It's always better to generate electricity on the ground than attempt to beam it to the ground from space. The efficiency loss of beamed power is huge.
The efficiency loss of nighttime is approximately 100% if we’re talking about solar energy. At least at a most basic level, it’s not totally absurd to stick some kind of power beaming contraption in space where it is mostly not shadowed by the Earth and beam power to a ground station.
Any process for beaming power from *outside Earth's shadow* to a point on the ground within the shadow (i.e. local night), necessarily can also send power from somewhere else on the ground that is in sun, even though the planet is in the way (ground->space->ground).
I wouldn't be too surprised by beamed power being used on Mars, because that planet has global dust storms during which nowhere on the surface is getting much light, but it doesn't make as much sense here: because of the atmospheric window, you either use 0.4µm-to-10µm-wavelengths or 10cm-to-10m-wavelengths* with not much in between, µm means lasers and the mere possibility you may have included lasers powerful enough to be useful means everyone else will demand something similar to the IEA nuclear inspection program or will put similar lasers on the ground and shoot them upward to destroy those satellites, while cm-wavelengths means each ground station is a *contiguous* roughly 10km diameter oval.
Given the expensive part of large-scale PV has shifted from the PV itself to the support structures they're on, the ground station ends up about the same cost as a same-sized PV installation, and because that's just the ground station this remains true even if all the space-side components are zero cost. Normal ground-based PV also has the advantage that it doesn't need to be contiguous.
It is also possible to use a purely-ground-based method to transfer power from the other side of the world; a cable thick enough that the resistance is only 1 Ω the long way around is already within the industrial capacity of China, but the same geopolitical issues that would make people hostile to foreign beamed power satellites also makes such a cable a non-starter for non-technical reasons.
I concur it’s not necessarily totally absurd — but when you consider that such contraptions require large — very large! — receiving arrays to be built on the ground, it’s hard to avoid concluding that building gigantic photovoltaic arrays in, say Arizona (for the US) along with batteries for overnight buffering and transmission lines would still be massively more efficient.
Is that more or less absurd than making deals with our neighbours to share their electricity? Build some solar farms around the planet and then distribute it over wire.
I honestly don't know the answer. I know there's some efficiency loss running over long wires too but I don't know what's more realistic.
In theory you can do HVDC over long distances. In practice that doesn't help much. Power would normally want to run north to south (not gonna do HVDC across the oceans anytime soon), and so the terminator hits you at the same time everywhere. It's got to be batteries if you want PV at scale.
The practical difficulties aren't really long distance transmission though. They're political and engineering. Spain had a massive blackout recently because a PV farm in the south west developed a timing glitch and they couldn't control the grid frequency - that nearly took out all of Europe and the power wasn't even being transmitted long distance! The level of trust you need to build a giant integrated continent-wide power grid is off the charts and it's not clear it's sustainable over the long run. E.g. the EU threatened to cut Britain's electricity supplies during Brexit as a negotiating tactic and that wasn't even war.
The political issues in space are mostly launch related, right? Once you have the birds up nobody cares about anything except space junk and bandwidth. They're getting experience of solving those with Starlink already. And if you can find a way to put the satellites really far out there's plenty of space - inferencing satellites don't need to be close to Earth, low latency chat stuff can stay on the ground and the flying servers can just do batch.
The politics on the ground is much harder. Countries own the land, you need lots of permits, electricity generation is in contest with other uses.
We have these things called batteries, you charge them during the day, and drain them at night.
A solar+battery setup is already cheaper than a new gas plant. Beaming power from space is absolutely asinine, quite frankly. The losses are absurd, the sun already does it 24/7, and we know how to make wires and batteries to shuffle the sun's power around however we need to. Why on earth would we involve satellites?
Beaming energy always sucks. Without some very fundamental discoveries in physics nobody will every make this work economically. This isn't just an engineering problem, it's a physics problem.
Right up to the radiation limit and then you'll either have to throttle your precious GPUs or you'll be melting your satellite or at least the guts of it. You're looking at an absolutely massive radiator here, many times larger than the solar panels that collect the energy to begin with.
> > absolutely massive radiator here, many times larger than the solar panels
> A_radiator / A_PV = ~3;
Seems like you're in agreement. There's a couple more issues here--
1. Solar panels are typically big compared to the rest of the satellite bus. How much radiator area do you need per 700W GPU at some reasonable solar panel efficiency?
2. Getting the satellite overall to an average 27C temperature doesn't necessarily keep the GPU cool; the satellite is not isothermal.
My back of the envelope estimate says you need about 2.5 square meters of radiator (perhaps more) to cool a 700W GPU and the solar panel powering the GPU. You can fit about 100 of these GPUs in a typical liquid-cooled rack, so you need about 250 square meters of radiator to match one rack. And, unfortunately, you can't easily use an inflatable structure, etc, because you need to conduct or convect heat into that radiator.
This assumes that you lose no additional heat in moving heat or in power conversion.
And they’re going to mass a -lot-. Not that anyone would use a pyramid— you would want panels with the side facing the sun radiating too. There are plenty of surfaces that radiate more than they absorb at reasonable temperatures in sunlight.
First of all a note on my calculations: they appear very simple, and its intentional, its not actually optimized, its intended to give programmers (who enjoyed basic high school physics but not more) the insight that cooling in space while hard, is still feasible. If you look around the thread you'll find categorical statements that cooling in space is essentially impossible etc.
The most efficient design and the most theoretically convincing one are not in general the same. I intentionally veer towards a configuration that shows it's possible without requiring radiating surface with an area of a square Astronomical Unit. Minimizing the physics and mathematics prerequisites results in a suboptimal but comprehensible design. This forum is not filled with physicists and engineers in the physical sciences, most commenters are programmers. To convince them I should only add the absolute minimum and configure my design to eliminate annoying integrals (for example the heat radiated by earth on the satellite is sidestepped by simply sacrificing 2 of the triangular sides of the pyramid to be mere reflectors of emissivity ~0, this way we can ignore the presence of a nearby lukewarm earth). Another example is the choice of a pyramid: it is convex and none of the surfaces are exactly parallel to the sun rays (which would result in ambiguity or doubt, or make the configuration sensitive to the exact orientation of the satellite), a more important consequence of selecting a convex shape is that we don't have to worry about heat radiated from one part of the satellite surface, being reabsorbed by another surface of the satellite (in view of the first surface), a convex shape insures no surface patch can see another surface patch of the satellite. And yes I pretend no heat is radiated by the solar panel itself, which is entirely achievable. So I intentionally sacrifice a lot of opportunities for more optimal design to show programmers (who are not trained in mathematical analysis, and not trained with physics textbook theorem-proof-theorem-proof-definition-theorem-proof-...) that physically it is not in the real of the impossible and doesn't result in absurdly high radiator/solar panel area ratios.
To convince a skeptic you 1) make pessimistic suboptimal estimates with a lot of room for improvement and 2) make sure those estimates require as little math and physics as possible, just the bare minimum to qualitatively and quantitatively understand the thermodynamics of a simple example.
You are asking the right questions :)
Given the considerations just discussed I feel OK forwarding you to the example mini cluster in the following section:
It describes a 230 kW system that can pretrain a 405B parameter model in ~17 days and is composed of 16x DGX B200 nodes, each node carrying 8x B200 GPUs. The naive but simple to understand pyramid satellite would require a square base (solar PV) side length of 30 m. This means the tip of the pyramid is ~90m away from the center of the solar panel square. This gives a general idea of a machine capable of training a 405B parameter model in 17 days.
We can naively scale down from 230 kW to 700 W and conclude the square base PV side length can then be 1.66 m; and the tip being 5 m "higher".
For 100 such 700 W GPU's we just multiply by 10: 16.6 m side length and the tip of the pyramid being 50 m out of the plane of the square solar panel base.
Why bother with all this crazy geometry? Why not just area as I've done above? You can design a radiator so that barely any of the light shines back on the spacecraft.
Your differences from my number: A) you're working based on spacecraft average temperature and not realizing you're going to have a substantial thermal drop; B) you're assuming just one side of the surface radiates. They're on the same order of magnitude. Both of us are assuming that cooling systems, power systems, and other support systems make no heat.
You can pick a color that absorbs very little visible light but readily emits in infrared-- so being in the sun doesn't matter so much, and since planetshine is pulling you towards something less than room temperature, it's not too bad either.
None of these numbers make me think "oh, that's easy". You're proposing a structure that's a big fraction of the size of the ISS for one rack of GPUs.
I don't really think cooling in space is easy. The things I have to do to get rid of an intermittent load of 40W on a small satellite are very very annoying. The idea of getting rid of a constant load of tens of kilowatts, or more, makes me sweat.
As I said, my geometry and properties are chosen to be easy to understand with a minimum of knowledge and mathematics.
Yes, I could make more optimistic calculations: use the steradians occupied by earth, find and use the thermal IR emissivities of solar panels place many thin layers of glass before the solar panel allowing energy generating photons through and forming a series of thermal IR black body radiators as a heat shield in thermal IR, the base also radiates heat outwards and at a higher temperature, use nonsquare base, target a somewhat higher but still acceptable temperature, etc... but all of those complicate the explanation, risking to lose readers in the details, readers that confuse the low net radiative heat transfer between similar temperature objects and room walls in the same room as if similar situation applies for radiative heat transfer when the counterbody is 4 K. Readers that half understand vacuum flasks / dewars: no or fewer gas particles in a vacuum means no or less energy those particles can collectively transport, that is correct but ignores the measures taken to prevent radiative heat loss. For example if the vacuum flask wasn't mirror coated but black-body coated then 100 deg C tea isolated from room temperature in a vacuum flask is roughly 400 K versus 300 K, but Stefan Boltzmann carries it to the fourth power (4/3) ^ 4 = 3.16 ! That vacuum flask would work very poorly if the heat radiated from the tea side to the room-temperature side was 3 times higher than the heat radiated by the room temperature side to the tea-side. The mirroring is critical in a vacuum flask. A lot of people think its just the vacuum effect and blindly generalize it to space. Just read the myriad of comments in these discussions. People seriously underestimate the capabilities of radiative cooling because the few situations they have encountered it, it was intentionally minimized or the heat flows were balanced by equilibrium, not representative for a system optimized to exploit radiative heat transfer.
Some small corrections:
>Both of us are assuming that cooling systems, power systems, and other support systems make no heat.
I do not make this assumption! all heat generated in the cooling, power and other support systems stem from electrical energy used to power them, and that energy came from the solar panels. The sum of the heat generated in the solar panel and the electrical energy liberated in the solar panel must equal the unreflected incident optical power. So we can ignore how efficient the solar panel is for the rest temperature calculation, any electrical energy will be transformed to heat and needs to be dissipated but by conservation of energy this sum total of heat and electrical energies turned into heat must simply equal the unreflected energy incident on the solar panel... The solar panel efficiencies do of course matter a lot for the final dimensions and mass of the satellite, but the rest temperature is dictated by the ratio of the height of the pyramid to the square base side length.
>You can pick a color that absorbs very little visible light but readily emits in infrared-- so being in the sun doesn't matter so much, and since planetshine is pulling you towards something less than room temperature, it's not too bad either.
emissivity (between 0 and 1) simultaneously dials how well it absorbs photons at that wavelength as well as how efficiently it sheds energy at that wavelength. A higher emissivity allows the solar panel to cool faster spontaneously, but at the cost of absorbing thermal photons from the sun more easily! Perhaps you are recollecting the optimization for the thermal IR window of our atmosphere, the reason that works is because it works comparatively to solar panels that don't exploit maximum emissivity in this small window. The atmospheric IR window location in the spectrum is irrelevant in space however.
> A) you're working based on spacecraft average temperature and not realizing you're going to have a substantial thermal drop;
of course I realize there will be a thermal gradient from base to apex of the pyramidal satellite, it is in fact good news: near the solar panel base the triangular sides have wider area and hotter temperature, so it sheds heat faster than assuming a homogenous temperature (since the shedding is proportional to the fourth power of temperature). When I ignore it it's not because I'm handwaving it away, it's because I don't wish to bore computer science audience with integral calculations, even if they bring better news. Before bringing the better news you need to bring the good news that its possible with similar order of magnitude areas for the radiator compared to the solar panels, without their insight that its feasible first, its impossible to make them understand the more complicated realistic and better news picture, especially if they want to not believe it... Without such proof many people would assume the surface of the radiator would need to be 10's to 100's of times the surface area of the solar panels...
> B) you're assuming just one side of the surface radiates.
No, I even explicitly state I only utilize 2 of the 4 side triangles of the pyramid (to sidestep criticisms that earth is also radiating heat onto the satellite). So I make a more pessimistic calculation and handicap my didactic example just to show you get non-extreme surface ratios even when handicapping
the design. If you look at history of physics, you will often find that insights were obtained much earlier by prior individuals, but the community only accepted the new insights when the experimental design was simplified to such an extent that every criticism is implicitly encoded in the design by making it irrelevant in the setup, this is not explicitly visible in many of the designs.
> I do not make this assumption! all heat generated in the cooling, power and other support systems
Nah -- when we're talking about how much it takes to power 70kW of GPUs, we need to include some kind of power utilization efficiency number. If 70kW is really 100kW, then we need to make this ridiculously big design 40% larger.
> >You can pick a color that absorbs very little *visible light* but readily emits in *infrared*-
> how well it absorbs photons at that wavelength as well as how efficiently it sheds energy at that wavelength.
Yes. Planetshine is infrared, 290K-ish; sunshine is 5500K-ish and planetary albedo is close enough to this, with a very small portion of its light being infrared. You are being long winded and not even reading what you reply to.
So, for example, white silicate paint or aluminized FEP has a equilibrium temperature in full sun, with negligible heat conducted to or away from it, somewhere in the span of -70 to -40C depending upon your assumptions. It will happily net radiate away heat from above-room temperature components while facing the sun.
It will also happily net radiate away heat when facing the planet because the planet is under room temperature and the planet doesn't subtend a whole hemisphere even in LEO.
I don't really like argument from authority, but... I will point out that I am the PI for multiple satellite projects and have owned thermal design, and that the stuff I've flown in space has ended up at very close to predicted temperatures. I don't feel like this is an easy thermal problem.
I mean, it's easy in the sense of "it takes a radiator area about the same as the floor area of my house". It's not easy in the sense of "holy shit I need to launch a radiator that's bigger than my house and somehow conduct all that heat to it while keeping the source cool."
> of course I realize there will be a thermal gradient from base to apex of the pyramidal satellite
No, there will be a thermal gradient from the hot thing -- the GPU -- to the radiator surface. S-B analysis is OK for an exterior temperature, but it doesn't mean the stuff you want to keep cool will be that average temperature. This is why we end up with heat pipes, active cooling loops, etc, in spacecraft.
If this wasn't a concern, you could fly a big inflated-and-then-rigidized structure and getting lots of area wouldn't be scary. But since you need to think about circulating fluids and actively conducting heat this is much less pleasant.
Datacenter capacity (and thus heat) grows by the cube law, but the ability to radiate heat grows by the square law, so it seems like it would be advantageous to have a bunch of smaller satellites, if you were concerned about cooling them.
> it would be advantageous to have a bunch of smaller satellites, if you were concerned about cooling them.
...That's only relevant if you start from the position that your datacenters have to be space.
You could already make smaller datacenters on earth, and still have better cooling, if you were concerned about that. We don't do that because on earth it's more efficient to have one large datacenter than many small ones.
> A few years into the company’s life, founders Larry Page and Sergey Brin actually wondered whether Google needed any managers at all. In 2002 they experimented with a completely flat organization, eliminating engineering managers in an effort to break down barriers to rapid idea development and to replicate the collegial environment they’d enjoyed in graduate school. That experiment lasted only a few months: They relented when too many people went directly to Page with questions about expense reports, interpersonal conflicts, and other nitty-gritty issues. And as the company grew, the founders soon realized that managers contributed in many other, important ways—for instance, by communicating strategy, helping employees prioritize projects, facilitating collaboration, supporting career development, and ensuring that processes and systems aligned with company goals.
IMO, this could be solved by having a finance team with good workflows and a real human resources team/psychologist on staff that would handle all of the interpersonal drama. It's an interesting anecdote but I don't think it was that great of an attempt or structured well enough to work.
With a USB stick and FTP. It's very easy to underestimate a problem when you've never encountered it or tried to tackle it in practice. Your shallow dismissal gives that away and brings no insight.
Human beings will always organically organize hierarchically. In a group one will have more initiative, one will be happier to be told what to do, etc. In the end informally you will end up with the same structure. And it's hell to deal with that when formally all have the same authority so none can override each other, but one guy just gathered enough support to do whatever he wants.
Do you think someone far away from everything you do will have a magic "workflow" that tells them what to do about the budget you requested, about the strategic decision you need, or about your conflicts, about who has to do the nice jobs or the shitty ones? And why would they have any say, they're not the boss.
Your logic is no better that those pretending today that a team of AI agents "with good workflows" can just replace all the programmers.
I think it could work if it was designed for it from the ground up. Google's experiment's lasted months, and was, what seems like a whim of the owners, where as a lot of the workers probably expected a traditional company.
Valve the "game" company, has a relatively flat structure from what I've heard, and it's working pretty well for them, but they've also had it for a long time.
So if you have a company, that works like that from the start, that people know it works like that, that it has support for it. You could make it work.
I agree that forcing this structure everywhere wouldn't work, some people can work like this, others can't.
> Valve the "game" company, has a relatively flat structure
Valve has ~300 employees and operates in a field where they can afford more freedoms (try building large infrastructure projects with flat structures). Valve struck a good balance between autonomy for employees while still having some informal central coordination. Formally there are few bosses but in practice project managers and some people with seniority also act in those roles. At scale it can't work if you don't delegate any of the authority to smaller units.
It's bad to have too many or too few layers. Sometimes the result looks the same, lack of coordination and inability to deliver consistently.
Amazon has 1.5M workers. Can't imagine a flat structure working but I'm sure they were overdoing it with layers of management.
Why not get rid of job titles and just have people do whatever needs to be done?
Because no one person is good at everything, and even if you managed to build a team of people who were good at everything, it is inefficient to make everyone keep up with all details of every aspect of the company so that they can be productive in an arbitrary role at the drop of a hat. Giving people a role allows them to specialize their knowledge and concentrate all their efforts into their area of expertise/competence.
Managers fill a role. Sure, some managers are bad, and some workplaces have seemingly mostly bad managers, and it leads to cynical opinions about how managers are busy-work-making dolts who don't understand anything. Some employers have mostly good managers and I feel sorry for you if you have never had the experience.
I'm 40 years into my EE career and I have always deflected efforts to make me a people manager or a project manager. I like being a grunt in the trenches solving problems at the bottom level, and a good manager increases their reports' productivity by shielding them from needing to deal with project management crap. I would have retired already except I've been blessed to have good managers for the past 20 years, while my managers have been attending umpteen resource allocation meetings and all the attendant report-making that requires.
Really? How often and for how many people? Which ones dominate and are more frequent, flat or hierarchical? Which ones do we use for our most complex endeavors?
I am reading this article and thinking, darn there's going to be too many people like me trying to find these on the used market, and the prices will stay high.
Big fancy expensive powerstroke mega trucks with a person-high wall in the front look cool, and occasionally haul heavy things, but little white trucks that are busted up and 20 years old do all the duty. And those trucks drive way less than the range on the lightning each day. Once these lightnings price down to work truck level, I expect to see them on the road a long time.
If you are familiar with all of these but not C or Java or some other "traditional" programming language, then yes, I think anyone would guess you were a sysadmin. This was the type of background GP was talking about - people familiar with shell scripting but not any other programming language, who come by Perl for the first time.
jimmy kimmel didn't self censor himself off the air