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Comment by spandrew | Hacker News Reader

There were a lot of YouTube science-fluencers talking about how dumb this idea was. Google themselves called it a Moonshot (har har).

Curious to see if the experiment changes our understanding of space radiators at a certain scale for non-space exploration purposes.

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Its running for 15 minutes and then must shut down for a long time to cool down. Thats exactly why those "science-fluencers" said its a dumb idea. This is far away from proving that its a viable idea.

They use passive cooling in their MVP satellite (for the sake of simplicity, probably). This, naturally, severely limits the heat rejection capacity.

They use passive cooling _because it's in a goddamn vacuum_. Passive cooling is basically your only option.

_Radiative cooling_ is the only option because it's in vacuum. But you can transfer heat to the radiator either passively (using thermal conductivity), or actively (using coolant). The second option allows to effectively use larger radiators.

BTW, we seem to have Noisesphere instead of Noosphere.

Source for that?

Edit: @kieranmaine thanks! Wonder how long they have to wait to turn them on again.

FTA:

> The cooling system will only be able to operate in brief spurts of about 15 minutes. After that, the TPUs need to shut down to allow the radiators to catch up.

I suspect it’ll go in the trash like their previous experimental infrastructure ideas did.

A lot of their experimental infrastructure has influenced later work.

No not really.

Sorry for the snark but that has the same level of credibility as your comment.

If Google did not exist, I don't think the world would be noticeably different.

It is 700w of heat radiating by 1m2 at 70C ( ie one GPU can sit on such a radiator) What is not to work ok here?

No air. No convection, only radiation.

That is what I said.

What you said was just a statement, not something with evidence or reasoning for why it should work. How large of an area is required to dissipate that much heat in a vacuum at a constant rate?

1m² of perfect black body in vacuum at 343K should emit about 700W, according to the Stephan-Bolzmann formula. Should do for a consumer GPU, or an H100.

Since the heat distribution over the radiator is not ideally uniform, I suppose that the emitted power will be less, if they want to keep the chips at 70C.

Since the temperature has the fourth power in the formula, having the GPU work at 100C would increase the radiator efficiency quite a bit.

>How large of an area is required to dissipate that much heat in a vacuum at a constant rate?

that is exactly what i said.

>something with evidence

middle-school physics, basic knowledge, at least if you decided to participate in such a discussion.

I read your statement as just stating what they had done (or planned to do), not that you had calculated that as the correct/sufficient amount. If you read it that way it sounds like 'they provided X amount, why shouldn't that work?' which reads like a statement without evidence of why it would work.

Sorry for misinterpreting your statement.

Just call it SkyNet and lean into the evil.

Golden Dome is the name https://en.wikipedia.org/wiki/Golden_Dome_(missile_defense_s...

It's a ground-targeting offensive system to be clear, not just missile defense.

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