Comment on Cooling stuff does not require any energy!
XeroxCool@lemmy.world 3 weeks ago
Atoms are surprisingly bad at removing heat. Being hit with slower atoms and transferring that energy ((like newton’s cradle with mismatched swings opposing each other) transfers energy much, much faster than what happens naturally in the vacuum of space. Most spacecraft have more of issue with overheating than freezing. The rate at which radiation is emitted is very low when you get to sub-human temperatures. There’s also tons of heat sources around us in space, so the last few degrees are so, so hard to shed.
Keeping a fridge stocked increases the thermal capacity of the coldness. Air falls out quickly and is subject to rapid temperature change when the door is open. Keeping a bunch of solid/sealed masses in there will bank the lack of heat. You’ll likely lose more air and the falling not-so-cool air will impart heat into your 24 pack of beer, but you’ll have a bunch of distirbuted cold objects to re-cool the air once the door is closed instead of relying on air circulation alone. Instead of raising the air temp by, say, 5 degrees once settled, it’ll only go up maybe 2 degrees - much better for food storage. But the fridge will still have to re-cool those beers, too.
Artisian@lemmy.world 3 weeks ago
“Spacecraft have more of an issue with overheating than freezing” is a really really
coolhot fact. Do you have an easy source, maybe somewhere that discusses techniques/history?XeroxCool@lemmy.world 3 weeks ago
I’d have to look for specific discussions, but I have some examples. The wiki page covers a lot. Spacewalk/moonwalk suits are white to reflect the sun’s heat (the orange suits are for takeoff/landing, a sin, terrestrial recovery). That shiny silver or gold foul appearance of classic space craft from the 60s/70s is for heat reflection. The JWST is on like 4 layers of wafers (they look like a sail) to isolate it from the sun’s heat. Quite visibly in depictions, the scrunched panels on the ISS are actually radiators.
There’s a misconception about space and heat. It didn’t originate, but I’m Sur eit was propogated by the 00s space movie that had an astronaut pop off their helmet and freeze. Mission to Mars? Red Planet? Space cowboys? Yes, you probably would freeze upon exposure to space, but not because it’s cold. The sudden drop in pressure would vaporized a tremendous amount of water from you. Jus like how sweat works, the evaporative cooling would drop your skin temperature greatly.
A side topic is that there’s narrow frequency range of radiation that is neither emitted by the sun nor reflected by the atmosphere. It’s in the near if rated range. There’s a NighthawkInLight video that develops a paint that resonates in this “window” to actually cool it below ambient air temperature. There’s always a control piece for science’s sake.
Dasus@lemmy.world 2 weeks ago
quora.com/Does-the-ISS-use-power-to-heat-or-cool
zener_diode@feddit.org 3 weeks ago
This is less of a source and more like a compilation of resources, but for anything spacecraft related I can always recommend Atomic Rockets. For this specifically, the page on Heat Radiators.
Artisian@lemmy.world 3 weeks ago
Thank you! (I think the second link lost a ‘p’ at the end. projectrho.com/public_html/rocket/heatrad.php )
zener_diode@feddit.org 3 weeks ago
Edited my comment to fix, thanks!