The central idea behind a Space Elevator involves lowering a cable — perhaps constructed from asteroid material — from geostationary Earth orbit to the surface of the Earth.
Based on the orbit equation of particle motion in central force field, the stable property and close property of orbit were discussed.
在中心势场中粒子运动轨道方程的基础上，进一步讨论粒子轨道的闭合性、稳定性。
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Mucormycosis is a kind of lethal infection caused by any fungus in the order Mucorales. It often involves the central nervous system, lungs, gastrointestinal tract, skin, orbit and paranasal sinuses.