> As launch costs fall, orbital data centers will leverage 24/7 solar energy and _passive cooling_, rapidly deploying to gigawatt-scale, avoiding permitting constraints on Earth.
It sounds like they want to use copper heatspreaders and radiators to dump gigawatts into space. From those little pods connected to the spine... without any active cooling components
Oh dear.
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There’s really no such thing as active cooling in space. You can move the heat from the component to the radiators with pumped water but ultimately the only way to get rid of heat in space is passively radiating it away.
And it’s very inefficient at removing heat unless there’s a large temperature differential. If the radiator heats up to 70C it can dissipate 785 watts per square meter of area facing into space. I guess assuming you have a front and also a back of a panel both radiating equally that could be 1570W per square meter of panel material. You can check it yourself with this equation: https://courses.lumenlearning.com/suny-physics/chapter/14-7-....
So for this “1 gigawatt” project you’d need 0.6 million square meters of double-sided radiators. Which is about the area of the Pentagon, or a quarter the area of Monaco. It would weigh around 6000 metric tons, which is the weight of half the trash produced in NYC in a day. This would require up to 300 Falcon Heavy launches for a total launch cost of $30 billion.
They say the launch cost for one 40MW unit (including radiators! and solar panels! and radiation shielding!) will be $5 million. That’s pretty laughable as just 25 of these 40MW units = 1GW. And 1/25 of $30 billion is … well over $1 billion.
Somehow, I estimate that JUST THE COOLING RADIATORS will cost >$1 billion to put into space. But they estimate they can put the whole everything in space for less than 0.5% of a very reasonable estimate.
EDIT: Actually, just launching enough H100’s to consume 40MW would cost at least $200 million. One H100 uses 700W so you’d need 57,000 of them to consume 40MW. Each H100 weighs 1.7kg so thats a total of 97 metric tons of H100’s. The falcon heavy can launch between 20-64 metric tons so you’ll need two launches at $100 million per launch.
There's one cool way of "passively cooling energy into space" from Earth
Build your datacenters in a cold place with clear skies and train at night.
If SpaceX can really pull that off, my math above would look a lot different.
True. But this relies a lot on software and probably some specialized details in hardware as well
Your Dragon docking maneuvering requires way less calculations than your typical AI training. Hence it is ok to have HW do the same calculation multiple times and check the values.
This is different from AI training where you want the most reliability 24h/day
Another aspect that is entirely missing from that pdf that doesn't necessarily convince me these people have a plan.
I'm fairly confident that for the next decade that if you want to launch ~10 tons into orbit, it'll cost you $70M whether you launch on Falcon9 or Starship or Neutron or New Glenn. If you want to launch 100 tons, it'll cost you more even though it's the same Starship, just because nobody else can do that.
If you want to launch 1000 rockets you will be able to call up SpaceX and negotiate a much better price, but only if you have good negotiating power -- if you can convince them you won't launch at all if you don't get a good price.