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Oct. 15th, 2014 05:58 am (UTC)
These shows always portray loss of life support with the temperature plummeting on account of space being airless. But the truth is, space being airless means that on a spaceship you wouldn’t need to heat the inside; the body heat from everyone, and heat from the computers and other machines, would have nowhere to go; it would get reflected back inside. Otherwise, outside radiation would be able to get in, and that would kill everyone.

So what life support would really need to do is to VENT heat into space in some way, to prevent everyone from baking to death from their own trapped body heat.

Mostly right answer, but for the wrong reason.

whether the hull absorbs, emits or reflects radiation depends *strongly* of what type of radiation.

A hull that'll stop the various nasty particles, gamma rays, etc can still be an *excellent* radiator of heat.

Body heat is a pretty minor component of the likely heat load for the ship though. The "engines" etc are handling more energy than the entire US power grid.

Oh yeah, for most practical purposes the amount of heat radiated away per unit area f hull *is* the temp of the hull. If they weren't ignoring physics, portions of the hull would be glowing white hot.

Oh yeah, you can't "vent" heat. Heat is just another form of energy. You have to get rid of it by radiating it away.

You could vent hot material, but simple calculation will show that you couldn't handle the heat output for more than a few *hours* before the mass of the vented material would exceed that of the ship.

So you need radiator "panels". The fins you see on things like heat sinks for computer CPUs are for conducting heat to *air* faster.

If you are working with just radiating heat away, any portion of the radiating surface that is "visible" from another part is wasted, as part of the heat radiated from point A will be intercepted by all the points that can "see" it.

So the *effective* surface area is what you'd get by stretching a sheet over the radiator. Sop all those fins and convolutions are useless.
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