alt Hacker NewsThe physics problem regarding radiator arrays isn't unsolved, but it's not a problem that scales up gracefully. Small-scale radiators could get by via passive cooling, but large-scale radiators need active cooling, and now you need fluid, pipes, and pumps that all represent additional launch mass and points of failure (and the pumps are generating heat of their own, so now you need more radiators...).
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AnthonyMouse • yesterday at 10:16 PM
Doesn't active cooling provide counterbalancing options to improve efficiency though? For example, use multi-stage heat pumps with different refrigerants so that you can make the hot side very hot and thereby need less mass for radiators.
nkrisc • yesterday at 10:57 PM
So what’s the unsolved physics problem? Everything you’re describing are engineering challenges.
Thermal dissipation scales quartically with T, that's about as graceful as you can get from a physics POV, very few things scale at that rate.
COTs GPUs throttle at about 90-100C but that's because they have plastic parts and solder that melts. Those are relatively easy to eliminate.
We haven't tried much to scale up operating temp.