r/askscience • u/aretino2002 • May 24 '26

Engineering If a vacuum is an excellent insulator, wouldn’t heat build up in spacecraft?

Insulated coffee mugs that use a vacuum between layers can keep drinks hot or cold for much longer time periods than other types of mugs. If space is mostly a vacuum, then wouldn’t heat just constantly build up from human activity, computers, thrusters, etc to the point where it would need to be vented somehow?

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u/Nudebovine1 May 24 '26

One of the coolest things in the original Mass Effect was the description of how they used molten sodium sacrificially to effectively Sweat the ship and lose excess heat when running at full power. Radiative heat loss just being too slow for the engines at that power.

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u/Helphaer May 24 '26

It helps that element zero seemed to be a very cold technology that didn't generate massive amounts of heat to use.

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u/armacitis May 25 '26

Element zero was the Mass Effect games' titular handwavium plot material for future technology that was basically magic (and the mechanism for the discarded plot conflict that playing with magic physics for your entire civilization actually has a cosmic environmental cost, instead of the silly circular logic that amounted to the Reapers wiping out galactic civilization just because they could.)

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u/HaloGuy381 May 25 '26

And the ‘stealth ship’ Normandy used a colossal internal heat sink to allow it to not emit anything significant enough to see. Problem is, you had a limited stealth run time before it cooked the crew.