^* Contrary to popular lore, an astronaut’s blood does not boil if his spacesuit tears or his craft depressurizes. And though he would swell, he would not burst. The body functions as a sort of pressure suit for the blood, keeping dissolved gases in their liquid state. Only body fluids directly exposed to a vacuum actually boil. (As happened to a 1965 NASA test subject in a leaky spacesuit in an altitude chamber. The last thing he recalled before losing consciousness was the sensation of his saliva bubbling on his tongue.) Also, current EVA suits are designed to compensate for tears or leaks by blasting in air at far greater pressure. Bottom line: Provided he has an oxygen supply, an astronaut in a spacecraft depressurization has about two minutes to figure out what’s wrong and set it right. Beyond that he’s in trouble. This is known from experiments in vacuum chambers that would, if you knew the details, make your blood boil.