A Starlink satellite uses about 5K Watts of solar power. It needs to dissipate around that amount (+ the sun power on it) just to operate. There are around 10K starlink satellites already in orbit, which means that the Starlink constellation is already effectively equivalent to a 50 Mega-watt (in a rough, back of the envelope feasibility way).
Isn't 50MW already by itself equivalent to the energy consumption of a typical hyperscaler cloud?
Why is starlink possible and other computations are not? Starlink is also already financially viable. Wouldn't it also become significantly cheaper as we improve our orbital launch vehicles?
1. The capital costs are higher, you have to expend tons of energy to put it into orbit
2. The maintenance costs are higher because the lifetime of satellites is pretty low
3. Refurbishment is next to impossible
4. Networking is harder, either you are ok with a relatively small datacenter or you have to deal with radio or laser links between satellites
For starlink this isn't as important. Starlink provides something that can't really be provided any other way, but even so just the US uses 176 terawatt-hours of power for data centers so starlink is 1/400th of that assuming your estimate is accurate (and I'm not sure it is, does it account for the night cycle?)
Presumably they're planning on doing in-orbit propellant transfer to reboost the satellites so that they don't have to let their GPUs crash into the ocean...
Minus one big one: permitting. Every datacentre I know going up right now is spending 90% of their bullshit budget on battlig state and local governments.
Hell, you're going to lose some fraction of chips to entropy every year. What if you could process those into reaction mass?
xAI’s first data center buildout was in the 300MW range and their second is in the Gigawatt range. There are planned buildouts from other companies even bigger than that.
So data center buildouts in the AI era need 1-2 orders of magnitude more power and cooling than your 50MW estimate.
Even a single NVL72 rack, just one rack, needs 120kW.
A single AI rack consumes 60kW, and there is apparently a single DC that alone consumes 650MW.
When Microsoft puts in a DC, the machines are done in units of a "stamp", ie a couple racks together. These aren't scaled by dollar or sqft, but by the MW.
And on top of that... That's a bunch of satellites not even trying to crunch data at top speed. No where near the right order of magnitude.
putting 1KW of solar on land - $2K, putting it into orbit on Starship (current ground-based heavy solar panels, 40kg for 4m2 of 1KW in space) - anywhere between $400 and $4K. Add to that that the costs on Earth will only be growing, while costs in space will be falling.
Ultimately Starship's costs will come down to the bare cost of fuel + oxidizer, 20kg per 1kg in LEO, i.e. less than $10. And if they manage streamlined operations and high reuse. Yet even with $100/kg, it is still better in space than on the ground.
And for cooling that people so complain about without running it in calculator - >>46878961
>2. The maintenance costs are higher because the lifetime of satellites is pretty low
it will live those 3-5 years of the GPU lifecycle.
All satellites launched into orbit these days are required to have de-orbiting capabilities to "clean up" after EOL.
I dunno, two years ago I would have said municipal zoning probably ain't as hard to ignore as international treaties, but who the hell knows these days.
Source? I can't immediately find anything like that.
And maintenance and replacing parts and managing flights and ... You're trying to yadda-yadda so much opex here!
> an engineering and physics problem that he will somehow solve
no he won't
1. Assuming 500,000 USD in permitting costs. See 2.
2. Permits and approvals: Building permits, environmental assessments, and utility connection fees add extra expenses. In some jurisdictions, the approval process alone costs hundreds of thousands of dollars. https://www.truelook.com/blog/data-center-construction-costs
3. Assuming a 60MW facility at $10M/MW. See 4.
4. As a general rule, it costs between $600 to $1,100 per gross square foot or $7 million to $12 million per megawatt of commissioned IT load to build a data center. Therefore, if a 700,000-square foot, 60-megawatt data center were to be built in Northern Virginia, the world’s largest data center market, it would cost between $420 million and $770 million to construct the facility, including its powered shell and equipping the building with the appropriate electrical systems and HVAC components. https://dgtlinfra.com/how-much-does-it-cost-to-build-a-data-...
A datacenter costs ~$1000/ft^2. How much equipment per square foot is there? say 100kg (1 ton per rack plus hallway). Which is $1000 to put into orbit on Starship at $100/kg. At sub-$50/kg, you can put into orbit all the equipment plus solar panels and it would still be cheaper than on the ground.
if the current satellite model dissipates 5kW, you can't just add a GPU (+1kW). maybe removing most of the downlink stuff lets you put in 2 GPUs? so if you had 10k of these, you'd have a pretty high-latency cluster of 20k GPUs.
I'm not saying I'd turn down free access to it, but it's also very cracked. you know, sort of Howard Hughesy.
Datacenters already exist. Putting datacenters in space does not offer any new capabilities.
More convenient. But I'm balancing the cost equation. There are regimes where this balances. I don't think we're there yet. But it's irrational to reject it completely.
> Or put it on a boat, which is still 100 times more sensible than outer space
More corrosion. And still, interconnects.
Now that I think of it, a big hydro dam would be perfect: power and cooling in one place.
That would make your solar panel (40kg) around $60K to put into space.
Even being generous and assuming you could get it to $100 per kg that's still $4000
There's a lot of land in the middle of nowhere that is going to be cheaper than sending shit to space.
Surely given starlinks 5ish year deorbit plan, you could design a platform to hold up for that long... And instead of burning the whole thing up you could just refurbish it when you swap out the actual rack contents, considering that those probably have an even shorter edge lifespan.
This isn't quite true. It's very possible that the majority of that power is going into the antennas/lasers which technically means that the energy is being dissipated, but it never became heat in the first place. Also, 5KW solar power likely only means ~3kw of actual electrical consumption (you will over-provision a bit both for when you're behind the earth and also just for safety margin).
These are all things which add weight, complexity and cost.
Propellant transfer to an orbital Starship hasn't even been done yet and that's completely vital to it's intended missions.
This adds weight and complexity and likely also forces a much higher orbit.
I would be. And granted, I know a lot more about launching satellites than building anything. But it would take me longer to get a satellite in the air than the weeks it will take me to fix a broken shelf in my kitchen. And hyperscalers are connecting in months, not weeks.
Yes. These are permitted in weeks for small groups, days for large ones. (In America.)
Permitting is a legitimate variable that weighs in favor of in-space data centers.
I’ve financed two data centers. Most of my time was spent over permitting. If I tracked it minute by minute, it may be 70 to 95%. But broadly speaking, if I had to be told about it before it was solved, it was (a) a real nuisance and (b) not technical.
Maybe the AI workloads running on it achieve escape velocity? ;)
Downtown Los Angeles: The One Wilshire building, which is the worlds most connected building. There are over twenty floors of data centers. I used Corporate Colo which was a block or two away. That building had at least 10 floors of Data Centers.
Aside from the point others have made that 50 MW is small in the context of hyperscalers, if you want to do things like SOTA LLM training, you can't feasibly do it with large numbers of small devices.
Density is key because of latency - you need the nodes to be in close physical proximity to communicate with each other at very high speeds.
For training an LLM, you're ideally going to want individual satellites with power delivery on the order of at least about 20 MW, and that's just for training previous-generation SOTA models. That's nearly 5,000 times more power than a single current Starlink satellite, and nearly 300 times that of the ISS.
You'd need radiator areas in the range of tens of thousands of square meters to handle that. Is it theoretically technically possible? Sure. But it's a long-term project, the kind of thing that Musk will say takes "5 years" that will actually take many decades. And making it economically viable is another story - the OP article points out other issues with that, such as handling hardware upgrades. Starlink's current model relies on many cheap satellites - the equation changes when each one is going to be very, very expensive, large, and difficult to deploy.
What starship? The fantasy rocket Musk has been promising for 10 years or the real one that has thus far delivered only one banana worth of payload into orbit?
That is exactly what you do - just like with Starlink - toss out the panels with attached GPUs, laser transmitter and small ion drive.
0. https://www.arccompute.io/solutions/hardware/gpu-servers/sup...
Just admit it was hyperbole.
The short answer is that ~100m2 of steel plate at 1400C (just below its melting point) will shed 50MW of power in black body radiation.
... if you completely ignore the difficulty of getting them up there. I'd be interested to see a comparison between the amount of energy required to get a solar panel into space, and the amount of energy it produces during its lifetime there. I wouldn't be surprised if it were a net negative; getting mass into orbit requires a tremendous amount of energy, and putting it there with a rocket is not an efficient process.
100 years later: "why does everything taste like cadmium?"
with the GPU costing the same, it would only double the capex.
>Even being generous and assuming you could get it to $100 per kg that's still $4000
noise compare to the main cost - GPUs.
>There's a lot of land in the middle of nowhere that is going to be cheaper than sending shit to space.
Cheapness of location of your major investment - GPUs - may as well happen to be secondary to other considerations - power/cooling capacity stable availability, jurisdiction, etc.
> or the real one that has thus far delivered only one banana worth of payload into orbit?
once it starts delivering real payloads, the time for discussions will be no more, it will be time to rush to book your payload slot.
You meet this with "well, once it works, it'll be amazing and you'll be queuing up"? How very very musky!
What a cult.
5kg, 500W panel (don’t exactly know what the ratio is for a panel plus protection and frame for space, might be a few times better than this)
Say it produces about 350kWh per month before losses.
Mass to LEO is something like 10x the weight in fuel alone, so that’s going to be maybe 500kWh. Plus cryogenics etc.
So not actually that bad
I wonder if you were thinking about muh emissions for a chemical rocket launched piece of machinery containing many toxic metals to be burnt up in the air in 3-5 years... It doesn't sound more environmentally friendly.
Ionizing radiation disrupts the crystalline structure of the semiconductor and makes performance worse over time.
High energy protons randomly flip bits, can cause latchup, single event gate rupture, destroy hardware immediately, etc.
At the end of the day I don't really care either way. It ain't my money, and their money isn't going to get back into the economy by sitting in a brokerage portfolio. To get them to spend money this is as good a way as any other, I guess. At least it helps fund a little spaceflight and satellite R&D on the way.
The known scammer guy? Like these ideas wouldn't pass the questions at the end of a primary school presentation.
"SmartIR’s graphene-based radiator launches on SpaceX Falcon 9" [1]. This could be the magic behind this bet on heat radiation through exotic material. Lot of blog posts say impossible, expensive, stock pump, etc. Could this be the underlying technology breakthrough? Along with avoiding complex self-assembly in space through decentralization (1 million AI constellation, laser-grid comms).
[1] https://www.graphene-info.com/smartir-s-graphene-based-radia...
Every DC I’ve been in (probably around 20 in total) has been multi storey.
(I'm ignoring installation costs etc. because actually creating the satellites is ignored here, too)
Yes, only doubling the capex. With the benefits of, hmm, no maintenance access and awful networking?
Current satellites get around 150W/kg from solar panels. Cost of launching 1kg to space is ~$2000. So we're at $13.3(3)/Watt. We need to double it because same amount need to be dissipated so let's round it to $27
One NVidia GB200 rack is ~120kW. To just power it, you need to send $3 240 000 worth of payload into space. Then you need to send additional $3 106 000 (rack of them is 1553kg) worth of servers. Plus some extra for piping
Just shoot it into space where it's all inaccessible and will burn out within 5 years, forcing a continuous replacement scheme and steady contracts with Nvidia and the like to deliver the next generation at the exact same scale, forever
The energy demand of these DCs is monstrous, I seriously can't imagine something similar being deployed in orbit...
That doesn't mean you need a gigawatt of power before achieving anything useful. For training, maybe, but not for inference which scales horizontally.
With satellites you need an orbital slot and launch time, and I honestly don't know how hard it is to get those, but space is pretty big and the only reasons for denying them would be safety. Once those are obtained done you can make satellite inferencing cubes in a factory and just keep launching them on a cadence.
I also strongly suspect, given some background reading, that radiator tech is very far from optimized. Most stuff we put into space so far just doesn't have big cooling needs, so there wasn't a market for advanced space radiator tech. If now there is, there's probably a lot of low hanging fruit (droplet radiators maybe).
A quick search gave me a lifespan of around 5 years for a starlink satellite.
If you put in orbit a steady stream of new satellites every year maintenance is not an issue, you just stop using worn out or broken ones.
I would assume such a setup involves multiple stages of heat pumps to from GPU to 1400C radiatoe. Obviously that's going to impact efficiency.
Also I'm not seriously suggesting that 1400C radiators is a reasonable approach to cooling a space data centre. It's just intended to demonstrate how infeasible the idea is.
Or you float them on the ocean circumnavigating the earth?
Or we put the datacenters on giant Zeppelins orbiting above the clouds?
If we are doing fantasy tech solutions to space problems, why not for a million other more sensible options?
Starship launch costs have a $100/kg goal, so we'd be at $40 / kW, or $4800 for a 120kW cluster.
120kW is 1GWh annually, costs you around $130k in Europe per year to operate. ROI 14 days. Even if launch costs aren't that low in the beginning and there's a lot more stuff to send up, your ROI might be a year or so, which is still good.
[1] - https://www.polytechnique-insights.com/en/columns/space/ultr... [2] - https://space.stackexchange.com/questions/12824/lightest-pos...
You'd be wrong. There's a huge incentive to optimized radiator tech because of things like the international space station and MIR. It's a huge part of the deployment due to life having pretty narrow thermal bands. The added cost to deploy that tech also incentivizes hyper optimization.
Making bigger structures doesn't make that problem easier.
Fun fact, heat pipes were invented by NASA in the 60s to help address this very problem.
This is the big thing, but Elon's child porn generator in orbit will be subject to US jurisdiction, just as much as if they were in Alaska. I guess he can avoid state law.
If jurisdiction is key, you can float a DC in international waters on a barge flying the flag of Panama or similar flag of convenience which you can pretty much buy at this scale. Pick a tin-pot country, fling a few million to the dictator, and you're set - with far less jurisdiction problems than a US, Russia, France launched satellite.
The physics of consuming bits of old chip in an inefficient plasma thruster probably work, as do the crawling robots and crushers needed for orbital disassembly, but we're a few years away yet. And whilst on orbit chip replacement is much more mass efficient than replacing the whole spacecraft, radiators and all, it's also a nontrivial undertaking
What that does have to do with anything? If you want to solar-power them, you still are subject to terrestrial effects. You can't just shut off a data center at night.
> Or we put the datacenters on giant Zeppelins orbiting above the clouds?
They'd have to fly at 50,000+ ft to be clear of clouds, I doubt you can lift heavy payloads this high using bouyancy given the low air density. High risk to people on the ground in case of failure because no re-entry.
> If we are doing fantasy tech solutions to space problems, why not for a million other more sensible options?
How is this a fantasy? With Starlink operational, this hardly seems a mere 'fantasy'.
Space has some huge downsides:
* Everything is being irradiated all the time. Things need to be radiation hardened or shielded.
* Putting even 1kg into space takes vast amounts of energy. A Falcon 9 burns 260 MJ of fuel per kg into LEO. I imagine the embodied energy in the disposable rocket and liquid oxygen make the total number 2-3x that at least.
* Cooling is a nightmare. The side of the satellite in the sun is very hot, while the side facing space is incredibly cold. No fans or heat sinks - all the heat has to be conducted from the electronics and radiated into space.
* Orbit keeping requires continuous effort. You need some sort of hypergolic rocket, which has the nasty effect of coating all your stuff in horrible corrosive chemicals
* You can't fix anything. Even a tiny failure means writing off the entire system.
* Everything has to be able to operate in a vacuum. No electrolytic capacitors for you!
So I guess the question is - why bother? The only benefit I can think of is very short "days" and "nights" - so you don't need as much solar or as big a battery to power the thing. But that benefit is surely outweighed by the fact you have to blast it all into space? Why not just overbuild the solar and batteries on earth?
However, with Starship SpaceX has both done more and less than putting a banana in orbit. Less, because it's never once been a true orbit; more, because these are learn-by-doing tests, all the reporting seems to be in agreement that it could already deliver useful mass to orbit if they wanted it to.
But without actually solving full reusability for the upper stage, this doesn't really have legs. Starship is cheap enough to build they can waste loads of them for this kind of testing, but not cheap enough for plans such as these to make sense if they're disposable.
A single server in a data center will consume 5-10 kW.
Quote: "emissivity higher than 0.99 over a wide range of wavelengths". Article title "Perfect blackbody radiation from a graphene nanostructure" [1]. So several rolls of 10 x 50 meters graphene-coated aluminium foil could have significant cooling capability. No science-fiction needed anymore (see the 4km x 4km NVIDIA fantasy)
[1] https://opg.optica.org/oe/fulltext.cfm?uri=oe-21-25-30964
Why not?
A capacity problem can be solved by having another data center the other side of the earth.
If it's that the power cycling causes equipment to fail earlier, then that can be addressed far more easily than radiation hardening all equipment so that it can function in space.
The energy demands of getting to the 240k mile Moon are IMMENSE compared to 100 mile orbit.
Ultimately, when comparing the 3 general locations, Earth is still BY FAR the most hospitable and affordable location until some manufacturing innovations drop costs by orders of magnitude. But those manufacturing improvements have to be made in the same jurisdiction that SpaceXAI is trying to avoid building data centers in.
This whole things screams a solution in search of a problem. We have to solve the traditional data center issues (power supply, temperature, hazard resilience, etc) wherever the data centers are, whether on the ground or in space. None of these are solved for the theoretical space data centers, but they are all already solved for terrestrial data centers.
We still don’t have any plan I’ve heard of for avoiding a cascade of space debris when satellites collide and turn into lots of fast moving shrapnel. Yes, space is big, but low Earth orbit is a very tiny subset of all space.
The amount of propulsion satellites have before they become unable to maneuver is relatively small and the more satellite traffic there is, the faster each satellite will exhaust their propulsion gasses.
The Outer Space Treaty (1967) has a loophole. If you launch from international waters (planned by SpaceX) and the equipment is not owned by a US-company or other legal entity there is significant legal ambiguity. This is Dogecoin with AI. Exploiting this accountability gap and creating a Grok AI plus free-speech platform in space sounds like a typical Elon endeavour.
And it’s still a vacuum with many of the same cooling issues. I suppose one upside is you could use the moon itself as a heat sink (maybe).
Starship isn't largely a government project. It was planned a decade before the government was ever involved, they came along later and said "Hey, this even more incredible launch platform you're building? Maybe we can hire SpaceX to launch some things with it?"
Realistically, SpaceX launches far more payload than any government.
Anyway, promising some fantasy and never delivering is definitely a typical Elon endeavor.
This is exactly like the Boring Company plans to "speed up" boring. Lots of hand waving away decades of commercial boring, sure that their "great minds" can do 10x or 100x better than modern commercial applications. Elon probably said "they could just run the machines faster! I'm brilliant".
Distributing useful work over so many small objects is a very hard problem, and not even shown to be possible at useful scales for many of the things AI datacenters are doing today. And that's with direct cables - using wireless communication means even less bandwidth between nodes, more noise as the number of nodes grows, and significantly higher power use and complexity for the communication in the first place.
Building data centres in the middle of the sahara desert is still much better in pretty much every metric than in space, be it price, performance, maintainance, efficiency, ease of cooling, pollution/"trash" disposal etc. Even things like communication network connectivity would be easier, as at the amounts of money this constellation mesh would cost you could lay new fibre optic cables to build an entire new global network to anywhere on earth and have new trunk connections to every major hub.
There are advantages to being in space - normally around increased visibility for wireless signals, allowing great distances to be covered at (relatively) low bandwidth. But that comes at an extreme cost. Paying that cost for a use case that simply doesn't get much advantages from those benefits is nonsense.
I'm not a space engineer but I'd imagine that smaller satellites can make due with a lot of passive cooling on the exterior of the housing, whereas a shopping-mall sized computer in space would will require a lot of extra plumbing.
The limiting factor isn't the emissivity, it's that you're having to rely on radiation as your only cooling mechanism. It's super slow and inefficient and it limits how much heat you can dissipate.
Like the other person said, you can't do any better than blackbody radiation (emissivity=1).
Is that 5kW of electrical power input at the terminals, or 5kW irradiation onto the panels?
Because that sounds like kind of a lot, for something the size of a fridge.
To use that loophole, the rockets launched by SpaceX would have to be “not owned by a US-company”. Do you think the US government would allow that to happen?
Are Earth-based datacenters actually bound by some bottleneck that space-based datacenters would not be? Grid connections or on-site power plants take time to build, yes. How long does it take to build the rocket fleet required to launch a space “datacenter” in a reasonable time window?
This is not a problem that needs to be solved. Certainly not worth investing billions in, and definitely not when run by the biggest scam artist of the 21st century.
Source: I am out of LEDs and LASERs and now handle aerospace solar for a private company. Guess who almost everyone in the private sector flies on?
Minimizing payload at any point was easily worth a billion dollars. And given how heavy and nessisary the radiators are (look them up), you can bet a decent bit of research was invested in making them lightweight.
Heck, one bit of research that lasted the entire lifetime of the shuttle was improving the radiative heat system [1]. Multiple contractors and agencies invested a huge amount of money to make that system better.
Removing heat is one of the most researched problems of all space programs. They all have to do it, and every gram of reduction means big savings. Simply saying "well a DC will need more of it, therefore there must be low hanging fruit" is naive.
To keep things in orbit ion thrusters work nicely and require just inert gases to keep them functioning. Plus on a low Earth orbit there are suggestions that a ramjet that capture few atoms of atmosphere and accelerates them could work.
Radiative cooling scales by 4th power temperature. So if one can design electronics to run at, say, 100 C, then calling would be much less problematic.
But radiation is the real problem. Dealing with that would require entirely different architecture/design.
Because the permitting process is much easier and there are way, way fewer authorities that can potentially shut you down.
I think this is the entire difference. Space is very, very lightly regulated, especially when it comes to labor, construction and environmental law. You need to be able to launch from somewhere and you need to automate a lot of things. But once you can do this, you escaped all but a few authorities that would hold power over you down on Earth.
No one will be able to complain that your data center is taking their water or making their electricity more expensive, for example.
Someone mentioned in the comments on a similar article that sun synchronous orbits are a thing. This was a new one to me. Apparently there's a trick that takes advantage of the Earth not being a perfect sphere to cause an orbit to precess at the right rate that it matches the Earth's orbit around the sun. So, you can put a satellite into a low-Earth orbit that has continuous sunlight.
https://en.wikipedia.org/wiki/Sun-synchronous_orbit
Is this worth all the cost and complexity of lobbing a bunch of data centers into orbit? I have no idea. If electricity costs are what's dominating the datacenter costs that AI companies are currently paying, then I'm willing to at least concede that it might be plausible.
If I were being asked to invest in this scheme, I would want to hear a convincing argument why just deploying more solar panels and batteries on Earth to get cheap power isn't a better solution. But since it's not my money, then if Elon is convinced that this is a great idea then he's welcome to prove that he (or more importantly, the people who work for him) have actually got this figured out.
Optimization is literally how contractors working for the government got rich. Every hour they spent on research was directly billed to the government. Weight reduction being one of the most important and consistent points of research.
Heck, R&D is how some of the biggest government contractors make all their dough.
SpaceX is built on the billions in research NASA has invested over the decades. It looks like it's more innovative simply because the USG decided to nearly completely defund public spending in favor of spending money on private contractors like SpaceX. That's been happening since the 90s.
It may happen one day, but we are very, very far from that. As of now, big countries watch their space corporations very closely and won't let them do this.
Nevertheless, as an American, you can escape state and regional authorities this way. IIRC The Californian Coastal Commission voted against expansion of SpaceX activities from Vandenberg [1], and even in Texas, which is more SpaceX-friendly, there are still regulations to comply with.
If you launch from international waters, these lower authority tiers do not apply.
[1] https://www.latimes.com/business/story/2025-08-14/california...
A grift the size of Dogecoin, or the size of "free speech" enthusiast computing, or even the size of the criminal enterprises that run on the dark web, is tiny in comparison to the footer cost and upkeep of a datacenter in space. It'd also need to be funded by investments (since criminal funds and crypto assets are quite famously not available in up-front volumes for a huge enterprise), which implies a market presence in some country's economy, which implies regulators and risk management, and so on.
This is a pump-and-dump bid for investor money. They will line up to give it to him.
There must be many power consumers in the satellite, e.g. radio receivers, lasers, computers and motors, where the consumed energy eventually is converted into heat, but the radio transmitter of a communication satellite must take a big fraction of the average consumed power.
The radio transmitter itself has a great efficiency, much greater than 50%, possibly greater than 90%, so only a small fraction of the electrical power consumed by the transmitter is converted into heat and most is radiated in the microwave signal that goes to Earth's surface.
So there's no regulatory or tax benefit to hosting in space.
Thus the extremities of the foil, which are far from the satellite body, will be much cooler than the body, so they will have negligible contribution to the radiated power.
The ideal heatsink has fins that are thick close to the body and they become thinner towards extremities, but a heatsink made for radiation instead of convection needs a different shape, to avoid a part of it shadowing other parts.
I do not believe that you can make an efficient radiation heatsink with metallic foil. You can increase the radiating surface by not having a flat surface, but one covered with long fins or cones or pyramids, but the more the surface is increased, the greater the thermal resistance between base and tip becomes, and also the tips limit the solid angle through which the bases radiate, so there must be some optimum shape that has only a limited surface increasing factor over the radiation of a flat body.
You'll note that there is still a frame that it gets unfolded with and that you've got the additional mechanical apparatus to do the unfurling (and the human there to fix it if there are problems.
Again, you'll note that there is frame material there.
You don't have a sheet of glass on it, but space doesn't give you the mass savings you think it does.
Those are cutting edge tech (designed to work at Jupiter's distance) and that's about 40 m^2 of space (ten times more than you're describing) and they mass 176 kg ( https://doi.org/10.1007/s11214-025-01190-6 ). If we assume that scales down linearly, the cutting edge technology for solar panels is 20kg for 4m^2 which is more than your estimates. ... And they have problems and can fail to deploy. https://spacenews.com/cygnus-solar-array-fails-to-deploy/ https://spaceflightnow.com/news/n1105/25telstar14r/index.htm... https://www.nasa.gov/history/50-years-ago-skylab-2-astronaut... https://ntrs.nasa.gov/api/citations/20210020397/downloads/Al...
You'll note that the Cygnus used the same design as Lucy, though smaller.
https://en.wikipedia.org/wiki/Cygnus_(spacecraft)
> Starting with the Enhanced variant, the solar panels were also upgraded to the UltraFlex, an accordion fanfold array, and the fuel load was increased to 1,218 kilograms (2,685 lb).
Digging more into Ultra Flex, https://www.eng.auburn.edu/~dbeale/ESMDCourse/Site%20Documen...
> Specific performance with 27% TJ cells: >150 W/kg BOL & > 40 kW/m3 BOL
So there's your number. 150 W/kg of solar panel array. 1 kW is about 7 kg.
They're not cheap.
https://spacenews.com/36576ousted-from-first-orion-flight-ci...
> In 2011, Orbital replaced Dutch Space on the project and gave ATK’s space components division, which was already supplying the substrates for Dutch Space’s Orion solar panels, a $20 million deal to provide UltraFlex arrays for later Cygnus flights.
The research article linked above does not claim a better emissivity than Vantablack, but a resistance to higher temperatures, which is useful for high temperature sensors (used with pyrometers), but irrelevant for a satellite that will never be hotter than 100 Celsius degrees, in order to not damage the electronic equipment.
Ah, I see the idea now. It is to get people to talk about robotics and how robots will be able to do all this on the moon or wherever.
Instantly pumps Tesla stock here now on earth!
Solar in space is about 5-10x as effective as solar on the ground.
Nobody describes a satellite by specifying the amount of heat that it produces, but by the amount of electrical energy that it consumes.
In a communication satellite, a large fraction of the consumed electrical energy goes into the radio transmitter. Radio transmitters are very efficient and most of the consumed power is emitted as radio waves and only a very small part is converted into heat, which must be handled by the cooling system.
So in any communication satellite, a significant fraction of the consumed energy does not become heat.
And take off again, if reusable spacecraft are meant to be used.
There’s some truly magical thinking behind the idea that government regulations have somehow made it cheaper to launch a rocket than build a building. Rockets are fantastically expensive even with the major leaps SpaceX made and will be even with Starship. Everything about a space launch is expensive, dangerous, and highly regulated. Your datacenter on Earth can’t go boom.
So your huge metal plate would radiate (1673/374)^4 = 400 times less heat, i.e. only 125 kW.
In reality, it would radiate much less than that, even if made of copper or silver covered with Vantablack, because the limited thermal conductivity will reduce the temperature for the parts distant from the body.
Moreover, a heat pump would add an equipment with moving parts that can fail, requiring maintenance.
Then it's roughly 10x-15x and still works.
> Invest in reality, not in billionaire's fantasies.
SpaceX has dramatically reduced payload cost already. How is that a fantasy?
Parent said it would make more sense.
I guess in terms of the relative level of stupidity on display, it would be slightly less stupid to build huge reflectors in space than it is to try to build space datacenters, where the electricity can only power specific pieces of equipment that are virtually impossible to maintain (and are typically obsolete within a few years).
From individual POV yes, but already Falcons are not that expensive. In the sense that it is feasible for a relatively unimportant entity to buy their launch services.
"The satellite is built on Earth, so I’m not sure how it dodges any of those regulations practically."
It is easier to shop for jurisdiction when it comes to manufacturing, especially if your design is simple enough - which it has to be in order to run unattended for years. If you outsource the manufacturing to N chosen factories in different locations, you can always respond to local pressure by moving out of that particular country. In effect, you just rent time and services of a factory that can produce tons of other products.
A data center is much more expensive to build and move around. Once you build it in some location, you are committed quite seriously to staying there.
That is clearly not true. How do you power the data center on antarctica? May i remind you it will be in the shadow of earth for half a year.
What do you mean we don’t have any plans to avoid that? It is a super well studied topic of satelite management. Full books have been written on the topic.
Here is just one: https://ntrs.nasa.gov/api/citations/20230002470/downloads/CA...
Did you think satelites are kept apart by good luck and providence?
The “+ solar power” part is the majority of the energy. Solar panel efficiency is only about 25-30% at beginning-of-life whereas typical albedos are effectively 100%. So your estimate is off by at least a factor of three.
Also, I’m not sure where you got 5 kw from. The area of the satellite is ~100 m2, which means they are intercepting over 100 kw of bolometric solar power.
This is a Musk escapade, so my guess would be extraterritoriality and absence of jurisdiction.
- SpaceX launched its first rocket successfully.
- California voted to build high speed rail.
Eighteen years later:
- SpaceX has taken over the space industry with reusable rockets and a global satcom network, which by itself contains more than half of all satellites in orbit.
- Californian HSR has spent over thirteen billion dollars and laid zero miles of track. That's more than 2x the cost of the Starship programme so far.
Building stuff on Earth can be difficult. People live there, they have opinions and power. Their governments can be dysfunctional. Trains are 19th century technology, it should be easier to build a railway than a global satellite network. It may seem truly magical but putting things into orbit can, apparently, be easier.
Space changes this. Laser based optical links offer bandwidth of 100 - 1000 Gbps with much lower power consumption than radio based links. They are more feasible in orbit due to the lack of interference and fogging.
> Building data centres in the middle of the sahara desert is still much better in pretty much every metric
This is not true for the power generation aspect (which is the main motivation for orbital TPUs). Desert solar is a hard problem due to the need for a water supply to keep the panels clear of dust. Also the cooling problem is greatly exacerbated.
The lack of launch costs more than offset the need for extra panels and batteries.
Of course this doesn't solve the myriad problems, but it does put dissipation squarely in the category of "we've solved similar problems". I agree there's still no good reason to actually do this unless there's a use for all that compute out there in orbit, but that too is happening with immense growth and demand expected for increased pharmaceutical research and various manufacturing capabilities that require low/no gravity.
In Spain, 1kWp of solar can expect to generate about 1800 kWh per year. There's a complication because seasonal difference is quite large - if we assume worst case generation (ie what happens in December), we get more like 65% of that, or 1170 kWh per year.
That means we need to overbuild our solar generation by about 7.5x to get the same amount of generation per year. Or 7.5kWp.
We then need some storage, because that generation shuts off at night. In December in Madrid the shortest day is about 9 hours, so we need 15 hours of storage. Assuming a 1kW load, that means 15kWh.
European wholesale solar panels are about €0.1/W - €100/kW. So our 7.5kWp is €750. A conservative estimate for batteries is €100/kWh. So our 15kWh is €1500. There's obviously other costs - inverters etc. But perhaps the total hardware cost is €3k for 1kW of off-grid solar.
A communications satellite like the Eurostar Neo satellite has a payload power of 22 kW and a launch mass of 4,500 kg. Assuming that's a reasonable assumption, that means about 204kg per kW. Current SpaceX launch costs are circa $1500 per kg - but they're targeting $100/kg or lower. That would give a launch cost of between $300k and $20k per kW of satellite power. That doesn't include the actual cost of the satellite itself - just the launch.
I just don't see how it will make sense for a long time. Even if SpaceX manage to drastically lower launch costs. Battery and solar costs have also been plummeting.
https://www.spaceconnectonline.com.au/manufacturing/4751-air...
https://www.nextbigfuture.com/2025/01/spacex-starship-roadma...
[1] https://www.nlr.gov/news/detail/features/2021/scientists-stu...
No, because of the costs of acquiring land that the railway goes through.
A data center is nowhere near that and requires constant physical interventions. How do they suggest to address this?
It's like his "Mars Colony" junk - and people lap it up, keeping him in the news (in a not explicitly negative light - unlike some recent stories....)
Anywhere on earth is better than space for this application.
Too bad the fire trucks can't get to you when you catch on fire from that hot GPU.
“The reason I concentrate my research on these urban environments is because the composition of soiling is completely different,” said Toth, a Ph.D. candidate in environmental engineering at the University of Colorado who has worked at NREL since 2017. “We have more fine particles that are these stickier particles that could contribute to much different surface chemistry on the module and different soiling. In the desert, you don’t have as much of the surface chemistry come into play.”
We use them because they're many orders of magnitude cheaper and simpler for anywhere near the same bandwidth for the distances required.
Is it reasonable to use Neo as a baseline? Modern Starlink satellites can weigh 800kg, or less than 20% of Neo. I see discussions suggesting they generate ~73kw for that mass. I guess because they aren't trying to blanket an entire continent in signal? Or, why are they so much more efficient than Neo?
Interestingly the idea of doing compute in space isn't a new one, it came up a few years ago pre-ChatGPT amongst people discussing the v2 satellite:
https://forum.nasaspaceflight.com/index.php?topic=58374.msg2...
Still, you make good points. Even if you assume much lighter satellites, the GPUs alone are very heavy. 700kg or so for a rack. Just the payload would be as heavy as the entire Starlink satellite.
What radiators look like is foil or sheet covering fluid loops to spread the heat, control the color, and add surface area.
In general, radiators are white because there's no reason for them to absorb visible light, and they're not hot enough to radiate visible light. You want them to be reflective in the visible spectrum (and strongly absorptive/emissive in the infrared).
A white surface pointing at the sun can be quite cool in LEO, < -40C.
They are usually white, because things in a spacecraft are not hot enough to glow in visible light and you'd rather they not get super hot if the sun shines on them.
The practical emittance of both black paint and white paint are very close to the same at any reasonable temperature-- and both are quite good, >90% of this magical material that you cite ;)
Better materials -- with less visible absorption and more infrared emittance -- can make a difference, but you still need to convect or conduct the heat to them, and heat doesn't move very well in thin materials as my sibling comment says.
The graphene radiator you cite is more about active thermal control than being super black. Cheap ways to change how much heat you are dumping are very useful for space missions that use variable amounts of power or have very long eclipse periods, or what move from geospace to deep space, etc. Usually you solve it on bigger satellites with louvers that change what color they're exposing to the outside, but those are mechanical parts and annoying.
There’s so much overhead you’re hand waving away to make your numbers work.
So the total heat load if 4 MW (of which 1 MW was temporarily electrical energy before it was used by the datacenter or whatever).
Let's assume a single planar radiator, with emissivity ~1 over the thermal infrared range.
Let's assume the target temperature of the radiator is 300 K (~27 deg C).
What size radiator did you need?
4 MW / (5.67 * 10 ^ -8 W / ( m ^2 K ^4 ) * 300 K ^4) = 8710 m ^2 = (94 m) ^2
so basically 100m x 100m. Thats not insanely large.
The solar panels would have to be about 3000 m ^2 = 55m x 55m
The radiator could be aluminum foil, and something amounting to a remote controlled toy car could drive around with a small roll of aluminum wire and locally weld shut small holes due to micrometeorites. the wheels are rubberized but have a magnetic rim, on the outside theres complementary steel spheres so the radiator foil is sandwiched between wheel and steel sphere. Then the wheels have traction. The radiator could easily weigh less than the solar panels, and expand to much larger areas. Better divide the entire radiator up into a few inflatable surfaces, so that you can activate a spare while a sever leak is being solved.
It may be more elegant to have rovers on both inside and outside of the radiator: the inner one can drop a heat resistant silicone rubber disc / sheet over the hole, while the outside rover could do the welding of the hole without obstruction of the hole by a stopgap measure.
Also I'm astounded how important AI data centers are when we are running out of freshwater, to mention a thing we could easily solve with focusing our efforts on it instead of this. But yeah, surely the Space AI Data Centers (aka. "SkyNet") is the most important we must build...
Also this is just about Elon jumping the shark...
As I've pointed it out to you elsewhere -- how do you couple the 4MW of heat to the aluminum foil? You need to spread the power somewhat evenly over this massive surface area.
Low pressure gas doesn't convect heat well and heat doesn't conduct down the foil well.
It's just like how on Earth we can't cool datacenters by hoping that free convection will transfer heat to the outer walls.
Nowadays such microwave power amplifiers should be made with gallium nitride transistors, which should allow better efficiencies than the ancient amplifiers using LDMOS or travelling-wave tubes, and even those had efficiencies over 50%.
For beamformers, there have been research papers in recent years claiming a great reduction in losses, but presumably the Starlink satellites are still using some mature technology, with greater losses.
Lets assume you truly believe the difficulty is the heat transport to the radiator, how is it solved on earth?
It's both. You have to spread a lot of heat very evenly over a very large surface area. This makes a big, high-mass structure.
> how is it solved on earth?
We pump fluids (including air) around to move large amounts of heat both on Earth and in space. The problem is, in space, you need to pump them much further and cover larger areas, because they only way the heat leaves the system is radiation. As a result, you end up proposing a system that is larger than the cooling tower for many nuclear power plants on Earth to move 1/5th of the energy.
The problem is, pumping fluids in space around has 3 ways it sucks compared to Earth:
1. Managing fluids in space is a pain.
2. We have to pump fluids much longer distances to cover the large area of radiators. So the systems tend to get orders of magnitude physically larger. In practice, this means we need to pump a lot more fluid, too, to keep a larger thing close to isothermal.
3. The mass of fluids and all their hardware matters more in space. Even if launch gets cheaper, this will still be true compared to Earth.
I explained this all to you 15 hours ago:
> If this wasn't a concern, you could fly a big inflated-and-then-rigidized structure and getting lots of area wouldn't be scary. But since you need to think about circulating fluids and actively conducting heat this is much less pleasant.
You may notice that the areas, etc, we come up with here to reject 70kW are similar to those of the ISS's EATCS, which rejects 70kW using white-colored radiators and ammonia loops. Despite the use of a lot of exotic and expensive techniques to reduce mass, the radiators mass about 10 tonnes-- and this doesn't count all the hardware to drive heat to them on the other end.
So, to reject 105W on Earth, I spend about 500g of mass; if I'm as efficient as EATCS, it would be about 15000g of mass.
And it still doesn’t solve the problem of a cascade causing shrapnel density to increase in an orbit shell which then causes satellites to use some of their scarce maneuver budget to avoid collision. But as soon as a satellite exhausts that budget, it becomes fodder for the shrapnel cascade.
And you still haven’t provided a source for your claim.
Well acttshually, it's 100% efficient. If you put 1W in, you will get exactly one watt out, steady state. The resulting steady state temperature would be close to watts * steady state thermal resistance of the system. ;)
I don't think you could use "efficiency" here? The math would be based on thermal resistance. How do you get a percentage from that? If you have a maximum operating temperature, you end up with a maximum operating wattage. Using actual operating wattage/desired operating wattage doesn't seem right for "efficiency".
Why not do the obvious comparison with terrestrial data centers?
Imagine a liquid which can be electrically charged, and has a low boiling point.
(Ask 3M/DuPont/BASF/Bayer... - context 'immersion cooling')
Attach heat-pipes with that stuff to the chips as is common now, or go the direct route via substrate-embedded microfluidics, as is thought of at the moment.
Radiate the shit out of it by spraying it into the vacuum, dispersing into the finest mist with highest possible surface, funnel the frozen mist back in after some distance, by electrostatic and/or electromagnetic means. Repeat. Flow as you go.
Wouldn't even need to be that 'autonomous', since the installation is fixed.
More like the things simulating fireworks with their LEDs in preprogrammed formation flight over a designated area.
The article itself said the maximum was 50% and it was significantly less of a problem in the desert. Even 50% still beats space by miles, that only increases per kWh cost by ~2c the need for batteries is still far more expensive.
So sure I could bring up other sources but I don’t want to get into a debate about the relative validity of sources etc because it just isn’t needed when the comparison point is solar on satellites.