研究者業績

西野 真木

ニシノ マサキ  (Masaki Nishino)

基本情報

所属
国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 主任研究開発員
学位
博士(理学)(東京大学)
修士(理学)(東京大学)
学士(理学)(東京大学)

連絡先
nishinostp.isas.jaxa.jp
研究者番号
50466794
ORCID ID
 https://orcid.org/0000-0001-5992-445X
J-GLOBAL ID
200901053437969501
researchmap会員ID
1000316000

外部リンク

現職は火星衛星探査機プロジェクトチームの主任研究開発員です。


専門分野1 磁気圏プラズマ物理学

専門分野2 月面環境学(月環境学)

【概要】 人類をはじめとする地球上の生命は厳しい宇宙環境に曝されています。これから人類は月面や火星に進出しようしていますが、月や火星の環境が周囲の宇宙プラズマの条件によってどのように変化するのかを、より深く知る必要があります。

私はこれまで、惑星磁気圏や月における宇宙プラズマの観測的研究をベースとして、太陽風-固体天体表面の相互作用や、極端な太陽風条件に対する磁気圏・電離圏の応答を一貫して調べてきました。特に、主として探査機の観測データを解析することによって宇宙空間で起きている物理過程の解明を目指しています。近い将来には宇宙天気予報の月版である「月面環境予報」を実現します。応用的研究として彗星のプラズマ環境も勉強中です。また、地球・月・水星・彗星などの「その場」観測によって得られた知見を太陽系外惑星へどのように応用するか模索しています。2024年の時点では火星探査機MAVENのデータ解析をおこなうとともに、地球の磁気圏電離圏結合を多点観測によって調べています。

2020年代には実現する月の着陸探査に向けて、これまでの理工連携の枠組みに加えて「理工医連携」による学際的研究が必要です。特に、月面の宇宙放射線や帯電ダストなどの厳しい環境が人体や宇宙機・建造物に対してどのような影響を与えるのか、早急に評価を進める必要があります。そのため、地球電磁気・地球惑星圏学会の将来衛星探査ワーキンググループの月・小天体パネルで月環境探査の検討を進めています。

【政策論】科学・技術政策や氷河期世代ポスドク問題にも興味を持っています。2008年頃から中国の宇宙開発計画に着目しています。

【芸術活動】国立音大附属幼稚園でピアノに出会い、その後は合唱部の伴奏などで活動を続けてきました。合唱音楽ではフランスのバロック音楽を得意としています。アウトリーチ行事のときに惑星科学の講演とピアノ演奏を両方とも自分でおこなうことがあります。また、高校音楽の教科書の指導用CDにピアノ演奏が採用されています。ピアノのコンクール入賞歴があります。また、独立行政法人日本芸術文化振興会の助成を受けた演奏会に参加しています。


主要な論文

 62
  • William M. Farrell, Jasper S. Halekas, Mihaly Horányi, Rosemary M. Killen, Cesare Grava, Jamey R. Szalay, Mehdi Benna, Pamela E. Clark, Michael R. Collier, Anthony Colaprete, Jan Deca, Richard C. Elphic, Shahab Fatemi, Yoshifumi Futaana, Mats Holmström, Dana M. Hurley, Georgiana Y. Kramer, Paul R. Mahaffy, Masaki N. Nishino, Sarah K. Noble, Yoshifumi Saito, Andrew R. Poppe, Kurt D. Retherford, Xu Wang, Shoichiro Yokota
    Reviews in Mineralogy and Geochemistry 89(1) 563-609 2023年12月1日  査読有り招待有り
  • Masaki Nishino, Hiroshi Hasegawa, Yoshifumi Saito, Benoit Lavraud, Yukinaga Miyashita, Motoharu Nowada, Satoshi Kasahara, Tsugunobu Nagai
    Earth, Planets, and Science 74(1) 2022年12月9日  査読有り筆頭著者責任著者
    Abstract The density of the solar wind plasma near the Earth’s magnetosphere sometimes decreases to only several per cent of the usual value, and such density extrema result in a significant reduction of the dynamic pressure and Alfvén Mach number ($$M_A$$) of the solar wind flow. While a symmetric expansion of the Earth’s magnetosphere by the low dynamic pressure was assumed in previous studies, a global magnetohydrodynamic (MHD) simulation study predicted a remarkable dawn-dusk asymmetry of the magnetospheric shape under low-density solar wind and Parker-spiral interplanetary magnetic field (IMF) configuration. Here, we present observations consistent with the asymmetric deformation of the magnetosphere under low-$$M_A$$ solar wind and Parker-spiral IMF conditions, focusing on the significant expansion of the dawn-flank magnetosphere detected by the Geotail spacecraft. A global MHD simulation reproduced the dawnward expansion of the near-Earth magnetosphere, which was consistent with the observation by Geotail. The solar wind flow had a non-negligible dusk-to-dawn component and partly affected the dawnward expansion of the magnetosphere. Local, roughly Alfvénic sunward acceleration of magnetosheath ions at the dawn flank magnetopause suggests magnetosheath plasma entry into the magnetosphere through open field lines generated by magnetic reconnection at the dayside magnetopause. At the same time, Cluster 1 and 3, located near the southern polar cusp, also detected continuous antisunward ion jets and occasional sunward jets, which are consistent with the occurrence of magnetic reconnection near the southern cusp. These observations suggest that enhanced plasma acceleration at the dayside magnetopause operates under the low-$$M_A$$ solar wind and Parker spiral IMF conditions and that plasma influx across the dawnside magnetopause is at work under such a low-$$M_A$$ condition. These results can be helpful in understanding interactions between low-$$M_A$$ solar/stellar winds and celestial objects, such as inner planets and exoplanets. Graphic Abstract
  • P. Wurz, S. Fatemi, A. Galli, J. Halekas, Y. Harada, N. Jäggi, J. Jasinski, H. Lammer, S. Lindsay, M. N. Nishino, T. M. Orlando, J. M. Raines, M. Scherf, J. Slavin, A. Vorburger, R. Winslow
    Space Science Reviews 218(3) 2022年4月  査読有り招待有り
    The Moon and Mercury are airless bodies, thus they are directly exposed to the ambient plasma (ions and electrons), to photons mostly from the Sun from infrared range all the way to X-rays, and to meteoroid fluxes. Direct exposure to these exogenic sources has important consequences for the formation and evolution of planetary surfaces, including altering their chemical makeup and optical properties, and generating neutral gas exosphere. The formation of a thin atmosphere, more specifically a surface bound exosphere, the relevant physical processes for the particle release, particle loss, and the drivers behind these processes are discussed in this review.
  • M. N. Nishino, H. Hasegawa, Y. Saito, N. Kitamura, Y. Miyashita, T. Nagai, S. Yokota, C. T. Russell, D. J. Gershman, B. L. Giles
    Journal of Geophysical Research: Space Physics 127(1) 2022年1月4日  査読有り筆頭著者責任著者
  • Shoichiro Yokota, Kentaro Terada, Yoshifumi Saito, Daiba Kato, Kazushi Asamura, Masaki N. Nishino, Hisayoshi Shimizu, Futoshi Takahashi, Hidetoshi Shibuya, Masaki Matsushima, Hideo Tsunakawa
    Science Advances 6(19) 2020年5月6日  査読有り
  • Masaki N. Nishino, Yoshifumi Saito, Hideo Tsunakawa, Yuki Harada, Futoshi Takahashi, Shoichiro Yokota, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu, Yukinaga Miyashita
    Icarus 335(1) 113392 2020年1月  査読有り筆頭著者責任著者
  • Masaki N. Nishino, Yuki Harada, Yoshifumi Saito, Hideo Tsunakawa, Futoshi Takahashi, Shoichiro Yokota, Masaki Matsushima, Hidetoshi Shibuya, Hisayoshi Shimizu
    ICARUS 293 45-51 2017年9月  査読有り筆頭著者責任著者
    There forms a tenuous region called the wake behind the Moon in the solar wind, and plasma entry/refilling into the wake is a fundamental problem of the lunar plasma science. High-energy ions and electrons in the foreshock of the Earth's magnetosphere were detected at the lunar surface in the Apollo era, but their effects on the lunar night-side environment have never been studied. Here we show the first observation of bow-shock reflected protons by Kaguya (SELENE) spacecraft in orbit around the Moon, confirming that solar wind plasma reflected at the terrestrial bow shock can easily access the deepest lunar wake when the Moon stays in the foreshock (We name this mechanism type-3 entry'). In a continuous type-3 event, low-energy electron beams from the lunar night-side surface are not obvious even though the spacecraft location is magnetically connected to the lunar surface. On the other hand, in an intermittent type-3 entry event, the kinetic energy of upward-going field-aligned electron beams decreases from similar to 80 eV to similar to 20 eV or electron beams disappear as the bow-shock reflected ions come accompanied by enhanced downward electrons. According to theoretical treatment based on electric current balance at the lunar surface including secondary electron emission by incident electron and ion impact, we deduce that incident ions would be accompanied by a few to several times higher flux of an incident electron flux, which well fits observed downward fluxes. We conclude that impact by the bow-shock reflected ions and electrons raises the electrostatic potential of the lunar night-side surface. (C) 2017 Elsevier Inc. All rights reserved.
  • Kentaro Terada, Shoichiro Yokota, Yoshifumi Saito, Naritoshi Kitamura, Kazushi Asamura, Masaki N. Nishino
    NATURE ASTRONOMY 1(2) 2017年2月  査読有り
    For five days of each lunar orbit, the Moon is shielded from solar wind bombardment by the Earths magnetosphere, which is filled with terrestrial ions. Although the possibility of the presence of terrestrial nitrogen and noble gases in lunar soil has been discussed based on their isotopic composition, complicated oxygen isotope fractionation in lunar metal(2,3) (particularly the provenance of a O-16-poor component) remains an enigma(4,5) . Here, we report observations from the Japanese spacecraft Kaguya of significant numbers of 110 keV O+ ions, seen only when the Moon was in the Earths plasma sheet. Considering the penetration depth into metal of O+ ions with such energy, and the O-16-poor mass-independent fractionation of the Earths upper atmosphere 6 , we conclude that biogenic terrestrial oxygen has been transported to the Moon by the Earth wind (at least 2.6 x104 ions cm(-2) s(-1)) and implanted into the surface of the lunar regolith, at around tens of nanometres in depth (3,4) . We suggest the possibility that the Earths atmosphere of billions of years ago may be preserved on the present-day lunar surface.
  • Masaki N. Nishino, Kazuo Shiokawa, Yuichi Otsuka
    ICARUS 280 199-204 2016年12月  査読有り筆頭著者責任著者
    The Moon possesses a long tail of neutral sodium atoms that are emitted from the lunar surface and transported anti-sunward by the solar radiation pressure. Since the earth crosses the lunar sodium tail for a few days around the new moon, the resonant light emission from sodium atoms can be detected from the ground. Here we show the first long-term (16 years) observation of the lunar sodium tail, using an all-sky imager at Shigaraki Observatory (35 degrees N, 136 degrees E), Japan. We have surveyed our database of all-sky sodium images at a wavelength of 5893 nm to find more than 20 events in which a bright spot emerges around the anti-lunar point during the new moon periods. We could not find any clear correlation between the sodium brightness and solar wind parameters (density, speed, dynamic pressure, and F10.7 index). In particular, no enhancement of the sodium spot brightness is detected even under very high density solar wind conditions (70 cm(-3); an order-of-magnitude higher than usual), which means that solar wind sputtering is not a principal mechanism of the formation of the lunar sodium tail. (C) 2016 Elsevier Inc. All rights reserved.
  • Nishino MN, Fujimoto M, Phan TD, Mukai T, Saito Y, Kuznetsova MM, Rastätter L
    Physical review letters 101(6) 065003 2008年8月  査読有り筆頭著者責任著者

主要なMISC

 57

講演・口頭発表等

 37

担当経験のある科目(授業)

 2

主要なWorks(作品等)

 7

共同研究・競争的資金等の研究課題

 6

学術貢献活動

 1

社会貢献活動

 1

メディア報道

 1

その他

 1