He told Reuters such a speed is " kind of a practical limit for the moon, " where gravity is one-sixth that of Earth.

他告诉路透社，这样的速度 “对月球来说实际上是一种限制”，因为月球的重力只有地球的六分之一。

For near-earth applications, both communication and transportation, may not be approaching their practical limits and may reach them by the turn of the century.

对于近地应用， 包括通信和交通，可能还没有达到实际极限， 可能会在世纪之交达到极限。