The moments preceding a disaster can tick by in slow motion. Flying down a highway in a runaway truck, cars fading in reverse, trees in a snapshot, doom can seem a foregone conclusion.
But the path to disaster or salvation can be decided by the flick of a wrist -- or, in the case of nuclear reactors badly damaged by the 9.0 earthquake that struck Japan in March 2011, the decision to flood the cores with seawater in a last-ditch attempt to cool the rods, then the rush to remove that water lest the casings corrode.
It all comes down to the wisdom of those final, Hail Mary schemes -- and probably some luck as well. Whether it's the threat of meltdown, a collapsing ecosystem, a cave-in, an unstoppable oil spill, a mass suicide or a spaceship headed for oblivion, when there's time to think, there's time to try anything and everything to save the day.
Sometimes those efforts prevail. Sometimes they don't.
In this article, we'll take a look at five attempts to avoid a terrible end, some of which succeeded in doing the impossible. We'll begin in 1970, with a spaceship stranded about 200,000 miles (321,868 kilometers) from Earth …