Now a thirdand far more significant motivation presents itself: meeting these goals may be necessary to prevent the collapse of our civilization.
现在,第三个也是更重要的动机出现了:为了防止我们文明的崩溃,这些目标可能是必须要实现的。
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Spacewalker Michael Good, barely visible in his white spacesuit against the space station, participated in the STS-132 mission's thirdand final spacewalk.