Space is a vacuum. i.e. The lack-of-a-thing that makes a thermos great at keeping your drink hot. A satellite is, if nothing else, a fantastic thermos. A data center in space would necessarily rely completely on cooling by radiation, unlike a terrestrial data center that can make use of convection and conduction. You can't just pipe heat out into the atmosphere or build a heat exchanger. You can't exchange heat with vacuum. You can only radiate heat into it.
Heat is going to limit the compute that can be done in a satellite data centre and radiative cooling solutions are going to massively increase weight. It makes far more sense to build data centers in the arctic.
Musk is up to something here. This could be another hyperloop (i.e. A distracting promise meant to sabotage competition). It could be a legal dodge. It could be a power grab. What it will not be is a useful source of computing power. Anyone who takes this venture seriously is probably going to be burned.
It probably increases Elon's share of the combined entity.
It delivers on a promise to investors that he will make money for them, even as the underlying businesses are lousy.
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?
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.
"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...
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
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.