You can't launch from the US without the federal government giving you permission. And SpaceX does not have (nor are they planning) any launch pads outside the US. [And because of ITAR, I'm not even sure they'd be allowed to build one.]
However, I do think avoiding local control (state/city permits) is a reason for this.
As long as the company has a HQ and owners that care about their quality of life, they don’t really gain any extra safety by moving their hardware to space compared to keeping it where they are based.
What did he do that others considered unthinkable? This is not a rhetorical question. Please give me a concrete example, with sources proving experts in the field thought the idea was "unthinkable".
Robofactories? The idea was roundly mocked and completely failed, costing many millions of dollars, leading to manufacturing defects on thousands of vehicles, and delaying Model 3 mass production.
Hyperloops? The idea was roundly mocked and completely failed. Somehow it attracted hundreds of millions of dollars of investment. (There's suspicion Musk proposed the idea cynically to distract from rail.)
Robotaxis? Waymo started in 2004 and is, today, ahead of Tesla.
Electric cars? Again, demonstrated long before Musk got involved. The frustration amongst environmentalists at the time was that the technology and demand both existed but manufacturers weren't interested in making them.
(Before you claim the EV1 was so obscure as to not count, GM built about 1,000 of them, vs 2500 Roadsters. If it doesn't count, neither does the Roadster.)
Reusable launch vehicles? Work started on them in the '70s at the latest and they were the American workhorse by the '80s. The basic design SpaceX settled on was demonstrated in the '90s.
Satellite internet? Obviously old hat, so let's restrict ourselves to LEO constellations. These were proposed in the Star Wars project and were built by several companies in the 1990s. Starlink is much larger and more modern, but the basic idea was proven.
This narrative that Musk has done things other people considered impossible is simply untrue. Everywhere he's found success, other people had already demonstrated the basic idea. Everywhere the consensus was that he had lost the plot, he failed completely. Impressive work should not require exaggeration.
I will have to grant that this was previously unthinkable:
If data centers in space end up being economically viable, then I don't see how anyone can catch SpaceX. They are ten years ahead in both launch capability and satellite manufacturing.
It's likely cheaper to put them in Antartica instead of space, but the sane and rational as been thoroughly abandoned. (In the case of rationality, that is in the process of being killed and replaced).
Its only cheaper to build them on the ground if you aren't factoring security concerns. No insurgents in space. Not every application needs this hardening, but you can imagine there are many applications that do.
Chinese rockets companies are evolving at insane pace, including RLVs. A couple of big milestones have been achieved this year alone, like first stage landing.
Also Stoke Space, YC startup, is interesting. They could even beat SpaceX to fully reusable if SpaceX find the refuel it and send it up again thing challenging.
They have a different approach - rather than a ceramic heat shield they have a metal shield to be cooled by the liquid H2+O2 fuel. https://youtu.be/3V6lfs7xFJM?t=191
I certainly hope ‘economically viable’ includes properly priced externalities for e.g. side effects of burning hundreds and hundreds of tonnes of aluminium and other materials in the high atmosphere.
No western company, no. That's why I can only hope SpaceX can get thru more red tape faster, and future administrations don't try to slow them down.
Even while current administration is kind of positive towards them, they are still even now just having to wait for no good reason for a FAA go-ahead. These kinds of stalls don't really exist in China.
I guess we're redefining "the scientific community", cutting out those who were wrong each time? Do you consider the French Space Agency (CNES), former NASA Administrator Charlie Bolden, the European Space Agency to be part of the scientific community? I still vividly remember one interview where Elon started to tear up because Neil Armstrong and Gene Cernan publicly denied the feasibility of SpaceX's mission.
"Scientists" being detractors and everyone going online to comment about how something is impossible while the people doing the thing just do it then all the detractors quietly shrug it off until the next time is so consistent it feels like Groundhog Day. I'd really like to learn about why so many people get off by saying something that other people are working on is impossible.
Could you share us a proof of concept or anything that might be a solution for the heat dissipation in space, at scale ?
You see, this is the difference between bullshit and not. I can claim "we'll do timetravel soon !", but unless I share some "things" (whatever they are) that might sustain that affirmation, this is just bullshit
Does it mean that no solution exists ? No. Just that today none are known (as far as I can tell).
This is the problem with European thinking, you have this built-in mindset that you think you're going to be so cool with a gotcha because I can't provide a "proof of concept" or solution right now for a problem that OTHER PEOPLE are working on. Sheesh, just get off your high horse and admit that other people that are smarter and harder working than you are going to solve problems you can't manage.
Your desire to call out bullshit is stronger than your ability to GSD.
Exactly! There's a quote I like to remember: "If I had listened to all the negativity and putative experts who expended so much energy telling me 'this is impossible, it will never work' I would never have gotten to where I am today." - Liz Holmes
People are working on problems I cannot manage (who could have known) and they cannot say anything about that but we have to trust them to bring results out of thin air ? Is this politics .. ?
If your personal accusations can be boiled down to : "shame ! you are not gullible!", then please know that, here in France, not being gullible is a compliment.
For real. It's an enormous problem solved only with 1) sheer scale, and 2) Science Fiction.
Both of those are expensive as hell, by the way.
Cooling via radiation follows Stefan–Boltzmann: P = εσAT⁴. Let's assume a good surface (emissivity ~0.9) at 300 K (27 °C) at 400 W per square meter per side. A flat panel radiating from both faces into deep space gets 800 W/m, not including the losses from, say, the Sun, or from IR coming off the Earth. Now, input power. Sunlight in orbit ~1,360 W/m², assume ~22% cell efficiency, we got 300 W/m². So each 1 MW compute, 3,300 m² of solar panel and minimum 1,200–1,500 m² of radiator.
In case ya didn't know - 1 MW is tiny from a present-day-datacenter perspective. It's like 8 racks. So we're talking orbital megastructures here, square kilometers, and this is with all the best case assumptions, and magic radiator panels that never see the sun, or the earth, or the moon.
This is just the basic numbers here, by the way. There's a garbage truck full of other unsolvable problems if you poke your head in there.
Aside from the "Avoid Regulations" aspect, and the "Everything That Burns Deorbiting is Depreciation" aka "The Starlink Trick", I'm not sure what the hell the draw is.
the other is that you could make tiny datacenters and flood the sky with them. in effect, not datacenters at all, but some kind of dataswarm coordinating at literal lightspeed via lasers.
they'd still be wildly expensive to deploy, and probably litter the orbit zone with fast-moving debris.
Cooling in space is hard but not impossible - while current (IMHO stupid without advanced in space infra) space data center projects work with a couple MW, many advanced space propulsion concepts might have to reject hundreds of MW if not a couple GW.
As for space data centers - I think the main issue is the complete lack of in space infrastructure for resource mining, processing and manufacturing & maintenance. It is kinda like building your first practical steam locomotive & the deciding to build directly an airliner. No suitable materils, experience, work force, material sources, etc.
We eventually went from locomotives to airliner, in an incremental manner & expanding the supporting infrastructure to support the ever more ambitious projects.
According to Wikipedia this reduces weight and not the required area. Also AI said the same thing, but I can't trust in it this blindly. So, how smaller would be the required surface area?
It might be eventually doable, as an experiment or as a flex, sure. But it's never going to come close to being cost-reasonable versus the equivalent infrastructure here on earth.
The security advantages are enormous since access to space is so tightly restricted and controlled, compared to the access potential of a land based data center. Only risk in space is maybe we start WWIII with china and the US directly trading blows. On the ground, any insurgent group can disable your infrastructure. Nothing is truly safe on the surface of the earth. Anyone can strap a bomb on a drone now. See examples from the currently active wars.
What? No, exactly the opposite. It's very easy to jam radio signals and much harder to cut wires. There's a reason the drones on the front lines in Ukraine are dragging fibre optic lines these days.
There's probably so many ways to get around that with space based technology. I can quickly imagine several methods. It depends on what the system is for which might be a good method to use.
Method 1: same as how u2 planes dumped their data: air drop physical media containing data and catch it in the air.
Method 2: laser based emission to specific detectors.
Method 3: baseball style communication: station is under observation and manipulates in some way to serve as a signalling language.
Method 4: numbers station
Method 5: bill yourself as an isp and have some coded syntax that can be supplied in plain sight with the rest of isp traffic.
Method 1: Sure datacenters with latency measured in several hours sure are useful, and can also be intercepted
Method 2: Can be jammed by drone with laserpointer.
Method 3: Let me just transfer gigabytes of data via physical signalling
Method 4: Can still be jammed
Method 5: Can in fact still be jammed?
If you’re receiving data optically from a space based laser, yes you are quite vulnerable to your detector being jammed by a much closer laser that doesn’t have to be nearly as powerful to add noise to the signal.
Why do you think GPS is so easy to spoof?
Actually I just googled (clauded?) to learn more about space lasers and found a paper describing interrupting quantum key distribution (tamper evident but not jam proof!) with a 1kw laser on the ground pointed at the satellite! So it really does not take many photons to fuck up an encrypted signal.
“ Vulnerability of Satellite Quantum Key Distribution to Disruption from Ground-Based Lasers”
You're going to have to be very close, basically in the direct line between ground station and satellite (which would be airspace that's easily guarded), have a lot of battery/cooling systems to run that laser on what would essentially be a one-way-trip all for disrupting comms for maybe a few minutes tops? And that's just for one ground station, where the blue team can just set another one up a few meters away and be safe. Honestly, you'd probably be better off dumping glitter or water in the sky than trying to actively jam laser comms.
Method 1 runs into the problem of how to replace that media. The DC is in space so it's not like with U2 planes where they landed. Also, I think you mean the keyhole satellites and not U2 planes, since a plane lands at a secure site and can offload media then.
It costs at least 50x more to put a GPU in space than it does on Earth. For that price you can have dozens more capacity in bunkers, under the sea, or on remote islands. Do you think your insurgents are going to get all two dozen? They could travel to the far corners of the earth, destroying 22 of them, and you'd still be ahead. Further, I wouldn't be surprised if a satellite with such a monstrous solar and radiator footprint wouldn't be susceptible to a laser based attack from the ground; either frying it or pushing it into an unstable orbit by vaporizing a few bits.
It costs much more than 50 times because there are no GPUs in space yet. Google is only planning to have some sort of space data centers mid 2030s, if everything works out. A big if, but if they don't start now then we'll never know.
What was it the 27th law that says radiating heat in to space does not work? I'm skeptical of the whole thing too, but it's not an impossible engineering challenge, just an expensive one.
The United States is relatively expensive because the world's cash reserves are priced in USD, and a large fraction of the eastern Eurasian continent lives inside a work camp.
The old Chicago School boogeymen of unions, regulations, and red tape are effectors, but they're a pimple on the back of the world-mutating effects of USD Seigniorage.
I imagine we're going to be living through the reverse of this Seigniorage experiment quite soon.
Radiating 1MW at 500K (227C) with a 0.4MW heat pump takes about 200 m^2 flat sheet surface. Inputs - solar+nuclear for double fun. So - quite feasible.
Do we even _have_ semiconductors that can work at 220C? And if you're thinking about using some kind of refrigeration cycle, its efficiency is going to be bad.
1) The chips don't reach 220C. The 220C is the temperature at the hot end of the heat pump. The chips are on the cold end of the heat pump.
2) The International Space Station has used a dual-loop ammonia/water-based heat pump to cool the station temperatures. It's been in place for several decades. Heat pumps are a proven technology.
> The 220C is the temperature at the hot end of the heat pump. The chips are on the cold end of the heat pump.
If we want the heat pump's cold end at about 40–65°C, then for each 1MW of GPU heat, we need another 1MW of heat pump power. Now you need 2MW of solar power.
Good news is that the radiator at 227C (500K) can emit about 5× more heat per square meter than at 57C (330K)
Moves 1 MW of heat with 0.4 MW of work? I.e. 2.5 COP {coefficient of performance). That's insane, and I mean that in a good way. Could you dig me up a cite for that?
That's thumping the Carnot limit: [[T_cold / (T_hot − T_cold)]].
2.5, while rejecting at 500 K, cold side's at least 357 K (eeehhhhhhh 84 °C) . . . and that's an absolutely perfect Carnot machine. At 50% Carnot -- a pretty good heat pump, real world performance is 40-60 -- cold side's at 417 K (144 °C). 417k, feeding your GPU coolant loops.
I believe that's Carnot COP for a heat pump used for heat+. I used the refrigeration version, T_cold / (T_hot - T_cold), which I'm 80 percent sure is the right one here.
Depends on which heat you want
Heat adding to hot side: COP_heat = Q_hot / W = T_hot / (T_hot − T_cold).
Heat leaving the cold side: COP_cool = Q_cold / W = T_cold / (T_hot − T_cold).
Another one (more common in the day to day, for me at least): heat-engine efficiency, η = 1 - T_cold / T_hot. Cycle forward to make work from heat.
Great read, thanks for sharing. I am interested in reading some more about the other unsolvable problems that exist in this space, do you have any recommendations that you wouldn't mind pointing me at? It would be greatly appreciated, and thank you :)
> Now, input power. Sunlight in orbit ~1,360 W/m², assume ~22% cell efficiency, we got 300 W/m². So each 1 MW compute, 3,300 m² of solar panel and minimum 1,200–1,500 m² of radiator.
We need > 2x more solar panels than we need radiators. Doesn't this imply radiation isn't really the limiting factor here?
Getting the energy back from the solar panel is easy via copper cables. Getting the heat back out there to the radiators is a bit harder, you needed fluids and pumps and heat exchangers which have lots of moving parts and need maintenance.
Doing it in a cost and weight effective way is still a big deal, because if it's not within ~10x the cost of ground based data centers, not enough people will use it to justify building it.
Getting this all up into orbit it obviously the hard part, but if you're already building so much solar capacity the cooling actually doesn't seem unreasonable?
Surface area is a materials problem? Folded microstructure, atomic-scale textured surface or some other science-fiction solution could have square kilometers of surface area in a shoebox.
Imagine you have two blackbody radiators with the same bulk properties, except one has surface area shenanigans like aerogels. In the far field as a whole, it seems like both should radiate essentially the same regardless of the internal details. You can shape emissive direction, or improve efficiency of non-ideal materials, but even ideal materials don't fix the issues pointed out by the parent.
Right; it's only area exposed to the exterior that counts. As an upper limit, a physical object can't thermally radiate more power than a perfect blackbody spanning its convex hull.
(This follows because a physical object can't absorb more light than a perfect blackbody spanning its convex hull. A perfect blackbody by definition absorbs 100% of incident light, which is a hard upper bound. Any line incident on an object is also incident on its convex hull).
(Consider an isothermal object that emits more power than a blackbody in the shape of its hull at the same temperature. If you were to place that object in a closed system at thermal equilibrium, the interior of an insulated emissive sphere—combining assumptions, it would emit more power than it absorbs, in violation of the 2nd law. Starting from an isothermal system, the object would grow colder, and the enclosing container hotter).
No point in running them at room temperature. GPUs, etc. run fine at 95 C. If you run your cooling loop at 70 C instead, you get 70% more cooling compared to 27 C.
At any rate, 1 MW for a single satellite is fine. Just launch several thousand of those and you get to real numbers.
Also, there's no need to talk about "magic" radiators. You orient them so they're at a knife edge to both the Sun and Earth. This is not difficult (the Moon is irrelevant).
Please stop with this argument. This is one of the easiest problems to solve. Heat dissipation requires a radiator, which is just a dumb hunk of metal. All you need is a cheap way to launch mass to orbit, which is exactly what SpaceX (and Chinese companies) are doing.
The only valid argument against data centers in space is the economic cost. If the per megatoken price for space datacenters is higher than terrestrial, then this won't work.
But the price for terrestrial datacenters keeps going up and technology keeps dropping the price of space-based.
That is not a fake argument, but real physics. Yes, you can design out X kw can be dissipated by this much radiators, but that adds an enormous quantity of mass, more than the solar panels that feed it.
If you are trying to actually generate a profit, every extra kg of orbital launch costs puts you further in the red.
So is it a physics problem or an economic problem? Sounds to me like you are acknowledging that it is just an economic problem. If it cost $1/kg to get to orbit then this wouldn't be a problem, right? Just make a bigger radiator.
But if it's an economic argument, then you need to do the actual math. How big is the radiator? How low could the price to orbit go? How much can you charge per million tokens in 2030?
The reason this is a fake argument is because the validity depends on the math, and nobody advancing the "you can't cool stuff in space" argument is actually doing the math.
The economics is constrained by physics. AI in space is not viable if it costs $1000/kg to launch to space. Starship promises to cut that down to $100/kg (more if you believe Elon, but most don't), but that's still not competitive.
Sure, things would be different if the cost was $1/kg, but short of somebody building a space elevator that's just not going to happen.
I won't believe less than $100/kg until I see it. I agree with you on that.
But are you sure that $100/kg is not competitive? I don't remember all the math, but even their initial AI1 design[1] would throw a lot of profit, if you can sell at the price they offered to Anthropic.
I suspect the price of manufacturing the satellite, plus chips, is the dominating factor, not necessarily the launch costs.
It's a fundamental physics problem. You need to have huge radiating surfaces.
A 1GW datacenter with chips operating at 100C (which is probably doable) will need a radiator that has a surface of one square _kilometer_, and this is with all the favorable assumptions. Realistically you'll need about 2x of that.
If you want your DCs to be on a 1000km orbit (for reasonable ping times), you'll be able to _resolve_ these satellites with a naked eye!
Okay any argument about why space is uniquely challenging is going to revolve around physics. Sure it's not literally physically impossible, but we need to explain to people why this is different from shipping the GPUs to Ohio.
If you want math then https://andrewmccalip.com/space-datacenters exists. The numbers are grim for orbital DC. Even if you drag the launch cost slider all the way to $1/kg (by the way this is literally sci-fi, per ChatGPT air freight of semiconductors from Taiwan to Ohio costs $9/kg and ocean/train freight costs a bit under $1/kg for a reasonable shipment so good luck with $1/kg to LEO this century) it is still more than twice as expensive as terrestrial DCs.
But that calculator shows most of the cost is in the satellite. At $8 per watt (or about $2 million per satellite) the cost of orbital compute matches terrestrial.
That sounds absolutely possible. But in any event, we're now arguing a different thing.
The only thing I'm arguing is that cooling is a solved problem. I don't know if SpaceX will ever get the price down so that it is economical. But I'm convinced that there is no universe in which they hit their foreheads and say, "Oh no, we forgot about cooling!"
Note that this calculator is actually quite optimistic for orbital wrt. many things including cooling and effect on launch, as:
> No additional mass for liquid cooling loop infrastructure; likely needed but not included
> Thermal: only solar array area used as radiator; no dedicated radiator mass assumed
In hardware and mfg. solvable vs. solved is a big difference. And I too believe that SpaceX's engineers know about radiator panels. But the more cynical interpretation is that whatever the SpaceX engineers think about the technical merits, they are not being asked for that. They are just being asked for a pretext that justifies the xAI acquisition. Elon is also discussing lunar satellite factories that launch the satellites via railgun. Now, is this physically impossible? No, that isn't physically impossible either and I will seriously defend the physical possibility of this. It's not going to happen though.
And you could spend all the engineering costs on building some seriously efficient terrestrial DCs, but somehow all these analyses start with "assume that launch and satellite technology advances manyfold and terrestrial DCs stagnate or become less efficient, then if you squint the two numbers get kinda close."
Certainly launch has to advance a lot for this to make sense. SpaceX is betting big on Starship getting close to $100/kg. But does satellite tech have to advance much at all to make this work? SpaceX has already successfully deployed one megaconstellation into orbit and it's extremely profitable. Isn't this just another Starlink with bigger solar panels and radiators?
Yes it has to advance a lot. In a DC all your supporting equipment has returns to scale and can be repaired if it breaks. If a GPU breaks, a sysadmin walks over to the offending rack and swaps the card. In space all that equipment serves just a few cards (this is more like orbital server racks) and it has to work in space (so instead of using an ~infinite heat sink like the Earth, you use radiators etc). We still don't exactly know what effect radiation in LEO would have on stock GPUs - IIRC the experiments to determine this started after Elon went all in on orbital DCs. If anything breaks, you have a flying brick.
This is why that calculator, even under extremely optimistic assumptions for orbital, and even if you assume launch is zero, still cannot make it competitive with terrestrial.
Doesn't Starlink already handle all that though, just with networking racks instead of GPU racks? What's so unique about GPUs compared to other computer equipment, besides the power budget?
Commercial GPUs already fail a lot and that's before you put them in LEO. Starlink is doing something that can't be accomplished anywhere else than space. If you could somehow have ground stations that can give wireless internet to every corner of the Earth you would much rather do that. Again, this is all physically possible, but the question is whether it's wise, whether it's saving money or if it's just a giant Rube Goldberg machine. If you assume Starlink satellite $/W then even if launch is zero, it costs twice as much as terrestrial using assumptions charitable to orbital.
Fair point about the failure rates. I wonder what causes that, given that there are no moving parts... if it's temperature fluctuations, maybe you could just run the GPU at 100% all the time even when idling, given that power in orbit is free?
> If you assume Starlink satellite $/W
Why would you assume that, given that high power output is not a design goal of Starlink?
The calculator I've cited elsewhere uses https://chatgpt.com/share/69391474-4b24-8005-bb93-ebd4340c65.... The various starlink versions have approximately the same cost per watt across very different power levels. Much of the cost is going to be ~proportional to power - solar panels, heat rejection, power electronics, etc. Listen, if they could make it cheaper to deliver the same amount of power they would. Starlink is approximately all of SpaceX's business.
ETA: power is absolutely important for Starlink. SNR is very important for shannon capacity and satellite systems are often limited in this respect.
So ChatGPT decided to assume a constant $800/kg to estimate cost, and you're using that as evidence that cost/W doesn't decrease with scale?
Anyway, my point is that Starlink is not primarily designed to harvest as much solar power as possible the way data center sats are. I'm sure they're not making it inefficient on purpose, but what you're suggesting is like using the cost/W of a solar powered traffic camera to estimate the cost/W of a solar farm. Yes, they both use solar power, but they have entirely different design goals.
It's reasonable to 0th order to assume a ball of heat management and phased array antennae has a roughly constant cost per kg, yes. And as I said starlink absolutely wants to use as much power as they can, as communications from space are heavily limited by power.
Not only that - it would be totally insane to launch something heavy & at the same time fragile from earth (under a lot of vibrations & heavy g-loading).
This is all a weird speedrun or race. If something we should be working on setting up resource mining from the Moon & asteroids, materials processing on the Lunar surface & in orbit, simple manufacturing in space, etc.
Instead some people think we can jump straight to a computronium Dyson swarm. :P
Now you've moved the goal posts. It's no longer "you can't cool stuff in space"; now it's "we can't launch a 10-gW compute cluster by the end of the year."
You don't need to send a multi-gigawatt satellite to space. You just need to launch a few thousand 250 kW satellites. That's not against the laws of physics.
Never is a long time and you're relying on a bunch of unknowns like the cost of launch to orbit in 2030 and the future regulatory environment here on earth.
If you know all that out to 2040 then you must be a time traveler. Please try to fix our timeline rather than wasting time on HN.
> Please stop with this argument. This is one of the easiest problems to solve. Heat dissipation requires a radiator, which is just a dumb hunk of metal.
Convective radiation does not happen in space and this challenge is far more significant than your comment implies. Rather than "a dumb hunk of metal", radiators for spacecraft are often made of ceramics and carbon laminates with higher IR emissivity than convective radiators made of simple metals.
From the article you're commenting on:
> The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
ML Infrastructure comes with some pros (larger emissive footprint) and cons (exponentially larger TDP) compared to the concerns there, but if you aren't familiar with the challenges of heat dissipation in space, please give it a read.
There's also a pretty interesting pop-sci article on cooling the Webb telescope, since it needs to be especially cold for its purpose. Not directly related, but may give insight into both challenges and solutions as well as well. https://science.nasa.gov/mission/webb/science-overview/scien...
Emissivity is one factor, but it is dwarfed by the T^4 term. Sure, maybe if you use exotic materials you can get from 0.9 to 0.95 emissivity, but why bother? Just run the radiators a little hotter.
The equation is:
A ~ (1000 P) / (2 e k T^4)
Where
A is the radiator area in square meters
P is the power in kilowatts
e is emissivity (usually 0.9)
k is the constant 5.67e-8
P and T are the dominating factors. Don't worry about emissivity.
Emissivity is an important factor here because as I said, and as the sources I linked for you to reference clearly stated convective radiation is not taking place in space.
Both Google and NASA are worried about this for a reason, if you think they are wrong, you should offer your assistance to them, rather than debating me.
and yet notice how the cooling video / section was the only one they didn't have a solution for... just saying "radiator" doesn't make sense - the radiator heats up too. it's how you get rid of the heat, not where you put it.
Huh? Radiators are known technology. They have them on ISS; they have them on every Starlink satellite. This isn't like warp drive or antigravity.
Moreover, you can easily calculate how big of a radiator you need for a given power level and temperature. You can use the Stefan–Boltzmann law:
A ~ (1000 P) / (2 e k T^4)
Where
A is the radiator area in square meters
P is the power in kilowatts
e is emissivity (usually 0.9)
k is the constant 5.67e-8
For a 1 kW test like Googles, you just need 1 square meter of radiators (assuming two-sided).
For SpaceX's 175 kW satellites, they will need ~170 square meters of radiators.
None of this is impossible or even difficult to calculate. That's why I think this is the laziest argument against space data centers. There are so many other more reasonable arguments (like whether they will be economically competitive) but people love to latch on to this one for some reason.
To your last paragraph: when opposing something, it makes sense to use the laziest argument first. Only if that doesn't achieve your goals, would you move towards less lazy arguments. I forget what the term for this is, it's generally criticized ("you should just put your strongest arguments first").
I don't think that is the argument, or if so it's an odd one because it's just a fact right now. Instead, people are claiming that it will never be feasible from a purely physics standpoint, which is something debatable.
Saying it’s impossible isn’t debatable because it obviously is. What would stop you from a physics standpoint to just launch 100 ISS with Server racks in each? A few kW of installed power in space is already reality, it’s just really expensive.
sure, the physics is solved: we know how radiators work, and we can calculate the area needed, blah blah. but we haven't put sustained-AI-computer systems into space yet - heat is a genuine concern, and personally I'm curious if they are developing something beyond simple radiators. if a ~1m^2 radiator works, great. but if the current test can only run the TPUs for ~15-minute bursts before it has to stop and dump heat, this issue isn't exactly "solved" in my book.
I think you misunderstand the argument of the people worrying about cooling. I don’t think most people think it’s literally physically impossible, they just think that this will be the thing that makes it economically uncompetitive. It’s a combined argument.
That may be the argument, but it's a dumb argument. Most of the cost is going to go to chips, solar panels, and launch. Radiators are probably one of the cheapest parts of the satellite: it's a hunk of metal with some pumps for liquid cooling.
People use that argument because it takes zero thought to make and significant effort to refute.
Again you’re missing the combined argument, the cooling will increase launch costs because your hunk of metal will increase the weight of the satellite.
People use that argument because one of the chief bullshit arguments put forward by proponents of space based datacentres is "space is cold", when what they actually mean is "space lacks the possibility of using relatively efficient conductive cooling, so we need to expensively launch large amounts of additional mass to use radiative cooling, consider the extent to which we can shield our miles of active cooling loops from impact, and under current plans all of this mass must be replaced on the same cycles as the chips"
"Space is cold" is classic zero effort to make, significant effort to refute stuff: proponents imply complete nonsense about vacuums being optimal for cooling and anyone who understands why this is a lie to gull retail investors ends up getting bogged down in "sure, but Boltzmann equations proving it's prohibitively expensive doesn't prove it isn't possible"...
We don't. This is all cover for the militarisation of space, there's no real benefit that'd be ever economical to put a DC up in space when you could build one on the ground. The whole narrative exists to allow google to tap into the Golden Dome / Space force bucket of pork that's basically SDI II.
You don't need civilian scale compute in space, but you absolutely can put miliary application up there and get filthy rich, like Elon, who doesn't care if it ever works, because he's getting paid as taxi service to shoot stuff up.
This is the most interesting perspective I've heard on this topic, which otherwise always converges on the same political dismissals or heat dissipation arguments (the latter are fascinating, but going in circles by now).
Sounds very probable: gives a plausible reasons for sending a lot of infra up, absolutely doesn't have to be profitable or even effective, puts the focus on AI instead of the MIC, and is in line with the kind of contracts Big Tech runs after.
To me this model explains a lot of why so many big companies seem to be investing into what every expert I've heard says goes against basic physics. The only thing missing for it to be more than an interesting idea is why China and the EU are not fighting this.
I watched a video with Elon musk the other day and he was very confident saying it's already a solved problem and they already do it with Starlink to some degree. He was baffled that this debate keeps coming up.
> He is free to launch his own space GPU if he is so confident it is profitable*.
Are you not aware that's exactly what SpaceX is doing?? https://www.spacex.com/spacexai/starmind Sure, it's now SpaceXAI or whatever, but how is that any different than Google sending up sats and selling the compute via Gemini?
> The biggest challenge was how to cool the A.I. chips, which heat up when they perform calculations and process information. Fans, which typically help dissipate the heat, do not work in space. So the Silicon Valley company instead developed a cooling system that uses layers of conductive material to expel the heat into space.
> The bottom layer is made up of Google’s A.I. chips, which sit on a green motherboard. The next layer consists of “thermal interface material,” a pale green putty that comes in sheets like Fruit Roll-Ups and connects the chips to layers of aluminum and copper, radiating heat away from the motherboard. Finally, there is a radiator panel, which projects heat into space.
> The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
> The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
From the article itself, sounds like it’s an open problem that they are experimenting with:
“ We’re working on a number of different approaches for this, including a combination of heat pipes and radiators to cool the chips. So far, our team has tested the technology in a thermal vacuum chamber that simulates both the thermal and vacuum environment in space. We’ll see how our new TPU cooling system works in space and refine our designs as we learn more.”
Imagine a heat pump circuit fails (solar rays? micrometeorite? random chance), I guess everything in that loop will just be dead forever? I guess you don't need to pay to dispose of it.
I tried asking Grok and a bunch of waffle came out but one interesting idea was "modular tiles" with solar cells on one side and a panel to radiate heat on the other with the processor bolted to the panel. (https://www.geekwire.com/2026/sophia-space-caltech-ai-patent...)
It's a bit like the hyperloop. They know it's not practical but having the idea out there makes money.
There will be some niche demand for military use though.
159 comments
[ 0.24 ms ] story [ 31.6 ms ] threadHowever, I do think avoiding local control (state/city permits) is a reason for this.
Not true
It's just far out research experiment like another commented quoted from the text: https://news.ycombinator.com/item?id=49834746
But even in this comment stream there are tons of people saying the cooling problem is insurmountable.
Robofactories? The idea was roundly mocked and completely failed, costing many millions of dollars, leading to manufacturing defects on thousands of vehicles, and delaying Model 3 mass production.
Hyperloops? The idea was roundly mocked and completely failed. Somehow it attracted hundreds of millions of dollars of investment. (There's suspicion Musk proposed the idea cynically to distract from rail.)
Robotaxis? Waymo started in 2004 and is, today, ahead of Tesla.
Electric cars? Again, demonstrated long before Musk got involved. The frustration amongst environmentalists at the time was that the technology and demand both existed but manufacturers weren't interested in making them.
https://en.wikipedia.org/wiki/General_Motors_EV1
(Before you claim the EV1 was so obscure as to not count, GM built about 1,000 of them, vs 2500 Roadsters. If it doesn't count, neither does the Roadster.)
Reusable launch vehicles? Work started on them in the '70s at the latest and they were the American workhorse by the '80s. The basic design SpaceX settled on was demonstrated in the '90s.
https://en.wikipedia.org/wiki/Space_Shuttle
https://en.wikipedia.org/wiki/McDonnell_Douglas_DC-X
Satellite internet? Obviously old hat, so let's restrict ourselves to LEO constellations. These were proposed in the Star Wars project and were built by several companies in the 1990s. Starlink is much larger and more modern, but the basic idea was proven.
https://en.wikipedia.org/wiki/Teledesic
https://en.wikipedia.org/wiki/Iridium_Communications
https://en.wikipedia.org/wiki/Globalstar
This narrative that Musk has done things other people considered impossible is simply untrue. Everywhere he's found success, other people had already demonstrated the basic idea. Everywhere the consensus was that he had lost the plot, he failed completely. Impressive work should not require exaggeration.
I will have to grant that this was previously unthinkable:
https://tinyurl.com/5aps6aam
And they never will be because it's always going to be cheaper to build them on the ground.
They have a different approach - rather than a ceramic heat shield they have a metal shield to be cooled by the liquid H2+O2 fuel. https://youtu.be/3V6lfs7xFJM?t=191
Even while current administration is kind of positive towards them, they are still even now just having to wait for no good reason for a FAA go-ahead. These kinds of stalls don't really exist in China.
TPU: 100,000+ watts/square-meter
Radiator: ~300 watts/square-meter
https://youtu.be/ktdbUIZKeSE?t=76
"Scientists" being detractors and everyone going online to comment about how something is impossible while the people doing the thing just do it then all the detractors quietly shrug it off until the next time is so consistent it feels like Groundhog Day. I'd really like to learn about why so many people get off by saying something that other people are working on is impossible.
You see, this is the difference between bullshit and not. I can claim "we'll do timetravel soon !", but unless I share some "things" (whatever they are) that might sustain that affirmation, this is just bullshit
Does it mean that no solution exists ? No. Just that today none are known (as far as I can tell).
Your desire to call out bullshit is stronger than your ability to GSD.
People are working on problems I cannot manage (who could have known) and they cannot say anything about that but we have to trust them to bring results out of thin air ? Is this politics .. ?
If your personal accusations can be boiled down to : "shame ! you are not gullible!", then please know that, here in France, not being gullible is a compliment.
Both of those are expensive as hell, by the way.
Cooling via radiation follows Stefan–Boltzmann: P = εσAT⁴. Let's assume a good surface (emissivity ~0.9) at 300 K (27 °C) at 400 W per square meter per side. A flat panel radiating from both faces into deep space gets 800 W/m, not including the losses from, say, the Sun, or from IR coming off the Earth. Now, input power. Sunlight in orbit ~1,360 W/m², assume ~22% cell efficiency, we got 300 W/m². So each 1 MW compute, 3,300 m² of solar panel and minimum 1,200–1,500 m² of radiator.
In case ya didn't know - 1 MW is tiny from a present-day-datacenter perspective. It's like 8 racks. So we're talking orbital megastructures here, square kilometers, and this is with all the best case assumptions, and magic radiator panels that never see the sun, or the earth, or the moon.
This is just the basic numbers here, by the way. There's a garbage truck full of other unsolvable problems if you poke your head in there.
Aside from the "Avoid Regulations" aspect, and the "Everything That Burns Deorbiting is Depreciation" aka "The Starlink Trick", I'm not sure what the hell the draw is.
one is marketing.
the other is that you could make tiny datacenters and flood the sky with them. in effect, not datacenters at all, but some kind of dataswarm coordinating at literal lightspeed via lasers.
they'd still be wildly expensive to deploy, and probably litter the orbit zone with fast-moving debris.
For that you might need more advanced stuff like liquid droplet radiators (https://en.wikipedia.org/wiki/Liquid_droplet_radiator), heat sinks & pulsed operation. Still, it should be eventually doable.
As for space data centers - I think the main issue is the complete lack of in space infrastructure for resource mining, processing and manufacturing & maintenance. It is kinda like building your first practical steam locomotive & the deciding to build directly an airliner. No suitable materils, experience, work force, material sources, etc.
We eventually went from locomotives to airliner, in an incremental manner & expanding the supporting infrastructure to support the ever more ambitious projects.
Method 1: same as how u2 planes dumped their data: air drop physical media containing data and catch it in the air.
Method 2: laser based emission to specific detectors.
Method 3: baseball style communication: station is under observation and manipulates in some way to serve as a signalling language.
Method 4: numbers station
Method 5: bill yourself as an isp and have some coded syntax that can be supplied in plain sight with the rest of isp traffic.
Training models takes weeks, are you really worried about a couple hours?
> Can be jammed by drone with laserpointer
Ok, you're just joking
Why do you think GPS is so easy to spoof?
Actually I just googled (clauded?) to learn more about space lasers and found a paper describing interrupting quantum key distribution (tamper evident but not jam proof!) with a 1kw laser on the ground pointed at the satellite! So it really does not take many photons to fuck up an encrypted signal.
“ Vulnerability of Satellite Quantum Key Distribution to Disruption from Ground-Based Lasers”
https://pmc.ncbi.nlm.nih.gov/articles/PMC8659886/
Definitely not signals from low earth orbit.
never? I doubt that.
Technology will improve over time. Eventually I bet it will become cheaper.
Have you tried building in the U.S.? Why do you think it's so expensive to build in the U.S.? It's due to regulation and red tape.
Thermodynamics says no today, no tomorrow, and no 100 years from now. That's not ever going to change.
The old Chicago School boogeymen of unions, regulations, and red tape are effectors, but they're a pimple on the back of the world-mutating effects of USD Seigniorage.
I imagine we're going to be living through the reverse of this Seigniorage experiment quite soon.
2) The International Space Station has used a dual-loop ammonia/water-based heat pump to cool the station temperatures. It's been in place for several decades. Heat pumps are a proven technology.
Other satellites have also used heat pumps, such as SES-17 in geostationary orbit https://www.esa.int/Applications/Connectivity_and_Secure_Com...
If we want the heat pump's cold end at about 40–65°C, then for each 1MW of GPU heat, we need another 1MW of heat pump power. Now you need 2MW of solar power.
Good news is that the radiator at 227C (500K) can emit about 5× more heat per square meter than at 57C (330K)
Looks like some experimental pumps within this region have CoP around 30%: https://www.sciencedirect.com/science/article/abs/pii/S03605...
So you'll need a lot of additional energy to run the pumps. Which will require additional radiator area.
That's thumping the Carnot limit: [[T_cold / (T_hot − T_cold)]].
2.5, while rejecting at 500 K, cold side's at least 357 K (eeehhhhhhh 84 °C) . . . and that's an absolutely perfect Carnot machine. At 50% Carnot -- a pretty good heat pump, real world performance is 40-60 -- cold side's at 417 K (144 °C). 417k, feeding your GPU coolant loops.
With those numbers, ideal carnot would be 500/(500-357) = 3.5.
Multi-stage could potentially get you to a COP of 2 or so. So 0.5MW.
Depends on which heat you want
Heat adding to hot side: COP_heat = Q_hot / W = T_hot / (T_hot − T_cold).
Heat leaving the cold side: COP_cool = Q_cold / W = T_cold / (T_hot − T_cold).
Another one (more common in the day to day, for me at least): heat-engine efficiency, η = 1 - T_cold / T_hot. Cycle forward to make work from heat.
Luckily, there are almost no rock in space.
We need > 2x more solar panels than we need radiators. Doesn't this imply radiation isn't really the limiting factor here?
(This follows because a physical object can't absorb more light than a perfect blackbody spanning its convex hull. A perfect blackbody by definition absorbs 100% of incident light, which is a hard upper bound. Any line incident on an object is also incident on its convex hull).
(Consider an isothermal object that emits more power than a blackbody in the shape of its hull at the same temperature. If you were to place that object in a closed system at thermal equilibrium, the interior of an insulated emissive sphere—combining assumptions, it would emit more power than it absorbs, in violation of the 2nd law. Starting from an isothermal system, the object would grow colder, and the enclosing container hotter).
At any rate, 1 MW for a single satellite is fine. Just launch several thousand of those and you get to real numbers.
Also, there's no need to talk about "magic" radiators. You orient them so they're at a knife edge to both the Sun and Earth. This is not difficult (the Moon is irrelevant).
They run fine for a short while, but not nearly as long.
Heat accelerates all aging processes. It's how they artificially age chips in order to calculate MTBF.
The only valid argument against data centers in space is the economic cost. If the per megatoken price for space datacenters is higher than terrestrial, then this won't work.
But the price for terrestrial datacenters keeps going up and technology keeps dropping the price of space-based.
If you are trying to actually generate a profit, every extra kg of orbital launch costs puts you further in the red.
But if it's an economic argument, then you need to do the actual math. How big is the radiator? How low could the price to orbit go? How much can you charge per million tokens in 2030?
The reason this is a fake argument is because the validity depends on the math, and nobody advancing the "you can't cool stuff in space" argument is actually doing the math.
Sure, things would be different if the cost was $1/kg, but short of somebody building a space elevator that's just not going to happen.
But are you sure that $100/kg is not competitive? I don't remember all the math, but even their initial AI1 design[1] would throw a lot of profit, if you can sell at the price they offered to Anthropic.
I suspect the price of manufacturing the satellite, plus chips, is the dominating factor, not necessarily the launch costs.
[1] https://www.spacex.com/spacexai/starmind
Why wouldn;t you? he delivered on almost everything he promised, just the timeline was a lot later.
we are talking sci-fi things here, these will take time but can be done.
would you rather we bury our heads in the sand and never innovated beyond basics?
A 1GW datacenter with chips operating at 100C (which is probably doable) will need a radiator that has a surface of one square _kilometer_, and this is with all the favorable assumptions. Realistically you'll need about 2x of that.
If you want your DCs to be on a 1000km orbit (for reasonable ping times), you'll be able to _resolve_ these satellites with a naked eye!
Sorry. But this idea is fundamentally unworkable.
If you want math then https://andrewmccalip.com/space-datacenters exists. The numbers are grim for orbital DC. Even if you drag the launch cost slider all the way to $1/kg (by the way this is literally sci-fi, per ChatGPT air freight of semiconductors from Taiwan to Ohio costs $9/kg and ocean/train freight costs a bit under $1/kg for a reasonable shipment so good luck with $1/kg to LEO this century) it is still more than twice as expensive as terrestrial DCs.
That sounds absolutely possible. But in any event, we're now arguing a different thing.
The only thing I'm arguing is that cooling is a solved problem. I don't know if SpaceX will ever get the price down so that it is economical. But I'm convinced that there is no universe in which they hit their foreheads and say, "Oh no, we forgot about cooling!"
> No additional mass for liquid cooling loop infrastructure; likely needed but not included
> Thermal: only solar array area used as radiator; no dedicated radiator mass assumed
In hardware and mfg. solvable vs. solved is a big difference. And I too believe that SpaceX's engineers know about radiator panels. But the more cynical interpretation is that whatever the SpaceX engineers think about the technical merits, they are not being asked for that. They are just being asked for a pretext that justifies the xAI acquisition. Elon is also discussing lunar satellite factories that launch the satellites via railgun. Now, is this physically impossible? No, that isn't physically impossible either and I will seriously defend the physical possibility of this. It's not going to happen though.
And you could spend all the engineering costs on building some seriously efficient terrestrial DCs, but somehow all these analyses start with "assume that launch and satellite technology advances manyfold and terrestrial DCs stagnate or become less efficient, then if you squint the two numbers get kinda close."
This is why that calculator, even under extremely optimistic assumptions for orbital, and even if you assume launch is zero, still cannot make it competitive with terrestrial.
> If you assume Starlink satellite $/W
Why would you assume that, given that high power output is not a design goal of Starlink?
ETA: power is absolutely important for Starlink. SNR is very important for shannon capacity and satellite systems are often limited in this respect.
Anyway, my point is that Starlink is not primarily designed to harvest as much solar power as possible the way data center sats are. I'm sure they're not making it inefficient on purpose, but what you're suggesting is like using the cost/W of a solar powered traffic camera to estimate the cost/W of a solar farm. Yes, they both use solar power, but they have entirely different design goals.
So... not easy? I don't suppose we're at a point where you could reasonably send a large-enough radiator for a multi-gigawatt cluster into space?
This is all a weird speedrun or race. If something we should be working on setting up resource mining from the Moon & asteroids, materials processing on the Lunar surface & in orbit, simple manufacturing in space, etc.
Instead some people think we can jump straight to a computronium Dyson swarm. :P
You don't need to send a multi-gigawatt satellite to space. You just need to launch a few thousand 250 kW satellites. That's not against the laws of physics.
If you know all that out to 2040 then you must be a time traveler. Please try to fix our timeline rather than wasting time on HN.
>> The current plan is for 250 kW peak with 160 m^2 radiators. It will weigh about 4 tons so you can pack 25 on one flight of Starship.
>> Deploy 4,000 and you're at 1 GW. That's 160 launches.
Convective radiation does not happen in space and this challenge is far more significant than your comment implies. Rather than "a dumb hunk of metal", radiators for spacecraft are often made of ceramics and carbon laminates with higher IR emissivity than convective radiators made of simple metals.
From the article you're commenting on:
> The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
The Thermal Control section on NASA's Small Spacecraft documentation center is quite an interesting read for this subject: https://www.nasa.gov/smallsat-institute/sst-soa/thermal-cont...
ML Infrastructure comes with some pros (larger emissive footprint) and cons (exponentially larger TDP) compared to the concerns there, but if you aren't familiar with the challenges of heat dissipation in space, please give it a read.
There's also a pretty interesting pop-sci article on cooling the Webb telescope, since it needs to be especially cold for its purpose. Not directly related, but may give insight into both challenges and solutions as well as well. https://science.nasa.gov/mission/webb/science-overview/scien...
The equation is:
Where P and T are the dominating factors. Don't worry about emissivity.Both Google and NASA are worried about this for a reason, if you think they are wrong, you should offer your assistance to them, rather than debating me.
Moreover, you can easily calculate how big of a radiator you need for a given power level and temperature. You can use the Stefan–Boltzmann law:
Where For a 1 kW test like Googles, you just need 1 square meter of radiators (assuming two-sided).For SpaceX's 175 kW satellites, they will need ~170 square meters of radiators.
None of this is impossible or even difficult to calculate. That's why I think this is the laziest argument against space data centers. There are so many other more reasonable arguments (like whether they will be economically competitive) but people love to latch on to this one for some reason.
That's like a quarter of a rack of modern AI hardware. Modern AI datacenters are now in the multi-GW range.
Now the argument is, what, you can't launch that many satellites?
How can anyone be certain of any of those numbers without (a) knowing how the technology will evolve, and (b) doing the math?
I'm just astounded that people can have such confidence.
They are showing that space-based DCs only make sense for criminal enterprises. Which probably IS what's going on here.
People use that argument because it takes zero thought to make and significant effort to refute.
"Space is cold" is classic zero effort to make, significant effort to refute stuff: proponents imply complete nonsense about vacuums being optimal for cooling and anyone who understands why this is a lie to gull retail investors ends up getting bogged down in "sure, but Boltzmann equations proving it's prohibitively expensive doesn't prove it isn't possible"...
You don't need civilian scale compute in space, but you absolutely can put miliary application up there and get filthy rich, like Elon, who doesn't care if it ever works, because he's getting paid as taxi service to shoot stuff up.
Sounds very probable: gives a plausible reasons for sending a lot of infra up, absolutely doesn't have to be profitable or even effective, puts the focus on AI instead of the MIC, and is in line with the kind of contracts Big Tech runs after.
To me this model explains a lot of why so many big companies seem to be investing into what every expert I've heard says goes against basic physics. The only thing missing for it to be more than an interesting idea is why China and the EU are not fighting this.
It's Golden Dome when Google does it.
I guess it's something along the same line when Jeff Bezos does it. He does indeed plan it.
What is China's motive? why do they also need to pretend they want space data centers? [0], [1]
How about Europe's? [2]
[0] - https://www.tomshardware.com/tech-industry/space/china-puts-...
[1] - https://www.reuters.com/science/china-vows-develop-space-tou...
[2] - https://ascend-horizon.eu/data-centres-in-space/
*Profitability requiring that other Musk controlled companies do not pay for the service at elevated rates in a classic self dealing scheme.
Are you not aware that's exactly what SpaceX is doing?? https://www.spacex.com/spacexai/starmind Sure, it's now SpaceXAI or whatever, but how is that any different than Google sending up sats and selling the compute via Gemini?
Regardless, those claim to have a maximum draw of 250kw. That’s one to two terrestrial data rack. Cute.
> The biggest challenge was how to cool the A.I. chips, which heat up when they perform calculations and process information. Fans, which typically help dissipate the heat, do not work in space. So the Silicon Valley company instead developed a cooling system that uses layers of conductive material to expel the heat into space.
> The bottom layer is made up of Google’s A.I. chips, which sit on a green motherboard. The next layer consists of “thermal interface material,” a pale green putty that comes in sheets like Fruit Roll-Ups and connects the chips to layers of aluminum and copper, radiating heat away from the motherboard. Finally, there is a radiator panel, which projects heat into space.
> The chips can operate for about 15 minutes in space before needing to be shut down so they can cool off, said Travis Beals, Google’s senior director of product management for Project Suncatcher.
Is it at least a 1:1 usage / cooling cycle?
“ We’re working on a number of different approaches for this, including a combination of heat pipes and radiators to cool the chips. So far, our team has tested the technology in a thermal vacuum chamber that simulates both the thermal and vacuum environment in space. We’ll see how our new TPU cooling system works in space and refine our designs as we learn more.”