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Cooling in Space

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Re: Cooling in Space

#91

Post by JoelJacobson »

tristanj wrote: post #64
JoelJacobson wrote: post #61

This article made me think of a strange claim by Elon Musk at 07:08 in this [1] interview: "Cooling is actually much easier in space than it is on earth. You can just radiate to the vacuum." I don't think that follows. The radiator is only the final heat sink. You still need to move heat from very dense chips into a deployable, space-rated radiator, and handle pumps, loops, leaks, redundancy, radiation damage, replac…

Radiators in space are a solved problem. The ISS has 70 kW of cooling via multiple radiators, using a dual loop water/ammonia system. The water loop cools the station and high-priority electronics, then the ammonia loop cools the water loop and transfers heat to the radiators, which release the heat out to space. There are additional radiators just for the solar panels. AI sat mini can use a simpler single ammonia lo…

Sorry, should have emphasized that it was the "much easier" part I didn't agree with in that interview.

Re: Cooling in Space

#92

Post by LargoLasskhyfv »

adrian_b wrote: post #68

The computation in TFA is wrong. The incoming power is not the electrical power generated by the solar panels, but the entire power of the light that is absorbed by the solar panels and by the body of the satellite. Even with a perfectly reflecting body and with SOTA solar panels, the amount of incoming power is at least double in comparison with the electrical power consumed by the datacenter. Also, the heat radiate…

There are other options:

https://spectrum.ieee.org/orbital-data-centers-heat#liquid-d...

https://en.wikipedia.org/wiki/Liquid_droplet_radiator

( Myself from 4 months ago: https://news.ycombinator.com/item?id=46895344 (giggle)

https://spectrum.ieee.org/microfluidics-cooling-ai-chips-cor... )

Re: Cooling in Space

#93

Post by jvanderbot »

zarzavat wrote: post #85
jvanderbot wrote: post #62

Earlier quoted context omitted.

That's fine, if the argument for DC in space is just "Let's put them in the hardest place possible". Then less hard -> absurd, implies more harder -> more absurder. But space based dc accomplish something that mountaintop dc do not. The different list of benefits/tradeoffs are why space DC are proposed and mountaintop ones are not. It's a difference of kind, not degree. It's not a meaningful experiment to just try to…

> - Power available 24/7 for "free" The Sun is visible from Earth as well, the last time I checked. In LEO you don't get power 24/7 because you are only 500km above the Earth. Yes the Sun is more attenuated on Earth but what we care about is $/W not raw wattage, and Earth certainly has cheaper $/W than space. > - coms w/o interruption using existing infra I'm perplexed how comms might be easier in space than on Earth…

We're losing the direct chain of thought here. My assertion is that "Nonexistence of Mountaintop DC is not a counter-example to space DC". That's it. The reasons were spelled out.

Your points: "Mountaintop" is how comms is easier in space vs on earth. Starlink already serves many rural areas simply b/c it is easier to go to/from space in some places than "running a cable". "Latency is nowhere near as good as on earth" is just false. "Mountaintop" is why. But more broadly, my most recent vacation cabin has higher latency than starlink offers. Case closed I guess?

And one more on latency: I was referring to latency in areas of interest far from USA mountaintops / USA in general. You might want to peruse the DARPA programs on low latency in-situ, closed loop comms for in theater (sometimes space based) compute. Something close to the action.

Power: "Mountaintop" is how space has a better power case than earth. Not all of earth. Mountaintop earth. top level comment was talking about a wind turbine on a mountaintop. That's an attempt at 24h power which is very likely strictly worse.

You can step back and make larger arguments, but this thread is narrower.

"Space is more regulated than Earth". Yes, again, you're talking about wider counts of regulation. Just go look around at the pushback to data centers and you'll see some of the case for DC in space. The path to getting equipment into space is clean - just get permits and launch same as SPX does for starlink. The path to building a data center on a mountaintop probably encounters at least some non-paperwork pushback that's likely to trip big political fights. That's it. Are there a lot of mountaintops that are sufficiently cold to warrant "cooling" arguments that are not part of large state/federal parks?

So going back to the thread - if you believe that a mountaintop datacenter is a counter example to the feasibility of a space-based data center, then I think you're making a category error on some of the above criteria. Your comments don't dissuade me at all about that because they don't address either side of that argument.

Re: Cooling in Space

#94

Post by naishoya »

lpapez wrote: post #33
jvanderbot wrote: post #29

Earlier quoted context omitted.

What would be accomplished by doing this vs placing them basically anywhere else on earth?

It is a comment on the absurdity of orbital data centers. Mountaintop data centers sound absurd, but are more feasible and efficient than orbital ones in nearly every aspect.

Cooling is not the crux of the real problem, it's the fact that we have no way to replace single failed units in a running space-based data center without another launch - and if youre stressing your total launch cadence with 'new' datacenters, at what % do you repair or replace the whole slab.

The launch tempo, following the invention of a functioning approach to in-space single node replacement for even a modest portion of the planned workload capacity is something that strains credulity, even at the normal earth-level maintenance rate.

Addressing the increased failure rates due to the hard rads and geomagnetic effects, while demanding that orbital systems remain above nm% load - that's n% of the hardware still operating - at 100% power and thermal, or 100% of hardware at m% of power and thermal, or the intersection of those two slopes at any given time - in order to meet shareholders profit expectations pushes that launch cadence and cost - to maintain the baseline of workload... and well, the math of that for even a minimal % of earthbound current deployed demand is just staggeringly many launches per year.

Maybe i'm missing something, but bigger vehicles for putting larger payloads doesnt make it better, it makes it worse.

Re: Cooling in Space

#95

Post by LargoLasskhyfv »

mkl wrote: post #88
LargoLasskhyfv wrote: post #71

Earlier quoted context omitted.

Resurrect https://en.wikipedia.org/wiki/Sea_Dragon_(rocket) , launch it 'anonymously' from international waters?

It doesn't say anything about launch location, and you'd need to ship it out there from a country using a large (registered) boat. That loophole won't work.

Staying with exploiting loopholes, that happens all the time with ships, while at sea, in international waters.

I think I've read something about similar things happening with new airliners for fiscal reasons.

OFC that doesn't really erase the track, but one could engage in rented or owned 'lawfare' by then?

Re: Cooling in Space

#96

Post by jauntywundrkind »

LargoLasskhyfv wrote: post #92
adrian_b wrote: post #68

The computation in TFA is wrong. The incoming power is not the electrical power generated by the solar panels, but the entire power of the light that is absorbed by the solar panels and by the body of the satellite. Even with a perfectly reflecting body and with SOTA solar panels, the amount of incoming power is at least double in comparison with the electrical power consumed by the datacenter. Also, the heat radiate…

There are other options: https://spectrum.ieee.org/orbital-data-centers-heat#liquid-d... https://en.wikipedia.org/wiki/Liquid_droplet_radiator ( Myself from 4 months ago: https://news.ycombinator.com/item?id=46895344 ( giggle ) https://spectrum.ieee.org/microfluidics-cooling-ai-chips-cor... )

I went in wanting this to look real bad. But the Scott Manley video alas has sort of convinced me this is pretty feasible, that the energy budget is quite doable. https://youtu.be/FlQYU3m1e80

I do think this is a pretty generous estimate he ends up at. I don't think emissivity is perfectly well dealt with. I don't know if his earth reflection emissivity includes the high energy thermal transfer from particles that do exist on the near vacuum (exosphere be hit, ya'll) or if that matters. But his figures seem ballpark correct & my concerns are at best marginal.

Re: Cooling in Space

#97

Post by essdas »

jauntywundrkind wrote: post #96
LargoLasskhyfv wrote: post #92

Earlier quoted context omitted.

There are other options: https://spectrum.ieee.org/orbital-data-centers-heat#liquid-d... https://en.wikipedia.org/wiki/Liquid_droplet_radiator ( Myself from 4 months ago: https://news.ycombinator.com/item?id=46895344 ( giggle ) https://spectrum.ieee.org/microfluidics-cooling-ai-chips-cor... )

I went in wanting this to look real bad. But the Scott Manley video alas has sort of convinced me this is pretty feasible, that the energy budget is quite doable. https://youtu.be/FlQYU3m1e80 I do think this is a pretty generous estimate he ends up at. I don't think emissivity is perfectly well dealt with. I don't know if his earth reflection emissivity includes the high energy thermal transfer from particles that do…

I vaguely recall the Scott Manley video (longtime follower of his channel) - wasn’t he assuming that the chips can be run hot, and because the T^4 factor it results in much better radiative cooling?

I don’t know if the “chips can be run hot” assumption is a fair one. It results in significant degradation of the chips life.

At minimum it needs a redesign of the current set of leading chips which are designed for a specific temperature range. Redesigning at a different operational temperature is not a walk in the park.

Re: Cooling in Space

#98

Post by simondotau »

XorNot wrote: post #84
simondotau wrote: post #73

Earlier quoted context omitted.

Absolutely no one, anywhere, ever, has the capability to damage or destroy many hundreds of satellites (assuming that SpaceX wouldn't be a willing launch partner).

> (assuming that SpaceX wouldn't be a willing launch partner) really think about that statement when discussing deliberately avoiding government jurisdiction... (perhaps also consider that it is not the case that no one can damage a lot of satellites in orbit, but that up until recently no one has had any incentive to build the number of interceptors you would need to do it. But how viable is a space-based datacenter…

Lots of words. Can’t honestly say I read them all. Meanwhile Russia had a pretty strong motivation to destroy Starlink. Motivations don’t get much stronger than that.

Re: Cooling in Space

#99

Post by [deleted] »

simondotau wrote: post #98
XorNot wrote: post #84

Earlier quoted context omitted.

> (assuming that SpaceX wouldn't be a willing launch partner) really think about that statement when discussing deliberately avoiding government jurisdiction... (perhaps also consider that it is not the case that no one can damage a lot of satellites in orbit, but that up until recently no one has had any incentive to build the number of interceptors you would need to do it. But how viable is a space-based datacenter…

Lots of words. Can’t honestly say I read them all. Meanwhile Russia had a pretty strong motivation to destroy Starlink. Motivations don’t get much stronger than that.

[deleted]

Re: Cooling in Space

#100

Post by [deleted] »

simondotau wrote: post #98
XorNot wrote: post #84

Earlier quoted context omitted.

> (assuming that SpaceX wouldn't be a willing launch partner) really think about that statement when discussing deliberately avoiding government jurisdiction... (perhaps also consider that it is not the case that no one can damage a lot of satellites in orbit, but that up until recently no one has had any incentive to build the number of interceptors you would need to do it. But how viable is a space-based datacenter…

Lots of words. Can’t honestly say I read them all. Meanwhile Russia had a pretty strong motivation to destroy Starlink. Motivations don’t get much stronger than that.

[deleted]
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