The equation has a ^4 to the temperature. If you raise the temperature of your radiator by ~50 degrees you double its emission capacity. This is well within the range of specialised phase change compressors, aka fancy air conditioning pumps.

Next up in the equation is surface emissivity which we’ve got a lot of experience in the automotive sector.

And finally surface area, once again, getting quite good here with nanotechnology.

Yes he’s distracting, no it’s not as impossible as many people think.

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sfink 13 hours ago | parent | next [-]

> And finally surface area, once again, getting quite good here with nanotechnology.

So your hot thing is radiating directly onto the next hot thing over, the one that also needs to cool down?

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marcosdumay 11 hours ago | parent | prev | next [-]

> aka fancy air conditioning pumps

Yeah, pumps, tubes, and fluids are some of the worst things to add to a satellite. It's probably cheaper to use more radiators.

Maybe it's possible to make something economical with Peltier elements. But it's still not even a budget problem yet, it's not plainly not viable.

> getting quite good here with nanotechnology

Small features and fractal surfaces are useless here.

	▲	pclmulqdq 8 hours ago \| parent \| next [-]
		Peltiers and heat pipes don't remove heat, they just move it. You still need the radiator.
	▲	aunty_helen 11 hours ago \| parent \| prev [-]
		My dude, heat pipes were invented for satellites and there’s people walking around with piezo pumps in their phones these days. We’re getting close. Peltiers generate a lot of heat to get the job done so even though electricity is pretty much free, probably not a sure bet.

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wat10000 12 hours ago | parent | prev | next [-]

Raise the temperature of your radiator by 50 degrees and you double its emission capacity. Or put your radiator in the atmosphere and multiply its heat exchange capacity by a factor of a thousand.

It's not physically impossible. Of course not. It's been done thousands of times already. But it doesn't make any economic sense. It's like putting a McDonald's at the top of Everest. Is it possible? Of course. Is it worth the enormous difficulty and expense to put one there? Not even a little.

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aunty_helen 12 hours ago | parent [-]

For thousands of years we never even looked to Mount Everest, then some bloke on the fiver said he’d give it a shot. Nowadays anyone with the cash and commitment can get the job done.

Same with datacenters in space, not today, but in 1000 years definitely, 100 surely, 10?

As for the economics, it makes about as much sense as running jet engines at full tilt to power them.

	▲	tialaramex 3 hours ago \| parent [-]
		> some bloke on the fiver said he’d give it a shot Hillary (he features on the NZ Five Dollar note) was one of those guys who does things for no good reason. He also went to both poles. This only tells us that it is indeed possible, but not that it's desirable or will become routine.

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stackghost 11 hours ago | parent | prev | next [-]

Even if you create a material with surface emissivity of 1.0:

- let's say 8x 800W GPUs and neglect the CPU, that's 6400W

- let's further assume the PSU is 100% efficient

- let's also assume that you allow the server hardware to run at 77 degrees C, or 350K, which is already pretty hot for modern datacenter chips.

Your radiator would need to dissipate those 6400W, requiring it to be almost 8 square meters in size. That's a lot of launch mass. Adding 50 degrees will reduce your required area to only about 4.4 square meters with the consequence that chip temps will rise by 50 degrees also, putting them at 127 degrees C.

No CPU I'm aware of can run at those temps for very long and most modern chips will start to self throttle above about 100

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aunty_helen 10 hours ago | parent [-]

Hence the fancy air conditioning pumps

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stackghost 10 hours ago | parent [-]

... on satellites?

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aunty_helen 8 hours ago | parent [-]

Yes, that’s what we’re talking about. Data centers in space.

You put the cold side of the phase change on the internal cooling loop, step up the external cooling loop as high temp as you can and then circulate that through the radiators. You might even do this step up more than once.

Imagine the data center like a box, you want it to be cold inside, and there’s a compressor, you use to transfer heat from inside to outside, the outside gets hot, inside cold. You then put a radiator on the back of the box and radiate the heat to the darkness of space.

This is all very dependent on the biggest and cheapest rockets in the world but it’s a tradeoff of convenience and serviceability for unlimited free energy.

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abenga 7 hours ago | parent [-]

Why not use the unlimited free energy on terrestrial data centers then? You can use solar power as we speak, no?

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aunty_helen 10 minutes ago | parent [-]

Because the sun hides at night. Scientists have yet to figure out where he goes. Until that happens it’s not a great power source.

	▲	direwolf20 a few seconds ago \| parent [-]
		What do the satellites do in earth's shadow?

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jamiek88 13 hours ago | parent | prev | next [-]

This makes zero sense.

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vel0city 13 hours ago | parent | prev [-]

> Next up in the equation is surface emissivity which we’ve got a lot of experience in the automotive sector.

My car doesn't spend too much time driving in vacuum, does yours?

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aunty_helen 12 hours ago | parent | next [-]

Engine bays have a lot of design go into where to keep heat and where to get rid of it. You can look up thermal coatings and ceramics etc.

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vel0city 12 hours ago | parent [-]

Sure and it all routes to dump the heat to...where again? A vacuum? Or to a radiator with a fan with some kind of cooler fluid/gas from the environment constantly flowing through it?

Seems like quite a massive difference to ignore.

	▲	darig 12 hours ago \| parent [-]
		[dead]

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MillionOClock 12 hours ago | parent | prev [-]

Let's just hope the person you are responding to isn't Elon Musk!

	▲	vel0city 12 hours ago \| parent [-]
		I wouldn't say that roadster isn't doing much driving but dang is it drifting!