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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

#151

Post by ithkuil »

terminalshort wrote: post #76
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…

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…

Pressure matters

Re: Economics of Orbital vs. Terrestrial Data Centers

#152

Post by [deleted] »

eldenring wrote: post #136
yabones wrote: post #51

Earlier quoted context omitted.

Yeah, I don't see a way to get around the fact that space is a fabulous insulator. That's precisely how expensive insulated drink containers work so well. If it was just about cooling and power availability, you'd think people would be running giant solar+compute barges in international waters, but nobody is doing that. Even the "seasteading" guys from last decade. These proposals, if serious, are just to avoid plann…

You should read the linked article, they talk about it there. You radiate the heat into space which takes less surface area than the solar panels and you can just have them back to back. In general I don't understand this line of thinking. This would be such a basic problem to miss, so my first instinct would be to just look up what solution other people propose. It is very easy to find this online.

[deleted]

Re: Economics of Orbital vs. Terrestrial Data Centers

#153

Post by lifeisstillgood »

I am struggling with a why for this (other than “huh cool, that will get investors”). All the jurisdiction and regulation arguments and the “we could get the costs down” seem to meet the objection of “for the same investment we could do just as well or better on the ground”.

The one that does not is the physics of the whole thing. I struggle to work out how exactly but being slightly time dilated compared to the ground does not seem like a win, but being able to gather data from opposite sides of the planet slightly faster than cables does seem like a potential win. Most stock exchanges make a significant chunk of their revenues renting out data space, so it seems a possibility.

But either way it seems very niche.

Re: Economics of Orbital vs. Terrestrial Data Centers

#154

Post by cdf »

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.

Re: Economics of Orbital vs. Terrestrial Data Centers

#155

Post by westpfelia »

simianwords wrote: post #148
zkmon wrote: post #144

Economics for who? The builder of the data center and plethora of all contractors and sub-contractors would see great economics though. Even the sponsor/owner of the data center might see economics work out, if you consider the reputational gain (why did we land on Moon? what's the economics?), experience gained and considering the burn of someone else's money. The money of mega companies that go into this kind of "m…

Who's money is it?

Tax payers

Re: Economics of Orbital vs. Terrestrial Data Centers

#156

Post by terminalshort »

modeless wrote: post #114
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…

The temperature that you raise to the fourth power is not Celsius, it's Kelvin. Otherwise things at -200 C would radiate more heat than things at 100 C. Also the temperature of space is ~3 K (cosmic microwave background), not 10 C.

Yeah, if you forget about the giant fucking star nearby

Re: Economics of Orbital vs. Terrestrial Data Centers

#157

Post by mkesper »

eldenring wrote: post #136
yabones wrote: post #51

Earlier quoted context omitted.

Yeah, I don't see a way to get around the fact that space is a fabulous insulator. That's precisely how expensive insulated drink containers work so well. If it was just about cooling and power availability, you'd think people would be running giant solar+compute barges in international waters, but nobody is doing that. Even the "seasteading" guys from last decade. These proposals, if serious, are just to avoid plann…

You should read the linked article, they talk about it there. You radiate the heat into space which takes less surface area than the solar panels and you can just have them back to back. In general I don't understand this line of thinking. This would be such a basic problem to miss, so my first instinct would be to just look up what solution other people propose. It is very easy to find this online.

Please have a look at how real stations like ISS handle the problem and do not trust in should-work science fiction. It's hard. https://en.wikipedia.org/wiki/International_Space_Station#Po...

Re: Economics of Orbital vs. Terrestrial Data Centers

#158

Post by fch42 »

ikiris wrote: post #83
echoangle wrote: post #11

Earlier quoted context omitted.

What’s software that would benefit from running in space? The only thing I can imagine is processing of data generated in space so you need less downlink or can reduce latency, everything else can be calculated wherever you want, no?

I think the point the original guy is hand wavingly getting at is the point of something like this is to avoid the possibility of say a FBI raid or Nuremburgish trials for a vast AI surveillance processing facility hub for other down looking satellites if they were to lose their newly acquired power, or similar technocratic ramblings / ideas like it would survive the end of society. Its like that scene at the end of…

Impossible to raid ?

It's definitely much easier and much much cheaper to send a single rocket there blowing the assembled rather large target into still sizeable chucks of orbital debris than it is to deploy and assemble the thing there in the first place. And there are a few terrestrial actors rather capable of this. More than there are who could make it happen under whatever optimistic assumptions anyway.

In itself, a structure of this size in orbit is an efficient catcher of micrometeorites and orbital debris. Over "non-eternal" timeframes you don't even need a bad actor with good rockets.

Nevermind that in such a case, the eventual fate of these sizeable chunks of orbital debris is to become rods of god ... just without particular steerability.

It'd be a sight.

Re: Economics of Orbital vs. Terrestrial Data Centers

#159

Post by rswail »

eldenring wrote: post #135
rswail wrote: post #134

Aside from the economics, the question is why do it in orbit vs on land (or sea)? What are the regulatory/legal gains? Lack of jurisdiction means open slather? What are the national security gains? Redundancy and resiliency by each satellite being a "micro-compute" connected by high speed laser links? So more resilient to attack? Why do it at all?

I think the main draw is its elegance. You have very efficient power from the sun, put that directly into your compute, radiate it out. Energy is ~free, no heavy infrastructure required, just a closed circuit for computing.

Elegance compared to a PV/Storage facility built next door to a data centre?

It doesn't make sense right now, and won't for at least 5-10 years.

By which time, this current round of hype will have burned up ~$1T if it doesn't fall apart from the current internal contradictions and lack of market/customers/uses.

We're still on the uphill ride of the Gartner hype cycle, not even at the "Peak of Inflated Expectations" yet.

Re: Economics of Orbital vs. Terrestrial Data Centers

#160

Post by uplifter »

terminalshort wrote: post #76
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…

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/(m^2*K^4)) The actual values for heat radiation energy output for objects at 90C and 20C objects is 1220 W/m^2 and 417 W/m^2

The incidence of solar flux must also be taken into account, and satellites at LEO and not in the shade will have one side bathing in 1361 W/m^2 of sunlight, which will be absorbed by the satellite with some fractional efficiency -- the article estimates 0.92 -- and that will also need to be dissipated.

The computer's waste heat needs to be shed, for reference[0] a G200 generates up to 700W, but the computer is presumably powered by the incident solar radiation hitting the satellite, so we don't need to add its energy separately, we can just model the satellite as needing to shed 1361 W/m^2 * 0.92 = 1252 W/m^2 for each square meter of its surface facing the sun.

We've already established that objects at 20C and 90C only radiate 1220 W/m^2 and 417 W/m^2, respectively, so to radiate 1252 W per square meter coming in from the sun facing side we'll need 1252/1220 = 1.026 times that area of shaded radiator maintained at a uniform 90C. If we wanted the radiator to run cooler, at 20C, we'd need 2.919x as much as at 90C, or 3.078 square meters of shaded radiator for every square meter of sun facing material.

[0] Nvidia G200 specifications: https://www.nvidia.com/en-us/data-center/h200/

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