运气

Apollo 13’s oxygen tank rupture occurred at just about the most opportune time.
Much earlier and their coast to the Moon and back would have been too long for the LM to sustain them.
Much later, and they might not have had a LM available to act as a lifeboat.

Huston, we have a problem!

意外永远猝不及防，但好的运气可以让它发生在天造地设那一刻。