太空|TAIKONG 国际空间科学研究所 - 北京 ISSI-BJ Magazine No
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太空|TAIKONG 国际空间科学研究所 - 北京 ISSI-BJ Magazine No. 9 October 2016 LINK BETWEEN SOLAR WIND, MAGNETOSPHERE, AND IONOSPHERE FOREWORD On July 6-7, 2016, the International recognized the very high scientifc Space Science Institute in value of the mission, and raised IMPRINT Beijing (ISSI-BJ) successfully constructive comments and organized a two-day Forum on suggestions on the mission concept, 太空 | TAIKONG “The Link between Solar Wind, payloads key techniques, and data ISSI-BJ Magazine Magnetosphere, Ionosphere”. product. They concluded that the ISSI-BJ Forums are informal, SMILE mission has complementary free debates, and brainstorming objectives to existing or future meetings among high-level solar space plasma missions. participants on open questions of Therefore, the SMILE mission is Address: No.1 Nanertiao, scientifc nature. In total, 28 leading yet another excellent example of Zhongguancun, scientists from eight countries how the Chinese Space Science Haidian District, participated in this Forum, which institutions can work together with Beijing, China was convened by Chi Wang the European Space Agency on Postcode: 100190 (NSSC, CAS), Graziella Branduardi- innovative and challenging, and Telephone: Raymont (MMSL-UCL, UK), Benoit complementary to the existing, +86-10-62582811 Lavraud (CNRS, France), Tony Lui missions. This offers signifcant Website: (APL, USA), and Maurizio Falanga opportunities for cooperation www.issibj.ac.cn (ISSI-BJ, China). through mission coordination and scientifc analysis that places The Forum’s main aims divided the Authors SMILE and China-Europe in a meeting into 4 sessions: Overview of central position, due to its unique the Solar Wind Magnetosphere and Graziella Branduardi - objectives and technology. Raymont (MSSL-UCL, UK), Ionosphere Coupling; Key Science C. Philippe Escoubet (ESA/ of the Solar wind, Magnetosphere, This TAIKONG magazine provides ESTEC, The Netherlands), Ionosphere Coupling; Instruments an overview of the scientifc Kip Kuntz (JHU/APL, USA), and Capability Required; Synergies objectives and the overall design Tony Lui (JHU/APL, USA), Complementary Missions and of the SMILE project, including Andy Read (Leicester U., International Collaborations. In spacecraft and instrumentation UK), David Sibeck (NASA/ this context, the European Space discussed during the Forum. Agency (ESA) and the Chinese GSFC, USA), Tianran Sun I wish to thank the conveners and Academy of Sciences (CAS) (NSSC/CAS, China), Brian organizers of the Forum, as well selected a joint small mission Walsh (Boston U., USA), as the ISSI-BJ staff, Lijuan En, (SMILE, to be launched in 2021) Chi Wang (NSSC/CAS, Anna Yang, and Xiaolong Dong, for to trace these processes from China) actively and cheerfully supporting beginning (the Sun) to end (the the organization of the Forum. In Earth's aurora), and investigate – in Editors particular, I wish to thank the authors, a way unmatched so far – how the who, with dedication, enthusiasm, solar wind interacts with the Earth's Anna Yang and seriousness, conducted the magnetic environment. Maurizio Falanga whole Forum and the editing of this The Forum started with an report. Let me also thank all those overview and goals of the who participated actively in this Front Cover SMILE mission. The participants stimulating Forum. discussed the interaction between the Earth's protective shield – Prof. Dr. Maurizio Falanga An artist's impression of the the magnetosphere – and the Solar-wind Magnetosphere supersonic solar wind. SMILE is Ionosphere Link Explorer expected to give an important (SMILE) mission. contribution to our understanding of space weather and, in particular, (Credit: CAS; the physical processes taking place Beijing Special thanks to: during the continuous interaction Chi Wang) between the solar wind and the October 2016 magnetosphere. The participants 2 太空|TAIKONG INTRODUCTION Forum Overview The interaction between the The Forum concentrated on Forum also reviewed the cur- solar wind and Earth’s mag- the main scientifc drivers for rent status and future plans for netosphere, and the geospace the Solar-wind Magnetosphere SMILE, the primary scientifc dynamics that result, comprise Ionosphere Link Explorer goals, the needed technolo- a fundamental driver of space (SMILE) mission, and how they gies, and how to best optimize weather, the conditions on the defne the mission specifca- international collaborations. Sun, in the solar wind, and tions, reviewed lessons learned in the magnetosphere, iono- from the previous in situ and The forum was sponsored by sphere and thermosphere, that imaging missions, discussed ISSI-BJ, with partial support can infuence the performance the SMILE mission for soft from the State Key Laboratory and reliability of technological X-ray magnetospheric imaging of Space Weather, National systems and endanger human and UV auroral imaging, com- Space Science Center (NSSC), life and health. Understanding pared the soft X-ray simulated and the Chinese Academy of how this vast system works results from different numeri- Sciences (CAS). requires knowledge of energy cal models, and examined op- and mass transport, and of the portunities for synergies with coupling both between regions complementary observations and between plasma and neu- from other space missions and tral populations. ground-based facilities. The Background of the Solar Wind, Magnetosphere, Ionosphere The solar wind is a stream of wind compresses charged particles (protons, the sunward side electrons, and heavier ionized of the magneto- atoms) released from the up- sphere but drags per atmosphere of the Sun. the nightside out The solar wind is divided into into a long mag- two components, respectively netotail. termed the slow solar wind and the fast solar wind. The slow The interaction solar wind has a velocity of of the solar wind about 400 km/s, a temperature with Earth leads of 1.4–1.6×106 K and a compo- to the formation sition that is a close match to of the magneto- the solar corona. By contrast, sphere, including the fast solar wind has a typi- the bow shock, cal velocity of 750 km/s, a tem- magnetosheath, perature of 8×105 K and it nearly cusps, mag- matches the composition of the netopause and Fig. 1: The dayside magnetosphere. The magne- Sun's photosphere. Near the the magnetotail topause represents the outer boundary of the mag- Earth, the solar wind encoun- (Figure 1). netosphere, and is compressed on the dayside. ters the Earth’s magnetic feld The bow shock compresses and defects the solar and the particles are defected wind so that it may fow around the magnetopause. by the Lorentz force. The solar 太空|TAIKONG 3 As shown in Figure 1, a col- wind plasma to penetrate deep and slow solar wind can be in- lisionless bow shock stands into the magnetosphere, all the terrupted by large, fast-mov- upstream from the magneto- way to the ionosphere. The ion- ing bursts of plasma called pause in the supersonic so- osphere is a region of Earth's interplanetary coronal mass lar wind. The shocked solar upper atmosphere, from about ejections, or CMEs. When a wind plasma fows around the 60 km to 1,000 km altitude. It is CME impacts the Earth's mag- magnetosphere through the ionized by solar radiation, plays netosphere, it temporarily de- magnetosheath. A relatively an important part in atmospher- forms the Earth's magnetic sharp transition from dense, ic electrical activity and forms feld, changing its direction and shocked, highly ionized solar the inner edge of the magneto- strength, and inducing large wind plasmas to tenuous, less sphere. electrical currents; this is called highly ionized magnetospher- a geomagnetic storm and it is ic plasmas marks the magne- The position and shape of the a global phenomenon. CME topause. High latitude cusps magnetopause change con- impacts can induce magnet- denote locations where feld stantly as the Earth’s magne- ic reconnection in the Earth's lines divide to close either in tosphere responds to varying magnetotail; this launches pro- the opposite hemisphere or far solar wind dynamic pressures tons and electrons downward down the magnetotail. Weak and interplanetary magnetic toward the Earth's atmosphere, feld strengths within the cusps feld orientations. Both the fast where they form the aurora. provide an opportunity for solar GLOBAL MEASUREMENTS AND THE SOLAR WIND- MAGNETOSPHERE INTERACTION Heliophysicists seek to un- A host of mechanisms have enhanced interactions during derstand, and model, the pro- been proposed to explain the intervals of southward inter- cesses governing the fow of nature of the solar wind-mag- planetary magnetic feld (IMF) solar wind mass, energy, and netosphere interaction, and in orientation. Therefore statistical momentum through the Sun - particular the entry into, stor- studies of remote observations Solar Wind - Magnetosphere - age within, and release from the demonstrating that ionospher- Ionosphere system. With this magnetosphere of solar wind ic convection, the strength of knowledge in hand, they will mass, energy, and momentum feld-aligned currents into and be able to forecast geomag- (Figure 2). Proposed mag- out of the ionosphere, the like- netic storms, the most haz- netopause entry mechanisms lihood of geomagnetic sub- ardous space weather events include solar wind pressure storms, and the magnitude in the near-Earth environment. variations battering the magne- of geomagnetic storms all in- Storms enhance the fuxes of tosphere, the Kelvin-Helmholtz crease for southward IMF ori- energetic particles within the (wind-over-water)