The moon's gravity is a sixth as strong as the earth's, so Chang'e-4's experiment was a test: would the earth plants know which way was up on the moon?
The mission was planned as a low-Earth orbit to test the Lunar Module, the lander later used by Apollo 11 and subsequent missions to land on the moon's surface.
他们的使命只是做地球低轨道飞行，以测试月球舱和阿波罗11号以及以后的登月任务所使用的登月舱。
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Yet the destruction of the Chinese Fengyun-1C in an anti-satellite missile test in 2007 accounts for more than a quarter of all catalogued objects in low-Earth orbit.