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Comment by mlindner | Hacker News Reader

We have radiators on the ISS. Even if you kept the terrible performance of those ancient radiator designs (regularly exposed to sunlight, simplistic ammonia coolant, low temperature) you could just make them bigger and radiate the needed energy. Yes it would require a bit of engineering but to call it an "unsolved problem" is just exaggerating.

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It's a solved problem. The physics is simply such that it's really inefficient.

> ... we'd need a system 12.5 times bigger, i.e., roughly 531 square metres, or about 2.6 times the size of the relevant solar array. This is now going to be a very large satellite, dwarfing the ISS in area, all for the equivalent of three standard server racks on Earth.

https://taranis.ie/datacenters-in-space-are-a-terrible-horri...

The gist of it is that about 99% of cooling on earth works by cold air molecules (or water) bumping into hot ones, and transferring heat. There's no air in space, so you need a radiator 99x larger than you would down here. That adds up real fast.

That’s the secret plan - cover LEO with solar cells and radiators, limiting sunlight on the ground, rendering ground base solar ineffective, cool earth and create more demand for heating; then sell expensive space electricity at a huge premium. Genius!

A really painfully laboured way of just saying conduction.

I think you may be thinking of cooling to habitable temperatures (20c). You can run GPUs at 70c , so radiative cooling density goes up exponentially. You should need about 1/3 of the array in radiators.

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