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
The limiting factor isn't the emissivity, it's that you're having to rely on radiation as your only cooling mechanism. It's super slow and inefficient and it limits how much heat you can dissipate.
Like the other person said, you can't do any better than blackbody radiation (emissivity=1).
So the total heat load if 4 MW (of which 1 MW was temporarily electrical energy before it was used by the datacenter or whatever).
Let's assume a single planar radiator, with emissivity ~1 over the thermal infrared range.
Let's assume the target temperature of the radiator is 300 K (~27 deg C).
What size radiator did you need?
4 MW / (5.67 * 10 ^ -8 W / ( m ^2 K ^4 ) * 300 K ^4) = 8710 m ^2 = (94 m) ^2
so basically 100m x 100m. Thats not insanely large.
The solar panels would have to be about 3000 m ^2 = 55m x 55m
The radiator could be aluminum foil, and something amounting to a remote controlled toy car could drive around with a small roll of aluminum wire and locally weld shut small holes due to micrometeorites. the wheels are rubberized but have a magnetic rim, on the outside theres complementary steel spheres so the radiator foil is sandwiched between wheel and steel sphere. Then the wheels have traction. The radiator could easily weigh less than the solar panels, and expand to much larger areas. Better divide the entire radiator up into a few inflatable surfaces, so that you can activate a spare while a sever leak is being solved.
It may be more elegant to have rovers on both inside and outside of the radiator: the inner one can drop a heat resistant silicone rubber disc / sheet over the hole, while the outside rover could do the welding of the hole without obstruction of the hole by a stopgap measure.