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In recent years, space debris increases because many rockets and satellites have been launched. A solar array of a spacecraft has become larger with the higher voltage and electrical power. Therefore, the risk of debris impact and possibility of discharge on the solar array is increasing. If space debris impacts solar array, it electric power decreases or loses. When space debris impact on the solar array, high-density plasma is discharged. The arc that led may generate the plasma. This is Temporary Sustained Arc. This discharge can lead to carbonize the insulation layer of the solar array by Joule heat due to the large current through the plasma, and form permanent short-circuit. If this phenomenon continues, a permanent short circuit course will be formed between a solar cell and a substrate. This is Permanent Sustained Arc. It causes decrease or loss of generating capacity of a solar array coupon. In this study, the first purpose is verified that sustained arc is discharged or not by space debris impacts on solar array. The second purpose is elucidated the threshold of sustained arc. We want to reduce the influence affect the missions of a satellite by those results. Therefore, we took notice a density and electron temperature of the plasma which induce to discharge and clarified the threshold of sustained arc generating for hypervelocity impact test by two-stage light gas gun. The triple probe method was used plasma measurement test. The results show that electron temperature and electron density have correlation with impact speed, and the plasma density is higher than the plasma environment on low earth orbit. A possibility of TSA (Temporary Sustained Arc) generation is large over 80 [V], and generating of PSA (Permanent Sustained Arc) was confirmed over 183 [V]-2.4 [A] of power supply voltage. The generating conditions of PSA are sustaining voltage is 50 [V], current is 2.2 [A] and dissipation power of discharge circuit is 110 [W]. Therefore, it is desirable that dissipation power of the satellite is less than 110 [W] for preventing generating of PSA., 資料番号: AA0063965011

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

The hybrid solar sail that has the potential to explore the Jupiter and asteroids requires very light weight photovoltaic solar array system with specific power exceeding 1 kW/kg. We expect to reduce the mass of the solar array system dramatically utilizing the thin-film solar cells. Recently, amorphous Silicon (a-Si) solar cells and CIGS (Copper Indium Gallium Selenide) solar cells have been developed as low-cost solar cell for the terrestrial commercial product conducted by New Energy and Industrial Technology Development Organization in Japan. In addition, high radiation tolerant of CIGS and a-Si solar cells was reported. We have been carrying out evaluation tests of the a-Si thin film solar cell concerning several space environmental conditions. In this paper, we describe results of the thermal equilibrium experiment, I-V characteristics of several temperature conditions, and electron and proton irradiation test for the a-Si thin film solar cell., 資料番号: AA0063965010

The anomaly of Japanese satellite ADEOS-2 (ADvanced Earth Observing Satellite-2: Midori-2) appeared in 2003 is supposed to be caused by arcing discharges initiated due to ESD (ElectroStatic Discharge) in the bundled wire-harnesses of the solar paddle. In order to make the conditions of the occurrence of the discharge clear, it is necessary to evaluate the arcing discharge characteristics in vacuum quantitatively. Therefore we tried to investigate the characteristics of arcing discharges between two exposed conductors consisting of a pair of insulating wires for space use. The discharges were triggered by ESD released from a capacitor. These characteristics were obtained as parameters of the amplitude of ESD, the pressure in the chamber, the direction of the current flowing the conductor and so on. We obtained the result that the arcing discharge time increased with the amplitude of the ESD and the time is affected by the magnetic field formed between the conductors by the current flowing the conductor itself., 資料番号: AA0063965012

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

ElectroDynamic Tether (EDT) is a long, thin conductive string deployed from a spacecraft. Traveling across the geomagnetic field and driving a current inside itself, EDT may be used to reboost/deboost a spacecraft to which EDT is attached. This is made possible by the Lorentz force acting on EDT. It is considered to be an alternative propulsion system for station-keeping, orbit-raising or de-orbiting purpose. EDT needs plasma contactor to collect ionospheric electrons. Bare-tether is one of the most efficient electron collectors. It has an uninsulated portion of the metallic tether itself to collect ionospheric electrons. It is extremely economical propulsion system because it can be operated without propellant. In order to put into practice EDT technology, we still need to solve several problems. One of them is the current-voltage characteristic of an electron collector. There exist some theories. When the radius of the electron collector is smaller than the local Debye length, current collection is limited by Orbital Motion Limit (OML). OML is the upper limit of the current collection in the steady-state collisionless uniform plasma. However, current collection to the bare-tether in space does not always drive OML because it is not taken into account plasma velocity and magnetic field. So ground-based experiments of current collection to a bare-tether were carried out to investigate the influence of surrounding plasma parameters, configuration of bare-tether, magnetic field and plasma velocity on the current-voltage characteristic. An anode-layer-type Hall Thruster was used as a plasma source. We could produce plasma velocity of approximately over 8 km/sec which is orbital velocity in Low Earth Orbit (LEO) where bare-tether is used, varying discharge voltage of Hall thruster. Experimental results showed that plasma velocity and configuration of bare-tether sample affected the current collection. In addition, for all cases, current collection to bare-tether sample was less than that predicted by OML. Accordingly, we need to modify OML when we estimate current collection to bare-tether in space., 資料番号: AA0063965014

In recent years, long-term employment and enlargement are becoming remarkable in space development. The increase in electric power may include discharges on the solar array panels of spacecrafts. Furthermore, the discharges involve the risk of producing surges which affect payloads in the spacecrafts. Testing with real satellites has many problems with time, effort, equipment, cost, etc., so an accurate evaluation by simulation is needed. In order to evaluate correctly, we have to imitate discharge currents that flow through a circuit. This discharge current can be obtained by modeling the plasma resistance generated by the discharges, as well as the equivalent circuit of the whole spacecraft. In this research, we modeled this plasma resistance. First, plasma resistance includes two resistance components, one of which exists in the discharging current path of the charges stored in the space body. The other resistance component exists in the inflowing current path of the charges stored on the surfaces of the solar cells. The former current and resistance are known as a blow-off current and blow-off resistance. The latter current and resistance are known as a flash-over current and flash-over resistance. In order to acquire experimental values of blow-off resistance, we measured the blow-off current using a solar cell, and analyzed it using SPICE simulation. From the results, it was confirmed that blow-off resistance decreased exponentially. Also, blow-off resistance had a relationship with discharge energy. In addition, we measured the flash-over resistance. We measured the flash-over current using a solar array coupon which had 50 cells on the coupon, and analyzed it using SPICE simulation. From the results, it was confirmed that flash-over resistance increased linearly in proportion to the distance from the discharge point. In the near future, we will create the equivalent circuit of the solar array panel. Moreover, there is a need to create the equivalent circuits of recently prevailing GaAs solar cells and triple-junction solar cells., 資料番号: AA0063965009

資料番号: AA0063997007, レポート番号: JAXA-SP-07-030

There is high possibility that space debris impacts to a solar array paddle in spacecraft parts, because the solar array paddle has large area. Space debris impact to the solar array causes not only mechanical damage but also electrical damage such as arcing on the solar array through local high density plasma created by hypervelocity impact. In the worst case, Joule heating of this arcing carbonizes insulation layer and permanent short-circuit path is created. This is permanent sustained arc. However, no permanent sustained arc caused by space debris impact in orbit has been reported. Purpose of this study is evaluation of possibility of permanent sustained arc through the plasma created by debris impact. Hypervelocity impact tests to solar array coupons in the condition of pseudo power generation were conducted. We ascertained that space debris impact can lead to permanent sustained arc on the solar array due to plasma created by hypervelocity impact., 資料番号: AA0063997018, レポート番号: JAXA-SP-07-030

Highly energetic electrons in the outer radiation disappear during the main phase of the magnetic storm, and rebuilding of the highly energetic electrons is made during the recovery phase of the magnetic storm. A distribution of the new peak of highly energetic electron flux with respect to the distance from the Earth is inversely proportional to the magnitude of the magnetic storm. In case of the super storm, the outer electron belt is pushed toward the Earth, filling so-called slot region. It is of interest to identify that the location of the intense low frequency plasma waves, which appear during the storm recovery phase, coincides with the location of the peak intensity of the highly energetic electrons in the outer radiation belt. This coincidence strongly suggests that an internal acceleration process takes place which leads to a large increase in the intensity of highly energetic electrons in the outer radiation belt during the storm recovery phase. A seasonal variation of the outer radiation belt is identified. The increase in the intensity of the highly energetic electrons is large both in spring and autumn seasons. The magnetic activity is also large both in spring and autumn seasons. Correlation of the increase in the intensity of highly energetic electrons with the magnetic activity is identified. A solar cycle variation of the outer radiation belt is identified. The location of the outer radiation belt was found closer to the Earth during the solar maximum periods and far from the Earth during the solar minimum periods. This variation is due to the evidence that large magnetic storms occur largely during the solar maximum periods, while small magnetic storms take place largely during the solar minimum periods, resulting a long-term solar cycle variation with respect to the distance from the Earth., 資料番号: AA0063997005, レポート番号: JAXA-SP-07-030

近年、衛星の帯電・放電に関連すると考えられる事故が国内外で多数、報告されることから、設計段階から帯電・放電の観点に立った検討を正しく行う必要性が認識されている。JAXAでは静止衛星についてはこれまで、米国で70年代に開発され世界のデファクトスタンダードとしての地位を確立していたNASCAP/GEO(NASA Charging Analyzer Program for GEosynchronous Orbit)と呼ばれる解析ツールを利用してきた。しかしその後、機能拡張、改良され、低軌道衛星、極軌道衛星にも対応可能となったツールは、輸出規制のために日本で使用することはできない。そこで2004年11月から衛星帯電解析ソフトウェアMUSCAT(Multi-Utility Spacecraft Charging Analysis Tool)の開発に着手し、2007年3月に完成した。本発表は、このMUSCATによる解析結果を実際の衛星(ETS-5: Engineering Test Satellite-5:きく5号)で取得したデータと比較し報告する。ETS-5は、静止軌道上で10年間の帯電データを取得しており、ほぼ太陽活動周期1回分のデータが得られている。このデータをMUSCATの解析結果と比較することにより、衛星電位と帯電サンプルとの電位差について検証することが可能であり、成果を帯電設計基準などに反映することができる。また、MUSCATにユーザ要求による機能の追加を行ったため、これについても報告する。, 資料番号: AA0063997026, レポート番号: JAXA-SP-07-030

A new method to simulate power generating solar arrays of spacecraft is presented. By combining a multijunction solar array, InGaP-GaAs-Ge, and a Metal Halide Lamp (MHL) secondary arcs were generated. The aim was that the arcs should be comparable to those generated by the currently used methods, which are the Solar Array Simulator (SAS) or a power supply combined with a Current Regulating Diode (CRD) circuit. The results of the experiment showed a successful generation of secondary arcs, especially of temporary sustained arcs. The arc duration is similar for all three simulation methods. The conclusion therefore is that the MHL method can be used in the same way the SAS or CRD method can be used, as it generates the same results., 資料番号: AA0063997012, レポート番号: JAXA-SP-07-030

The purpose of this research work is to develop a small size measurement system to observe the surface charge distribution on insulator in vacuum chamber for space environmental test. Recently, a lot of satellites many purposes like a telecommunication, a weather report are being launched. These satellites are flying in a very severe space environment where the high energy radiations are scattered from the sun. In this environment, electrical charging phenomenon occurs on the insulation of spacecraft surface and electrical discharge or dielectric breakdown occurs by the high electric field. Therefore devices in spacecraft have a risk of failure. So we need to find out a mechanism for the occurrence of surface discharge on insulation and a best insulating materials for space conditions. Until now, my senior at our laboratory has made a measuring system of surface charging on insulation using the BSO (Bismuth Silicon Oxide) crystal has Pockels effect. The measuring system has been used the observation of surface discharging on insulation under conditions of non-destructive and non-contact. However this measuring system is large size and the techniques for setting an optical axis is hard. So it was difficult to apply the measuring system to the space environment simulator of small vacuum chamber. So we need to make a small size measurement system for surface discharging observation. By using a plate type light source of LED (Light Emitting Diode) and changing a optical type, the system area can be reduced 200 x 150 mm from 1,200 x 700 mm. Then we researched surface charging on BSO crystal and Kapton film, by using the small system. Then we researched measuring accuracy of the small system., 資料番号: AA0063997024, レポート番号: JAXA-SP-07-030

In this paper, we report about the test results on coupons made for Working Group 1 (WG1), which was established to make a Japanese guideline for spacecraft charging design. Laboratory tests were carried out with an external circuit simulating a spacecraft power system. The solar array coupon panels simulating the hot and return ends of a string circuit were tested under various combinations of string voltage and string current. We revealed that the threshold conditions for sustained arc were different in string voltage., 資料番号: AA0063997011, レポート番号: JAXA-SP-07-030

The spacecraft like a communication or a broadcasting satellite flying in GEO (Geostationary Earth Orbit) is always exposed to plasma and/or radioactive-rays such as alpha-, beta- and gamma-rays. When the dielectric materials, in which the spacecraft is wrapped to keep temperature in it stable, are irradiated by the high energy electron beam, sometimes an unexpected accident due to an electrostatic discharge happens. The accident sometimes causes a serious mission error of the spacecraft. However, there remain many unknown factor about a charge accumulation in dielectric materials by irradiation of electron beam. Therefore, we need to measure the charge distribution in the bulk of dielectric materials. We have been developing a system for measuring such a charge distribution in dielectric materials using pressure wave propagation method. Using this system, we tried to measure the charge distribution under electron beam irradiated Low Density Polyethylene, Polyethylene Terephthalate, Polycarbonate, Polyethylene Naphthalate in addition to Polyimide and PTFE (PolyTetraFluoroEthylene) films which are used as a thermal control layer or a optical solar reflector of spacecrafts. We observed accumulation behavior of charge in each sample, survey relationship with each sample's molecular structure. As a result, It's believed that charging characteristics of insulating material is linked to benzene ring in each sample's molecular structure., 資料番号: AA0063997025, レポート番号: JAXA-SP-07-030

資料番号: AA0063997008, レポート番号: JAXA-SP-07-030

Recently many spacecraft use Triple-Junction (TJ) solar cells as their primary electrical power source because of their excellent efficiency. However it is also known that triple-junction solar cells are easy to be broken by a low reverse bias voltage. Therefore a discrete by-pass diode should be connected to every solar cell in parallel for the shadow protection. Under these circumstances, TJ solar cells with integrate Monolithic Diode (MD) have been introduced to market recently. In the CICing (Coverglass Interconnect Cell) of TJ solar cell with MD, cell-to-cell interconnector is connected on MD pad. The interconnector region forms triple-junction in orbit, making primary arc inception easy. Therefore, it is necessary to study the behavior of arcs on MD solar cell array. The result of the ESD (ElectroStatic Discharge) test for MD solar array revealed that the degradation of MD solar cell is caused by not only large current but also total energy of the discharge. The waveform seems to be affected by the impedance of the solar array circuit. This paper presents the recent results of ESD test for MD solar array and proposes further investigation based on the test results., 資料番号: AA0063997013, レポート番号: JAXA-SP-07-030

資料番号: AA0063997009, レポート番号: JAXA-SP-07-030

Erosion property of polyimide was studied through the ground-based synergistic studies. Hyperthermal atomic oxygen and 172 nm VUV (Vacuum UltraViolet) exposed to polyimide and polyethylene in various conditions. In-situ mass loss measurement of polymers during the atomic oxygen and/or VUV exposures was achieved with a quartz crystal microbalance. The effect of simultaneous ultraviolet exposure on the atomic oxygen-induced erosion was observed at the ultraviolet intensity of 0.5-2.6 x 10(exp -15) mJ/atom for polyethylene. In contrast, the similar effect was observed in polyimide at the relative ultraviolet intensities one order greater than that of polyethylene. It was also found that the effect of 172 nm ultraviolet was different in polyimide and polyethylene; i.e., photo-induced erosion was observed only for polyethylene. It was concluded that polyimide is less sensitive to the simultaneous ultraviolet exposure during atomic oxygen bombardment, and thus evaluated as a better material for measuring atomic oxygen fluence in space., 資料番号: AA0063997020, レポート番号: JAXA-SP-07-030

High-energy electron flux at geosynchronous orbit significantly increases associated with high speed solar wind. The high-energy electron cause internal charging of satellites. It is important for satellite operations to forecast increase of the flux. Here, we report a forecast model using neural network with inputs of solar wind data., 資料番号: AA0063997010, レポート番号: JAXA-SP-07-030

The current status of measuring radiation using JAXA satellites is reviewed. Starting with Engineering Test Satellite-5 (ETS-5; KIKU-5 in Japanese) in 1987, efforts to conduct radiation measurements in space have continued using almost all Japan Aerospace Exploration Agency (JAXA formerly NASDA) satellites (ETS-6 (Engineering Test Satellite-6: KIKU-6), ADEOS (ADvanced Earth Observing Satellite: Midori), ADEOS-2 (ADvanced Earth Observing Satellite-2: Midori-2), MDS-1 (Mission Demonstration test Satellite-1: Tsubasa), DRTS (Data Relay Test Satellite: KODAMA)(ongoing) and ETS-8 (Engineering Test Satellite-8: KIKU No.8)(ongoing), and ALOS (Advanced Land Observing Satellite: Daichi)(ongoing)), in Geostationary Orbit (GEO), Geostationary-Transfer Orbit (GTO), and Low-Earth Orbit (LEO). Electrons, protons, alpha particles, and heavy ions have been the main objects of study. Future plans for radiation monitoring in JAXA, including GOSAT (Greenhouse gases Observing SATellite), Jason-2 (in collaboration with CNES), and ISS (International Space Station)/JEM (Japanese Experiment Module)/Exposure Facility/SEDA-AP (Space Environment Data Acquisition equipment-Attached Payload), are presented., 資料番号: AA0063997004, レポート番号: JAXA-SP-07-030

Preliminary ESD (ElectroStatic Discharge) ground tests with two meter-class solar panels were conducted in a simulated GEO (Geostationary Earth Orbit) environment. The results indicated that the plasma propagation velocity was approximately 10(exp 4) m/s, and the plasma propagation length was greater than 2.8 m. The neutralization current decreased with an increase in the distance from the arc spot., 資料番号: AA0063997019, レポート番号: JAXA-SP-07-030

今現在、地球周りの放射線環境を模擬したモデルが多数存在している。放射線帯に捕捉されている陽子線や電子線に関してはAP-8、AE-8モデル、太陽陽子線に関してはJPL-1991、SOLPROモデル、銀河宇宙線に関してはCREMEモデルなどである。しかし、これらの放射線モデルはどれも1990年代よりも昔のデータに基づいて作成されており、データの精度があまり良くないという問題点がある。また、モデルによる計算結果が実際の放射線環境とはズレが生じていることがわかってきており、さまざまな問題点や改良すべき点が報告されている。それらの問題点や改善点を考慮した新しい放射線モデル作成の提案が出ているが、まだまだ議論や観測データが必要とされている。そこで本研究では、新しい放射線モデル作成に有益な情報を得ることを目的として、だいち(ALOS: Advanced Land Observing Satellite)衛星によって観測されたデータとこれらのモデルの計算結果を用いることで、だいち衛星の軌道に於いてという限られた範囲ではあるが、既存モデルと実際の放射線環境との比較を行った。, 資料番号: AA0063997027, レポート番号: JAXA-SP-07-030

資料番号: AA0063997028, レポート番号: JAXA-SP-07-030

As the power level of geostationary satellites increases, discharge phenomena on solar array are becoming serious threat to safe operation. Arcs on solar array can short-circuit the satellite circuit, decrease the satellite power, and then cause the satellite permanent failure. To prevent the failure caused by charging and arcing, it is necessary to investigate the mechanism of satellite charging and arcing phenomenon. The purpose of this paper is to investigate the occurrence condition of a secondary arc by measuring arc plasma characteristics in ground test. We measured the arc plasma temperature and identified the materials emitted using spectrometer at arbitrary time during arc occurring. We investigated the difference of secondary arcs occurrence condition during secondary arcs. From the spectroscopic measurement results, we found that it was necessary for shifting to the secondary arc that the metallic vapor same as the cathode material was emitted. In case of PA (Permanent Arc) dimension changes, the probability of secondary arc and TSA (Temporary Sustained Arc) occurrence became high. And plasma temperature was not affected by PA dimension. However, the metallic vapor emission of silver was greatly affected. Thus, secondary arc occurrence greatly depends on metallic vapor emission from cathode., 資料番号: AA0063997017, レポート番号: JAXA-SP-07-030

Recently, the satellite plays many roles depending on the purpose, including communication, weather observation, astronomy observation and space development. The satellite is requisitioned long life and high reliability in such situation. However, around an altitude of several 100 km, there is Atomic Oxygen (AO) which is a main ingredient agents. AO has high reactivity and its density is about 10(exp 15) atoms/cu m. Because the satellite collides with AO, surface materials of the satellite are deteriorated. As a result, it leads unevenness and oxidation. Accordingly, it is necessary to monitor the surface condition. In this study, photoemission characteristics of several materials, such as metals, glasses and polymers are measured by use of the deuterium lamp and the band path filters. From the measurement the threshold energy for photoemission and the quantum efficiency was evaluated. As a result, the thresholds of samples are 4.9 to 5.7 eV. The quantum efficiency of metals is about 100 times higher than other samples. The quantum efficiency of PS (PolyStyrene) which includes benzene ring is several times higher compared with PP (PolyPropylene) and PTFE (PolyTetraFluoroEthylene). From these results, it is deduced that deteriorated materials may emit large amount of photoelectron., 資料番号: AA0063997015, レポート番号: JAXA-SP-07-030

Possibility of arcing in high voltage arrays have necessitated the theoretical and experimental study of charging and arcing by Indian Space Research Organisation (ISRO), which is planning to increase the satellite bus voltage above the current level of 42 volt. The study, named Spacecraft Plasma Interaction eXperiment (SPIX) was undertaken, together with Institute for Plasma Research (IPR), India to (1) develop software, which is able to predict the floating potential of an object of simplified geometry in space plasma typically of geosynchronous bimaxwellian type, which is also able to calculate the differential potential between two such objects, (2) to develop software to solve the differential equations describing primary arcing phenomena developed by Cho, a pioneer in the field, (3) to study the primary arcing threshold and frequency and to identify the arcing sites of a solar array coupon immersed in a LEO (Low Earth Orbit) like laboratory plasma and to (4) find out the arcing threshold of sustained arcs by introducing a solar array simulator voltage between adjacent strings in a solar array coupon immersed in a LEO-like plasma environment. The experiments have largely yielded results akin to that of other investigators, although some differences have been observed in some experiments. A short term future aim would be to increase the sample space in the last type of experiments mentioned above., 資料番号: AA0063997001, レポート番号: JAXA-SP-07-030

Polar Earth Orbit (PEO) is a peculiar orbit where energetic auroral electrons and low-temperature ionospheric plasma coexist. There is a risk of charging and subsequent arcing in PEO, which was demonstrated unfortunately by the total loss of ADEOS-2 (ADvanced Earth Observing Satellite-2: Midori-2) satellite in 2003. Charging in PEO must be properly assessed in the early satellite design phase by a spacecraft charging analysis tool. The plasma environment, namely its density and energy, is the crucial parameter for the spacecraft charging analysis. The balance between the auroral electrons and the low temperature ionospheric ions determine the charging potential of a PEO satellite. We statistically analyzed the environmental condition in PEO using the data of auroral electrons and thermal ions measured by DMSP (Defense Meteorological Satellite Program) satellites. Probability of a given combination of current densities of auroral electrons and thermal ions has been derived. The energy spectrum of the auroral electrons are also classified into several types and correlation with the thermal ions is analyzed. Combinations of the plasma parameters used by a spacecraft charging simulation software have been identified and database regarding the probability of occurrence of each combination has been formulated., 資料番号: AA0063997006, レポート番号: JAXA-SP-07-030

資料番号: AA0063997029, レポート番号: JAXA-SP-07-030

Butt weld experiments on aluminum pipe were performed by the space GHTA (Gas Hollow Tungsten Arc) welding process with feeding a filler wire in a simulated space environment. The weld metal shape and mechanical properties of those butt weld joints and welding phenomena such as the arc discharge and base metal melting were investigated. As a result, it was clarified that the weld metal shape and mechanical properties were improved by the feeding filler wire compare with those of butt weld joints welded by melt-run., 資料番号: AA0063706020

Laminated beam structures are designed in order to minimize thermal deformations in steady or unsteady temperature field. To suppress thermal deformation, composite materials that has negative longitudinal coefficient of thermal expansion are layered with material that has positive Coefficient of Thermal Expansion (CTE). Assuming steady temperature fields, beam with no strain at central axis and no curvature can be designed. In unsteady temperature fields, it is possible to suppress thermal deformations while lowering thermal stresses. If it takes a long time until the temperature distribution get steady, the beam should be designed with considering unsteady temperature distributions because the beam that was designed with considering only steady temperature distribution could have large thermal deformations in its transitional period. For suppressing thermal deformations, interlaminar shearing stress, and interlaminar moment, materials with large Young's Modulus, CTE, and thermal conductivity are effective to use for low temperature side, oppositely, materials with small Young's Modulus, CTE, and thermal conductivity are effective to use for high temperature side., 資料番号: AA0063824014, レポート番号: JAXA-SP-07-008E

The ground-based experimental results of the incident angle dependence on the erosion rate of polyimide under hyperthermal atomic oxygen beam exposures are reported. A hyperthermal atomic oxygen beam was generated by a laser detonation-type atomic oxygen beam source. In-situ mass loss measurement was made during the atomic oxygen exposure using a quartz crystal microbalance. It was observed that the erosion rate of polymers was followed cosine function with respect to the incident angle of atomic oxygen. This experimental finding clearly indicates that the reaction yield of atomic oxygen with polymers is independent of the incident angle. As for the fluence monitoring material, erosion depth or mass loss of polyimide simply reflects the effective atomic oxygen fluence which is calculated by multiplying normal flux and cosine of the incident angle., 資料番号: AA0063585016, レポート番号: JAXA-SP-06-035

情報通信研究機構(NICT: National Institute of Information and Communications Technology)のリアルタイム磁気圏シミュレーションから得られる静止軌道のプラズマ環境と衛星観測との比較解析をおこない、静止軌道プラズマ環境予報とそれに関連する衛星帯電予報についても述べる。, 資料番号: AA0063585005, レポート番号: JAXA-SP-06-035

小型科学観測衛星「れいめい」(INDEX: INnovative technology Demonstration EXperiment)は、2005年8月に打ち上げられ順調にオーロラ微細構造の観測を続けている。我々は、れいめいに搭載された3対のラングミュアプローブ(CRM: plasma CurRent Monitor)を用いたプラズマパラメータの高分解能観測を行っている。CRMのデータはオーロラ帯プラズマの密度、温度の計測に有効であるだけでなく、飛翔体環境の理解を深めるためにも有効で、シミュレーションによる解析と比較することによって、オーロラ粒子による衛星帯電の機構解明に役立つものと考えられる。一般に、極域においては降り込みオーロラ粒子の影響によって衛星は負に帯電し、ラングミュアプローブによるプラズマパラメータの計測は困難であるといわれている。CRMでは、シングルプローブ1対とダブルプローブ2対による複数センサーによる観測を行い、衛星帯電の影響や太陽光による光電子の影響、ウェイクの影響を考慮した観測を試みた。これらの影響は非常に複雑で、計算機シミュレーションとの比較を行うことによって初めて、複雑な飛翔体環境の効果を取り除いたプラズマパラメータの推定が可能になる。れいめい衛星が打ち上げられてから現在までの観測データとNuSPACEによるシミュレーションと比較することによって、CRMによる観測によってプラズマパラメータ以外に衛星の帯電状態、降り込み粒子との因果関係などが明らかになった。, 資料番号: AA0063585014, レポート番号: JAXA-SP-06-035

資料番号: AA0063585023, レポート番号: JAXA-SP-06-035

資料番号: AA0063585002, レポート番号: JAXA-SP-06-035

資料番号: AA0063585027, レポート番号: JAXA-SP-06-035

Some kinds of paint-type coating materials are used as a thermal control material for the dual-frequency precipitation radar of the GPM (Global Precipitation Measurement) core satellite. It is necessary to survey the characteristics of the thermal or optical properties and mechanical properties, electrical properties about them. However, there is a few data for electrical properties, in particular, the photoelectron emission characteristic in Japan. This report describes results of measurement of the photoemission current from the paint-type coating materials excited by ultraviolet-light. The used coating samples were seven kinds of white coating materials (inorganic conductive, inorganic nonconductive, silicon based conductive, silicon based nonconductive) which are used for the antenna portion of DPR (Dual frequency Precipitation Radar). The following measurement results were obtained. Photoemission currents value of silicon based samples were smaller than those of inorganic samples. Photoemission sites on inorganic conductive samples were distributed into active area and inactive area. Photoemission currents value of conductive samples were larger than those of nonconductive samples except for AZ-93 (inorganic nonconductive sample)., 資料番号: AA0063585028, レポート番号: JAXA-SP-06-035

資料番号: AA0063585006, レポート番号: JAXA-SP-06-035

MUSCAT(Multi-Utility Spacecraft Charging Analysis Tool)は地球低軌道(LEO: Low Earth Orbit)、静止軌道(GEO: Geosynchronous Earth Orbit)並びに極軌道(PEO: Polar Earth Orbit)それぞれの環境に相当する、帯電状態を含む宇宙機-宇宙プラズマ相互作用を解析する計算ツールである。本開発プロジェクトは2004年11月に開始され、2006年3月にβ版がユーザーテストのために公開された。ベータ版では宇宙環境を模擬するために必要な要素の大部分を既に含んでいる。この要素とは、(1)高機能なグラフィカル・ユーザー・インターフェース(GUI: Graphical User Interface)、(2)各種物理現象を模擬するに必要な数値解析機能、(3)高速計算機能、(4)検証実験結果およびスーパーコンピューターによる大規模高精度計算結果との相互比較による妥当性の検証である。(1)として、MUSCATユーザーはGUIを用いて衛星形状と表面材料物性を容易に入力し、解析モデルを作成することが出来る。(2)として、MUSCATは光電子放出、2次電子放出、誘電体表面の導電電流による効果に加え、GEOプラズマのダブル・マクスウェル分布、PEOにおけるオーロラ電子電流の効果を解析モデルに含んでいる。(3)としてMUSCATは並列ワークステーション上での並列計算機能を実装している。さらに4)としてMUSCATの解析結果は検証実験結果と非常に良好な一致を示した。また、MUSCATの試験的な運用をGreenhouse gases Observing SATellite(GOSAT)に対して行った。この目的の1つは地上試験と平行して現実の詳細な衛星形状を用いてGOSATの帯電状態を推定することであるが、もう1つの目的はMUSCATの性能検証である。MUSCATは2007年3月に完成予定である。, 資料番号: AA0063585026, レポート番号: JAXA-SP-06-035

資料番号: AA0063585004, レポート番号: JAXA-SP-06-035

資料番号: AA0063585015, レポート番号: JAXA-SP-06-035

資料番号: AA0063585013, レポート番号: JAXA-SP-06-035

資料番号: AA0063585012, レポート番号: JAXA-SP-06-035

国際宇宙ステーションロシアサービスモジュール利用微小粒子捕獲実験および材料曝露実験装置(Service Module/Micro-Particles Capturer and Space Environment Exposure Device: SM/MPAC&SEED)の実験概要、目的などについて述べる。, 資料番号: AA0063224001, レポート番号: JAXA-SP-06-021

資料番号: AA0063585019, レポート番号: JAXA-SP-06-035

軌道上宇宙環境の把握、宇宙用部品・材料の耐宇宙環境性評価、高性能・長寿命材料の開発、JAXA認定部品・材料の宇宙実証を目的として、国際宇宙ステーション(ISS: International Space Station)を利用した宇宙実験である、「国際宇宙ステーションロシアサービスモジュール利用微小粒子捕獲実験および材料曝露実験」(SM/MPAC&SEED実験: Service Module/Micro-Particle Capturer and Space Environment Exposure Device)を、2001年8月より開始している。本実験は、同一試料構成の実験装置3式を同時にISS外壁で宇宙空間に曝露開始し、約1年間隔で1式ずつ地上に回収するというものである。本材料曝露実験に供している試料は、JAXAのほか、大学、研究機関、メーカから提案を受け、23種類の試料が選定されている。本稿では、JAXAから提案した宇宙用材料について、第2式目回収試料(曝露期間約28ヶ月)を中心に報告する。, 資料番号: AA0063224011, レポート番号: JAXA-SP-06-021

Frequent satellite failures due to charging and arcing on solar array surface, there are strong demands for more thorough ElectroStatic Discharge (ESD) ground test before the launch. It is necessary to validate that a given solar array design can withstand repeated arcing in space before the launch. Test conditions, however, differ among countries, as there is no international standard to define the conditions. An international research project started in 2005 to establish International Standard Organization (ISO) standard on ESD test. In the first year, test coupons of the international round robin tests were produced and the preliminary experiments were carried out. In September 2006, the team members gathered at ONERA, Toulouse France. Demonstration experiments were carried out and in-depth discussion was done regarding the preliminary test results of KIT (Kyushu Institute of Technology). In November 2006, the First International Workshop on ISO Standardization of Electrostatic Discharge Test of Satellite Solar Array was held in Kitakyushu. The first version of the working draft of ISO document was discussed in the workshop and the participants agreed to seek the ISO standard by as early as Fall 2008., 資料番号: AA0063585003, レポート番号: JAXA-SP-06-035

Spacecrafts flying in GEO (Geo-synchronous Earth Orbit) are always exposed to plasma and radioactive-rays such as alpha-, beta- or gamma-rays. Especially in GEO, dielectric materials are expected to be irradiated by high energy electron-beam. In the case of high energy electron beam irradiation, the electrons are injected into the bulk of dielectric materials and they accumulate in them. Because there are no basic data based on practical experiments, it is difficult to expect when and how an accident of ESD (Erector-Static Discharge) caused by accumulated charge will happen on spacecraft. Therefore, we need to measure the charge distribution in the bulk of dielectric materials. We have been developing a system for measuring such a charge distribution in dielectric materials using, so-called, PIPWP (Piezo-Induced Pressure Wave Propagation) method. However, the spatial resolution was low and it was difficult that the space charge distribution measurement in the material used with actual spacecrafts. To obtain a good experiment result, we must use the PEA (Pulsed Electro-Acoustic) method. It is necessary to develop a new PEA measurement system, for a real-time, continuous measurement to secure reliability while irradiating the sample. In this report, It introduces a small, real-time Space Charge Measurement System using PEA method., 資料番号: AA0063585030, レポート番号: JAXA-SP-06-035

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