GEM: Magnetotail Reconnection Signatures at Lunar Orbit

地球的磁场把它包裹在一个被称为磁层的保护性茧中，使它周围的大部分太阳风发生偏转。太阳风是一股从太阳向外吹出的带电粒子流和磁场，其强度随太阳活动而变化。由于与太阳风的相互作用，磁层在白天被压缩，而在夜晚被拉长成一条长长的“磁尾”。被拉伸的磁尾场线储存了从太阳风中提取的能量。这种能量是通过一个叫做磁重联的过程释放出来的，这是本研究的主题，在这个过程中，磁能被转换成等离子体流，以及地球磁层内等离子体的加热和通电。磁重联发生在两个位置：一个在距离地球半径15-30倍的近尾，另一个在距离地球半径100-200倍的远尾。近地重联是爆炸性的，会产生高能带电粒子，这些粒子是高层大气中动态极光的原因，也是对地球轨道卫星造成破坏的原因。近地重联在很大程度上与被称为磁暴和亚暴的太空天气事件有关。相比之下，远尾重连（对此所知甚少）被认为更为稳定。目前还不清楚这两个重连接位点是如何相互作用的。对于目前的研究来说，最重要的是，从这些重联点中产生的快速等离子体流既向地球移动，也向地球移动。在两个地点之间的月球轨道（~60地球半径）上的卫星具有重要的优势，能够探测到近地地点的尾流和远地地点的尾流。因此，两者之间的联系，以及对各自磁尾条件的影响，可以从相同的中尾有利位置进行研究。从建议的研究中获得的关于磁重联的新见解对行星磁层以及天体物理学和实验室等离子体的研究有价值。建议的工作将为研究生提供重要的训练。它还包括公众宣传和教育活动。为了实现上述目标，建议者将分析在地球半径约60的月球轨道上的Artemus（加速、重联、湍流和月球与太阳相互作用的电动力学）卫星的观测结果，使用案例和统计研究来调查近尾和远尾重联点重联外流的发生率，以及它们在一系列空间天气条件（静止到磁暴）下的变化。它们之间的时间（即哪个位置首先激活），以及对中尾空间环境的影响，如瞬态电场增强、磁场几何形状的变化和高能粒子通量的增强。

Earth's magnetic field encloses it in a protective cocoon, called the magnetosphere, deflecting most of the solar wind around it. The solar wind is a stream of charged particles and magnetic fields blowing outward from the Sun, which varies in intensity with solar activity. Because of its interaction with the solar wind, the magnetosphere is compressed on the dayside and extended in a long "magnetotail" on the nightside. The stretched magnetotail field lines store energy extracted from the solar wind. This energy is released by a process called magnetic reconnection, the subject of the present study, during which magnetic energy is converted into plasma flows as well as heating and energization of plasmas within the Earth's magnetosphere. Magnetic reconnection occurs at two locations: one in the near-tail at a distance of 15-30 Earth radii and the other in the distant tail at 100-200 Earth radii. The near-Earth reconnection is explosive, creating high-energy charged particles that are responsible for the dynamic auroras in the upper atmosphere but also for damage to Earth-orbiting satellites. Near-Earth reconnection is largely associated with space weather events called magnetic storms and substorms. In contrast, the distant tail reconnection (about which much less is known) is envisioned to be steadier. It is not understood how the two reconnection sites interact. Of major importance for the present study, fast plasma flows are produced moving both Earthward and tailward from each of these reconnection sites. A satellite at lunar orbit (~60 Earth radii) between the two sites has the important advantage of being able to detect tailward flows from the near-Earth site, and earthward flows from the distant tail site. Thus the connection between the two, and the impact on magnetotail conditions of each, can be investigated from the same mid-tail vantage point. New insights into magnetic reconnection from the suggested study are valuable for research in planetary magnetospheres, as well as astrophysical and laboratory plasmas. The suggested work will provide important training for graduate students. It also includes public outreach and educational activities.To accomplish the goals described above, the proposers will analyze observations from the Artemus (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) satellites in lunar orbit at ~60 Earth radii using case and statistical studies to investigate the occurrence rates of reconnection outflows from both near- and distant-tail reconnection sites, their variations over a range of space weather conditions (quiescent to magnetic storming), the timing between them (i.e., which site activates first), as well as consequences to the mid-tail space environment, such as transient electric field enhancements, changes in the magnetic field geometry, and enhancements in high-energy particle fluxes.