA as low-loss phase shifter and antenna layer. By using an electromagnetic coupling between an AIA and waveguide slot antenna, thin and light antenna structure can be realized. This system also has low insertion loss and is suitable for high power from the PCM because of the use of the waveguide as an input port. One of the important factors of the slot-coupled AIA is coupling factor of the electromagnetic coupling between microstrip lines and waveguide slots. The aim of this study is to improve the coupling factor by reconsideration of the electromagnetic coupling structure. Coupling factor of nearly 90 percent was achieved by changing waveguide dimensions., 資料番号: AA0047275026

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この論文は宇宙空間における大型宇宙構造物の建設に関する研究の成果をまとめたものである。宇宙空間に太陽発電衛星のような巨大な体積を持つ構造物を効率的に形成するためには、構造物のトラス構成化と展開機構化が重要な技術的課題となる。ここでは、まず、トラス構造物の構造特性をパラメトリックに記述する。次に、パソコンで簡便な構造解析を行えるように、トラス構造で形成された長大マストを1本の円筒ビームに置き換えて構造解析を行う場合の構造データの置換条件と問題点について述べる。最後に、宇宙構造物の収納・展開を可能とする展開構造機構について検討を行う。, This paper summarizes the result of the research on construction of the large-scale structure in space. In order to construct efficiently the space structure, which has huge volume like a solar power satellite, the formation of truss structure becomes the important technical subject. First, the structural characteristics of truss structures are described in parametric forms. Next, the method and problem in replacing the huge truss-constituted mast to a single tube to perform simple structural analysis by personal computer is discussed. Last, typical examples of truss-constituted structures are shown, which are formed by structural deployment in space., 資料番号: AA0045497022