阐述了基本轨道应用分析理论，包括星下点轨迹计算、可见性分析、覆盖评估和轨道寿命估算。
Expatiated on the application theory of basic orbit, including subastral point calculation, visibility analysis, coverage evaluating and spacecraft life-span estimate.
针对这一难点，提出了一种卫星轨道快速计算的方法-提取轨道的控制点，结合透视裁剪体来判断轨道的可见性。
According to this difficulty, a kind of fast calculation method of satellite orbit-extract the orbits control points is put forward, and perspective frustum is combined to judge the orbits visibility.
当可见性最为关键时，要确保探头甚至能在网络接近饱和点上收集数据。
Also make sure a probe is capable of collecting data even at the network near-saturation point, when visibility is most crucial.
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