Abstract Past planetary missions have been broad and detailed for Gas Giants, compared to flyby missions for Ice Giants. Presently, a mission to Neptune using electrodynamic tethers is under consideration due to the ability of tethers to provide free propulsion and power for orbital insertion as well as additional exploratory maneuvering — providing more mission capability than a standard orbiter mission. Tether operation depends on plasma density and magnetic field B , though tethers can deal with ill-defined density profiles, with the anodic segment self-adjusting to accommodate densities. Planetary magnetic fields are due to currents in some small volume inside the planet, magnetic-moment vector, and typically a dipole law approximation, which describes the field outside. When compared with Saturn and Jupiter, the Neptunian magnetic structure is significantly more complex: the dipole is located below the equatorial plane, is highly offset from the planet center, and at large tilt with its rotation axis. Lorentz-drag work decreases quickly with distance, thus requiring spacecraft periapsis at capture close to the planet and allowing the large offset to make capture efficiency (spacecraft-to-tether mass ratio) well above a no-offset case. The S/C might optimally reach periapsis when crossing the meridian plane of the dipole, with the S/C facing it; this convenient synchronism is eased by Neptune rotating little during capture. Calculations yield maximum efficiency of approximately 12, whereas a 10 ∘ meridian error would reduce efficiency by about 6%. Efficiency results suggest new calculations should be made to fully include Neptunian rotation and consider detailed dipole and quadrupole corrections.

中文翻译：

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在海王星系绳捕获航天器

摘要 与冰巨人的飞越任务相比，过去的行星任务对于气体巨人来说是广泛而详细的。目前，正在考虑使用电动系绳执行海王星任务，因为系绳能够为轨道插入以及额外的探索性机动提供自由推进和动力——提供比标准轨道飞行器任务更多的任务能力。系绳操作取决于等离子体密度和磁场 B ，尽管系绳可以处理不明确的密度分布，阳极段会自我调整以适应密度。行星磁场是由行星内部某个小体积中的电流、磁矩矢量以及通常描述外部磁场的偶极定律近似值引起的。与土星和木星相比，海王星的磁结构要复杂得多：偶极子位于赤道平面下方，与行星中心高度偏移，并与其旋转轴倾斜很大。洛伦兹阻力功随着距离的增加而迅速减少，因此需要航天器在靠近行星的位置进行捕获，并允许大偏移使捕获效率（航天器与系绳质量比）远高于无偏移情况。当穿过偶极子的子午面时，S/C 可能会以最佳方式到达近点，S/C 面向它；海王星在捕获过程中旋转很小，从而缓解了这种方便的同步。计算得出的最大效率约为 12，而 10 ∘ 子午线误差会使效率降低约 6%。