Comment by kin
1 month ago
For those questioning viability, there's a startup called Starcloud https://www.starcloud.com/ with a public whitepaper explaining a bit their hardware and economics https://www.starcloud.com/wp. They've already had one small proof of concept launched. Not trying to promote, I just heard about them on the ycomb podcast
“A 5 GW data center would require a solar array with dimensions of approximately 4 km by 4 km”
I think dodging debris is challenging at that scale.
Also this is the solar cells not the radiators
Desert land is full of that amount of area available for peanuts.
That’s 4000 acres. I see a 6000 acre ranch available in Arizona for $7m. The cost of building a 5GW DC is about 100 billion. Land including enough for all the solar and battery you need to be completely self sufficient is basically free.
You can fly a drone laden with fireworks across a desert. Harder to do in LEO
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Presumably that’s not a single satellite.
Nope, it's a single massive panel sat and they're using $30/kg as their launch costs.
Up to you how plausible you think that is.
There's an artist's impression of the frigging thing in the whitepaper! It's very obviously a single enormous thing!
> Figure 3. A data center in Sun Synchronous Orbit, showing a 4km x 4km deployed solar array and radiators.
Right, the goal here is a more realistic Dyson swarm, not a Dyson sphere (yet)
I wonder if the shadows from such a large area would have a climate cooling effect?
The Earth's surface area is ~ 510,000,000 km^2. For simplicity, say exactly half of it is receiving sunlight. If the satellite perfectly shadows 16 km^2, it would reduce incoming solar energy reaching Earth by 16/205,000,000 = 0.00000078%, I think.
So not really. There are some proposals for space-based geoengineering, https://www.sciencedirect.com/science/article/pii/S146290112... has a summary. I can't say how plausible any of them are.
Ideally you'd put it in an orbit that wouldn't shadow earth, since if it goes in front of earth in part of the orbit then it'll go behind earth (and be in shadow) for part of the orbit. They mention they'd want it in a dawn-dusk sun-synchronous orbit, which would be in sunlight all the time and would never shadow the earth.
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Would be cool if so, but I wonder what the plan is regarding radiation pressure pushing things out of orbit.
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I think the principle is correct but probably it would need to be much bigger.
That whitepaper puts the cost of a 40 MW cluster at $167m on land and $8.2m in space, inclusive of launch costs.
They seem to not be counting the $1B of GPUs on either side, making the difference pretty small. They also think launching 200 racks of equipment into space will cost $5M.
that sounds ridiculous. How could it be so much cheaper
Because launch costs and density are completely imaginary. The whole thing is predicated on launch vehicles they hope someone builds eventually. They also appear to have profoundly miscalculated their radiation shielding costs and amounts, but I'm not really motivated to calculate that correctly.
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Because they have factored in a genie’s lamp, which they will use to wish costs down significantly
They're assuming $30/kg launch costs.
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how much area do you need to radiate away 40 MW, assuming you want to keep your GPUs at a toasty 90 celcius. Every space datacenter fan/promoter enthuses about the free solar power, but forget to mention how the heat will be dissipated.
I don't know why people are so fixated on heating as some kind of gotcha. If we already assumed magical 16km^2 solar array, then we can also assume matching size radiator, with heatpumps. If ISS can do it, then there is no technical issue with doing it on bigger scale. It "only" doesn't make any sense from financial viewpoint, terrestrial datacenters beat it in every way.
NVidia's recent support for warm (45 °C) water cooling for their new racks probably had more impact on price of compute than than space servers will ever have.
Is there not enough space in space?
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Historically there have been many startups with pitches that haven’t worked out. The existence of a startup who think they can tackle a particular problem isn’t evidence of the viability of their proposed solution. If they succeeded, that would be evidence.
Yeah. Starcloud is notable for two things: firstly that they've raised a lot of money and secondly that theyve already abandoned the nonsense in their white paper and shifted to a "lots of satellites" model like everyone else exploring orbital datacentres...
I think SpinLaunch is great example. They were actually able to fund and make a working prototype, tested it, but still decided it is not practical after all, before pivoting to production of knockoff Starlink-like satellites.
What happens to all the precious metals that go up with these data centers? At least with a land based data center we have a vague hope of recycling the raw materials at some point in the future.
Just like with all the satellites, the recycling plan is to allow them to burn in atmosphere. Maybe after we breathe enough of it, we can recover the metals via crematories.
Precious metals stop being precious metals once asteroid mining begins. I don't think it will be super soon but I could certainly foresee it being a thing within 10 - 15 years which is about 2 - 3 generations of satellites from my very brief Google.
We are decades away from asteroid mining at best, even assuming we go all in starting today. The difficulties and numerous engineering challenges of mining at zero g cannot be understated.
Starcloud seems like a whole lot of hand waving and BS. This is a good video that goes over their problems:
https://www.youtube.com/watch?v=_qpdUNMt2yg
It reminds me of the Hyperloop white paper, whose existence for many was proof enough that it was viable and beyond questioning.
Admiral Rickover explains the difference between PoC and practical: https://whatisnuclear.com/rickover.html. It is about nuclear, but applies here as well.
Note how their cost comparison table mentions "launch" but not a word about how to retrieve systems parts after their end-of-life. "There's so much junk already circling around the planet, what does it matter if we'll leave it there to rot?" can't possibly be the stance they're taking.
If it’s in low orbit then it will just burn up. Satellites have to keep thrusting slightly in order to keep their position.
So I suppose recycling is not a thing in space?
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