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Starcloud

blogs.nvidia.com

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Re: Starcloud

#121

Post by Polizeiposaune »

dlisboa wrote: post #110
petesergeant wrote: post #8

Earlier quoted context omitted.

Their website pitches it as 16 square km

Wouldn't a 16km² gigantic solar roof on Earth already cover the energy needs that they're pitching will be saved with this space data center?

No. It would need to be larger, probably by a factor of 3 or 4, for a couple reasons.

1) The atmosphere attenuates sunlight (even when it's not cloudy)

2) The solar array in orbit can pivot to face the sun all the time.

3) While most orbits will go into earth's shadow some of the time, on average they'll be in sunlight more of the time than a typical point on the surface.

see https://en.wikipedia.org/wiki/Solar_irradiance

Re: Starcloud

#122

Post by Gravityloss »

amelius wrote: post #86
Gravityloss wrote: post #81

Earlier quoted context omitted.

By my back of the envelope calculations, the radiators would be comparable to the solar arrays, probably somewhat smaller and not massively bigger at least.

Care to share them?

Extremely rough one significant digit analysis from first principles, containing a lot of assumptions:

For solar panels:

Assuming area of 1000 square meters (30m x 30m square), solar irradiance of 1 kW/m^2, efficiency of 0.2. As a result power is 200 kW.

For radiators:

Stefan-Boltzmann constant 6E-8, temperature difference of 300 K, emissivity of one, we get total radiator power 1000 x 6E-8 x 300^4 = 486 kW.

The radiator number is bigger so the radiator could be smaller than the solar panels and could still radiate away all the heat. With caveats.

Temperature difference in the radiator is the biggest open question, and the design is very sensitive to that. Say if your chips run at 70 C (340 K), what is the cool temperature needed to cool down to, what is the assumed solar and earth flux hitting the radiator, depends on geometry and so on. And then in reality part of the radiator is cooler and radiates way less, so most of the energy is radiated from the hot part. How low do you need to get the cool end temperature to, in order to not fry your chips? I guess you could run at very high flow rates and small temperature deltas to minimize radiator size but then rest of the system becomes heavier.

Re: Starcloud

#124

Post by Geee »

The rate of radiative cooling scales proportionally to (T^4-Tenv^4) which approximates to just T^4 in space (Tenv = 3K). The hotter they can run it, the smaller heatsinks they need; for every doubling of temperature, the heatsink area can be reduced by a factor of 16. Also, it might be possible to boost the output temperature, e.g. with a chemical heat pump for even smaller heat sinks.

Re: Starcloud

#125

Post by notahacker »

nine_k wrote: post #94
notahacker wrote: post #62

Earlier quoted context omitted.

But read/write access to the datacentre is on someone's land, and spacefaring powers without access to that can still interfere with its effective operation...

The access is the customer's concern, much like starlink.

The customer is going to be extremely concerned when it turns out physically locating datacentres in space doesn't actually render the data inaccessible or uncensorable...

Re: Starcloud

#126

Post by NaomiLehman »

0xcb0 wrote: post #54

They state that in 10 years all data centers will be in outer space. I state that in 10 years we will look back and think this was a ridiculous idea. The meta and maintenance costs, the pollution of sending them to space, the space pollution itself, the outer space radiation, the extra redundant error correction needed*,* and much more all speak against this. Why not throw that trillion dollars into optical computing…

Right. also wouldn't space debris eventually hitting the huge solar panel system be an issue?

Re: Starcloud

#127

Post by caminante »

tmvphil wrote: post #116
caminante wrote: post #100

Earlier quoted context omitted.

Sounds like a "slippery slope" fallacy without further explanation.

Not sure what the slippery slope is here. The linked page imagines a 4km x 4km radiator/solar array. The cross-sectional area of the array is going to be directly proportional to the probability of impacting high velocity space debris. In such an event the amount of debris that would be generated could also scale with the area of the array. This seems bad

> This seems bad

e.g., Cianide seems bad, but it won't kill you if the relative volumes are small.

tl;dr: You haven't characterized the denominator.

Re: Starcloud

#128

Post by tmvphil »

caminante wrote: post #127
tmvphil wrote: post #116

Earlier quoted context omitted.

Not sure what the slippery slope is here. The linked page imagines a 4km x 4km radiator/solar array. The cross-sectional area of the array is going to be directly proportional to the probability of impacting high velocity space debris. In such an event the amount of debris that would be generated could also scale with the area of the array. This seems bad

> This seems bad e.g., Cianide seems bad, but it won't kill you if the relative volumes are small. tl;dr: You haven't characterized the denominator.

See my edit. Just one starcloud would represent an increase in a risk factor of over 300 c.f. status quo. Then multiply that by the number of starclouds you think would be deployed.

Re: Starcloud

#129

Post by Geee »

sanex wrote: post #68
welferkj wrote: post #42

Earlier quoted context omitted.

It's not a real issue, but it's truthy enough to generate real opposition to datacenter buildout and catalyze AI hate. So definitionally avoiding it from the get-go might end up being worth it.

It really depends where they get the water. If they're pumping an aquifer fry and doing evaporative cooling they could be just boiling an entire areas water source. If they could figure out how to use salt water it'd be ideal.

Just run your closed loop cooling through a heat exchanger in sea water. They probably do something like this already.

Re: Starcloud

#130

Post by deepanwadhwa »

Reubend wrote: post #3

Last time these folks were mentioned on HN, there was a lot of skepticism that this is really possible to do. The issue is cooling: in space, you can't rely on convection or conduction to do passive cooling, so you can only radiate away heat. However, the radiator would need to be several kilometers big to provide enough cooling, and obviously launching such a large object into space would therefore eat up any cost s…

Not sure if I follow really. Cooling from it's own generated heat? Are we even sure the system would get that hot in the first place? The temperatures can plunge up to -200 degrees. If needed, they'd cool it just like they keep the James Webb Telescope cool.
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