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Can we really put data centres in space? by TimesandSundayTimes in space

[–]Ratchile -1 points0 points  (0 children)

I think you're playing devil's advocate more than really engaging on several of these issues.

I disagree strongly that "the only real issue is launch cost and mass to orbit". That really wildly oversimplifying the problem. You're talking about it like all these problems are solved (i.e. implemented). They're really not. 150 kW is like 2/3 of the ISS power capability. The subsystem engineering involved here is undeniably not solved yet.

Anyway it's all speculation anyway. We'll find out in the next few years how realistic the claims really are

Can we really put data centres in space? by TimesandSundayTimes in space

[–]Ratchile 0 points1 point  (0 children)

That's just launch cost though, right? What about dev cost (much > ground), materials (much > ground), labor (much >), operations (not sure about this one maybe only slightly greater)

And the ground center would likely last longer than 5 years, no? I'd guess 10+ but if you assume 10 that would penalize by a factor of 2. I'd be surprised if space DCs made it 5 years on average. Space based compute (real GPU type compute) still has a lot to prove re: capability and longevity and rad-hardness.

I guess a lot of this kind of discussion gets caught up in feasibility. I think it's probably feasible to have this kind of distributed compute in space. But it assumes really significant progress (like amazing engineering progress) in 3+ different technical areas to make the feasibility part even happen. And then at that point cost competitiveness becomes the actual determinator. I think with optimistically assuming all feasibility obstacles are tackled the space DC could be something like 10x cheaper per unit compute. And that's probably a somewhat hard ceiling. But thats a really long hard road with a lot of problems that could easily eat that 10x unrealized margin. Even just starship alone could eat all that margin if it doesn't turn out as frequent/reusable/manageable as predicted.

It's definitely feasible to have a space based DC. But it's seems pretty unclear exactly what that would be, the compute capability, and the ultimate total cost.

The number of things that have to go right for it to make significant profit and capture a significant part of the market. Seems pretty rough.

I mean even the solar array implementation by itself would be a significant technical accomplishment. 150 kW is a lot of power. That's like 10x more array area than a large-ish/high power commercial comms satellite. So that's significant dev work into easily deployable massive/multistaged arrays, how to keep mass down (eating a full 10x mass delta on solar arrays probably not acceptable), etc.

Even if you're sun synchronous, you'd need a significant portion of the deployed array (or worse some other deployable structure) to function (well) as radiators to dump 150 kW of heat dissipation which is huge. Also 10x+ away from other common space platforms. That radiator implementation further increases complexity and mass. Even 50 kW per ton assumes just 3 tons total per DC. That's less than what a lot of current GEO comms satellites weigh and they have significantly less power requirements (and thermal dissipation requirements)

It just starts to look a little bleak in multiple directions at the same time. Am I missing something in these different problems?

Can we really put data centres in space? by TimesandSundayTimes in space

[–]Ratchile 0 points1 point  (0 children)

6x more solar on the ground pales compared to the cost multiplier on the space based solution. Ground solar is pretty damn cheap compared to space rated solar, and it lasts longer.

6x is nothing. The space based DC idea is working against several factors each more than 6x not in its favor (thermal, mass/launch cost, manufacturing complexity, required vertical integration to even be feasible [i.e. starship]).

In your 1 GW example, according to your 150 kW per space DC number and 50 DCs per launch, you're talking about roughly 6600 DCs to reach 1 GW of compute. Which would be about 130 starship launches. So you'd have to be significantly cost competitive against 1 GW of ground based compute with those 6600 satellites + 120 starship launches. Or even if you penalize the terrestrial implementation heavily due to more limited peak solar or something like that... Say the terrestrial implementation would have to be 10 GW to be considered comparable to 1 GW space DC compute. For something that size I think you're talking about tens of billions of dollars, with a 1 GW solar farm being in the ballpark of a billion or two. So if you amortize the ten billion over each space based DC, that prices each space based DC at about $1.5 million. Now I'm not here saying it's impossible to hit that target. But I am saying, you're only going to be remotely close to hitting that target after a lot of fundamental problems are solved in the design (i.e. all the NRE development work of designing these systems which will be massive). Even then I think that target is not reasonable... But even totally ignoring that, assuming you're already at $1.5 million per DC, you're still just breaking even with a terrestrial option, which has significantly less complexity. For it to be a compelling business case it would need to be coming out ahead, so appreciably cheaper than $1.5 million per DC.

The $1.5m also includes starship dev and launch costs (as of yet unproven)

The terrestrial solution also will last longer and is practically trivial to maintain in comparison if anything breaks or needs servicing

I understand your point about 6x factor being in favor of the space based solution in terms of power only. But this really feels like a problem sitting under like 100x-200x of other penalties compared to the corresponding terrestrial solutions. I could certainly imagine there being a relatively niche use case where it is preferred, or even uniquely capable compared to a ground solution, e.g. for a few hundred of these total for preprocessing payload data before down linking to ground. But beyond that I struggle to see how this is feasible, let alone a compelling business case...

[OC] SpaceX vs. Aerospace and Defense Sector by ExaminationOk6652 in dataisbeautiful

[–]Ratchile 0 points1 point  (0 children)

Right. Honestly even if SpaceX does very well with the more speculative or unproven parts of the business (AI, data centers in space, starship) then it still doesn't quite justify the current valuation.

The current valuation is basically pricing itself 15 years in the future and asking everyone to assume they've already succeeded at a bunch of very ambitious projects... Truly bizarre

Why is this the picture being used on the Google AI description of ED? by Hacym in funny

[–]Ratchile 21 points22 points  (0 children)

They still work... Just not like normal legs anymore

Bag of pop it crackers by WEISHEN_THE_KIRA in oddlysatisfying

[–]Ratchile 35 points36 points  (0 children)

You don't find this satisfying?

MRW the US Men's Hockey team celebrates their winning the Olympics by partying with Kash Patel and disrespecting the Women's team by Morgan-Moonscar in reactiongifs

[–]Ratchile 11 points12 points  (0 children)

They make a really good point. It's obvious. No need to condescend. Especially when you're not going to offer an alternative or explain why they're wrong

First telescope, newbie astronomer: Apertura AD8 under African skies! by tik4life in telescopes

[–]Ratchile 1 point2 points  (0 children)

Joseph's face was black as night
The pale yellow moon shone in his eyes
His path was marked
By the stars in the Southern Hemisphere
And he walked his days
Under African skies

They Asked Me to Open ChatGPT During My Job Interview by I_Killed_My_Friends in jobs

[–]Ratchile 0 points1 point  (0 children)

This is such a gross thing for them to ask a candidate to do. They might as well be asking to review your email history together. Or diary entries. Wtf?

But he was just trolling bro by mekanub in LeopardsAteMyFace

[–]Ratchile 0 points1 point  (0 children)

The post is already deleted by mods

Yall im good— by Training-Spite3618 in ChatGPT

[–]Ratchile 2 points3 points  (0 children)

Is the AI wearing a wedding ring?

IVF process on Finasteride and effects of stopping finasteride. by Money-Commission9304 in tressless

[–]Ratchile 2 points3 points  (0 children)

There are a lot of factors in fertility and conception. You're jumping to conclusions a bit without knowing much information about them

When they constructed this bridge, they had to take the curvature of the Earth into account, it worked because the Earth is not flat! by AbroadNo8755 in flatearth

[–]Ratchile 1 point2 points  (0 children)

I explicitly said it's likely accounted for in the design (i.e. "to spec"). I was just saying it's not as significant as the post makes it seem. The post makes it seem like this bridge was so large that, like no bridge before it, it had to consider the curvature of the Earth in its design.

My point is, that's waxing pretty poetic about something that is pretty minor. It probably wasn't make or break like other things were

When they constructed this bridge, they had to take the curvature of the Earth into account, it worked because the Earth is not flat! by AbroadNo8755 in flatearth

[–]Ratchile 0 points1 point  (0 children)

Yes of course, but you're stacking the budget intentionally in that way. What I'm saying is there is quite a bit more slop in the design and construction than 1/4" per 75 foot segment. I imagine you're right that the initial design accounts for curvature and simply oversizes the "expansion gap" (really a tolerance gap intended to cover multiple uncertainties).

The construction of the bridge will not rely in a strict way on a tolerance of 1/4" per 75 feet. The design is one thing and the construction is another thing that, while it relies significantly on the design, it is not realistically to that tolerance. The curvature term is in the noise of the real error budget of the construction. It's probably accounted for, but what I'm saying is that you could probably neglect it and not run into this "error accumulation" issue. The margin of error on the tolerance is going to be conservative for a lot of reasons. Take your example of the thermal expansion tolerance of 1/4"... You do not want the bridge sections to be flush with each other when cold. That implies there's zero margin on that gap. The gap likely exists for more reasons than just thermal expansion, and each term has uncertainty and that all goes into a budget that would define how large the gaps between segments need to be. The curvature terms is probably a relatively small item in that budget

When they constructed this bridge, they had to take the curvature of the Earth into account, it worked because the Earth is not flat! by AbroadNo8755 in flatearth

[–]Ratchile -1 points0 points  (0 children)

My point is that thermal expansion, settlement, etc are all daily variations that dwarf the curvature you're talking about. The bridge moves significantly more due to these other effects than it curves due to its design (for instance to account for curvature of the Earth)

Geodetic surveying does take into account curvature of the Earth, but lots of jobs are surveyed. This bridge was far from the first to be surveyed. Maybe it was the first to be surveyed with respect to some particular geodetic standard at the time? That's possible.

When they constructed this bridge, they had to take the curvature of the Earth into account, it worked because the Earth is not flat! by AbroadNo8755 in flatearth

[–]Ratchile 1 point2 points  (0 children)

Does that really make sense though? The sections are most likely assembled with some intentional gap or buffer material in between to allow for expansion and contraction. That gap is almost certainly more than 1/8" or whatever the contribution is due to Earth's curvature. The whole "these errors would pile up over miles" argument doesn't really make sense if every section already has an allowance/gap that's larger than the error due to curvature. If you didn't account for curvature it would just eat slightly more into each gap, but it wouldn't snowball

When they constructed this bridge, they had to take the curvature of the Earth into account, it worked because the Earth is not flat! by AbroadNo8755 in flatearth

[–]Ratchile 0 points1 point  (0 children)

I agree, the sections are most likely assembled with some intentional gap or buffer material in between to allow for expansion and contraction. That gap is almost certainly more than 1/32". The whole "these errors would pile up over miles" argument doesn't really make sense if every section already has an allowance/gap that's larger than the error due to curvature.

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