5 ms·

> Simple cooling sinks, dense I think you need to go back to physics class. You seem to not even understand the very basics of heat transfer. You need more tha

> Simple cooling sinks, dense I think you need to go back to physics class. You seem to not even understand the very basics of heat transfer. You need more than "cold". I'll give you a hint, the problem is the same problem as "in space no one can hear you scream." I'll also mention that the moon isn't very cold, except on the dark side. In the moon's day the temperature is 120C and at night -130C. The same side of the moon always faces us and the moon isn't always full. I'll let you figure out the rest.

NetMageSCW 9mo ago
Well, there are the permanently dark crater bottoms that might contain water ice and are definitely very cold. Turn the water ice into thermal transfer fluid and drill (The Boring Company) cooling loops underneath and the try to heat sink into the very cold ground. I’m sure you could run the Data Center for months before you exceed the radiative heat dispersal available to the ground.
- godelski 9mo ago
  You don't need to but in a dark crater to use the ground as your sink. Also you need to consider that the thermal conductivity of lunar regolith is quite low. I'm not saying it's not possible but I am saying there's a lot of technical challenges that make naïve approaches not so simple. The reason doing things in space is hard is not just the difficulty of getting things up into space. It's that all the things you take for granted just don't work. Oversimplification is a footgun. Or more accurately, in this case a foot taser (if you know why you've found one of the major challenges of doing anything on the moon and mars)
Nevermark 9mo ago
> You seem to not even understand the very basics of heat transfer. Basic physics: The moon is very cold in surface shadows and below the surface. It is an enormous pre-chilled heat sink. The surface is also the support structure for any scale of radiative cooling with the same heat physics as orbit, but much better for larger and enhanced radiative engineering. For example, heat pumps can centralize waste heat energy. Higher heat density vastly increases radiative efficiency. • Permanent shadow: 40-60 ˚K, -230 to 210 ˚C • In polar shadow: 25-30 ˚K, -250 to -245 ˚C • Under 1 meter of surface, equatorial: 250 ˚K, -23 ˚C • Under 1 meter of surface, polar: 200-220 ˚K, -75 to -50 ˚C Many advantages beyond unlimited heat sink/radiative area: all compute in one place, i.e no size limit, so low inter-center latencies, no orbit safety negotiations or periodic orbit re-lifts required, able to update entire data center in a single trip, easier maintenance and stability in gravity on a surface, solar panels can be distributed over distance limiting total space debris risk, different component lifetimes don't result in wasted components, ... Only downsides are a higher Earth-Datacenter latency, lunar dust resistant design, and a need to be at a pole for all-month solar power. Nuclear power, or nuclear + solar, would allow any site. Note that shade can be created anywhere on the surface via reflective shielding, and power can be used to heat, in order to stabilize temperatures in a desired band. Buried installations can use insulation for even greater temperature control.
- godelski 9mo ago
  Great, now do the math and let's talk
  - Nevermark 9mo ago
    Things scale so differently, we don’t need a parts list to make a general tradeoff relationship. Of the moon and orbital, orbit is much closer and will be cheaper to start with. But a lunar site would scale to much greater mean density and unlimited total capacities. And be much cheaper for reasons I gave, at some threshold scale. Neither is easy, and it’s not at all clear that either is actually better than down here. Especially with nuclear efforts and funding rising quickly.
    - godelski 9mo ago
      I'm not asking for a parts list, I'm asking for math
      - Nevermark 9mo ago
        if you want some math beyond identifying different scaling issues, go for it.
        godelski 9mo ago
        I have. That's why I'm certain you're wrong. But if you're too lazy to do it yourself there's plenty of papers written on this stuff
        Nevermark 9mo ago
        Well then, use your math to address a point. Just one. In a vacuum, radiative heat loss per time hyper scales with temperature to the 4th power. In orbit large and complex heat transfer systems are not going to be practical. On a surface, specialized heat pumps can localize heat energy to very high intensity. With critical reliability advantages of stability, vibration control, complete sun shading, weaker size constraints, etc. That is a tremendous advantage that will overwhelm most other details and tradeoffs, because the two main constraints, and operating costs, are energy production and heat dispersion. The latter imposing a limit on the former. (You have no knowledge of how effectively I use my time. If you have a valid point, make it, instead of - whatever you are doing. Claiming you know things without sharing your reasoning and aspersive language are for the posers. Just communicate why you think, what you think.)

NetMageSCW 9mo ago

Well, there are the permanently dark crater bottoms that might contain water ice and are definitely very cold. Turn the water ice into thermal transfer fluid and drill (The Boring Company) cooling loops underneath and the try to heat sink into the very cold ground. I’m sure you could run the Data Center for months before you exceed the radiative heat dispersal available to the ground.

godelski 9mo ago
You don't need to but in a dark crater to use the ground as your sink. Also you need to consider that the thermal conductivity of lunar regolith is quite low. I'm not saying it's not possible but I am saying there's a lot of technical challenges that make naïve approaches not so simple. The reason doing things in space is hard is not just the difficulty of getting things up into space. It's that all the things you take for granted just don't work. Oversimplification is a footgun. Or more accurately, in this case a foot taser (if you know why you've found one of the major challenges of doing anything on the moon and mars)

Nevermark 9mo ago

> You seem to not even understand the very basics of heat transfer. Basic physics: The moon is very cold in surface shadows and below the surface. It is an enormous pre-chilled heat sink. The surface is also the support structure for any scale of radiative cooling with the same heat physics as orbit, but much better for larger and enhanced radiative engineering. For example, heat pumps can centralize waste heat energy. Higher heat density vastly increases radiative efficiency. • Permanent shadow: 40-60 ˚K, -230 to 210 ˚C • In polar shadow: 25-30 ˚K, -250 to -245 ˚C • Under 1 meter of surface, equatorial: 250 ˚K, -23 ˚C • Under 1 meter of surface, polar: 200-220 ˚K, -75 to -50 ˚C Many advantages beyond unlimited heat sink/radiative area: all compute in one place, i.e no size limit, so low inter-center latencies, no orbit safety negotiations or periodic orbit re-lifts required, able to update entire data center in a single trip, easier maintenance and stability in gravity on a surface, solar panels can be distributed over distance limiting total space debris risk, different component lifetimes don't result in wasted components, ... Only downsides are a higher Earth-Datacenter latency, lunar dust resistant design, and a need to be at a pole for all-month solar power. Nuclear power, or nuclear + solar, would allow any site. Note that shade can be created anywhere on the surface via reflective shielding, and power can be used to heat, in order to stabilize temperatures in a desired band. Buried installations can use insulation for even greater temperature control.

godelski 9mo ago
Great, now do the math and let's talk
- Nevermark 9mo ago
  Things scale so differently, we don’t need a parts list to make a general tradeoff relationship. Of the moon and orbital, orbit is much closer and will be cheaper to start with. But a lunar site would scale to much greater mean density and unlimited total capacities. And be much cheaper for reasons I gave, at some threshold scale. Neither is easy, and it’s not at all clear that either is actually better than down here. Especially with nuclear efforts and funding rising quickly.
  - godelski 9mo ago
    I'm not asking for a parts list, I'm asking for math
    - Nevermark 9mo ago
      if you want some math beyond identifying different scaling issues, go for it.
      - godelski 9mo ago
        I have. That's why I'm certain you're wrong. But if you're too lazy to do it yourself there's plenty of papers written on this stuff
        Nevermark 9mo ago
        Well then, use your math to address a point. Just one. In a vacuum, radiative heat loss per time hyper scales with temperature to the 4th power. In orbit large and complex heat transfer systems are not going to be practical. On a surface, specialized heat pumps can localize heat energy to very high intensity. With critical reliability advantages of stability, vibration control, complete sun shading, weaker size constraints, etc. That is a tremendous advantage that will overwhelm most other details and tradeoffs, because the two main constraints, and operating costs, are energy production and heat dispersion. The latter imposing a limit on the former. (You have no knowledge of how effectively I use my time. If you have a valid point, make it, instead of - whatever you are doing. Claiming you know things without sharing your reasoning and aspersive language are for the posers. Just communicate why you think, what you think.)