高島 健

The fluxgate magnetometer for the Arase (ERG) spacecraft mission was built to investigate particle acceleration processes in the inner magnetosphere. Precise measurements of the field intensity and direction are essential in studying the motion of particles, the properties of waves interacting with the particles, and magnetic field variations induced by electric currents. By observing temporal field variations, we will more deeply understand magnetohydrodynamic and electromagnetic ion-cyclotron waves in the ultra-low-frequency range, which can cause production and loss of relativistic electrons and ring-current particles. The hardware and software designs of the Magnetic Field Experiment (MGF) were optimized to meet the requirements for studying these phenomena. The MGF makes measurements at a sampling rate of 256 vectors/s, and the data are averaged onboard to fit the telemetry budget. The magnetometer switches the dynamic range between +/- 8000 and +/- 60,000 nT, depending on the local magnetic field intensity. The experiment is calibrated by preflight tests and through analysis of in-orbit data. MGF data are edited into files with a common data file format, archived on a data server, and made available to the science community. Magnetic field observation by the MGF will significantly improve our knowledge of the growth and decay of radiation belts and ring currents, as well as the dynamics of geospace storms.

© 2017, The Author(s). The medium-energy particle experiments–ion mass analyzer (MEP-i) was developed for the exploration of energization and radiation in geospace (ERG) mission (Arase), in order to measure the three-dimensional distribution functions of the inner-magnetospheric ions in the medium energy range between 10 and 180 keV/q. The energy, mass, and charge state of each ion are determined by a combination of an electrostatic energy/charge analyzer, a time-of-flight mass/charge analyzer, and energy-sensitive solid-state detectors. This paper describes the instrumentation of the MEP-i, data products, and observation results during a magnetic storm.

The medium-energy particle experiments-ion mass analyzer (MEP-i) was developed for the exploration of energization and radiation in geospace (ERG) mission (Arase), in order to measure the three-dimensional distribution functions of the inner-magnetospheric ions in the medium energy range between 10 and 180 keV/q. The energy, mass, and charge state of each ion are determined by a combination of an electrostatic energy/charge analyzer, a time-of-flight mass/charge analyzer, and energy-sensitive solid-state detectors. This paper describes the instrumentation of the MEP-i, data products, and observation results during a magnetic storm.

© Published under licence by IOP Publishing Ltd. The ERG (Exploration of energization and Radiation in Geospace) is Japanese geospace exploration project. The project focuses on relativistic electron acceleration mechanism of the outer belt and dynamics of space storms in the context of the cross-energy coupling via wave-particle interactions. The project consists of the satellite observation team, the ground-based network observation team, and integrated-data analysis/simulation team. The satellite was launched on December 20 2016 and has been nicknamed, "Arase". This paper describes overview of the project and future plan for observations.

DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consists of three drag-free spacecraft arranged in an equilateral triangle with 1000 km arm lengths whose relative displacements are measured by a differential Fabry-Perot interferometer, and four units of triangular Fabry-Perot interferometers are arranged on heliocentric orbit around the sun. DECIGO is vary ambitious mission, we plan to launch DECIGO in era of 2030s after precursor satellite mission, B-DECIGO. B-DECIGO is essentially smaller version of DECIGO: B-DECIGO consists of three spacecraft arranged in an triangle with 100 km arm lengths orbiting 2000 km above the surface of the earth. It is hoped that the launch date will be late 2020s for the present..

When quaternions are used for representing the attitude of a spinning spacecraft in an attitude estimation filter, several problems appear due to their rapid variations. These problems include numerical integration errors and violation of the linear approximations for the filter. In this study, we propose representing the attitude of a spinning spacecraft using a set of spin parameters. These parameters consist of the spin-axis orientation unit vector in the inertial frame and the spin phase angle. This representation is advantageous as the spin axis direction components in the inertial frame do not change rapidly and the phase angle changes with a constant rate in the absence of a torque. The attitude matrix and the kinematics equations are derived in terms of spin parameters. As the equations are highly nonlinear an Unscented Kalman Filter (UKF) is implemented to estimate the spacecraft's attitude in spin parameters. The estimation results are compared with those of a quaternion based UKF in different scenarios using the simulated data for JAXA's ERG spacecraft.

Conventional protocols have been integrated with SpaceWire through service oriented approach with reference to SPACECRAFT ONBOARD INTERFACE SERVICES (SOIS). The design framework is based on the definition of determinism provided by SpaceWire-D draft standard in order to keep established services inherited from previous satellite projects. The implementation result is under evaluation in order to establish the consistency with the draft standard of SpaceWire - Plug-and-play protocol. This paper describes the integration approach and the evaluation of implementation experience.

© 2014 SPIE. Recent progress in wide field of view or all-sky observations such as Swift/BAT hard X-ray monitor and Fermi GeV gamma-ray observatory has opened up a new era of time-domain high energy astro-physics addressing new insight in, e.g., particle acceleration in the universe. MeV coverage with comparable sensitivity, i.e. 1 ∼ 10 mCrab is missing and a new MeV all-sky observatory is needed. These new MeV mission tend to be large, power- consuming and hence expensive, and its realization is yet to come. A compact sub-MeV (0.2-2 MeV) all-sky mission is proposed as a path finder for such mission. It is based on a Si/CdTe semiconductor Compton telescope technology employed in the soft gamma-ray detector onboard ASTRO-H, to be launched in to orbit on late 2015. The mission is kept as small as 0:5 X 0:5 X 0:4 m3, 150 kg in weight and 200 W in power in place of the band coverage above a few MeV, in favor of early realization as a sub-payload to other large platforms, such as the international space station.

In the upcoming JAXA/ERG satellite mission, Wave Particle Interaction Analyzer (WPIA) will be installed as an onboard software function. We study the statistical significance of the WPIA for measurement of the energy transfer process between energetic electrons and whistler-mode chorus emissions in the Earth's inner magnetosphere. The WPIA measures a relative phase angle between the wave vector E and velocity vector ν of each electron and computes their inner product W, where W is the time variation of the kinetic energy of energetic electrons interacting with plasma waves. We evaluate the feasibility by applying the WPIA analysis to the simulation results of whistler-mode chorus generation. We compute W using both a wave electric field vector observed at a fixed point in the simulation system and a velocity vector of each energetic electron passing through this point. By summing up W of an individual particle i to give W , we obtain significant values of W as expected from the evolution of chorus emissions in the simulation result.We can discuss the efficiency of the energy exchange through wave-particle interactions by selecting the range of the kinetic energy and pitch angle of the electrons used in the computation of W . The statistical significance of the obtained W is evaluated by calculating the standard deviation σ of W . In the results of the analysis, positive or negative W is obtained at the different regions of velocity phase space, while at the specific regions the obtained W values are significantly greater than σ , indicating efficient wave-particle interactions. The present study demonstrates the feasibility of using the WPIA, which will be on board the upcoming ERG satellite, for direct measurement of wave-particle interactions. © Author(s) 2013. i int int int int W int int int W

JAXA・研究開発本部・宇宙実証研究共同センターでは,100kg級の小型実証衛星1型を2009年1月に打上げた.衛星は所期の目標以上の成果を得て2010年9月8日に運用を終了した.SDS-1の開発は研究開発本部の若手技術者が主体となって,設計,組立試験から打上げ,運用までの衛星のライフサイクルの実務をインハウスで行った.また,次号機となるSDS-4を2012年5月に打上げ,現在,運用を行って種々の実証データを取得している.このように,SDS-1はSDSプログラムの初号機として,新規技術の軌道上実証の目的を達成するとともに,小型衛星の活用,軌道上実証シリーズ化の先鞭を付けた.本稿ではSDS-1の打上げから運用終了までを振り返って,運用結果を評価し,最後に反映事項・教訓事項について述べる.

A thermal control system (TCS) of a microsatellite is proposed with loop heat pipes (LHPs) including bypass valves. "Free from restrictions in thermal design," all instruments can be mounted anywhere on the internal side of the six structure panels making up the satellite without concern for the thermal design of the entire satellite and other instruments. The temperatures of all instruments are maintained under any attitude (i.e., external thermal environment) by concentrating dissipated heat in a "center heat source" (CHS) using six LHPs mounted between the CHS and structure panels and other heat transport devices. An experimental study and numerical simulation are conducted to validate the microsatellite TCS. In the experimental study, two LHPs are connected to a heat source and a heat load is input to a condenser to simulate the heat input to a radiator in orbit. The heat from the heat source is successfully transported via one LHP if heat is input to the radiator connected to the second LHP. Orbital thermal analyses of the microsatellite are also conducted. Typical low-Earth, geostationary, and polar orbits are investigated for spinning and three-axis stabilized satellites. Heat from the CHS is transported via the LHPs, and the CHS temperature is maintained within the required temperature range in all analysis cases as a result of bypass valve operation. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

The Energization and Radiation in Geospace (ERG) project for solar cycle 24 will explore how relativistic electrons in the radiation belts are generated during space storms. This geospace exploration project consists of three research teams: the ERG satellite observation team, the ground-based network observation team, and the integrated data analysis/simulation team. Satellite observation will provide in situ measurements of features such as the plasma distribution function, electric and magnetic fields, and plasma waves, whereas remote sensing by ground-based observations using, for example, HF radars, magnetometers, optical instruments, and radio wave receivers will provide the global state of the geospace. Various kinds of data will be integrated and compared with numerical simulations for quantitative understanding. Such a synergetic approach is essential for comprehensive understanding of relativistic electron generation/loss processes through crossenergy and cross-regional coupling in which different plasma populations and regions are dynamically coupled with each other. In addition, the ERG satellite will utilize a new and innovative measurement technique for wave-particle interactions that can directly measure the energy exchange process between particles and plasma waves. In this paper, we briefly review some of the profound problems regarding relativistic electron accelerations and losses that will be solved by the ERG project, and we provide an overview of the project. © 2012. American Geophysical Union. All Rights Reserved.

The objectives of the DECi-hertz Interferometer Gravitational Wave Observatory (DECIGO) are to open a new window of observation for gravitational wave astronomy and to obtain insight into significant areas of science, such as verifying and characterizing inflation, determining the thermal history of the universe, characterizing dark energy, describing the formation mechanism of supermassive black holes in the center of galaxies, testing alternative theories of gravity, seeking black hole dark matter, understanding the physics of neutron stars and searching for planets around double neutron stars. DECIGO consists of four clusters of spacecraft in heliocentric orbits; each cluster employs three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by three pairs of differential Fabry-Perot Michelson interferometers. Two milestone missions, DECIGO pathfinder and Pre-DECIGO, will be launched to demonstrate required technologies and possibly to detect gravitational waves.

We report the performance of an Avalanche Photodiode (APD) that has a large-area (1 cm(2)) and a thick depletion layer (similar to 30 mu m) in application to electron measurements. It is shown that the dead layer is sufficiently thin for the detection of electrons at energies less than 10 keV; the lowest measurable energy is similar to 5 keV. We also confirmed that the energy resolution is not significantly deteriorated by the non-uniformity of the thickness of the dead layer or the internal gain. The energy resolution at the lower energy range (<10 keV) is limited by the electric noise. Dependence of the electric noise on the detector size is also discussed. Furthermore, the effective multiplication profile in the normal direction is inferred from the experimental data.

A space gravitational-wave antenna, DECIGO (DECI-hertz interferometer Gravitational wave Observatory), will provide fruitful insights into the universe, particularly on the formation mechanism of supermassive black holes, dark energy and the inflation of the universe. In the current pre-conceptual design, DECIGO will be comprising four interferometer units; each interferometer unit will be formed by three drag-free spacecraft with 1000 km separation. Since DECIGO will be an extremely challenging mission with high-precision formation flight with long baseline, it is important to increase the technical feasibility before its planned launch in 2027. Thus, we are planning to launch two milestone missions. DECIGO pathfinder (DPF) is the first milestone mission, and key components for DPF are being tested on ground and in orbit. In this paper, we review the conceptual design and current status of DECIGO and DPF.

The high precision gamma-ray spectrometer (GRS) onboard the Japanese lunar explorer, SELENE (KAGUYA) consists of a large Ge crystal as the main detector and massive BGO and plastic scintillators as anticoincidence detectors. After a series of initial health checks, it started regular observation officially on December 21, 2007. Energy spectra of lunar gamma rays were obtained by GRS with very good energy resolution being 0.6% at 1.46MeV over the lunar surface. Many peaks of gamma rays from major elements and natural radioactive elements in the lunar surface have been observed. Individual gamma-ray lines emitted from the lunar surface have been identified. Here, we report the initial results obtained practically during the period from December 14, 2007 to February 17, 2008. Global maps of K and Th gamma-ray intensities are reported using count rates in several energy bands.

SPRITE-SAT is a micro satellite in the size of 50 cm cube and weighing 45-kg, designed and developed by Tohoku University. Its mission objective is to conduct scientific observation of atmospheric luminous emissions called "sprites" and terrestrial Gamma-ray flushes. Both are recently discovered phenomena and their mechanisms are still under the veil. SPRITE-SAT was developed to achieve significant observations to determine clear models of these mysterious phenomena. On January 23rd, 2009, SPRITE-SAT was successfully launched by JAXA's H-IIA rocket as a piggyback payload of Greenhouse Gas Observation Satellite (GOSAT). The spacecraft is now in a sun-synchronous polar orbit with 670 km altitude from the Earth's surface. This paper describes a general overview of the spacecraft and its mission.

A space gravitational wave antenna, DECIGO (DECI-hertz interferometer Gravitational wave Observatory) will provide fruitful insights into the universe, particularly on dark energy, the formation mechanism of supermassive black holes, and the inflation of the universe. In the current pre-conceptual design, DECIGO will be comprised of 4 interferometer units; each interferometer unit will be realized by formation flight of three drag-free spacecraft with 1000 km separation. Since DECIGO will be an extremely challenging mission with high-precision formation flight, it is important to increase the technical feasibility before its planned launch in 2024. Thus, we are planning two milestone missions. DECIGO pathfinder (DPF) is the first milestone mission for DECIGO, and key components for DPF are being tested on ground and in orbit. In this article, we review the conceptual design and current status of DECIGO and DPF.

The combination of an electrostatic analyzer and a silicon strip solid detector is proposed for measuring the energy and charge state of medium energy (10-200 keV/q) ions in space. Based on laboratory experiments, it is shown that a single-sided silicon strip detector (SSSD) has low-noise levels that provide sufficient energy resolution for charge state measurements of medium energy ions. It is also demonstrated that energy loss at a dead-layer is a critical factor for the energy resolution and measurement energy threshold; the dead-layer is measured to be similar to 370 mm. A single-sided silicon strip detector with a thin dead-layer is important for the development of medium energy ion measurements into next generation satellite-borne missions. (C) 2009 Elsevier B.V. All rights reserved.

DECIGO pathfinder (DPF) is a milestone satellite mission for DECIGO (DECi-hertz Interferometer Gravitational wave Observatory), which is a future space gravitational wave antenna. DECIGO is expected to provide fruitful insights into the universe, particularly about dark energy, the formation mechanism of supermassive black holes and the inflation of the universe. Since DECIGO will be an extremely challenging mission, which will be formed by three drag-free spacecraft with 1000 km separation, it is important to increase the technical feasibility of DECIGO before its planned launch in 2024. Thus, we are planning to launch two milestone missions: DPF and pre-DECIGO. In this paper, we review the conceptual design and current status of the first milestone mission, DPF.

From the viewpoint of plasma particle measurements in the radiation belt, background noise is a serious problem. High-energy particles penetrating the sensor shielding generate spurious signals, and their count rate often can be comparable to the true signals. In order to attenuate such background noise during medium-energy (5-83 keV) electron measurements, we propose the double energy analyses (DEA) method. DEA is conducted by a combination of an electrostatic analyser (ESA) and avalanche photo-diodes (APDs) ESA and APD independently determine the energy of each incoming particle. By using the DEA method, therefore, the penetrating particles can be rejected when the two energy determinations are inconsistent spurious noise are caused only when the deposited energy at an APD is by chance consistent with the measured energy by ESA. We formulate the noise count rate and show the advantage of DEA method quantitatively. © 2008 COSPAR.

The exploration of the Jovian System and its fascinating satellite Europa is one of the priorities presented in ESA's "Cosmic Vision" strategic document. The Jovian System indeed displays many facets. It is a small planetary system in its own right, built-up out of the mixture of gas and icy material that was present in the external region of the solar nebula. Through a complex history of accretion, internal differentiation and dynamic interaction, a very unique satellite system formed, in which three of the four Galilean satellites are locked in the so-called Laplace resonance. The energy and angular momentum they exchange among themselves and with Jupiter contribute to various degrees to the internal heating sources of the satellites. Unique among these satellites, Europa is believed to shelter an ocean between its geodynamically active icy crust and its silicate mantle, one where the main conditions for habitability may be fulfilled. For this very reason, Europa is one of the best candidates for the search for life in our Solar System. So, is Europa really habitable, representing a "habitable zone" in the Jupiter system? To answer this specific question, we need a dedicated mission to Europa. But to understand in a more generic way the habitability conditions around giant planets, we need to go beyond Europa itself and address two more general questions at the scale of the Jupiter system: To what extent is its possible habitability related to the initial conditions and formation scenario of the Jovian satellites? To what extent is it due to the way the Jupiter system works? ESA's Cosmic Vision programme offers an ideal and timely framework to address these three key questions. Building on the in-depth reconnaissance of the Jupiter System by Galileo (and the Voyager, Ulysses, Cassini and New Horizons fly-by's) and on the anticipated accomplishments of NASA's JUNO mission, it is now time to design and fly a new mission which will focus on these three major questions. LAPLACE, as we propose to call it, will deploy in the Jovian system a triad of orbiting platforms to perform coordinated observations of its main components: Europa, our priority target, the Jovian satellites, Jupiter's magnetosphere and its atmosphere and interior. LAPLACE will consolidate Europe's role and visibility in the exploration of the Solar System and will foster the development of technologies for the exploration of deep space in Europe. Its multi-platform and multi-target architecture, combined with its broadly multidisciplinary scientific dimension, will provide an outstanding opportunity to build a broad international collaboration with all interested nations and space agencies. © The Author(s) 2009.

The Solar-Sail Project has been investigated by JAXA as an engineering mission with a small orbiter into the Jovian orbit. This paper summarizes the basic design of this project and possible Jovian system studies by this opportunity. The large-scale Jovian mission has been discussed as a long future plan since the 1970s, when the investigation of the future planetary exploration program started in Japan. The largest planet and its complex planetary system would be studied by several main objectives: (1) The structure of a gas planet: the internal and atmospheric structures of a gas planet which could not be a star. (2) The Jovian-type magnetosphere: the structure and processes of the largest and strongest magnetosphere in the solar system. (3) The structure, composition, and evolution of Jupiter and its satellite system. The small Jovian orbiter accompanied with the Solar-Sail Project will try to establish the technical feasibility of such future outer planet missions in Japan. The main objective is the second target, the Jovian magnetospheric and auroral studies with its limited payload resources.

The Japanese lunar explorer SELENE was launched from Tanegashima Space Center on September 14, 2007. It consists of a main orbiter KAGUYA at 100 km altitude and two daughter satellites (relay satellite OKINA and VRAD satellite OUNA) with 14 scientific instruments. The high precision gamma-ray spectrometer (GRS) on KAGUYA measures 200 keV - 12 MeV gamma rays to determine the elemental composition of the lunar surface. The GRS is composed of a large Ge crystal as a main detector and massive bismuth germinate (BGO) crystals and a plastic scintillator as anticoincidence detectors. The Ge detector is cooled by a Stirling cryocooler below 90 K during the observation. After successful launch of the spacecraft and initial checkouts, the GRS started the nominal observation on December 21, 2007, and the temperatures and counting rates of the GRS were confirmed to be stable. Energy spectra of gamma rays with a good energy resolution are being obtained over the lunar surface, which will allow us to make global maps of the elemental abundances of the Moon soon. © 2009 The Physical Society of Japan.

The high precision gamma-ray spectrometer (GRS) is carried on the first Japan's large- scaled lunar explorer, SELENE (KAGUYA), successfully launched by the H-IIA rocket on Sep. 14, 2007. The GRS consists of a large Ge crystal as a main detector and massive bismuth germanate crystals and a plastic scintillator as anticoincidence detectors. After a series of initial health check of the GRS, it started a regular observation on December 21, 2007. Energy spectra including many clear peaks of major elements and trace elements on the lunar surface have been measured by the GRS. Global measurement of thorium counting rate on the lunar surface is presented. The region showing the highest count rate of thorium extends from Kepler to Fra Mauro region in the Procellarum. And Apennine Bench and Aristillus region and the northwestern region of Mare Imbrium are high in thorium count rate. Second high count rate region is located in the South Pole-Aitken basin of the farside. Arago and Compton/Belkovich craters are also enriched in thorium. The initial results observed by GRS during the period from Dec. 21, 2007 to Feb. 17, 2008 is reviewed. © 2009 The Physical Society of Japan.

The information on energy spectra of 1-100 keV electrons is expected to provide an important clue to understand heating and acceleration mechanisms of magnetospheric plasmas. However, electrons of several keV to several tens of keV are not properly verified by observations owing to the problems in the measurement techniques. This study aims to bridge this gap by applying Avalanche Photodiodes (APDs) to the detection of electrons. The internal gain of APDs enables high-resolution detection of low-energy electrons down to several keV. We have tested an APD: Type spl 3989, Hamamatsu Photonics Co. Ltd. The APD responded to 2-40 keV electrons with the fine peaks of the out put pulse height distributions. Although the experiment is limited to 40 keV, electrons up to about 60 keV are predicted to be detectable with this APD from the simulation. We also have successfully made a verification test by the sounding rocket of ISAS/JAXA targeting medium energy electrons.

In regions such as the reconnection sites and the ring current, plasmas are highly accelerated and their energies sometimes exceed the uppermost energy level of low-energy plasma sensors (typically similar to 40 keV). In order to study acceleration mechanisms in such key regions, in-situ observations with continuous energy coverage from low (similar to eV) to medium (similar to 10- similar to 200 keV) or to even higher energies are necessary. In fact, ERG and Cross scale missions are planned to explore the above regions with plasma instrument packages that require covering the majority of the energy range. We, therefore, develop a medium energy ion mass spectrometer, which consists of an Electrostatic Analyser (ESA), a Time-of-Flight mass spectrometer (ToF), and solid-state detectors (SSDs). It can simultaneously and independently measure energy-per-charge (E/q), velocity (v), and energy (E) of incoming ions, thus deducing E, m, and q. In addition, the coincidence method via the combination of ToF start-stop signals and SSD signals is useful to reject background noise that is caused by radiation belt electrons and/or solar energetic protons. In order to enable electrostatic analyses with a practical sensor size, we have developed a novel "cusp type" electrostatic analyser. This design provides us a relatively small instrument that has an energy range up to similar to 200 keV/q with a full solid angle coverage (using the spacecraft spin motion). This kind of electrostatic analyser may also be used for electron measurements.

The high precision gamma-ray spectrometer (GRS) is carried on the first Japan's large-scaled lunar explorer, SELENE (KAGUYA), successfully launched by the H-IIA rocket on Sep. 14, 2007. The GRS consists of a large Ge crystal as a main detector and massive bismuth germanate crystals and a plastic scintillator as anticoincidence detectors. The Ge detector is cooled and kept below 90K by a Stirling cryocooler. After a series of initial health check of the GRS, it started a regular observation on December 21, 2007. Energy spectra of gamma rays are obtained with a good energy resolution over the lunar surface. Energy spectra including many peaks of major elements and trace elements on the lunar surface have been measured by the GRS. The GRS identified individual gamma-ray lines emitted from the lunar surface and provided the global intensity maps of naturally radioactive elements. Here, we review an in-flight performance of the GRS and the initial results observed during the period from Dec. 21, 2007 to Feb. 17, 2008.

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the planned Japanese space gravitational wave antenna, aiming to detect gravitational waves from astrophysically and cosmologically significant sources mainly between 0.1 Hz and 10 Hz and thus to open a new window for gravitational wave astronomy and for the universe. DECIGO will consist of three drag-free spacecraft, 1000 km apart from each other, whose relative displacements are measured by a differential Fabry-Perot interferometer. We plan to launch DECIGO in middle of 2020s, after sequence of two precursor satellite missions, DECIGO pathfinder and Pre-DECIGO, for technology demonstration required to realize DECIGO and hopefully for detection of gravitational waves from our galaxy or nearby galaxies. © 2009 IOP Publishing Ltd.

In order to reach the new horizon of the space physics research, the Plasma Universe, via in-situ measurements in the Earth's magnetosphere, SCOPE will perform formation flying observations combined with high-time resolution electron measurements. The simultaneous multi-scale observations by SCOPE of various plasma dynamical phenomena will enable data-based study of the key space plasma processes from the cross-scale coupling point of view. Key physical processes to be studied are magnetic reconnection under various boundary conditions, shocks in space plasma, collisionless plasma mixing at the boundaries, and physics of current sheets embedded in complex magnetic geometries. The SCOPE formation is made up of 5 spacecraft and is put into the equatorial orbit with the apogee at 30Re (Re: earth radius). One of the spacecraft is a large mother ship which is equipped with a full suite of particle detectors including ultra-high time resolution electron detector. Among other 4 small spacecraft, one remains near (̃10km) the mother ship and the spacecraft-pair will focus on the electron-scale physics. Others at the distance of 100̃3000km (electron ̃ ion spatial scales) from the mother ship will monitor plasma dynamics surrounding the mother-daughter pair. There is lively on-going discussion on Japan-Europe international collaboration (ESA's Cross-Scale), which would certainly make better the coverage over the scales of interest and thus make the success of the mission, i.e., clarifying the multi-scale nature of the Plasma Universe, to be attained at an even higher level. © 2009 American Institute of Physics.

With two electron beam sources, we have tested two new Hamamatsu [Hamamatsu Photonics K.K., Shizuoka, Japan 〈http://www.hamamatsu.com/〉] avalanche photodiodes (APDs) of spl 3988 and spl 6098 to detect electron beams up to 100 keV. Though our previous results showed the effectiveness and the advantage of an APD to measure 2-40 keV electrons, its upper limit was not high enough to detect so-called medium-energy electrons. In addition to the limitation of its detectable range, the response at different energies was also not linear. These newly developed APDs, which have thicker depletion-layers, provide full coverage of this missing range along with a good linearity. The depletion-layer thickness was increased to 140 μ m for both APDs, the dead-layer of spl 3988 became 10 times thicker than that of spl 6098. The thin-surface dead-layer and thick depletion-layer of spl 6098 allows the detection of electrons from 3 keV up to 100 keV with a good linearity and with an excellent energy resolution of 4 keV at 100-keV electrons. The wide dynamic range from 3 keV to 100 keV of those APDs will increase their appeal in detecting electrons for space plasma research. © 2008 Elsevier B.V. All rights reserved.

This paper summarizes the cut-rent status of the BepiColombo Mercury magnetospheric orbiter (MMO) spacecraft design. The MMO is a spinning spacecraft of 223 kg mass whose spin axis is nearly perpendicular to the Mercury orbital plane. The current status of the overall MMO system and subsystems such as thermal control, communication, power, etc., are described. The critical technologies are also outlined. Furthermore, the outline of the international cooperation between Japan Aerospace Exploration Agency and European Space Agency is also presented. (C) 2008 Elsevier Ltd. All rights reserved.

We have developed a new energy/mass spectrometer for medium energy range (similar to 10-200 keV/q) ion measurements in the Earth's magnetosphere and interplanetary space. The wide field-of-view (similar to 360 degrees fan) enables acquisition of 3-D distribution functions for all the major ions, by utilizing spacecraft spin motions. The g-factor is much larger than the previous ion mass spectrometers in the medium energy range. The mass analysis unit that measures ion time-of-flights is well designed to realize a lightweight and simple signal processing. Laboratory experiments with a test model show that the performance of mass spectroscopy agrees with numerical simulations. Medium energy ion mass spectrometer with this new design will surely be useful for upcoming space missions in the inner magnetosphere, reconnection regions, and other energetic plasma structures/phenomena in space.

The Soft X-ray Imager (SXI) is the X-ray CCD detector system on board the NeXT mission that is to be launched around 2013. The system consists of a camera, an SXI-specific data processing unit (SXI-E) and a CPU unit commonly used throughout the NeXT satellite. All the analog signal handling is restricted within the camera unit, and all the I/O of the unit are digital.The camera unit and SXI-E are connected by multiple LVDS lines, and SXI-E and the CPU unit will be connected by a SpaceWire (SpW) network. The network can connect SXI-E to multiple CPU units (the formal SXI CPU and neighbors) and all the CPU units in the network have connections to multiple neighbors: with this configuration, the SXI system can work even in the case that one SpW connection or the formal SXI CPU is down.The main tasks of SXI-E are to generate the CCD driving pattern, the acquisition of the image data stream and HK data supplied by the camera and transfer them to the CPU unit with the Remote Memory Access Protocol (RMAP) over SpW. In addition to them, SXI-E also detects the pixels whose values are higher than the event threshold and both adjacent pixels in the same line, and send their coordinates to the CPU unit. The CPU unit can reduce its load significantly with this information because it gets rid of the necessity to scan whole the image to detect X-ray events.

DECi-hertz Interferometer Gravitational wave Observatory (DECIGO) is the future Japanese space gravitational wave antenna. DECIGO is expected to open a new window of observation for gravitational wave astronomy especially between 0.1 Hz and 10 Hz, revealing various mysteries of the universe such as dark energy, formation mechanism of supermassive black holes, and inflation of the universe. The pre-conceptual design of DECIGO consists of three drag-free spacecraft, whose relative displacements are measured by a differential Fabry-Perot Michelson interferometer. We plan to launch two missions, DECIGO pathfinder and pre-DECIGO first and finally DECIGO in 2024.

In order to improve a detection efficiency of the improved Fourier Synthesis imaging telescope, we are developing a one-dimensional γ-ray position sensor using crystal scintillators coupled to a silicon strip detector (SSD). We have manufactured thin Gd2SiO5:Ce (GSO) scintillator plates with a dimension of 10 mm × 5 mm × 0.3 mm. Twenty scintillator plates, with a light reflective sheet between adjacent plates, have been stacked into a block (stacked GSO). The SSD has 32 strip electrodes of 400 μ m pitch on its p-side, while its n-side common electrode is not metallic. The pulse height of the 32 channels are read out simultaneously by an analog ASIC. We coupled the stacked GSO to the n-side of the SSD with the GSO plates running parallel to the SSD strips. By irradiating the coupled device with γ-rays from137Cs and22Na, we successfully obtained their spectra, and achieved a position resolution significantly finer than 1 mm. © 2007 Elsevier B.V. All rights reserved.

We present the unsaturated peak profile of the giant flare from SGR 1900 + 14 on 1998 August 27. This was obtained by the particle counters of the Low Energy Particles instrument on board the Geotail spacecraft. The observed peak profile revealed four characteristic features: an initial steep rise, an intermediate rise to the peak, an exponential decay, and a small hump in the decay phase. From this light curve, we found that the isotropic peak luminosity was ergs s(-1)and that the total energy was ergs s(-1) ( keV), assuming 46 44 2.3 *10 4.3 * 10 E >= 50 that the distance to SGR 1900 + 14 is 15 kpc and that the spectrum is optically thin thermal bremsstrahlung with keV. These values are consistent with the previously reported lower limits derived from Ulysses and kT p 240 Konus- Wind observations. A comparative study of the initial spikes of the SGR 1900 + 14 giant flare in 1998 and of the SGR 1806 -20 giant flare in 2004 is also presented. The timescale of the initial steep rise shows a magnetospheric origin, while the timescale of the intermediate rise to the peak indicates that it originates from crustal fracturing. Finally, we argue that the four features and their corresponding timescales provide us with a clue to identify extragalactic soft gamma- ray repeater giant flares among short gamma- ray bursts.

This paper describes the initial performance of a two-dimensional analog ASIC that has been developed to read out CdTe pixel detectors for the next-generation hard X-ray imager. The readout chip consists of a 32 x 32 matrix of identical 200 mu m x 200 mu m pixel cells. Each readout cell contains a low noise charge-sensitive amplifier, three-stage pulse shaping amplifiers and a comparator circuit. Pulse processing circuits have been also designed to achieve lower power consumption for the space application. Analog outputs by injecting a test pulse have been obtained from 991 pixels out of 1024 pixels. The mean noise level is 297 +/- 29 electrons (rms) and power consumption is 110 mu W/pixel. (c) 2007 Elsevier B.V. All rights reserved.

Charge-coupled devices (CCDs) are widely used in X-ray astronomy as a focal plane detector for X-rays up to 10 keV. For future X-ray space missions, thick CCDs are being developed to improve the detection efficiency of high energy X-rays beyond 10 keV. We propose a new method to produce a novel multi-collimator using a barium phosphate glass, BP-1, which was originally developed as a solid state track detector. The BP-1 collimator allows the realization of small through-holes, several hundred nano-meters in radius. We performed the first experiment of this project in which a xenon beam of 80 MeV/u was used to irradiate the 1.3 mm-thick-BP-1 glass. After an etching process, we obtained the first prototype BP-1 collimator. There were a large number of tapered pinholes which are randomly distributed and with extremely high aspect ratio. Taking X-ray photographs demonstrated that the first prototype has a capability of fine collimation for X-rays up to 20 keV. (c) 2006 Elsevier B.V. All rights reserved.

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations.