Comment by rybosworld
11 hours ago
An 8 GPU B200 cluster goes for about $500k right now. You'd need to put thousands of those into space to mimic a ground-based data center. And the launch costs are best case around 10x the cost of the cluster itself.
Letting them burn up in the atmosphere every time there's an issue does not sound sustainable.
A Falcon Heavy takes about 63 tons to LEO, at a cost of about $1,500 per kg. A server with 4x H200s and some RAM and CPU costs about $200k, and weighs about 60kg, with all the cooling gear and thick metal. As is, it would cost $90k to get to LEO, half of the cost of the hardware itself.
I suppose that an orbit-ready server is going to cost more, and weigh less.
The water that serves as the coolant will weigh a lot though, but it can double as a radiation shield, and partly as reaction mass for orbital correction and deorbiting.
Just so we can agree on numbers for the napkin math - an 8x H200 weighs 130 kg:
https://www.nvidia.com/en-eu/data-center/dgx-h200/?utm_sourc...
Power draw is max 10.2 kW but average draw would be 60-70% of that. let's call it 6kW.
It is possible to obtain orbits that get 24/7 sunlight - but that is not simple. And my understanding is it's more expensive to maintain those orbits than it would be to have stored battery power for shadow periods.
Average blackout period is 30-45 minutes. So you'd need at least 6 kWh of storage to avoid draining the batteries to 0. But battery degradation is a thing. So 6 kWh is probably the absolute floor. That's in the range of 50-70 kg for off-the-shelf batteries.
You'd need at least double the solar panel capacity of the battery capacity, because solar panels degrade over time and will need to charge the batteries in addition to powering the gpu's. 12 kW solar panels would be the absolute floor. A panel system of that size is 600-800 kg.
These are conservative estimates I think. And I haven't factored in the weight of radiators, heat and radiation shielding, thermal loops, or anything else that a cluster in space might need. And the weight is already over 785 kg.
Using the $1,500 per kg, we're approaching $1.2 million.
Again, this is a conservative estimate and without accounting for most of the weight (radiators) because I'm too lazy to finish the napkin math.
I think we're on the same page. Lifting the actual computing devices would be not that expensive, compared to lifting a lot of other related mass, principally the cooling systems, and the solar panels.
The solar panels used in space are really lightweight, about 2 kg / m² [1], it's like ten times lighter weight than terrestrial panels. Still they need load-bearing scaffolding, and electrical conductors to actually collect the hundreds of kilowatts.
Water can't be made as lightweight though.
[1]: https://space.stackexchange.com/a/30238
Are launch costs really 10x!? Could I get a source for that?
In the back on my head this all seemed astronomically far-fetched, but 5.5 million to get 8 GPUs in space... wild. That isn't even a single TB of VRAM.
Are you maybe factoring in the cost to powering them in space in that 5 million?
The Falcon Heavy is $97 million per launch for 64000 kg to LEO, about $1,500 per kg. Starship is gonna be a factor 10 or if you believe Elon a factor 100 cheaper. A single NVidia system is ~140kg. So a single flight can have 350 of them + 14000kg for the system to power it. Right now 97 million to get it into space seems like a weird premium.
Maybe with Starship the premium is less extreme? $10 million per 350 NVidia systems seems already within margins, and $1M would definitely put it in the range of being a rounding error.
But that's only the Elon style "first principles" calculation. When reality hits it's going to be an engineering nightmare on the scale of nuclear power plants. I wouldn't be surprised if they'd spend a billion just figuring out how to get a datacenter operational in space. And you can build a lot of datacenters on earth for a billion.
If you ask me, this is Elon scamming investors for his own personal goals, which is just the principle of having AI be in space. When AI is in space, there's a chance human derived intelligence will survive an extinction event on earth. That's one of the core motivations of Elon.
I guess he adds the weight of all the hardware to make the whole thing work.
You also need square kms of radiators to cool 100MW
Playing devil's advocate, when a GPU dies you don't typically fix it, right? You just replace it.
What if you could keep them in space long enough that by the time they burn up in the atmosphere, there are newer and better GPUs anyway?
Still doesn't seem sustainable to me given launch costs and stuff (hence devil's advocate), but I can sort of see the case if I squint?
Let me rip my bong real quick..
What if you had a fleet of Optimus robots up there who would actually operate a TSMC in space and they would maintain the data centers in space?
Hold on let me enter a K hole…
What if we just did things?
YC founder spotted