Space Without a Space Suit
Two of my most favorite science fiction movies of all time involve the main characters exposing themselves to low pressure. Ripley (Sigourney Weaver) spaces the alien in… well… probably every movie with her and the aliens, but Aliens is the best. Quaid (Arnold Schwarzenegger) spends some quality time sans spacesuit on Mars in Total Recall. When I watch those movies, I always wonder if spacing the alien or breathing Martian air would be survivable.
Martian air is pretty corrosive, so I don’t know the answer to that question for sure, but spacing an alien could work, if you could re-pressurize the spacecraft quickly enough and get medical attention.
Does it surprise you to learn you really can survive in space without a spacesuit, probably for a few minutes? The vacuum won’t be instantaneously lethal unless you try to hold your breath beforehand, which would result in your near-immediate and excruciatingly painful death, as the air in your lungs would expand and burst your alveoli. There’s documentation about the near-vacuum experience. A survivor of a 1965 NASA accident described feeling his saliva boil before he passed out.
In the 15 or so seconds you would have before you lost consciousness, you’d be very cold, but wouldn’t suffer immediate frostbite, because you wouldn’t have air to accelerate the heat transfer. What you would get is an industrial-strength sunburn from the ambient ultraviolet radiation and space-hickeys from the bursting of some capillaries at your skin’s surface.
Covering your skin would help to keep you warmer and protect you from the radiation. Upon getting rescued, you’d need to be treated for the bends (gas bubbles in your bloodstream), much like a deep-sea diver who had surfaced too quickly.