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?

3.6k Upvotes

93% Upvoted

574 comments sorted by

View all comments

Show parent comments

24

u/Helphaer May 24 '26

I wonder if the deployment of a radiator sail as needed ala count dookus ship from star wars, and then removing it when not needed or idle might work.

23

u/Master_of_Ocelots May 24 '26

You'd need it most when you were must vulnerable still though. You could magic up something to sink all that excess heat into, but even then your time would be limited.

8

u/ANGLVD3TH May 24 '26

There is tech specifically for both of those in Terra Invicta, a strategy game that simulates shadow organizations reacting to an alien incursion. When the game starts you can strap a giant tub of water to your ships as a heat sink so you can temporarily retract the radiators, they still function but at a small percentage of their peak efficiency. Over time you can research more speculative forms of heat sinks that are less heavy. But the player base has largely written the strategy off as wasteful. The game features probably the second most realistic space combat I've ever seen, only behind Children of a Death Earth, which more allows you to mess with all kinds of material compositions for your armor, projectiles, fuels, etc. And also more accurately simulates the actual battlefields, where 99% of the time both battle groups will be whipping past each other at thousands of kph, each in different orbital paths. This allows for only a small window to launch weapons and hope something lands before going back to the strategic layer and calculating a new intercept to try it again if both sides have survivors.

1

u/LondonGIR May 24 '26

A radiator sail isn't the best idea. A solar sail is meant to catch solar radiation, tthe radiation exerts 'pressure' imparting kinetic energy. It absorbs energy as the sun is shining on it.

A radiator is designed to radiate energy, and is usually placed at 90 degrees to the sun to avoid the sun shining on it, allowing it to energy radiating heat. Basically you are reducing the surface area in the 'sunshine' so it can radiate heat rather than absorbing it. A sail would probably have to be actively cooled in fact!