The center conducts large-scale cyber defense drills, sort of like digital military training, though it’s not technically a NATO operational unit.

该中心进行大规模的网络防御演习， 有点像数字军事训练，尽管从技术上讲它不是北约的作战单位。

The greatest concern the authors raise is space debris — pieces of " junk" that orbit the earth, with the potential to cause serious damage if they collide with operational units, including the ISS.

作者提出的最大担忧是空间碎片——环绕地球运行的“垃圾”碎片，如果它们与包括国际空间站在内的运行单位相撞， 可能会造成严重破坏。