This classification is the analogy of our previous picture of stable orbits. 这种区分类似于前面的稳定轨道图形。
Stations are normally built on their definitive orbit.Their thrusters are just good enough to maintain them on a stable orbit. 通常它们都在固定轨道上运行,所附的推进器只要足够把站点调整到稳定轨道就够了。