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How do you cool a data center in a vacuum?


How is Starlink cooled? How is ISS cooled? They all use radiators, which work in a vacuum by--wait for it--radiating infrared into space.

Orbital data centers do not defy the laws of physics. TBD whether they are economical relative to terrestrial data centers, but please don't succumb to misinformation.


For some perspective, the entire heat rejection system on the ISS at peak can do a little less than one rack of dense AI compute power.

All of that plumbing, all of that area, all that stuff to put in orbit just to cool one rack of compute equipment.

How much stuff do we need to put up there for each rack? The External Active Thermal Control System on the ISS is ~20,000lbs, about 10 tons. How many racks are in a single datacenter? The Colossus is allegedly ~1,500 compute racks, ignoring other equipment. So that's like 15,000 tons for just the cooling equipment if its like the ISS. At SpaceX's current public launch costs (which makes a profit for them, so not base costs) to launch that much stuff is somewhere around $40B. Just the launch cost for the cooling equipment alone for just one datacenter building worth of pure compute capacity, that isn't even that big compared to what companies are talking about building.

All of that is very rough back of the napkin math. I don't expect that to be the actual numbers at all, but I'd imagine somewhere in that neighborhood unless they've got something really radical up their sleeve.

They better have a much better way to cool these things than what the ISS is doing.


Current SpaceX design is 75 kW of computer per ton, including solar panels, radiators, everything: https://www.spacex.com/spacexai/starmind

That's ~13 tons per megawatt, or 1,330 tons for 100 MWs. That's 13 launches of Starship (at $10 million per launch, or $130 million). Of course, that's probably 600 individual satellites, at maybe $5 million per, so we're at ~$3 billion to deploy 100 MW to space.

You can sell 100 MW of compute for $3-4 billion per year, so SpaceX would make their money back in 1 year.


> Current SpaceX design is 75 kW of computer per ton, including solar panels, radiators, everything

Anyone can make a website. Let's see them actually make it and put it in orbit.

According to another Musk website we'd be riding hyperloops and drive through solo tunnels under our cities and we'd all own our own autonomous cab companies back in 2016.

Another website said we'd be able to buy a Cybertruck for $40k and the three-motor variety for $70k.


It's amazing. These guys see a conman with a history of lies and failures - hyperloop, cybertruck, full self driving teslas, robotaxi fleets - and somehow all their critical thinking goes out the window.

Let's just trust him this time guys, he's definitely going to nail it.


I mean to be fair to him, he's built an innovative car company, a pretty rocking space company, and now controls access to basically all government officials and politicians (X).

He's definitely super successful and not a complete conman.

Then again, he's kinda a conman because he's promised absolutely absurd things that haven't happened.

He's a complicated character, 13 years ago I thought he was great, and now I mostly think he's a douchebag. insert complicated shrug emoji.


Nah.

Tesla - Martin Eberhard and Marc Tarpenning

SpaceX - Tom Mueller

PayPal - Max Levchin

Musk is a spoiled nepo-baby with rich parents and daddy issues who bought his way to success. His only skill is spewing attractive lies, and he does that quite well. In everything else he is - at best - mediocre.


Okay, so you admit that they are possible, but they just might cost more than expected?

That's actually a reasonable prediction.


I've got little doubt they can put some kind of compute in orbit. Shit, load a tiny model on the next batch of Starlink birds, boom, space AI datacenter done. Will it be anywhere close to the numbers they're claiming? Will it actually be useful and competitive to terrestrial datacenters? I guess we'll see.

Did the Cybertruck have 500mi of range? Was there a $40k model at launch?


I think we're in full agreement.

I don't know if orbital datacenters will work out--it depends on the price of launch and the price of tokens in 2030. Maybe they'll try it and abandon it. We'll see.

But my point is that if it does work, if they can be cheaper than terrestrial tokens, then SpaceX can dominate the market because no one else is even close to being able to deploy orbital compute.

And if it doesn't work, SpaceX will be fine because they are printing money with Starlink.

Cybertruck is a good example--they never hit their sales targets, but Tesla is fine because they are making money on Model Y and they are investing in Robotaxi (which has a bigger potential than Cybertruck anyway). And if Robotaxi doesn't work out, they will pivot to a cheaper model or something.

SpaceX will be fine, not because orbital datacenters are guaranteed, but because they keep betting on things that may or may not work, but if they do work, they make a ton of money.


Many things are possible while still being very stupid.


They do and you’re the one spreading misinformation… the amount of energy you need to radiate for inference GPUs is enormous compared to any computer currently used in space. Energy dissipation by radiating is literally the least effective method and would require insanely large radiators just to be effective on paper. You also need to mitigate bit flips, meaning you throw away around 2/3 of your compute capacity.

And that’s just the most basic things, before taking in account ALL the other problems you face doing compute in space someone with expertise in the domain could mention.

Datacenters in space is a grift that won’t happen in any meaningful capacity and can be debunked by a 15y old who followed their physics courses


You've listed:

1. Radiating heat needs large radiators 2. Bit flips require extra compute capacity

Neither of those violate the laws of physics. As I said, they may not work economically, but that depends on a large number of unknowns, including the cost per ton to orbit and the cost per GW of new power capacity on Earth in 2030. If you have a time machine and know those numbers, then can I please borrow your time machine?

Moreover, when you say, "ALL the other problems ... someone with expertise in the domain could mention," you're saying either:

A) SpaceX engineers do not have expertise in this domain. B) SpaceX engineers are hiding all the problems that they know about.

B is basically a conspiracy theory. It is one YouTube video away from saying the moon landing was a hoax.

A is just delusional.


Or potentially:

C) SpaceX engineers enjoy their cushy salary funded by a guy who won't take "that doesn't make sense" for an answer to work on rockets and neat technology, even if it may never really work out.


Do you know anyone that works at SpaceX? They get paid well, yes, but my friends who work there say they work you really hard. The bet that's being made is that there will be advancements in materials science that make data centers in space viable. If you hypothesize that there's a way to cool things down in space if you just had the right material to do it, it makes sense. Starlink satellites are already compute plus solar panels. Just scale it up! Or course "just" is doing a lot of work here, but that's the theory.


> Starlink satellites are already compute plus solar panels. Just scale it up!

Starlink satellites use probably less than 1/100th the power budget of even these earlier supposed plans. They don't use much power at all in comparison. They're also big flat pancake for their body, as they want to have a good bit of area for their antenna array. So the other side can just focus on cooling very close to the actual compute parts. It's a radically different set of engineering requirements.

For something line the AI1, you're looking at a few million in launch costs for the mass of the cooling system alone and that's assuming they get Starship flying around their projected costs. What's the install cost per rack or cooling equipment on the ground? Even say I'm overshooting it 100%, those numbers still don't sound very good!


That's a different conspiracy theory, for which there is also no evidence.


> Neither of those violate the laws of physics. As I said, they may not work economically, but that depends on a large number of unknowns, including the cost per ton to orbit and the cost per GW of new power capacity on Earth in 2030. If you have a time machine and know those numbers, then can I please borrow your time machine?

Alphabet researchers have estimated future launch costs based on learning curves; they estimate that after Starship has launched 370,000 tons to LEO, they will have figured out how to reduce launch costs by enough to make space data centres viable.

They optimistically suggested this might take ten years.

Given the rate of development of Starship as a launch system, I suspect that Musk will reach federal pension age before this is viable.


So between the giant radiator per GPU and the diminished compute capacity, how much mass are we shooting up exactly? This just seems utterly infeasible.

You're missing C) SpaceX engineers know it's a bad idea, but can't say anything because it's the tyrant manchild's latest obsession, technology constraints be damned.

Remember the vision-only FSD? How's that coming along?


> because it's the tyrant manchild's latest obsession, technology constraints be damned.

Imho, there's only one reason that justifies Musk's space-based compute obsession: sovereignty.

Specifically, avoiding terrestrial country's.

This isn't about AI in space (though I'm sure dumb investors love that), it's about uncensorable Twitter in space, beamed down to Starlink terminals.

Which would be one of the few things you'd care about, if you were one of the richest people on the planet... but still subject to those damned nations and their meddling laws.


That's exactly it. Musk sees space as extraterritorial, which in the true sense of the word of course it absolutely is. But all those bits have to go to ground somewhere. As long as that somewhere is friendly no problem. That can change.


If Elon wants to offer space-twitter, he still needs to abide by the rules of the country he is offering the service to.

Unless he's offering it to the aliens orbiting his magical lawless space data centers.


Does he?

Short of countrywide ku-band jamming and/or drone-based RDF at scale, what's the country going to do?

It was one thing when you needed a C-band dish to receive, but much harder to deal with a 1-2 ft dish.


They could, but this would be unnecessary.

I suspect that simply blocking payments from locals to Musk may be enough, considering how Musk reacted when advertisers voted with their wallets to leave X.

But nations have other tools, as Brazil showed when a judge ordered a freeze on Starlink assets because X didn't have reachable assets within Brazil to be frozen.


They could shoot down those data centers for example.


Unreasonably expensive for pLEO volumes (same problem/advantage militaries are looking at) + collateral damage to other nations satellites

The only nations who would realistically have that as an option would have a robust scaled ASAT capability (maybe US and China) but no pLEO satellites (rules out US and China).


Currently, yes.

However, based on the rapid development of high-powered lasers, I think we're not too far from it being very cheap. Mostly an optics (adaptive and aperture) problem.

This also means it's likely to get deniable very quickly.


Yeah, I think Musk loves the idea of sticking his CSAM generators in space, where he thinks they will be beyond the reach of terrestrial laws and morals.




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