3 ms·
The computation in TFA is wrong. The incoming power is not the electrical power generated by the solar panels, but the entire power of the light that is absorb
by adrian_b 4mo ago
The computation in TFA is wrong.
The incoming power is not the electrical power generated by the solar panels, but the entire power of the light that is absorbed by the solar panels and by the body of the satellite.
Even with a perfectly reflecting body and with SOTA solar panels, the amount of incoming power is at least double in comparison with the electrical power consumed by the datacenter.
Also, the heat radiated is smaller than in TFA, because no radiator is perfectly black at the radio waves in the frequency range corresponding to the ambient temperature.
I am too lazy to make the correct computation, but there was another article linked on HN some days ago where a more plausible computation was done and the conclusion was that the minimum area of the radiators is slightly larger than the area required for solar panels.
This would still be feasible, but in reality the area would have to be even larger, because the radiator cannot have a uniform temperature, the parts where the cooling fluid is incoming will be hotter than the parts where the cooling fluid is outgoing. Moreover, the pumping of the cooling fluid requires extra power that must be added to the power budget.
There is no doubt that it is possible to build a space datacenter, if much more GPUs are installed in it than necessary, to enable to correct the more severe transient errors and to preserve enough capacity after many GPUs become permanently defective, but the cost will not be competitive with terrestrial datacenters any time soon.
- LargoLasskhyfv 4mo agoThere are other options: https://spectrum.ieee.org/orbital-data-centers-heat#liquid-droplet%20radiators:~:text=Another%20possibility%20is%20to%20use%20liquid%2Ddroplet%20radiators https://spectrum.ieee.org/orbital-data-centers-heat#liquid-d... https://en.wikipedia.org/wiki/Liquid_droplet_radiator https://en.wikipedia.org/wiki/Liquid_droplet_radiator ( Myself from 4 months ago: https://news.ycombinator.com/item?id=46895344 https://news.ycombinator.com/item?id=46895344 (giggle) https://spectrum.ieee.org/microfluidics-cooling-ai-chips-corintis https://spectrum.ieee.org/microfluidics-cooling-ai-chips-cor... )
- jauntywundrkind 4mo agoI went in wanting this to look real bad. But the Scott Manley video alas has sort of convinced me this is pretty feasible, that the energy budget is quite doable. https://youtu.be/FlQYU3m1e80 https://youtu.be/FlQYU3m1e80 I do think this is a pretty generous estimate he ends up at. I don't think emissivity is perfectly well dealt with. I don't know if his earth reflection emissivity includes the high energy thermal transfer from particles that do exist on the near vacuum (exosphere be hit, ya'll) or if that matters. But his figures seem ballpark correct & my concerns are at best marginal.
- essdas 4mo agoI vaguely recall the Scott Manley video (longtime follower of his channel) - wasn’t he assuming that the chips can be run hot, and because the T^4 factor it results in much better radiative cooling? I don’t know if the “chips can be run hot” assumption is a fair one. It results in significant degradation of the chips life. At minimum it needs a redesign of the current set of leading chips which are designed for a specific temperature range. Redesigning at a different operational temperature is not a walk in the park.
- jauntywundrkind 4mo agoHe starts with something hot today but viable, 80C. And he goes on to cite and discuss a M*sk tweet about hotter, 97C, and what that density that enables. https://youtu.be/FlQYU3m1e80#t=13:48 https://youtu.be/FlQYU3m1e80#t=13:48 and https://youtu.be/FlQYU3m1e80#t=22:11 https://youtu.be/FlQYU3m1e80#t=22:11