The quoted "1 TW of photovoltaic cells per year, globally" is the peak output, not the average output. They're only about 20% higher peak output in space… well, if you can keep them cool at least.
That wasn't the original question. The head of this thread was quoting Musk's claim, which I repeat here:
> it is possible to put 500 to 1000 TW/year of AI satellites into deep space
This is 500-1000 times as much as current global production.
Musk is talking about building on the Moon 500-1000 times as much factory capacity as currently exists in aggregate across all of Earth, and launching the products electromagnetically.
Given how long PV modules last, that much per year is enough to keep all of Earth's land area paved with contiguous PV. PV doesn't last as long in space, but likewise the Moon would be totally tiled in PV (and much darker as a consequence) at this production rate.
In fact, given it does tile the moon, I suspect Musk may have started from "tile moon with PV" and estimated the maximum productive output of that power supply being used to make more PV.
I mean, don't get me wrong, in the *long term* I buy that. It's just that by "long term" I mean Musk's likely to have buried (given him, in a cryogenic tube) for decades by the time that happens.
Even being optimistic, given the lack of literally any experience building a factory up there and how our lunar mining experience is little more than a dozen people and a handful of rovers picking up interesting looking rocks, versus given how much experience we need down here to get things right, even Musk's organisation skills and ability to enthuse people and raise capital has limits. But these are timescales where those skills don't last (even if he resolves his political toxicity that currently means the next Democrat administration will hate his guts and do what they can to remove most of his power), because he will have died of old age.
The 1TW is the rated peak power output. It's essentially the same in space. The thing that changes is the average fraction of this sustained over time (due to day/night/seasons/atmosphere, or the lack of all of the above).
It's still the same 1TW theoretical peak in space, it's just that you can actually use close to that full capacity all the time, whereas on earth you'd need to over-provision substantially and add storage, so 1TW of panels can only drive perhaps a few hundred GW of average load.
The dominant factor is "balance of system" aka soft costs, which are well over 50%.[0]
Orbit gets you the advantage of 1/5th the PV and no large daily smoothing battery, but also no on-site installation cost, no grid interconnect fees, no custom engineering drawings, no environmental permitting fees, no grid of concrete footers, no heavy steel frames to resist wind and snow loads. The "on-site installation" is just the panels unfolding, and during launch they're compact so the support structure can be relatively lightweight.
When you cost building the datacenter alone, it's cheaper on earth. When you cost building the solar + batteries + datacenter, it (can be) cheaper in space, if you build it right and have cheap orbital launch.
I do say it's predicated on cheap orbital launch. Clearly they expect Starship to deliver, and they're "skating to where the puck will be" on overall system cost per unit of compute.
But yeah, I didn't include that delivering all that stuff by truck (including all the personnel) to a terrestrial PV site isn't free either.
Yeah, soft costs like permitting and inspections are supposedly the main reason US residential solar costs $3/watt while Australian residential solar costs $1/watt. It was definitely the worst and least efficient part of our solar install, everything else was pretty straightforward. Also, running a pretty sizable array at our house, the seasonal variation is huge, and seasonal battery storage isn’t really a thing.
Besides making PV much more consistent, the main thing this seems to avoid is just the red tape around developing at huge scale, and basically being totally sovereign, which seems like it might be more important as tensions around this stuff ramp up. There’s clearly a backlash brewing against terrestrial data centers driving up utility bills, at least on the East Coast of the US.
The more I think about it, the more this seems like maybe not a terrible idea.
So far most of the datacenters are built in very convenient places and people will start to build them in inconvenient places like Sahara or Mongolia way before they will building them in space
Maybe. But for SpaceX, it’s more aligned with what they’re trying to do to just learn to manufacture them at scale and lob them into space. And one of the benefits there is the uniformity of it - they can treat them all the same, rather than dealing with a bunch in different geographies with different power issues, governmental issues, etc. That’s been one of the major issues with rolling out solar. In the US, there are >20,000 AHJs, each with different rules and processes. A huge constellation of satellites seems easier to reason about and build systems to maintain en masse, because it’s more uniform.
I’m not saying this is a good idea. I’ve got a lot of SpaceX stock, and I wasn’t really happy to hear the news, this is mostly me trying to understand why they might think this is a good idea, and brainstorming out loud, with a dash of coping. Seems most here think that it’s just stupid, but then, most commenters thought Starlink was stupid, iirc, and that turned out to be wildly wrong. But it might also just be stupid this time.
Do you imagine there'd be less red tape involved in launching multiple rockets per day carrying heavy payloads?
Like this argument just gets absurd: you're claiming building a data center on earth will be harder from a permitting perspective than FAA flight approval for multiple heavy lift rocket launch and landing cycles.
Mining companies routinely open and close enormous surface area mines all over the world and manage permitting for that just fine.
There's plenty of land no one will care if your build anything on, and being remote with maybe poor access roads is still going to be enormously cheaper then launching a state of the art heavy lift rocket which doesn't actually exist yet.
> Ok, why are so many being built in Northern Virginia, rather than in the middle of nowhere where there will be no backlash?
Right? So if that's the case why would putting them in Space, far less accessible in every conceivable way, with numerous additional expenses and engineering constraints, be cheaper?
Just based on weight, looks like a Block 4 starship should be able to bring up ~150 30 panel pallets of 550W panels, about 2 MW. They're trying to get a starship launch down to $2M with full reuse. GPU DCs are frequently in the neighborhood of 500GW, so maybe 250 launches for just the power generation, or $500M? And then there's radiators, so let's say $1B for launch of power and heat dissipation. For comparison, 500MW of H100 machines retails for >$10B, and the launch cost for those shouldn't be too bad compared to the power, since they're more value dense. And then there's land and ongoing power and cooling spending for the terrestrial version, which you don't have for the space version. So actually, doesn't seem terrible economically? This is obviously very back-of-the-envelope, and predicated on the optimistic scenario for starship launch cost.
This is really underselling it tbh. Any land that's growing corn in a developed country is likely top 1% of land on earth. Half of the earth is desert and tundra. Which is still incredibly easier to work with than space because you can ship there with a pickup very cheaply. Maybe when nevada and central australia are wall-to-wall solar panels we can check back on space.
The Technology Connections Youtube channel recently did a great video arguing pretty convincingly that the land used to grow corn for cars would be vastly more efficiently used from an energy perspective if we covered it with solar panels.
You just have to remember, most of these people live in high density regions and have little comprehension about how much surface area humanity truly occupies... And that isn't even accounting for offshore constructs.
Realizing the impracticality of it (and that such approaches often collapse under the infeasibility of it) ... wouldn't it be better to... say... cover the Sahara in solar panels instead? That's gotta be cheaper than shipping them into space.
From an engineering perspective, with today’s costs, yes. But don’t forget the political complications of dealing with all those countries that own the Sahara, that’s going to come at it’s own cost.
I think this is all ridiculous, to be clear, but re: this problem couldn't the radiators in theory be oriented so that they vent in opposite directions and cancel out any thrust that would be generated?
Solar modules you can buy for your house usually have quoted power ratings at "max STC" or Standard Testing Conditions, which are based on insolation on Earth's surface.
STC uses an irradiance of irradiance 1000W/m2, in space it seems like you get closer to 1400W/m2. That's definitely better, but also not enormously better.
Seems also like they are rated at 25C, I am certainly not a space engineer but that seems kind of temperate for space where cooling is more of a challenge.
Seems like it might balance out to more like 1.1x to 1.3x more power in space?
Satellites can adjust attitude so that the panels are always normal to the incident rays for maximum energy capture. And no weather/dust.
You also don't usually use the same exact kind of panels as terrestrial solar farms. Since you are going to space, you spend the extra money to get the highest possible efficiency in terms of W/kg. Terrestrial usually optimizes for W/$ nameplate capacity LCOE, which also includes installation and other costs.
For one or a few-off expensive satellites that are intended to last 10-20 years, then yes. But in this case the satellites will be more disposable and the game plan is to launch tons of them at the lowest cost per satellite and let the sheer numbers take care of reliability concerns.
It is similar to the biological tradeoff of having a few offspring and investing heavily in their safety and growth vs having thousands off offspring and investing nothing in their safety and growth.
I think it's because at this scale a significant limit becomes the global production capacity for solar cells, and SpaceX is in the business of cheaper satellites and launch.
You don't even need a particularly large scale, it's efficient resource utilization.
Humanity has a finite (and too small) capacity for building solar panels. AI requires lots of power already. So the question is, do you want AI to consume X (where X is a pretty big chunk of the pie), or five times X, from that total supply?
Using less PV is great, but only if the total cost ends up cheaper than installing 5X the capacity as terrestrial PV farms, along with daily smoothing batteries.
SpaceX is only skating to where they predict the cost puck will be.
That's still a smaller ratio than the ~4X gain in irradiance over LEO. But if you're doing it at scale you could use orbital tugs with ion drives or something, and use much less fuel per transfer.
It's probably not competitive at all without having fully reusable launch rockets, so the cost to LEO is a lot lower.
8 tons over 22 is a little over 1/3rd the original payload to LEO. If 4x the solar generation potential (not irradiance - the sun is not 4x brighter in space at Earth's orbital radius) is the reward, that's putting an incredible premium on a 3x multiplier on launch costs per kg (at minimum - likely higher, you're also inheriting a worse radiation environment).
But those two parameters are not equals: 3x the cost per kg is a much higher number then 4x the solar power.
Here in Maine in the depths of winter (late December), 1 m^2 of ground can collect 4 kwh per day (weird units).
That's why people are trying to build solar here. Our power is expensive due partially to failing to build basically any new generation, and some land is very cheap, and the operational cost of a solar farm is minuscule.
Solar farming is basically an idle game in real life and my addiction is making me itchy.
You can overprovision, and you should with how stupidly cheap solar is.
That we aren't spending billions of Federal dollars building solar anywhere we can, as much as we can, is pathetic and stupid and a national tragedy.
We got so excited about dam building that there's no where to build useful dams anymore, and there is significant value to be gained by removing those dams, yet somehow we aren't deploying as much solar as we possibly can?
It's a national security issue. China knows this, and is building appropriately.
The southwest should be generating so much solar power that we sequester carbon from the atmosphere simply because there is nothing else left to do with the power.
> And then there’s that pesky night time and those annoying seasons.
The two options there are cluttering up the dawn dusk polar orbit more or going to high earth orbit so that you stay out of the shadow of the earth... and geostationary orbits are also in rather high demand.
I grew up on a rural farm in California with a dial-up connection that significantly hampered my ability to participate in the internet as a teenager. I got Starlink installed at my parents' house about five years ago, and it's resulted in me being able to spend considerably more time at home.
Even with their cheapest home plan, we're getting like 100 Mbps down and maybe 20 to 50 up. So it's just not true at all that you would have connections that are a megabit or two per second.
That's not what I'm suggesting. The post says "deep space". If you're going to try to harvest even a tiny percentage of the sun's energy, you're not doing that in Earth's orbit. The comparison is a webcam feed from Mars.
The intractable problem is heat dissipation. There is to little matter in space to absorb excess heat. You'd need thermal fins bigger than the solar cells. The satellite's mass would be dominated by the solar panels and heat fins such that maybe 1% of the mass would be usable compute. It would be 1000x easier to leave them on the moon and dissipate into the ground and 100000x easier to just keep making them on earth.
> There is to little matter in space to absorb excess heat.
If that were true the Earth would have overheated, molten and turned to plasma long ago. Earth cools by.... radiative cooling. Dark space is 4 K, thats -267.15 deg C or -452.47 deg Fahrenheit. Stefan-Boltzmann law can cool your satellite just fine.
> You'd need thermal fins bigger than the solar cells.
Correct, my pessimistic calculation results in a factor of 3,...
but also Incorrect, there wouldn't be "fins" thats only useful for heat conduction and convection.
That's pretty much a solved problem. We've had geostationary constellations for TV broadcast at hundreds of megabytes for decades now, and lasers for sat-to-sat comms seems to be making decent progress as well.
> it is possible to put 500 to 1000 TW/year of AI satellites into deep space, meaningfully ascend the Kardashev scale and harness a non-trivial percentage of the Sun’s power
3. vLLMa exist and take video and images as input.
4. When a new model checkpoint needs to go up, are we supposed to wait months for it to transfer?
5. A one million token context window is ~4MB. That's a few milliseconds terrestrially. Assuming zero packet loss, that's many seconds
6. You're not using TCP for this because the round trip time is so high. So you can't cancel any jobs if a user disconnects.
7. How do you scale this? How many megabits has anyone actually ever successfully sent per second over the distances in question? We literally don't know how to get a data center worth of throughput to something not in our orbit, let alone more than double digit megabits per second.
and, of course and inter-satellite comms and earth base station links to get the data up and down. Starlink is one thing at just above LEO a few hundred km and 20km apart, but spreading these around 10s of thousands of km and thosands of km apart is another thing