GEM: Magnetotail Reconnection Signatures at Lunar Orbit

地球的磁场将它包裹在一个被称为磁层的保护性茧中，使其周围的大部分太阳风偏转。太阳风是从太阳向外吹来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，在夜晚以一条长长的“磁尾”形式展开。伸展的磁尾磁力线存储了从太阳风中提取的能量。这种能量是通过一种称为磁重联的过程释放出来的，这是本研究的主题，在此过程中，磁能被转化为等离子体流，以及地球磁层内等离子体的加热和能量。磁重联发生在两个位置：一个在近尾部，距离地球半径15-30；另一个在远尾部，距离地球半径100-200。近地重联是爆炸性的，产生了高能带电粒子，这些粒子对高层大气中的动态极光负有责任，但也对地球轨道卫星造成了损害。近地重联在很大程度上与被称为磁暴和亚暴的空间天气事件有关。相比之下，远距离的尾巴重联(人们对此知之甚少)被设想为更稳定。目前还不清楚这两个重新连接站点是如何相互作用的。对于这项研究来说，最重要的是产生快速的等离子体流，从这些重联点向地球和向尾部移动。在两个地点之间的月球轨道(~60地球半径)上运行的卫星有一个重要的优势，即能够探测到来自近地站点的尾流和来自遥远尾站的地球流。因此，两者之间的联系，以及它们对磁尾条件的影响，可以从相同的中尾部有利位置进行研究。从建议的研究中获得的关于磁场重联的新见解对于行星磁层以及天体物理和实验室等离子体的研究是有价值的。建议的工作将为研究生提供重要的培训。它还包括公众宣传和教育活动。为了实现上述目标，提出者将分析Artemus(月球与太阳相互作用的加速、重联、湍流和电动力学)卫星在地球半径~60的月球轨道上的观测结果，使用案例和统计研究来调查从近尾和远尾重联站点重连流出的发生率、它们在一系列空间天气条件下的变化(静止到磁暴)、它们之间的时间(即，哪个站点最先激活)以及对尾部空间环境的影响，如瞬时电场增强，磁场几何结构的变化，以及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.