I don't think dissipating heat would be an issue at all. The cost of launch I think is the main bottleneck, but cooling would just be a small overhead on the cost of energy. Not a fundamental problem.
Either that or your talking out of your ass.
FYI a single modern rack consumes twice the energy of the entire ISS, in a much much much much smaller package and you'll need thousands of them. You'd need 500-1000 sqm of radiator per rack and that alone would weight several tonnes...
You'll also have to actively cool down your gigantic solar panel array
No need to apply at NASA, to the contrary, if you don't believe in Stefan Boltzmann law, feel free to apply for a Nobel prize with your favorite crank theory in physics.
Without eventually moving compute to space we are going to have compute infringe on the space, energy, heat dissipation rights of meatbags. Why welcome that?!?
Sure, it occurs, but what does the Stefan–Boltzmann law tell us about GPU clusters in space?
I provided the calculation for the pyramidal shape: if the base of a pyramid were a square solar panel with side length L, then for a target temperature of 300K (a typical back of envelope substitute for "room temperature") the height of the pyramid would have to be about 3 times the side length of the square base. Quite reasonable.
> Sure, it occurs, but what does the Stefan–Boltzmann law tell us about GPU clusters in space?
The Stefan-Boltzmann law tells us that whatever prevents us from putting GPU clusters in space, it's not the difficulty in shedding heat by thermal radiation that is supposedly stopping us.
If the base were a solar panel aimed perpendicular to sun, then the tip is facing away and all side triangles faces of the pyramid are in the shade.
I voluntarily give up heat dissipation area on 2 of the 4 triangular sides (just to make calculations easier, if we make them thermally reflective -emissivity 0-, we can't shed heat, but also don't absorb heat coming from lukewarm Earth).
The remaining 2 triangular sides will be large enough that the temperature of the triangular panels is kept below 300 K.
The panels also serve as the cold heat baths, i.e. the thermal sinks for the compute on board.
Not sure what you mean with wings, I intentionally chose a convex shape like a pyramid so that no part of the surface of the pyramid can see another part of the surface, so no self-obstruction for shedding heat etc...
If this doesn't answer your question, feel free to ask a new question so I understand what your actual question is.
The electrical power available for compute will be approximately 20% (efficiency of solar panels) times the area of the square base L ^ 2 times 1360 W / m ^ 2 .
The electrical power thus scales quadratically with the chosen side length, and thus linearly with the area of the square base.
Also this assumes a flat surface on both sides. Another commenter in this thread brought up a pyramid shape which could work.
Finally, these gpus are design for earth data centers where power is limited and heat sinks are abundant. In the case of space data centers you can imagine we get better radiators or silicon that runs hotter. Crypto miners often run asics very hot.
I just don't understand why every time this topic is brought up, everyone on HN wants to die on the hill that cooling is not possible. It is?? the primary issue if you do the math is clearly the cost of launch.
My example is optimized not for minimal radiator surface area, but for minimal mathematical and physical knowledge required to understand feasibility.
Your numbers are different because you chose 82 C (355 K) instead of my 26 C (300 K).
Near normal operating temperatures hardware lifetime roughly doubles for every 10 deg C/K decrease in temperature (this does not hold indefinitely of course).
You still need to move the heat from the GPU to the radiator so my example of 26 deg C at the radiator just leaves a lot of room against criticism ;)
You can prove that the lower efficiency can be managed, and they will still say the only thing they know: "Thermal radiation is not efficient".
as an example my points almost instantly fell down 15 points, but over the last 11 hours it has recuperated back to just a 1 point drop.
it's not because they don't like to write an apology (which I don't ask for) that they aren't secretly happy they learnt something new in physics, and in the end thats what matters to me :)
Yeah doesn't sound particularly feasible, sorry. Glad you know all the math though!
For a 230 kW cluster: 16 x DGX (8x)B200; we arrived at a 30m x 30m solar PV area, and a 90 meter distance from the center of the solar array to the tip of the pyramid.
1 GW = 4348 x 230 kW
sqrt(4348)= ~66
so launch 4348 of the systems described in the calculation I linked, or if you insist on housing them next to each other:
the base length becomes 30 m x 66 = 1980 m = ~ 2 km. the distance from center of square solar array to the tip of the pyramid became 6 km...
any of these systems would need to be shipped and collected in orbit and then assembled together.
a very megalomaniac endeavor indeed.
To run just one cluster (which would be generally a useless endeavor given it is just a few dozen GPUs) would be equivalent to the best we've ever done, and you wonder why you're being downvoted? Your calculations, which are correct from a scientific (but not engineering) standpoint, don't support the argument that it is possible, but rather show how hard it is. I can put the same cluster in my living room and dissipate the heat just fine, but you require a billion dollar system to do it in space.
The main benefit is that solar panels go from a complicated mess of batteries + permitting to a very stable, highly efficient energy source.