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令和3年度関東近県SSH指定校合同発表会, 東京, 2022.3.21, 工学院大学

資料番号: AA0063997008, 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

本研究は、南極周回超伝導スペクトロメータによる宇宙線観測(BESS(Balloon-borne Experiment with a Superconducting Spectrometer)-Polar実験)を通して、「宇宙起源反粒子、反物質の精密探査」を目的としている。地球磁極領域に降り注ぐ低エネルギー宇宙線に注目し、反陽子スペクトルを精密に測定して、衝突(2次)起源反陽子流束の理解を深めるとともに、「原始ブラックホール(PBH: Primordial Black Hole)の蒸発」、「超対称性粒子・ニュートラリーノの対消滅」など、初期宇宙における素粒子現象の痕跡となる「宇宙(1次)起源反粒子」を精密探査する。反ヘリウムの直接探査を通して、宇宙における物質・反物質の存在の非対称性を検証する。同時に陽子、ヘリウム流束を精密に観測し、これまでのカナダでの観測(BESS実験、1993-2002)の結果と合わせて、太陽活動変調とその電荷依存性について系統的に観測し、宇宙線の伝播、相互作用に関する基礎データを提供する。本研究では、これまでのBESS実験で培われた超伝導スペクトロメータによる宇宙線観測の経験をもとに、低エネルギー領域での観測感度を高め、南極周回長時間飛翔を可能とする超伝導スペクトロメータを新たに開発した。2004年12月13日、南極(米国、マクマード基地)での観測気球打ち上げ、高度37kmでの9日間に及ぶ南極周回飛翔に成功し、9億イベントの宇宙線観測データを収集した。運動エネルギー0.1〜1.3GeVの範囲に於いて、これまでの約4倍の統計量でエネルギースペクトルを決定した。結果は、衝突(2次)起源モデルとよく整合し、1次起源反陽子の兆候は観測されていない。太陽活動が極小期にむけた過渡期にあたる2004年の観測として予想に沿った結果を得た。反ヘリウム探索は、これまでのヘリウム観測の総統計量を2倍以上に高め、反ヘリウム／ヘリウム比の上限値を2.7×10(exp -7)にまで押し下げた。本報告では、BESS-Polar(2004年)の成果を纏め、次期太陽活動極小期(2007年)における第2回南極周回気球実験計画を述べる。, The Balloon-borne Experiment with a Superconducting Spectrometer with long duration flights in Antarctica (BESS-Polar) has been progressed. It aims at searches for primordial antiparticles in low-energy cosmic rays with unprecedented sensitivity in the solar minimum period. This report describes the status and future plan of the BESS-Polar experiment., 資料番号: AA0063732006, レポート番号: JAXA-RR-07-009

We evaluated potentiality of lunar terminator observations by X-Ray Spectrometer (XRS) onboard SELENE (SELenological and Engineering Explorer: KAGUYA). We quantitatively estimated X-ray spectra at low solar altitudes by a numerical X-ray interaction model, and investigated critical measuring times which are required for analyses of the X-ray fluorescence lines from the target elements. The results show that effective observations at the terminator can be carried out within a double or triple measuring time as long as that at the sub solar point. Better signal-to-noise ratios at the terminator, furthermore, provide suitable situation to detect Ca and Fe, and possibly Cr and Mn., 資料番号: AA0063723041

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

The onboard electronic devices and astronauts on spacecrafts have many effects on the space radiation. It is one of the important issues for space mission planning to predict the space radiation environment and to evaluate it. Because the space vehicles must be designed to decrease the radiation exposure to protect devices and astronauts. Among many kinds of radiation in space, the radiation belts particles having continuously high fluxes give a large dose contribution to a near-earth space mission. The radiation belts have been measured with various satellites and detectors. NASA's radiation belt models, AP8 (Sawyer and Vette, 1976) and AE8 (Vette, 1991) were derived from the data which had been observed in the 1960s and 1970s. In the recent, CRRES models have been developed with the data of the CRRES satellite (Gussenhoven et al., 1996). NOAAPRO (NOAA proton) model have been developed with the data of the NOAA-TIROS satellite (Huston, 1998). POLE model have been developed with the data of the LANL's geostationary satellite (Boscher et al., 2003). We have developed the radiation belt models (beta version) using MDS-1 data., 資料番号: AA0049500029, レポート番号: JAXA-SP-06-006

The Jovian Synchrotron Radiation (JSR) is a radio wave emitted from the relativistic electrons in the Jovian radiation belt, which has information of dynamics of high-energy particles and electromagnetic disturbances in the Jovian inner magnetosphere. JSR is known to both indicate long-term (11 year) and short-term (day to weeks) variations but the short-term variation has not been studied well because of few continuous observation. Then we have observed JSR for several months a year since 1994 to reveal characteristics of the flux variations especially at time variations. The regular observations have been made at a frequency of 327 MHz by using parabolic cylinder antennas of the Solar Terrestrial Environment Laboratory (STEL), Nagoya University. The observed JSR flux includes apparent variation due to inevitable system gain variation of the radio receiving system. In order to compensate the system gain variation, Nomura et al., (2005), have evaluated the system gain using a flux reference radio source that was observed quasi-simultaneously with Jupiter, and made additional observations of 'actual' galactic Back-Ground radiation (BG) with the highly stable radio receiving system of Tohoku University. In this study, we have derived the JSR flux densities to improve reliability of the JSR flux densities by revaluation of BG radiation using a revised technique. As the result, we derived the JSR flux densities for 1995 and 1996 with the error range of about 50 percent. We report the improved results of the JSR observations and infer causalities of the variations based on correlation analyses between the JSR flux variations and parameters of the solar activity and solar wind., 資料番号: AA0063505009

Jupiter's Synchrotron Radiation (JSR) is generated by the relativistic electrons trapped in the radiation belt. Variation of JSR is, therefore, an important probe to investigate generation and dissipation processes of the relativistic electrons and deformation of their global distribution. Regular and systematic JSR observations have been made by several groups and revealed the existence of short term variations at a time scale of several days to months inferring some electro-magnetic activities in the inner magnetosphere. Now it's the time to investigate the details of variation characteristics and origin of the time variation. A program of a multi-frequency observation for JSR has been started since 2001. The JSR spectrum measurements give us information of variations of pitch angle and/or characteristics of radial diffusion of the relativistic electrons. In this program three observation frequencies measured with different facilities have been adopted; i.e., 325 MHz at Tohoku Univ., 930 MHz at European Incoherent Scatter Facility (EISCAT), Sweden and 2.22 GHz at National Institute of Information and Communications Technology (NiCT). JSR at the frequency range is generated from the relativistic electrons at the energy from 6 to 16 MeV, and has been hardly observed regularly. We have made approximately two week observation in October 2003 and one month observation in June to July 2004. A preliminary analysis shows existence of radio flux variations. In particular, the variation showed frequency dependent and rapid decreasing feature in October 2003, which infers that new ideas of energy loss process are required in the dynamics of low energy radiation belt electrons., 資料番号: AA0063350054

The Jovian Synchrotron Radiation (JSR) is a radio wave emitted from the relativistic electrons in the Jovian radiation belt, which has information of dynamics of high-energy particles and electromagnetic disturbances in the Jovian inner magnetosphere. JSR indicates long-term (11 year) and short-term (day to weeks) variation. The short-term variation is not studied well because of the lack of continuous observation, while the long-term variation is well studied. Then we have observed JSR for several months a year since 1994 to reveal characteristics of the flux variations especially at short-term and long-term time variations. The regular observations have been made at a frequency of 327 MHz by using parabolic cylinder antennas of the Solar Terrestrial Environment Laboratory (STEL), Nagoya University. The observed JSR flux includes apparent variation due to inevitable system gain variation of the radio receiving system. In order to compensate the system gain variation, we have evaluated system gain using a flux reference radio source that was observed quasi-simultaneously with Jupiter, and made additional observations of 'actual' galactic Back-Ground radiation (BG) with the highly stable radio receiving system of Tohoku University. As the result, we derived the JSR flux densities for 1994-2003 successfully and confirmed significant flux variations in both short and long time scales. In this paper, we report the results of the JSR observations for 1994-2003 and infer causalities of the variations based on correlation analyses between the JSR flax variations and parameters of the solar activity and solar wind., 資料番号: AA0063350055

資料番号: AA0063353014

CALETによる電子観測(鳥居2005)のうち、数十GeV以下の低エネルギー領域の観測から期待される成果について述べる。この領域の観測は、気球や衛星により過去数多く行われているが、太陽磁気圏内の宇宙線連続観測はいずれも数GeV以下が主体で、それ以上のエネルギーではデータはほとんど存在せず観測精度も不十分である。従来1次宇宙線の観測は10GeV以上の高エネルギーになるとその影響をほとんど受けないとされてきたが、実際はそのような長期変動の観測値がないため議論の対象になってこなかったという面がある。CALETでは1GeV以上のスペクトル観測を精度良く観測可能であり、電子スペクトルの変動を長期間観測(3年間)することにより、太陽磁気圏の構造の解明や太陽活動の宇宙線観測に与える影響を調べることができると考えている。具体的な目的としては、長期変動の観測から太陽磁気圏における宇宙線の伝播モデルの検証を行う。また、フォーブッシュ減少のような短期変動もあわせて観測し、その原因と構造の解明を行い、これらの長期変動と短期変動の関連性についても調べる予定である。次に、CALETにより2010年以降、電子スペクトルの長期変動と短期変動の観測を行った場合に期待できる成果について報告する。, 資料番号: AA0049122064

Physical Sciences Inc. (PSI), in cooperation with the Boston University Center for Space Physics, and under the sponsorship of the Air Force Research Laboratory Space Vehicle Directorate, has developed and tested a lightweight multi-configuration sensor to monitor the space weather environment. The scintillator-based, Low-Energy Imaging Particle Spectrometer (LIPS) is ideally suited to monitoring the lower energy (20 to 2,000 keV) charged particle environment responsible for deep dielectric charging. The LIPS design is also compatible with the weight, volume, and power requirements of small satellites (less than 1 kg, less than 2 W). The LIPS design does not rely upon a magnetic sector to discriminate between particle types; rather it takes advantage of particle cross-section characteristics and scintillator properties to discriminate. We have previously reported on the feasibility demonstration of our approach; i.e., using thin films of materials to create particle-specific detectors, coupled to a position-sensitive photomultiplier tube. We have since developed a fully-functional and calibrated engineering model of LIPS. We are currently preparing LIPS for flight validation as part of the Air Force Research Laboratory (AFRL) Space Weather Experiment (SWx) that will fly as part of the Cygnus flight demonstration program. Herein we report on the engineering model development and calibration of LIPS., 資料番号: AA0049206090, レポート番号: JAXA-SP-05-001E

Ion emitter instruments ASPOC (Active Spacecraft Potential Control) have been used successfully in several magnetospheric missions including the ESA Cluster Project. An improved version has been developed for the equatorial spacecraft of the Chinese-European Double Star mission (TC-1) launched in December 2003. The modifications include a new design of the ion emitter modules. As a result, higher currents than in previous missions can be achieved. The main objective of the investigation lies in a reduction of positive spacecraft potential in order to minimize the perturbations to the plasma measurements on board, in particular to the plasma electron instrument PEACE. These data show an almost complete suppression of photo-electrons when ASPOC is emitting at 30 to 50 micro-A beam current. The angular distribution of the electrons in the presence of the ion beam is investigated in detail. The measurement of ambient electron distributions is highly improved., 資料番号: AA0049206091, レポート番号: JAXA-SP-05-001E

The space environment in Low-Earth orbit (LEO) has until recently been considered relatively benign to high levels of spacecraft charging. However, it has been found that the DMSP spacecraft at 840 km can charge to very large negative voltages (up to - 2,000 V) when encountering intense precipitating electron events (auroral arcs) while traversing the auroral zone. The occurrence frequency of charging events, defined as when the spacecraft charged to levels exceeding 100 V negative, was highly correlated with the 11-year solar cycle with the largest number of events occurring during solar minimum. This was due to the requirement that the background thermal plasma density be low, at most 10(exp 4)/sq cm. During solar maximum, the plasma density is typically well above that level due to the solar EUV ionizing radiation, and although the occurrence frequency of auroral arcs is considerably greater than at solar minimum, the occurrence of high-level charging is minimal. Indeed, of the over 1,600 events found during the most recent solar cycle, none occurred during the last solar maximum. A dependence of the magnitude of the spacecraft frame charge on density was observed with the largest negative voltages, approximately 2,000 V, only occurring at very low densities. A 'worst-case' charging electron spectrum for low-altitude was developed by applying a potential drop of 20 kV to source data that went into the MIL-STD-1809 specification for near-geosynchronous orbit and combining it with DMSP spectra consistent with a 20-kV drop. The results of this study have implications on a number of LEO satellite programs, including the International Space Station (ISS). The plasma density in the ISS orbit, at a much lower altitude than DMSP, is well above that at 840 km and rarely below 10(exp 4)/sq cm. However, in the wake of the ISS, the plasma density can be two orders of magnitude or more lower than the background density and thus conditions are ripe for significant charging effects. With an inclination of 51.6 degrees, the ISS does enter the auroral zone, particularly during geomagnetic storms and substorms when the auroral boundary can penetrate to very low latitudes. This has significant implications for EVA operations in the ISS wake., 資料番号: AA0049206094, レポート番号: JAXA-SP-05-001E

We present event studies and results of a statistical investigation on charging events seen by the Freja satellite in the auroral zone at 1,500-1,700 km altitude. Charging up to kilovolts is sometimes observed, though lower values are more normal. Comparing to DMSP at 840 km, Freja experiences fewer charging events, but some of them are found in sunlit conditions, which has not been seen on DMSP. No charging event occurred for a density above 2,000 cu cm, though correlation between density and charging otherwise was weak. All charging events show enhanced electron fluxes around or above 10 keV, including enhanced tails up to 100 keV, while electrons around 1 keV instead counteracts charging, as is expected from high secondary yields in this energy range. Simulations using POLAR reproduced moderate charging events, but not the events with kilovolt charging., 資料番号: AA0049206093, レポート番号: JAXA-SP-05-001E

資料番号: AA0048468018, レポート番号: JAXA-SP-04-010

Extremely huge solar storms happened from 19 October to 6 November 2003. It affected some satellite operation and some satellite was killed by this event. Surveyed were satellite anomalies and preparations and action for satellite during this event. This information will contribute to the satellite design and operation in the future. Also sent were Satellite Environment Alert messages to some users in this period. Presented are the survey results and the release status of the Satellite Environment Alert messages., 資料番号: AA0048057031, レポート番号: JAXA-RM-04-010

資料番号: AA0047899149

HETE-2衛星は高度が600km、軌道傾斜角2度の赤道上空円軌道を約100分で周回する小型天文衛星である。HETE-2衛星には、広視野X線モニター(WXM:2〜25keV)、ガンマ線検出器(FREGATE:6〜400keV)が搭載されている。WXMの観測データから、南米西岸付近上空の限られた領域で、粒子数の異常増加現象が発生することを発見した。これまでの解析により、南大西洋地磁気異常帯とは異なる領域の現象であり、常に見えている現象では無いことが分かっている。この粒子数の異常増加現象が主にエクアドル上空で起こっていることから、この現象を「エクアドル・アノマリー」と呼ぶことにした。詳細な解析の結果、粒子数の異常増加現象は太陽活動と強い相関を持つ事が分かった。粒子数の異常増加現象は、2002年までは西経80度付近においてのみ観測される事が多かったが、2003年になって西経50度付近においても頻繁に観測されるようになり、FREGATEにおいても観測されるようになった。この事は太陽風速度の平均値の上昇に良く相関している。また、粒子数の異常増加現象の観測位置におけるL値(磁気座標のパラメータ)を調べたところ、L=1.2付近に集中している事が分かった。観測されたスペクトルから、入射粒子は主に低エネルギーの電子で構成されているのではないかと考えられるが、より定量的に研究するためには、荷電粒子に対するWXM/FREGATEの検出器応答を考慮する必要がある。そこで、Geant4を用いて種々のパラメータ(スペクトル・入射角度)の荷電粒子(電子・陽子)についてシミュレーションを行ない、観測された現象が再現されるかどうかを検討した。その結果、粒子数の異常増加現象の構成粒子は電子であり、典型的なエネルギーは485keV以下である事が分かった。WXMとFREGATEのBe窓は、それぞれ100μm、800μmであり、FREGATEで検出されるためには、粒子のエネルギーはWXMよりも高い必要がある。観測データから2003年になってFREGATEのカウント数が増加した事が分かっており、シミュレーションから2003年になって全体的に粒子のエネルギーが高くなっている事が示唆される。, 資料番号: AA0047899146

資料番号: AA0046920052

資料番号: AA0046920026

Jovian synchrotron radiations (JSR) which are emitted from relativistic electrons trapped in the Jupiter's radiation belt were observed during a rarely strong solar event occurred on October 28 and 29, 2003. The observation was made by the Iitate Planetary Radio Telescope (IPRT) at Iitate Observatory in Japan during the period from October 16 to November 20 in 2003. Variations of the JSR intensity were compared with the solar F10.7 flux and it was found that the intensity of the JSR showed unusual increase of its magnitude by about 50 percent and the subsequent rapid decrease after the solar event with the decay rate of about 0.3 Jy/day. Comparing with the previous observations of the short term variation of the JSR, an unusual response of Jupiter's radiation belt associated with the rarely strong solar activity is supposed., 資料番号: AA0047898043

GPS衛星から送信される2周波の電波の伝搬遅延から、全電子数(Total Electron Content: TEC)が求まる。TECとは、衛星と受信機を結ぶ伝播経路上に含まれる電子の積分値であり、1m(sup 2)に含まれる電子の数で表される。このデータには各送信・受信機の持つバイアスが含まれている。このバイアスを最小2乗法で推定することにより、TECの絶対値を算出することができる。日本には現在、国土地理院により約1,000点の受信機(GEONET: GPS Earth Observation NETwork)が配置されており、30秒という高時間分解能、緯度・経度0.15度という高空間分解能でTECを求めることができる。本研究は絶対値TECの基本的な振る舞いを調べることを目的として、1999年5月〜2002年12月のTEC絶対値の経験的モデルを作成し、統計的解析を行った。地方時・太陽活動度・季節の各依存性を求めた。電離圏トップサイドの影響を見積もるためにNmF2との比較を行った。また、冬季夜間においてTEC絶対値の異常増加が観測された。この原因究明のため、IGS受信局との比較から考察を行っていく。GEONETの密なデータを利用した、絶対値TECの統計的解析は世界初の試みである。, Empirical models of the Total Electron Content (TEC) over Japan are developed with GPS-based observations to investigate fundamental behavior of absolute TEC. The network of about 1,000 GPS receivers, which are installed by the Geographical Survey Institute (GSI), realizes the dense mapping of TEC over Japan. Recently, many researches using TEC are made. TEC is practically used to evaluating the influence of the earth ionosphere in satellite communication. However, the statistical analysis and models of absolute TEC with GEONET was not made so far. Since absolute TEC is an integration value along the ray path, it differs from the behavior of maximum electron density of the F2 layer (NmF2), which is obtained with Ionosonde. TEC is influenced from compositions of bottomside of the ionosphere, neutral winds of topside of the ionosphere, and the plasmasphere. Therefore, more information is included in TEC than NmF2. However, the many features of TEC still remain to be studied. Statistical analyses of absolute TEC of Japan from May 1999 to December 2002 are performed. Dependence of the TEC variation is investigated on the local-time, season and 10.7-cm solar flux index (F 10.7). The contribution of topside of ionosphere is discussed in a comparison of NmF2. Seasonal anomaly and equinoctial asymmetry of electron density in the ionosphere observed with the Ionosonde and MU radar has been confirmed using TEC derived from the GPS data. However, the season to take the maximum of TEC and NmF2 differs slightly. Anomalous nighttime increase in a TEC was observed in winter. These increases appear mainly in high and mid-latitude and are discussed in a comparison of international GPS service (IGS) data., 資料番号: AA0045981027

資料番号: AA0045981048

資料番号: AA0045981051

第232回生存圏シンポジウム, 2013/08/19-20, 国立極地研究所(東京都)

第221回生存圏シンポジウム「地球環境科学における分野横断研究の最前線 : 分野横断研究のためのe-infrastructureとサイエンスへの応用」(2013年2月28日-3月1日)京都大学生存圏研究所

日本地球惑星科学連合2013年大会, 2013/05/19-5/24, 幕張メッセ（千葉県）

日本気象学会2013年度春季大会, 2013/05/15-18, 国立オリンピック記念青少年総合センター(東京都)

IUGONETデータ解析講習会, 2013/02/27, 京都大学生存圏研究所(京都府)

21世紀には、有人宇宙活動および有人宇宙利用がさらに進む。しかし、宇宙は厳しい環境で、放射線に覆われ、高エネルギー粒子線の飛び交う殆ど真空状態である。これらの粒子線や惑星間の擾乱は、宇宙機器、宇宙飛行士などに対し危険である。よって通信総合研究所では日本の宇宙天気予報計画をスタートさせることにした。この計画は、宇宙環境を支配している基礎的物理過程に対する知識を蓄積することにより実現され、また、宇宙で人間の健康を守るために重要な役割を果たすものと期待できる。本実験では試験的に宇宙天気予報/警戒システムをおこない、シャトル飛行中に宇宙環境(太陽活動と地磁気活動)を分析し続けた。リアルタイム放射線モニター装置(RRMD)データと宇宙天気予報の交換を、コンピュータネットワークとファクシミリを通じて数日間毎日おこなったが、これは放射線観測の地上での活動に有益であった。放射線データは現在分析中で、試験結果は、南大西洋偏差周辺に停滞する粒子の浸透を示している。, In the 21st century, it is expected that manned space activity and space utilization will make further progress. However, space is a harsh environment: almost a vacuum bathed with radiation and penetrated by streams of energetic particles. These particles and interplanetary disturbances are hazardous to space equipment, astronauts, etc. This is why the Communications Research Laboratory decided to start the Space Weather Forecast Program of Japan. This program is realized by the accumulation of knowledge on basic physical processes governing the space environment, and is expected to play a significant role in the protection of human health in space and reliable operation of space equipment. In this investigation, the space weather information/warning system was tentatively operated, and the space environment (solar and geomagnetic activities) during the shuttle flight has been being analyzed. The exchange of RRMD (Real time Radiation Monitoring Device) data and the space weather information were performed by the computer network and the facsimile every few days, and was useful for the ground operation of the radiation observation. The radiation data is now being analyzed and tentative results show stationary particle penetration around the South Atlantic Anomaly., 資料番号: AA0000271013, レポート番号: NASDA-TMR-960004

GEONETにより得られた絶対値TECから日本上空の絶対値TEC平均的描像を作成し、地方時、緯度、太陽活動度、季節の各依存性を調べた結果を以下に報告する。, 資料番号: AA0046920050

日本学術会議フォーラム「データと発見ーDeta Intensive Scientific Discovery」,2012/09/10, 日本学術会議講堂（東京都）

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