this question comes from Jason who asks how long could a nuclear submarine last in orbit the answer is not very long but not for the reason I expected the submarine wouldn't burst submarine holes are strong enough to withstand 50 to 80 atmospheres of external pressure from water so they'd have no problem containing One internal atmosphere of pressure from the air and the hull would likely be reasonably airtight although watertight seals don't necessarily hold back air the fact that water can't find a way through the hull under 50 atmospheres of pressure suggests that when the sub is in space air won't Escape quickly dangerous carbon dioxide buildup wouldn't be an issue as submarines use CO2 scrubbers that can be run indefinitely as long as they have power but oxygen is another story nuclear submarines use electricity to extract oxygen from water in space there's no water so they wouldn't be able to manufacture more air they carry enough oxygen in reserve to survive for a few days at least but eventually they'd be in trouble the really big problem though would be overheating because space is so much warmer than the ocean if you're pedantic that's not really true space is of course very cold but if if you're even more pedantic and I am it is true in two different ways space in Earth orbit seems cold because it's so empty without a warm environment around you radiating heat back to you you lose heat by radiation much faster than normal but space in Earth orbit is actually warm the pedantic reason for this is that temperature is a measure of the average kinetic energy of a collection of particles and in space near the Earth molecules can have average kinetic energies in the thousands of degrees this doesn't make space feel warm though when I was a kid I remember watching my dad use a metal grinder whenever metal touched the grinding wheel Sparks flew everywhere sometimes falling in a shower on his hands and clothes I couldn't understand why they didn't hurt him after all the glowing Sparks were several thousand deg I later learned that the reason the Sparks didn't hurt him was that they were tiny the heat They Carried could be absorbed into the body without warming anything more than a tiny patch of skin the hot molecules in space are like the sparks in my dad's machine shop they might be hot or cold but they're so small and there are so few of them they don't change your temperature very much instead your heating and cooling is dominated by how much heat you produce and how quickly it pours out of you into the void and this is the Practical reason that space is warm without air or water around you to carry heat away from your surface you don't lose heat by conduction or convection just radiation which often isn't a very effective way to cool down for most human carrying spacecraft the big problem isn't staying warm it's keeping cool and a nuclear submarine isn't just carrying humans it's carrying a 200 megawatt nuclear reactor it's hard to get good numbers on the efficiency of nuclear reactors in military submarines but a conservative gas basis on civilian reactors is around half the reactor's energy or around 100 megawatt has lost his Heat this heat is normally dissipated by sea water but again no water in space without cooling a 200 megawatt nuclear reactor outputs enough heat to warm the entire Submarine by about half a de Cel every minute the submarine would become too hot for hum survivability within an hour but the nuclear reactor isn't designed to warm the submarine in this way so instead the heat would build up within the reactor and lead to a meltdown it appears keeping a nuclear submarine in orbit is a bad idea but to get out of orbit the submarine would need to slow down enough that it hit the atmosphere which would slow it down the rest of the way without Rockets it has no way to do this okay technically the submarine does have Rockets the problem is they're not attached to the submarine launching the missiles won't meaningfully propel the sub but they don't need to be attached they just need to be turned around if the ballistic missiles carried by a nuclear submarine were placed in the tubes backward they could each change a large nuclear submarine speed by about 4 m/s a typical deorbiting maneuver requires in the neighborhood of 100 m/s speed change which means that the 24 Trident missiles carried by an Ohio class submarine could be just enough to get it out of orbit now because the submarine has no heat dissipating ablade of tiles and because it's not aerodynamically stable at Hypersonic velocities it would inevitably tumble and break up in the atmosphere the debris disintegrating in the air or plowing into the ground at several hundred knots if you tucked yourself into the right crevice in the submarine and were strapped into an acceleration couch there is a tiny tiny tiny chance you could survive the rapid deceleration into the atmosphere spere then You' need to jump out of the wreckage with a parachute before it hit the ground if you ever try this I have one piece of advice that is absolutely critical remember to disable the detonators on the missiles