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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

#131

Post by Nevermark »

pavon wrote: post #70
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…

Cooling isn't anymore difficult than power generation. For example, on the ISS solar panels generate up to 75 W/m², while the EATCS radiators can dissipate about 150 W/m². Solar panels have improved more than cooling technology since ISS was deployed, but the two are still on the same order of magnitude.

So just 13.3 million sq. meters of solar panels, and 6.67 million sq. meters of cooling panels for 1 GW.

Or a 3.651 km squared and 2.581 km squared butterfly sattelite.

I don't think your cooling area measures account for the complications introduced by scale.

Heat dissipation isn't going to efficiently work its way across surfaces at that scale passively. Dissipation will scale very sub-linearly, so we need much more area, and there will need to be active fluid exchangers operating at speed spanning kilometers of real estate, to get dissipation/area anywhere back near linear/area again.

Liquid cooling and pumps, unlike solar, are meaningfully talked about in terms of volume. The cascade of volume, mass, complexity and increased power up-scaling flows back to infernal launch volume logistics. Many more ships and launches.

Cooling is going to be orders of magnitude more trouble than power.

How are these ideas getting any respect?

I could see this at lunar poles. Solar panels in permanent sunlight, with compute in direct surface contact or cover, in permanent deep cold shadow. Cooling becomes an afterthought. Passive liquid filled cooling mats, with surface magnifying fins, embedded in icy regolith, angled for passive heat-gradient fluid cycling. Or drill two adjacent holes, for a simple deep cooling loop. Very little support structure. No orbital mechanics or right-of-way maneuvers to negotiate. Scales up with local proximity. A single expansion/upgrade/repair trip can service an entire growing operation at one time, in a comfortable stable g-field.

Re: Economics of Orbital vs. Terrestrial Data Centers

#132

Post by PeterHolzwarth »

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 our mind of being ejected out of an airlock from a space station in orbit around Earth results in instant ice-cube, the reality is that, due to our distance from the sun, that situation - ignoring the lack of oxygen etc that would kill you - is such that we would in fact die from heat exhaustion: our bodies would be unable to radiate enough heat vs what we would receive from the sun.

In contrast, were one to experience the same unceremonious orbital defenestration around Mars, the distance from the sun is sufficient that we would die from hypothermia (ceteris paribus, of course).

Re: Economics of Orbital vs. Terrestrial Data Centers

#133

Post by kragen »

klysm wrote: post #113
kragen wrote: post #85

Earlier quoted context omitted.

At Satellogic, we famously flew mostly just regular cellphone parts on orbit. We did have higher rates of various kinds of failures than is usual on Earth, but hardware failure can generally be masked by software redundancy.

RAM corruption is not cheap to protect against

You need parity, which is cheap, or lockstep duplexing, which isn't. Or, you know, sometimes you can just restart malfunctioning processes and repair corrupted filesystems while you run the failed tasks again on another node.

Re: Economics of Orbital vs. Terrestrial Data Centers

#134

Post by rswail »

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?

Re: Economics of Orbital vs. Terrestrial Data Centers

#135

Post by eldenring »

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.

Re: Economics of Orbital vs. Terrestrial Data Centers

#136

Post by eldenring »

yabones wrote: post #51
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…

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.

Re: Economics of Orbital vs. Terrestrial Data Centers

#137

Post by eldenring »

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…

Google did a study with their TPU v6

> For ML accelerators to be effective in space, they must withstand the environment of low-Earth orbit. We tested Trillium, Google’s v6e Cloud TPU, in a 67MeV proton beam to test for impact from total ionizing dose (TID) and single event effects (SEEs). > > The results were promising. While the High Bandwidth Memory (HBM) subsystems were the most sensitive component, they only began showing irregularities after a cumulative dose of 2 krad(Si) — nearly three times the expected (shielded) five year mission dose of 750 rad(Si). No hard failures were attributable to TID up to the maximum tested dose of 15 krad(Si) on a single chip, indicating that Trillium TPUs are surprisingly radiation-hard for space applications.

Re: Economics of Orbital vs. Terrestrial Data Centers

#138

Post by deddy »

waterTanuki wrote: post #48

I'm not really interested in the problems that can come with orbital compute. We've seen them listed ad nauseam. Have we seen any benefits to orbital computing by launching a cluster of raspberry pis to LEO? Surely this isn't an impossible task to test out on a smaller scale?

There isn’t really much benefit to having compute on orbit unless you’re working on VERY specific applications that have such tight latency requirements where you need to process the data immediately as it comes out of the sensor. In which case you just implement the algorithms in ASICs or FPGAs anyways.

There have been NVIDIA Jetsons or better on orbit since at least 2021 and that had no meaningful impact on any actual meaningful compute workloads beyond proof of concept demos.

Re: Economics of Orbital vs. Terrestrial Data Centers

#139

Post by zeofig »

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…

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.
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