How long could a human survive unprotected in outer space?
You might be able to survive in space for over a minute, so long as you got back to safety and medical care immediately after. Following a sudden exposure to the vacuum of space, the first thing to do would be breathe out – if you held your breath, the gas expanding in your lungs due to the reduced external pressure would cause them to rupture. Around ten seconds in, you’d start to lose consciousness and vision due to oxygen depletion. In the low-pressure environment, your body fluids would begin to vaporise, causing tissue to swell up. If you were in sunlight without the protective effect of Earth’s atmosphere, serious sunburn would occur. Training accidents suggest that if astronauts are returned into a pressurised oxygen environment within 90 seconds, injuries are reversible. But with so many factors at play, the survival limits are not well known.