If you're exposed to space, most likely you'll just have the death. In fact, the only people who've ever died in space were killed by sudden loss of pressure. It was June 30, 1971, and cosmonauts, Georgy Dobrovosky, Viktor Patsayev and Vladislav Volkov were returning from Salyut-1. […] The three cosmonauts entered the capsule, and after some brief issues getting the hatch to seal, undocked and began their descent. When the ground crew arrived and the capsules was opened, the men were found, still seated, serene in death. Attempts to revive them proved useless- each had suffered massive brain hemorrhaging. Subsequent investigation determined that when they undocked from their space station, a valve on the return craft had unexpectedly popped open, exposing them to a near-perfect vacuum.

— A City On Mars by Kelly Weinersmith, Zach Weinersmith (Page 120 - 122)