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Datacenters in space aren't going to work

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Re: Datacenters in space aren't going to work

#271

Post by mjhay »

eldenring wrote: post #264
dijit wrote: post #263

Earlier quoted context omitted.

I always believed thermal conductivity to be one of the hardest problems in space. Today the way we diffuse temperature is via the air itself, and without air to carry heat away from components we don’t really have very much to work with. I know space is cold, but diffusing the cold onto the warm is an ongoing problem as far as I understood it. Which is why for example of nuclear submarines would not bode well in spa…

The comment you were replying to mentioned this. Yes you cant remove heat via convection, but you can use radiators to emit heat as radiation into space.

You need HUGE radiators to emit a lot of low-temp waste heat into space. That kills this idea right there.

Re: Datacenters in space aren't going to work

#272

Post by pfdietz »

I'm not impressed by these arguments.

(1) Solar panels can be made much lighter in space. On Earth, panels have to withstand wind and gravity loads, flying debris, and precipitation including hail. The PV material itself doesn't have to be thick: thin film CdTe cells can be ~1 micron thick (the absorption length of the relevant photons in CdTe is something like 0.1 microns.) There has to be a protective layer to prevent solar wind ions from degrading the cells but this doesn't have to be very thick. It's not like shielding against high energy particles.

(2) Heat dissipation can be addressed by refrigeration. Yes, this takes energy, and yes that extra energy also has to be radiated. But the area of the radiator goes down as the fourth power of its absolute temperature. If you radiate 2x as much heat but at 2x the absolute temperature, the area of the radiator declines by a factor of 8. Even with inefficiencies one should be able to come out ahead by pumping the waste heat to higher temperature before radiating it.

(3) Ionizing radiation is dealt with by shielding. The amount of shielding per unit of capacity declines as you make your installation larger, by the square cube law. So this is really just a matter of scale. We're talking about potentially enormous amounts of capacity here so shielding shouldn't be a problem at scale.

Re: Datacenters in space aren't going to work

#273

Post by jeltz »

eru wrote: post #248
rsynnott wrote: post #241

Earlier quoted context omitted.

At the point, it's beginning to feel a bit like the 419 scam (where you make the details deliberately absurd so as to ward off people inclined to be sceptical early, leaving you with only the easiest marks.) SMRs! Data centres in space! "phD level AIs".

You can short the publicly traded companies that do this.

No, because to do that and not ruin myself I need to know roughly when the double will burst. Just knowing it is a bubble is not enough.

Re: Datacenters in space aren't going to work

#274

Post by thelastgallon »

>The first reason for doing this that seems to come up is abundant access to power in space. This really isn't the case. You basically have two options: solar and nuclear.

I guess that rules our any funding from US govt or Saudi money. Unless someone figures out a way to use fossil fuels to run the data centers! It has to be private equity or a new data center coin offering. Offered to the public and take away the pain and suffering of carrying their current paper currency. We need a new messiah (SBF + Musk + WeWork guy) to craft this narrative.

Re: Datacenters in space aren't going to work

#275

Post by thisisauserid »

cladopa wrote: post #258

It is not a good idea listening to experts tell you what can't be done. Science and technology progresses one funeral at at time. Einstein's ideas were crazy for classical scientists and Heisenberg's for Einstein. The most important thing is making space access ten to one hundred times cheaper with reusable rockets. Then a lot of the problems in the article will not be problems at all. E.g ISS was designed and create…

Please don't propagate the myth that Einstein couldn't wrap his head about Heisenberg.

The EPR paper says otherwise and Bohr's response to it was incomprehensible (and still is).

Einstein was simply saying science should not stop looking into the why.

Re: Datacenters in space aren't going to work

#276

Post by noselasd »

foobarian wrote: post #146
noselasd wrote: post #106

Earlier quoted context omitted.

Is it an advantage though ? One of the main objections in the article is exactly that. There's no atmosphere that helps with heat loss through convection, there's nowhere to shed heat through conduction, all you have is radiation. It is a serious engineering challenge for spacecrafts to getting rid of the little heat they generate, and avoid being overheated by the sun.

I think it is an advantage, the question is just how big, and assume we look only at ongoing operation cost. - Earth temperatures are variable, and radiation only works at night - The required radiator area is much smaller for the space installation - The engineering is simple: CPU -> cooler -> liquid -> pipe -> radiator. We're assuming no constraint on capex so we can omit heat pumps

A typical CPU heatsink dissipates 10-30% of heat through radiation, and the rest through convection. In space you're in a vacuum so you can't disipated heat through convection.

You need to rework your physical equipment quite substantially to make up for the fact you can't shed 70-90% of the heat in the same manner as you can down here on Earth

Re: Datacenters in space aren't going to work

#277

Post by jeltz »

hedora wrote: post #159
kevdev wrote: post #6

As someone with a similar background to the writer of this post (I did avionics work for NASA before moving into more “traditional” software engineering), this post does a great job at summing up my thoughts on why space-based data centers won’t work. The SEU issues were my first though followed by the thermal concerns, and both are addressed here fantastically. On the SEU issue I’ll add in that even in LEO you can s…

Single event upsets are already commonplace at sea level well below data center scale. The section of the article that talks about them isn’t great. At least for FPGAs, the state of the art is to run 2-3 copies of the logic, and detect output discrepancies before they can create side effects. I guess you could build a GPU that way, but it’d have 1/3 the parallelism as a normal one for the same die size and power budg…

Sounds like it would remove a lot of the benefits gain from more solar power.

Re: Datacenters in space aren't going to work

#278

Post by peppersghost93 »

cladopa wrote: post #258

It is not a good idea listening to experts tell you what can't be done. Science and technology progresses one funeral at at time. Einstein's ideas were crazy for classical scientists and Heisenberg's for Einstein. The most important thing is making space access ten to one hundred times cheaper with reusable rockets. Then a lot of the problems in the article will not be problems at all. E.g ISS was designed and create…

Counterpoint: oceangate

Sometimes when people tell you something can't be done they're right. No amount of gumption will cancel out physics.

Re: Datacenters in space aren't going to work

#279

Post by bregma »

verzali wrote: post #231
ACCount37 wrote: post #218

Earlier quoted context omitted.

Antisatellite weapons are expensive and rare, and also woefully inadequate for dealing with megaconstellations. If there's one large orbital datacenter, then sure, ASAT is a threat to it. But if it's a dispersed swarm like the Starlink system? Good luck making a dent in that. You'd run out of ASAT long before Musk runs out of Starlink.

You only need to destroy a few. Then you have a cloud of debris that will take down the rest or at the very least force them to use all their fuel making evasive manoeuvres.

And they'd get away with it too if it weren't for that pesky orbital mechanics.

Re: Datacenters in space aren't going to work

#280

Post by mr_toad »

collinmcnulty wrote: post #197

To say the quiet part out loud, I don't think any serious companies have any intention to build a data center in space. There is no benefit in actually trying this. There is however, benefit in saying you'll do it to advance a narrative and distract from the problems terrestrial data centers are facing to an audience that mostly doesn't understand how heat transfer in a vacuum works.

The only real advantage is 24/7 power without having to use batteries (or some other power supply at night or when cloudy). The way solar prices are going the problem of suppling power when the sun isn’t visible is a real bottleneck.
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