2 ms·

You can radiate the excess energy away on the non-sun facing part. In theory.

fhars 11mo ago
There are even commercially available prototypes of that vacuum cooling technology, if you want to perform your own experiments with that concept: https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/dp/B01DZQSWQ4?th=1 https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/...
- RugnirViking 11mo ago
  this kind of sarcasm will go over their head. People truly don't understand vacuums
  - ReptileMan 11mo ago
    I absolutely don't understand how vacuum works. So I absolutely cannot model how a Dewar flask which has 15 billion light year thickness between the inner and outer wall - a wall that is very close to absolute zero will behave.
- sanex 11mo ago
  That's my water bottle. 10/10 would recommend for not passing temperature gradients.
- ahartmetz 11mo ago
  To be fair, they have mirror surfaces inside. A more realistic prototype would be ultra-black for something like 10-50x better radiative heat transfer. Of course it would still be more like shitty insulation than like good conduction.
Sharlin 11mo ago
Yes. And it's an absolutely terrible way to get rid of heat. Cooling in space is a major problem because the actually effective ways to do it are not available.
dayjah 11mo ago
Serious question: how in theory? I’m under the impression you need to radiate through matter (air, water, physical materials, etc). Is my understanding of the theory just wrong?
- LegionMammal978 11mo ago
  Heat conduction requires a medium, but radiation works perfectly fine in a vacuum. Otherwise the Sun wouldn't be able to heat up the Earth. The problem for spacecraft is that you're limited by how much IR radiation is passively emitted from your heat sinks, you can't actively expel heat any faster.
- ethmarks 11mo ago
  There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use for cooling systems. The main way that heat dissipates from space stations and satellites is through thermal radiation: https://en.wikipedia.org/wiki/Thermal_radiation https://en.wikipedia.org/wiki/Thermal_radiation.
- estimator7292 11mo ago
  Hot objects emit infrared light no matter the conditions. The hotter the object, the more light it throws off. By radiating this light away, thermal energy is necessarily consumed and transformed into light. It's kind of wild actually
Avicebron 11mo ago
It's not the Sun..it's the lack of medium.
ethmarks 11mo ago
There's no air and negligible thermal medium to convect heat away. The only way heat leaves is through convection from the extremely sparse atmosphere in low Earth orbit (less than a single atom per cubic millimeter) and through thermal radiation. Both of which are much, much slower than convection with water or air. Space stations need enormous radiator panels to dissipate the heat from the onboard computers and the body heat of a few humans. Cooling an entire data center would require utterly colossal radiator panels.
jhanschoo 11mo ago
You can radiate the excess energy away on the non-sun facing part on Earth almost just as well..., though corrosion is an issue.
- ffsm8 11mo ago
  "just as well"? I man you totally can radiate excess heat energy on earth, but your comment implies that the parents idea of radiating off excess "energy", specifically HEAT energy in space is possible, which it isn't. You can radiate excess energy for sure, but you'd first have to convert it away from heat energy into light or radio waves or similar. I don't think we even have that tech at this point in time, and neither do we have any concepts how this could be done in theory.
  - ReptileMan 11mo ago
    >specifically HEAT energy in space is possible, which it isn't. https://en.wikipedia.org/wiki/Black-body_radiation https://en.wikipedia.org/wiki/Black-body_radiation
    - ffsm8 11mo ago
      I see, yes. I was thinking more along the lines of radiating heat energy at a scale that's useable for cooling, not at the more extreme levels of over 500°C/1k fahrenheit That's technically correct I guess, at some temperature threshold it becomes possible to bleed some fractions of energy while the material is exceedingly hot.
      - jhanschoo 11mo ago
        Yeah, my comment was intended to be mildly sarcastic in that the proposed heat transmission mechanism already happens on Earth and is yet so dramatically insignificant at usual temperatures that we struggle all the time with managing heat transfer through other means.
Ekaros 11mo ago
I wonder if there should be levels of "in theory". Yes theoretically black body radiation exist and well stuff cools down to near background radiation via that. But the next level is theoretical implementation. Like actually moving around the heat from source and so on. Maybe this could be the spherical cow step... Reminds me of the hyperloop. Well yes, things in vacuum tube go fast. Now does enough things go fast to make any sense...
- salawat 11mo ago
  >Now does enough things go fast to make any sense... You're worried about rates when we can't even get the ball rolling on safety for human occupancy, maintenance, workability. I swear, nothing on Earth more dangerous than someone with dollar signs in their eyes.
morshu9001 11mo ago
Passively yeah. Can't imagine it's anywhere near as fast as evap or chillers
adastra22 11mo ago
No, you can't. You need to radiate away all the heat being received from the sun facing half, AND excess heat from the compute. Even in theory, the non-sun-facing part doesn't give you any benefit. It's already part of the system that accounted for the temperature of the sun-facing side.

fhars 11mo ago

There are even commercially available prototypes of that vacuum cooling technology, if you want to perform your own experiments with that concept: https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/dp/B01DZQSWQ4?th=1 https://www.amazon.com/Thermos-Stainless-Ounce-Drink-Bottle/...

RugnirViking 11mo ago
this kind of sarcasm will go over their head. People truly don't understand vacuums
- ReptileMan 11mo ago
  I absolutely don't understand how vacuum works. So I absolutely cannot model how a Dewar flask which has 15 billion light year thickness between the inner and outer wall - a wall that is very close to absolute zero will behave.
sanex 11mo ago
That's my water bottle. 10/10 would recommend for not passing temperature gradients.
ahartmetz 11mo ago
To be fair, they have mirror surfaces inside. A more realistic prototype would be ultra-black for something like 10-50x better radiative heat transfer. Of course it would still be more like shitty insulation than like good conduction.

Sharlin 11mo ago

Yes. And it's an absolutely terrible way to get rid of heat. Cooling in space is a major problem because the actually effective ways to do it are not available.

dayjah 11mo ago

Serious question: how in theory? I’m under the impression you need to radiate through matter (air, water, physical materials, etc). Is my understanding of the theory just wrong?

LegionMammal978 11mo ago
Heat conduction requires a medium, but radiation works perfectly fine in a vacuum. Otherwise the Sun wouldn't be able to heat up the Earth. The problem for spacecraft is that you're limited by how much IR radiation is passively emitted from your heat sinks, you can't actively expel heat any faster.
ethmarks 11mo ago
There is some medium in low Earth orbit. Not all vacuums are created equal. However, LEO vacuum is still very, very sparse compared to the air and water we use for cooling systems. The main way that heat dissipates from space stations and satellites is through thermal radiation: https://en.wikipedia.org/wiki/Thermal_radiation https://en.wikipedia.org/wiki/Thermal_radiation.
estimator7292 11mo ago
Hot objects emit infrared light no matter the conditions. The hotter the object, the more light it throws off. By radiating this light away, thermal energy is necessarily consumed and transformed into light. It's kind of wild actually

Avicebron 11mo ago

It's not the Sun..it's the lack of medium.

ethmarks 11mo ago

There's no air and negligible thermal medium to convect heat away. The only way heat leaves is through convection from the extremely sparse atmosphere in low Earth orbit (less than a single atom per cubic millimeter) and through thermal radiation. Both of which are much, much slower than convection with water or air. Space stations need enormous radiator panels to dissipate the heat from the onboard computers and the body heat of a few humans. Cooling an entire data center would require utterly colossal radiator panels.

jhanschoo 11mo ago

You can radiate the excess energy away on the non-sun facing part on Earth almost just as well..., though corrosion is an issue.

ffsm8 11mo ago
"just as well"? I man you totally can radiate excess heat energy on earth, but your comment implies that the parents idea of radiating off excess "energy", specifically HEAT energy in space is possible, which it isn't. You can radiate excess energy for sure, but you'd first have to convert it away from heat energy into light or radio waves or similar. I don't think we even have that tech at this point in time, and neither do we have any concepts how this could be done in theory.
- ReptileMan 11mo ago
  >specifically HEAT energy in space is possible, which it isn't. https://en.wikipedia.org/wiki/Black-body_radiation https://en.wikipedia.org/wiki/Black-body_radiation
  - ffsm8 11mo ago
    I see, yes. I was thinking more along the lines of radiating heat energy at a scale that's useable for cooling, not at the more extreme levels of over 500°C/1k fahrenheit That's technically correct I guess, at some temperature threshold it becomes possible to bleed some fractions of energy while the material is exceedingly hot.
    - jhanschoo 11mo ago
      Yeah, my comment was intended to be mildly sarcastic in that the proposed heat transmission mechanism already happens on Earth and is yet so dramatically insignificant at usual temperatures that we struggle all the time with managing heat transfer through other means.

Ekaros 11mo ago

I wonder if there should be levels of "in theory". Yes theoretically black body radiation exist and well stuff cools down to near background radiation via that. But the next level is theoretical implementation. Like actually moving around the heat from source and so on. Maybe this could be the spherical cow step... Reminds me of the hyperloop. Well yes, things in vacuum tube go fast. Now does enough things go fast to make any sense...

salawat 11mo ago
>Now does enough things go fast to make any sense... You're worried about rates when we can't even get the ball rolling on safety for human occupancy, maintenance, workability. I swear, nothing on Earth more dangerous than someone with dollar signs in their eyes.

morshu9001 11mo ago

Passively yeah. Can't imagine it's anywhere near as fast as evap or chillers

adastra22 11mo ago

No, you can't. You need to radiate away all the heat being received from the sun facing half, AND excess heat from the compute. Even in theory, the non-sun-facing part doesn't give you any benefit. It's already part of the system that accounted for the temperature of the sun-facing side.