倾角为90°的人造地球卫星轨道。又称极地轨道。在极轨道上运行的卫星，每一圈内都可以经过任何纬度和南北两极的上空。
大多数情况下，人造卫星自观测者的西方升起，经过中天，然后在东方落下，虽然越极轨道人造卫星可以在天空的任意部分升起和落下！
In most cases, the satellite will rise in the west, cross the observer's meridian, and set in the east, although satellites in a polar orbit can rise or set in any part of the sky!
大气层外极薄的微粒层会撞击进入减慢轨道物体的速度。
A whisper-thin veil of molecules at the atmosphere's outer reaches bumps into and slows down orbiting objects.
2008年1月21日，以色列的首颗24小时、全天候、高分辨率雷达卫星TechSAR由印度的极轨卫星运载火箭(PSLV)送入轨道。
Israel's first 24-hour, all-weather, high-resolution radar satellite, dubbed TechSAR, was inserted into orbit Jan. 21 by an Indian Polar satellite Launch Vehicle (PSLV).
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