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Economics of Orbital vs. Terrestrial Data Centers

andrewmccalip.com

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Re: Economics of Orbital vs. Terrestrial Data Centers

#211

Post by mojosam »

> That "why" is almost missing from the public conversation. People jump straight to hardware and hand-wave the business case, as if the economics are self-evident. They aren't.

But then he never answers that fundamental question, and jumps straight to the hardware and power and cost? What problems are orbital data centers trying to solve? What optimizations are they intended to deliver? Are these optimizations beneficial to everyone who uses a data centers, or just operators or users of orbiting satellite constellations?

> But the knock-on effects are why this keeps pulling at people. If you can industrialize power and operations in orbit at meaningful scale, you're not just running GPUs. You're building a new kind of infrastructure that makes it easier for humans to keep spreading out. Compute is just one of the first excuses to pay for the scaffolding.

This seems to be the closest we get to a “Why”, but it doesn’t make much sense. A constellation of 40,000 satellites with GPUs “infrastructure that makes it easier for humans to keep spreading out”? How?

> The target I care about is simple: can you make space-based, commodity compute cost-competitive with the cheapest terrestrial alternative? That's the whole claim. … Can you deliver useful watts and reject the waste heat at a price that beats a boring Crusoe-style tilt-wall datacenter tied into a 200–500 MW substation?

Isn’t the answer clearly “No”? The default settings of his model — which I assume he considers optimal — tell us that power for orbital data enters will cost 3.5X terrestrial ones. And that only SpaceX has the vertical integration to do even attempt to do this. So again, where is the competitive advantage?

Also, I don’t understand why he’s including satellite construction and launch costs for a 40,000 satellite constellations in his analysis, if he’s assuming SpaceX as he claims. Wouldn’t SpaceX simply implement these compute capabilities in the next gen of Starlink, so which would reduce costs significantly.

> It might not be rational. But it might be physically possible.

But isn’t that precisely what everyone has been saying? I don’t think the question has been whether orbital data centers are possible, it’s been whether they are rational. And that centers foremost h the unanswered question, Why is this a good idea?

Re: Economics of Orbital vs. Terrestrial Data Centers

#212

Post by Symmetry »

zozbot234 wrote: post #19

Will these space-based data centers run on rad-hard silicon (which is dog slow compared to anything on Earth) or just silently accept wrong results, hardware lockups and permanent failure due to the harsh space environment? Will they cool that hardware with special über-expensive high-temperature Peltiers that heat the radiators up to visible incandescence so that the heat can be shed with any efficiency? There's zil…

It's very important in this case to specify which orbit the satellite is going to be in. If you're in LEO like the international space station you spend all day inside the Van Allen Belt protected from all those charged particles that the sun is pumping out. You're still lacking the atmosphere's protection from cosmic rays but that's not a huge dosage.

If you go out to MEO then suddenly you're outside that protective magnetic shield and you have to deal with charged particles smashing into you and you want a large mass of water or wax shielding if you don't have radiation tolerant electronics.

SSO, a low earth orbit whose plane is perpendicular to the direction of the sun so it gets constant sunlight, is harsher than normal LEO orbits because it passes over the poles where the protection from the Earth's magnetic field is weakest, but it's still a lot better than higher orbits. This is probably where you want a datacenter to get constant sunlight and as much protection as possible.

Re: Economics of Orbital vs. Terrestrial Data Centers

#213

Post by teeray »

PeterHolzwarth wrote: post #132
jofer wrote: post #39

What really worries me is that I keep hearing "cooling is cheap and easy in space!" in a lot of these conversations, and it couldn't be farther from the truth. Cooling is _really_ hard and can't use efficient (i.e. advection-based air or water cooling) approaches and are limited to dramatically less efficient radiative cooling. It doesn't matter that space is cold because cooling is damned hard in a vacuum. The artic…

"space is cold" I've always enjoyed thinking about this. Temperature is a characteristic of matter. There is vanishingly little matter in space. Due to that, one could perhaps say that space, in a way of looking at it, has no temperature. This helps give some insight into what you mention of the difficulties in dealing with heat in space - radiative cooling is all you get. I once read that, while the image we have in…

> Temperature is a characteristic of matter. There is vanishingly little matter in space. Due to that, one could perhaps say that space, in a way of looking at it, has no temperature.

Temperature: NaN °C

Re: Economics of Orbital vs. Terrestrial Data Centers

#214

Post by bee_rider »

zeofig wrote: post #139
PeterHolzwarth wrote: post #132

Earlier quoted context omitted.

"space is cold" I've always enjoyed thinking about this. Temperature is a characteristic of matter. There is vanishingly little matter in space. Due to that, one could perhaps say that space, in a way of looking at it, has no temperature. This helps give some insight into what you mention of the difficulties in dealing with heat in space - radiative cooling is all you get. I once read that, while the image we have in…

A perfect vacuum might have no temperature, but space is not a perfect vacuum, and has a well-defined temperature. More insight would be found in thinking about what temperature precisely means, and the difference between it and heat capacity.

I think your second sentence is what they were referencing. Space has a temperature. But because the matter is so sparse and there’s so little thermal mass to carry heat around as a result, we don’t have an intuitive grasp on what the temperature numbers mean.

Re: Economics of Orbital vs. Terrestrial Data Centers

#215

Post by titzer »

cdf wrote: post #154

Does anybody actually work with H100s and the like? Their failure rate is so high, I dont understand why anybody will even consider it feasible to put the machines in orbit or even the sea. By my ballpark estimate, if you have 800 H100s, after 6 months, about 100 would be overheating or throttling, and a few will disappear and one or two will crash the machine with load.

> Does anybody actually work with H100s and the like?

They don't. The expectation the cloud develops in people is that magic computers just appear. They're living at a virtualized layer where all the nitty gritty of real machines going down and needing to be serviced all the time is handled by unseen minions (sorry SREs and DC staff) and cluster management and provisioning software.

The reality is that datacenters in space is mind-boggling stupid, just from the infeasibility of maintenance alone.

Re: Economics of Orbital vs. Terrestrial Data Centers

#216

Post by kibwen »

This is AI slop in a pretty dress. It's fascinating that space-based datacenters are such a catastrophically bad investment that even limp apologia like this can, at best, argue that maybe it's not quite as bad as you think, as long as you still manage to ignore half the costs because you're a loser who delegated your thinking to a chatbot.

Re: Economics of Orbital vs. Terrestrial Data Centers

#217

Post by oivey »

jcattle wrote: post #168
davedx wrote: post #162

Earlier quoted context omitted.

Yeah that's just flat out wrong then: you can't use the solar array as a radiator.

Of course you can. You can use everything as a radiator. Unless you have something which is literally 0 Kelvin everything radiates. See here for all the great ways of getting rid of thermal energy in space: https://www.nasa.gov/smallsat-institute/sst-soa/thermal-cont...

You can rivet people onto the outside of the ISS to radiate heat, too, but it may be detrimental to the overall system.

Re: Economics of Orbital vs. Terrestrial Data Centers

#220

Post by terminalshort »

uplifter wrote: post #160
terminalshort wrote: post #76

Earlier quoted context omitted.

But space isn't actually cold, or at least not space near Earth. It's about 10 C. And that's only about a 10 C less than room temperature, so a human habitable structure in near earth space won't radiate very much heat. But heat radiated is O(Tobject^4 - Tbackground^4), and a computer can operate up to around 90C (I think) so that is actually a very big difference here. Back of the envelope, a data center at 90C will…

It's actually only about 3x. As you intimated, the radiated heat Energy output of an object is described by the Stefan-Boltzmann Law, which is E = [Object Temp ]^4 * [Stefan-Boltzmann Constant] However, Temp must be in units of an absolute temperature scale, typically Kelvin. So the relative heat output of a 90C vs 20C objects will be (translating to K): 383^4 / 293^4 = 2.919x Plugging in the constant (5.67 * 10^-8 W…

You forgot about the background. The background temp at Earths distance from the sun is around 283K. Room temperature is around 293K, and a computer can operate at 363K. So for an object at 283K the radiation will be (293^4 - 283^4) = , and a computer will be (363^4 - 283^4)

(293^4 - 283^4) = 9.55e8

(363^4 - 283^4) = 1.09e10

So about 10x

I have no problem with your other numbers which I left out as I was just making a very rough estimate.

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