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The video at the end of the article is absolutely fascinating. Also, it's the first time I hear that rejecting heat is a big deal in space. If anything, I woul
by gregschlom 12y ago
The video at the end of the article is absolutely fascinating.
Also, it's the first time I hear that rejecting heat is a big deal in space. If anything, I would have assumed that heating the station would have been a problem, rather than keeping it cold.
- matt4077 12y agoSame exposure to the sun, but no air convection.
- wmil 12y agoMost people assume that, and most sci-fi reinforces that opinion. But a generic Thermos is a vacuum flask. Space is an incredible insulator. The only way to cool things is to radiate heat.
- fsniper 12y agoThank you. TIL, actually not learned realized, space is actually a good insulator out of earth conditions too. Prejudices. We can never know what if something we thing is a reality or prejudice. Science and skepticism is that important.
- darkmighty 12y agoAlso of note is that while a vacuum doesn't necessarily have a temperature (it's just a medium), space does. Even if you go far away from anything else, you will still reach thermal equilibrium at the Cosmic microwave background (CMB) temperature, which is 2.7K -- it's essentially the "temperature of the universe", radiation which has been emitted as far back as the first moments of the universe. And of course, if you create a vacuum chamber on Earth, any object inside will always reach equilibrium at ambient temperature (in the lack of any heat engines on the body -- even then the fuel would deplete some time).
- deleted 12y ago[deleted]
- s_kilk 12y agoThe sci-fi game series Mass Effect had a good explaination for this, and tied it in with the notion of ships having recognizable "signatures": http://masseffect.wikia.com/wiki/Codex/Ships_and_Vehicles#Starships:_Heat_Management http://masseffect.wikia.com/wiki/Codex/Ships_and_Vehicles#St...
- golergka 12y agoIt also works similarly in Eve Online, btw.
- s_kilk 12y agoIndeed, whenever corp-mates would ask why there are brightly lit "windows" on their ships I would point out that they were actually heat dissipation panels.
- teamonkey 12y agoA major mechanic in Elite Dangerous is managing your ship's internal heat and heat signature.
- teamonkey 12y agoTechnically interplanetary space is a hot plasma too. The particles emitted by the Sun are very hot according to kinetic theory (which only depends on the mean velocity of particles) since they have a lot of energy. It's a plasma because the particles are charged and accelerated by the Sun's magnetic field. Of course the density of these particles is very low, so if your definition of heat factors those in then space is cold.
- ams6110 12y agoEvaporative cooling ought to work really well?
- prodigal_erik 12y agoIt would with an unlimited supply of coolant, but bringing mass is expensive. Unless you start grabbing asteroids and using your waste heat to vaporize them or something....
- toomuchtodo 12y agoBolt habitat to asteroid heatsink, profit.
- TeMPOraL 12y agoThat's what we have Planetary Resources for ;).
- lnanek2 12y agoBut that would use up material, all of which has to be trucked up to orbit at great expense.
- drm237 12y agoWhy did it get so cold inside of Apollo 13 then?
- Crito 12y agoMy understanding is that the spacecraft was designed to radiate large amounts of heat, with the expectation that systems inside the spacecraft would be producing a lot of it. Apollo 13 shut down much of the equipment inside the spacecraft, which meant that it was no longer producing as much heat as was expected.
- LoSboccacc 12y agoyou can have further insight here http://www.projectrho.com/public_html/rocket/misconceptions.php http://www.projectrho.com/public_html/rocket/misconceptions.... and then lose countless hours on that website if the topic fascinates you
- Shivetya 12y agoso my stupid question is, cannot it be used for power? Surely the same system which radiates the heat can be exploited to generate power with something akin to a sterling engine.
- SEMW 12y agoA heat engine is great when your cold sink is 'free', but here, the cold sink would be the radiator fins, and extracting energy from the temperature difference between main ISS and radiator fins would effectively just make the radiator fins worse at cooling the ISS. Which is fine if you have lots of excess radiator fins. But they almost certainly don't -- shipping up extra radiator fins in order to get power from the excess cooling capacity would be less efficient than just adding solar cells (efficiency of a heat engine maxes out at 1 - (T_cold / T_hot)).
- mr_olive 12y agoThese radiators exist specifically to deal with power which has already been used. As stated in the article, the station needs a few kW of electrical power. Eventually all this power ends up as a waste heat energy. There is nothing that can be done with it, so it has to be dumped into space.
- tesseract 12y agoThere's also solar heating of the station itself to worry about. Although to some extent you can make the station reflective (white) to deal with that.
- benihana 12y agoThe barbecue roll. The Apollo spacecraft would slowly rotate along it's longitudinal axis while it traveled to the moon to help dissipate heat.
- mrec 12y agoHmm. That made me wonder about Apollo 13, where the "crew endured temperatures at or below freezing for the bulk of the return flight" [1], apparently [2] because they had to turn off heaters and electronic gear to conserve power. The fact they had heaters suggests that the roll wasn't so much to dump heat as to spread it around, to reduce the risk of structural damage from differential heating [3]. That's presumably less viable on a big structure like the ISS. [1] http://www.spaceline.org/flightchron/apollo13.html http://www.spaceline.org/flightchron/apollo13.html [2] https://answers.yahoo.com/question/index?qid=20121015080310AAoCJB2 https://answers.yahoo.com/question/index?qid=20121015080310A... [3] https://books.google.com/books?id=31GqndM3fk8C&pg=PA419&dq=differential+heating+structural+damage https://books.google.com/books?id=31GqndM3fk8C&pg=PA419&dq=d...
- rasz_pl 12y ago> it's the first time I hear that rejecting heat is a big deal in space Play some Mass Effect :)
- rbanffy 12y agoSpace is pretty much a perfect storm. As if relying only on radiating heat were not enough, you need gravity (or some acceleration) for convection to work. And then simply pumping a fluid through tubes is an interesting issue when the fluid does not know which way is down.