How long could you survive in deep space?
Vacuum kills by taking oxygen out of the blood, not by cold and not by pressure differential. With no external pressure, oxygen actually diffuses out of the lungs into the vacuum, so blood leaving the lungs is deoxygenated and the brain loses supply within about fifteen seconds. Gas in the body expands, which is why the standing instruction in NASA training is to exhale rather than hold a breath — holding it risks rupturing lung tissue. Water in exposed tissue begins to vaporise, causing swelling and the sensation reported in the one well-documented chamber accident of saliva boiling on the tongue; the technician in that 1966 test recovered fully after about 27 seconds of exposure. Temperature is a slow problem, not a fast one: with no air to conduct heat, a body loses heat only by radiation and takes hours to freeze. Beyond the vacuum, deep space adds a radiation environment with no magnetosphere to filter it, which becomes the limiting factor for any long journey.
What happens, in order
| When | What |
|---|---|
| 0-15 seconds | Useful consciousness; gas expands, moisture on exposed surfaces vaporises |
| 15-30 seconds | Unconscious; recovery still possible if repressurised, as in the 1966 chamber accident |
| ~90 seconds | Circulatory failure; beyond this, repressurisation does not help |
| Hours | Only now does the body approach freezing, because vacuum insulates |
You do not explode and you do not freeze instantly. Both are film conventions; the real mechanism is hypoxia within seconds.
Physiology, not instruction. Every figure here is a population range under particular conditions, and individual variation is large — temperature, exertion, fitness and health move all of them substantially. Nothing on this page is medical advice.
Places
- Could you survive on Mars? Unprotected, under two minutes. In a pressurised habitat, indefinitely — the limits become supply and radiation.
- How long can you survive in the death zone on Everest? Hours to a couple of days. Above about 8,000 metres the body deteriorates no matter what you do.
- How long can you survive adrift in the open ocean? In warm water with a raft, three to five days without drinking water — but immersion in cold water is measured in hours.
- How long could you survive on the Moon? About fifteen seconds of consciousness without a suit. With one, the record stay is 75 hours.
- How long could you survive in the Mariana Trench? Unprotected, no measurable time at all — the pressure is over a thousand times atmospheric. In a submersible, as long as the life support lasts.
- How long can you survive in Antarctica? Minutes to an hour unprotected in a winter storm — or indefinitely, since around a thousand people overwinter there every year.
- How long can you survive in the Sahara Desert? Around a day without water in summer daytime heat, and several days if you can stay in shade and move only at night.
- How long could you survive on Venus? Seconds. The surface is 465 °C at ninety-two times Earth's atmospheric pressure — the hardest place in the solar system to land on.
- Could you survive on Jupiter? There is no surface to survive on — you would fall inward until pressure and heat ended it, within minutes.
- How close to the Sun could you survive? Nothing solid survives contact — but a shielded spacecraft has flown within about 6 million kilometres of the surface.
- How long could you survive on a desert island? Fresh water decides it. With a spring or reliable rain, years; without, about three days.
- How long can you survive on the International Space Station? Indefinitely while it is resupplied — it has been continuously crewed since November 2000.
- How long can you survive in the Arctic? Hours unprotected in winter — but roughly four million people live above the Arctic Circle permanently.
- How long can you survive in a cave? With water and warmth, months — people have done it deliberately. Without light or a way out, hypothermia is the clock.
Common questions
- How long could you survive in deep space?
- About fifteen seconds of consciousness, and roughly ninety seconds before the damage becomes irreversible.
Related pages
- Could you survive on Mars? Unprotected, under two minutes. In a pressurised habitat, indefinitely — the limits become supply and radiation.
- How long can you survive in the death zone on Everest? Hours to a couple of days. Above about 8,000 metres the body deteriorates no matter what you do.
- How long can you survive adrift in the open ocean? In warm water with a raft, three to five days without drinking water — but immersion in cold water is measured in hours.
- How long could you survive on the Moon? About fifteen seconds of consciousness without a suit. With one, the record stay is 75 hours.
- How long could you survive in the Mariana Trench? Unprotected, no measurable time at all — the pressure is over a thousand times atmospheric. In a submersible, as long as the life support lasts.
- How long can you survive in Antarctica? Minutes to an hour unprotected in a winter storm — or indefinitely, since around a thousand people overwinter there every year.
- How long can you survive in the Sahara Desert? Around a day without water in summer daytime heat, and several days if you can stay in shade and move only at night.
- How long could you survive on Venus? Seconds. The surface is 465 °C at ninety-two times Earth's atmospheric pressure — the hardest place in the solar system to land on.
- How long can you survive without water? Going without something
- How long can you survive without food? Going without something
- How long can you survive without air? Going without something
- How long can you survive without sleep? Going without something
- Can you survive being struck by lightning? Conditions
- How long can you survive in freezing water? Conditions
Sources
- NASA — National Aeronautics and Space Administration (Public domain (US Government))