Could you survive on Mars?

Martian surface pressure averages around 610 pascals, about 0.6 per cent of sea level and far below the Armstrong limit of roughly 6.3 kilopascals at which body fluids begin to vaporise at body temperature. Unprotected, the failure is not cold and not the carbon dioxide atmosphere but that pressure: consciousness goes in around fifteen seconds and death follows within a couple of minutes. The atmosphere is 95 per cent carbon dioxide, so there is nothing to breathe in any case, and surface temperatures average about -63 °C. Inside a pressurised suit or habitat none of that applies, and the constraints become the slow ones — food, water and air recycling, plus a radiation dose that NASA measured at roughly 0.66 sieverts for a round trip using the instrument aboard Curiosity. Mars has no global magnetic field and almost no atmospheric shielding, so surface radiation is the long-term problem rather than the immediate one.

What happens, in order

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

• How long could you survive in deep space? About fifteen seconds of consciousness, and roughly ninety seconds before the damage becomes irreversible.
• 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.