Air in the atmosphere's outermost layer is very thin, but air molecules still create drag that slows down satellites, requiring engineers to periodically boost them back into their proper orbits.

大气最外层的空气非常稀薄，但空气分子仍能产生阻力减慢人造卫星的速度，这样工程师们就得定期把它们推回到其正确的轨道上。

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Air in the atmosphere's outermost layer is very thin, but air molecules still create drag that slows down satellites, requiring engineers to periodically boost them back into their proper orbits.

大气最外层的空气非常稀薄，但空气分子仍能产生阻力减慢人造卫星的速度，这样工程师们就得定期把它们推回到其正确的轨道上。

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