<P> A more severe long - term effect is the direct exposure to high energy photons (ultraviolet, X-ray, and gamma) and energized subatomic particles (primarily protons). </P> <P> Spacing is a staple of science fiction, where it often occurs as a method of execution (or other sort of killing) by vacuum exposure in space--usually accomplished by ejecting the subject through the airlock of a spacecraft or space station without a space suit . Spacing is sometimes used as a means of dispatching enemies, usually by luring or herding the target (s) into an airlock, hangar or cargo bay with an exterior hatch and then flushing them out into space, or opportunistically double - opening an airlock--or even blowing out a window or hull panel--that happens to be near the target, with similar results . The primary cause of death would be asphyxia . An example can found in the novel 2001: A Space Odyssey by Arthur C. Clarke in which astronaut David Bowman is exposed to the vacuum of space inside the Discovery One spacecraft after the computer controlling its life support malfunctions and opens the doors of the airlock . A passage in the novel claims, </P> <P> Like any properly trained man in good health, he could survive in vacuum for at least a minute--if he had time to prepare for it . But there had been no time; he could only count on the normal fifteen seconds of consciousness before his brain was starved and anoxia overcame him . Even then, he could still recover completely after one or two minutes in vacuum--if he was properly recompressed; it took a long time for the body fluids to start boiling, in their various well - protected systems . </P>

How does it feel to die in space