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Data centers in space makes no sense

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Re: Data centers in space makes no sense

#471

Post by numpad0 »

philipwhiuk wrote: post #366
elamje wrote: post #353

I was talking to someone about this the other day. I was part of a team at NASA that developed a cooling system for the ISS and this whole premise makes no sense to me. 1. Getting things to space is incredibly expensive 2. Ingress/egress are almost always a major bottleneck - how is bandwidth cheaper in space? 3. Chips must be “Rad-hard” - that is do more error correcting from ionizing radiation - there were entire t…

> Chips must be “Rad-hard” - that is do more error correcting from ionizing radiation - there were entire teams at NASA dedicated to special hardware for this. They don't do RAD hardening on chips these days, they just accept error and use redundant CPUs.

There are apparently rad-hard DDR4 chips these days so this is patently false. SpaceX used to talk a lot about substituting rad-hard components with triple redundant regular x86 years ago, that's true.

I think I've also seen someone mention that the cost and power benefit of substituting rad-hard chips with garden variety wean off fast once the level of redundancy goes up, and also it can't handle deep space radiations that just kill Earthbound chips rather than partially glitching them.

Re: Data centers in space makes no sense

#472

Post by dboreham »

dsl wrote: post #467
m463 wrote: post #456

Earlier quoted context omitted.

I used to really enjoy musk's talks when he was spooling up tesla. He was an engineer and obviously the world is missing what engineers see clearly. But now looking back and accounting for the claims he made there's a pattern. I saw this article: https://www.wired.com/story/theres-a-very-simple-pattern-to-... that said... he did jumpstart the EV industry. He has put up satellites every week for years. He is still a n…

> he did jumpstart the EV industry. He has put up satellites every week for years. He is still a net benefit to all of us. Talk to any former SpaceX or Tesla employee. They will clue you in that both were successful in spite of Elon, not because of him. The Cybertruck was really the first product he saw to completion from his own design. And well...

I think you under appreciate him a bit here. No he's not a super genius. He's probably not even a good engineer. But he is a) a total a.hole and b) a tremendous bullshitter. There are circumstances in which you need such a person to succeed (see also Steve Jobs). He yelled at people for 10 years straight and he was crucial in facilitating capital to build these very capital intensive products. A regular smart person would absolutely not have succeeded, for these reasons.

Re: Data centers in space makes no sense

#473

Post by 7bees »

stogot wrote: post #446
lancewiggs wrote: post #177

Earlier quoted context omitted.

It's exiting the 5th best social network and the 10th (or worse) best AI company and selling them to a decent company. 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.

xAI includes twitter? I thought twitter was just X?

xAI acquired twitter in 2025 as part of Musk's financial shell game (probably the same game he is playing with SpaceX/xAI now).

Re: Data centers in space makes no sense

#474

Post by stevep98 »

Surely, the question is: how big do the radiators have to be?

gemini says that the NVIDIA DGX H100 is 130kg and takes 11kW.

It says space-based radiators in the 100kW range are approx 15kg per kW. And space-based solar panels are approx 1kg per kW.

So let's says we're talking about 1 system that bundles 9 DGX H100's. That's 1.2T for the computing system, 1.5T for the radiator, 100kg for the solar panels, and let's say 2T for the propulsion, propellant, guidance, and all the other spacecraft stuff. That's a total of about 5T, and the radiator is just about 20% of the mass budget.

The power radiated is proportional to the 4th power of the temperature, so they would be incentivized to develop a heat exchanger with a high temperature working fluid.

Re: Data centers in space makes no sense

#475

Post by pdpi »

gpt5 wrote: post #235
lancewiggs wrote: post #177

Earlier quoted context omitted.

It's exiting the 5th best social network and the 10th (or worse) best AI company and selling them to a decent company. 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.

I'm confused about the level of conversation here. Can we actually run the math on heat dissipation and feasibility? 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 rou…

5kW means you can't even handle a single one of these[0], compared to a handful per rack on an earthbound data centre.

0. https://www.arccompute.io/solutions/hardware/gpu-servers/sup...

Re: Data centers in space makes no sense

#476

Post by fnordpiglet »

pclmulqdq wrote: post #439
sam wrote: post #414

Earlier quoted context omitted.

This is mistaken. In space a radiator can radiate to cold (2.7K) deep space. A thermos on earth cannot. The temperature difference between the inner and outer walls of the thermos is much lower and it’s the temperature difference which determines the rate of cooling.

"Radiate" is exactly what you have to do, and that is extremely slow. You need a huge area to dissipate the amount of power you are talking about.

Basically you concentrate the heat into a high emissivity high temperature material that’s facing deep space and is shaded. Radiators get dramatically smaller as temperature goes up because radiation scales as T⁴ (Stefan–Boltzmann). There are many cases in space where you need to radiate heat - see Kerbal Space Program

Re: Data centers in space makes no sense

#478

Post by hirsin »

tensor wrote: post #425
hirsin wrote: post #310

Earlier quoted context omitted.

Simply put no, 50MW is not the typical hyperscaler cloud size. It's not even the typical single datacenter size. 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 e…

How much of that power is radiated as the radio waves it sends?

Good point - the comms satellites are not even "keeping" some of the energy, while a DC would. I _am_ now curious about the connection between bandwidth and wattage, but I'm willing to bet that less than 1% of the total energy dissipation on one of these DC satellites would be in the form of satellite-to-earth broadcast (keeping in mind that s2s broadcast would presumably be something of a wash).

Re: Data centers in space makes no sense

#479

Post by MadnessASAP »

gpt5 wrote: post #235
lancewiggs wrote: post #177

Earlier quoted context omitted.

It's exiting the 5th best social network and the 10th (or worse) best AI company and selling them to a decent company. 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.

I'm confused about the level of conversation here. Can we actually run the math on heat dissipation and feasibility? 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 rou…

I ran the math the last time this topic camps up

The short answer is that ~100m2 of steel plate at 1400C (just below its melting point) will shed 50MW of power in black body radiation.

https://news.ycombinator.com/item?id=46087616#46093316

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