6 ms·

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 sens

by elamje 8mo ago

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 teams at NASA dedicated to special hardware for this. 4. Gravity and atmospheric pressure actually do wonders for easy cooling. Heat is not dissipated in space like we are all used to and you must burn additional energy trying to move the heat generated away from source. 5. Energy production will be cheaper from earth due to mass manufacturing of necessary components in energy systems - space energy systems need novel technology where economies of scale are lost. Would love for someone to make the case for why it actually makes total sense, because it’s really hard to see for me!

philipwhiuk 8mo ago
> 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.
- elamje 8mo ago
  Where did you hear this?
- adastra22 8mo ago
  You are confidently incorrect. Even Starlink uses rad-hardened CPUs. Redundant error correction is only really an option on launch hardware that only spends minutes in space. Note that on modern hardware cosmic rays permanently disable circuits, not mere bitflips.
  - NitpickLawyer 8mo ago
    > You are confidently incorrect. No, he's not. Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space. > AWST: So, NASA does not require SpaceX to use radiation-hardened computer systems on the Dragon? John Muratore: No, as a matter of fact NASA doesn't require it on their own systems, either. I spent 30 years at NASA and in the Air Force doing this kind of work. My last job was chief engineer of the shuttle program at NASA, and before that as shuttle flight director. I managed flight programs and built the mission control center that we use there today. On the space station, some areas are using rad-hardened parts and other parts use COTS parts. Most of the control of the space station occurs through laptop computers which are not radiation hardened. > Q: So, these flight computers on Dragon – there are three on board, and that's for redundancy? A: There are actually six computers. They operate in pairs, so there are three computer units, each of which have two computers checking on each other. The reason we have three is when operating in proximity of ISS, we have to always have two computer strings voting on something on critical actions. We have three so we can tolerate a failure and still have two voting on each other. And that has nothing to do with radiation, that has to do with ensuring that we're safe when we're flying our vehicle in the proximity of the space station. I went into the lab earlier today, and we have 18 different processing units with computers in them. We have three main computers, but 18 units that have a computer of some kind, and all of them are triple computers – everything is three processors. So we have like 54 processors on the spacecraft. It's a highly distributed design and very fault-tolerant and very robust. [1] - https://aviationweek.com/dragons-radiation-tolerant-design https://aviationweek.com/dragons-radiation-tolerant-design
    - adastra22 8mo ago
      > Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space. Those are not independent facts. They put the hardware inside, behind the radiation shielding they use to keep the astronauts safe. It's why regular old IBM laptops work on the Space Station too. That kind of shielding is going to blow your mass budget if you use it on these satellites. SpaceX, which prefers COTS components when it can use them, still went with AMD Versal chips for Starlink. Because that kind of high performance, small process node hardware doesn't last long in space otherwise (phone SoC-based cubesats in LEO never lasted more than a year, and often only a month or so).
- numpad0 8mo ago
  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.
kortilla 8mo ago
>Ingress/egress are almost always a major bottleneck - how is bandwidth cheaper in space? Free space optics are much faster than data to/from the ground. If the training workloads only require high bandwidth between sats, this isn’t a real issue.
TheDong 8mo ago
> Would love for someone to make the case for why it actually makes total sense, because it’s really hard to see for me! Elon musk has a history of making improbable-sounding promises (buy a tesla now, by 2018 it will be a self-driving robotaxi earning money while you sleep, humanoid robots, hyperloops). The majority of these promises have sounded cool enough to enough people that the stock associated with him (TSLA) has made people literal millionaires just by holding onto the stock, and more and more people have bought in and thus have a financial interest in Musk's ventures being seen in a good light (since TSLA stock does not go up or down based on tesla's performance, it goes up or down based on the vibes of elon musk. It is not a car company stock, it is an elon vibes check). The thing he's saying now pattern matches to be pretty similar, and so given Musk's goal is to gain money, and he gains money by TSLA and SpaceX stock going up, this makes perfect sense as a thing to say and even make minor motions towards in order to make him richer. People will support it too since it pattern matches with the thing prior TSLA holders got rich off of, and so people will want to keep the musk vibes high so that their own $tsla holdings go to the moon. Make sense now?
- adastra22 8mo ago
  The story here is even simpler. SpaceX is going public this year. Elon made a monumentally shitty investment in Twitter and then poured a stupid amount of money into xAI at the peak of the cycle. By having SpaceX buy xAI, he gets to swap worthless shares in that company for more SpaceX liquidity. Simple as that.
  - rockemsockem 8mo ago
    Really seems silly to think that the guy with $800 billion is spending most of his time maximizing his money.
    - z3t4 8mo ago
      He probably have 700 billion in loans and need to pay rent
    - kadoban 8mo ago
greengrassi 8mo ago
When they talk about "space" they are, right now, talking about the moon. Which has some gravity. They are putting the data centers on the moon. And the satellites are lunar satellites not earth-orbit satellites. Lonestar physical data center payload landed on the moon in Feb 2025 and Sidus space developing the lunar satellites.
- adastra22 8mo ago
  They are not. xAI/SpaceX is talking about millions of satellites in sun-synchronous orbit.
  - nosianu 8mo ago
    Yeah, the cost of doing it on the moon would be even more astronomical. Then there also is the three second of round-trip latency to consider (ca. 2.6 s just the signal, but processing adds a bit more).
mike_hearn 8mo ago
It sounds hard but it shouldn't not make sense. 1. Solving cost of launching mass has been the entire premise of SpaceX since day one and they have the track record. 2. Ingress/egress aren't at all bottlenecks for inferencing. The bytes you get before you max out a context window are trivial, especially after compression. If you're thinking about latency, chat latencies are already quite high and there's going to be plenty of non-latency sensitive workloads in future (think coding agents left running for hours on their own inside sandboxes). 3. This could be an issue, but inferencing can be tolerant to errors as it's already non-deterministic and models can 'recover' from bad tokens if there aren't too many of them. If you do immersion cooling then the coolant will protect the chips from radiation as well. 4. There is probably plenty of scope to optimize space radiators. It was never a priority until now and is "just" an engineering problem. 5. What mass manufacture? Energy production for AI datacenters is currently bottlenecked on Siemens and others refusing to ramp up production of combined cycle gas turbines. They're converting old jet engines into power plants to work around this bottleneck. Ground solar is simply not being considered by anyone in the industry because even at AI spending levels they can't store enough power in batteries to ride out the night or low power cloudy days. That's not an issue in space where the huge amount of Chinese PV overproduction can be used 24/7.
- FranklinJabar 8mo ago
  > There is probably plenty of scope to optimize space radiators. It was never a priority until now and is "just" an engineering problem. Well, it's a physics problem. The engineering solution is possibly not cost efficient. I'd put a lot of money that it isn't.
  - bborud 8mo ago
    That bit reminded me of someone who wanted us to design a patch the size of a small postage stamp, at most 0.2mm thick, so you could stick on products. It was to deliver power for two years of operation, run an LTE modem, a GNSS receiver, an MCU, temperature and humidity sensor and would cost $0.10. And it would send back telemetry twice per day.
energy123 8mo ago
> 5. Energy production will be cheaper from earth Sun-synchronous orbit means solar panels collect the same amount 24/7. I guess that's the #1 benefit. Cheap energy.
- donkey_brains 8mo ago
  Read the whole sentence. He’s talking about the cost to make solar panels that can be deployed in space, not the efficacy of said panels.
Symmetry 8mo ago
Regarding 3, they're almost certainly thinking of putting these in SSO where the radiation environment isn't too much worse than you see on the ISS. If they were going to go outside the Van Allen belts it would be a different story.
matthewdgreen 8mo ago
The whole AI bubble makes way more sense if you model it not as rational economic activity, but rather as the actions of a rogue AI slowly taking over our institutions and redirecting them towards its goals. Data centers in space make no sense economically, but think of how survivable the rogue AI will be once we build those orbiting data centers! (I am joking about this, but it's weird that my logic makes sense.)
tgtweak 8mo ago
Added some math on my comment that outlines the boundaries of economics of this considering most of what you mentioned.
mghackerlady 8mo ago
for the chips to both be radiation hardened and as powerful as our current chips they'd need to be massive. There's a reason the mars rover uses a PowerPC G3
UltraSane 8mo ago
It doesn't make sense. It is just Musk trying to pump up SpaceX valuation before the IPO.
RGamma 8mo ago
Think Elon: A swarm of advanced AIs working from space, untouchable for most, steering execution of his power fantasy on earth. And if not he has military goons to sell it to. The technical discussions here are distractions to the avoid dealing with the glaring dissonance that for the vast majority none of this will improve life on earth.
MarceliusK 8mo ago
On the engineering side, your list pretty much nails why this reads as sci-fi dressed up as a roadmap

by elamje 8mo ago

philipwhiuk 8mo ago

> 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.

elamje 8mo ago
Where did you hear this?
adastra22 8mo ago
You are confidently incorrect. Even Starlink uses rad-hardened CPUs. Redundant error correction is only really an option on launch hardware that only spends minutes in space. Note that on modern hardware cosmic rays permanently disable circuits, not mere bitflips.
- NitpickLawyer 8mo ago
  > You are confidently incorrect. No, he's not. Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space. > AWST: So, NASA does not require SpaceX to use radiation-hardened computer systems on the Dragon? John Muratore: No, as a matter of fact NASA doesn't require it on their own systems, either. I spent 30 years at NASA and in the Air Force doing this kind of work. My last job was chief engineer of the shuttle program at NASA, and before that as shuttle flight director. I managed flight programs and built the mission control center that we use there today. On the space station, some areas are using rad-hardened parts and other parts use COTS parts. Most of the control of the space station occurs through laptop computers which are not radiation hardened. > Q: So, these flight computers on Dragon – there are three on board, and that's for redundancy? A: There are actually six computers. They operate in pairs, so there are three computer units, each of which have two computers checking on each other. The reason we have three is when operating in proximity of ISS, we have to always have two computer strings voting on something on critical actions. We have three so we can tolerate a failure and still have two voting on each other. And that has nothing to do with radiation, that has to do with ensuring that we're safe when we're flying our vehicle in the proximity of the space station. I went into the lab earlier today, and we have 18 different processing units with computers in them. We have three main computers, but 18 units that have a computer of some kind, and all of them are triple computers – everything is three processors. So we have like 54 processors on the spacecraft. It's a highly distributed design and very fault-tolerant and very robust. [1] - https://aviationweek.com/dragons-radiation-tolerant-design https://aviationweek.com/dragons-radiation-tolerant-design
  - adastra22 8mo ago
    > Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space. Those are not independent facts. They put the hardware inside, behind the radiation shielding they use to keep the astronauts safe. It's why regular old IBM laptops work on the Space Station too. That kind of shielding is going to blow your mass budget if you use it on these satellites. SpaceX, which prefers COTS components when it can use them, still went with AMD Versal chips for Starlink. Because that kind of high performance, small process node hardware doesn't last long in space otherwise (phone SoC-based cubesats in LEO never lasted more than a year, and often only a month or so).
numpad0 8mo ago
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.

kortilla 8mo ago

>Ingress/egress are almost always a major bottleneck - how is bandwidth cheaper in space? Free space optics are much faster than data to/from the ground. If the training workloads only require high bandwidth between sats, this isn’t a real issue.

TheDong 8mo ago

> Would love for someone to make the case for why it actually makes total sense, because it’s really hard to see for me! Elon musk has a history of making improbable-sounding promises (buy a tesla now, by 2018 it will be a self-driving robotaxi earning money while you sleep, humanoid robots, hyperloops). The majority of these promises have sounded cool enough to enough people that the stock associated with him (TSLA) has made people literal millionaires just by holding onto the stock, and more and more people have bought in and thus have a financial interest in Musk's ventures being seen in a good light (since TSLA stock does not go up or down based on tesla's performance, it goes up or down based on the vibes of elon musk. It is not a car company stock, it is an elon vibes check). The thing he's saying now pattern matches to be pretty similar, and so given Musk's goal is to gain money, and he gains money by TSLA and SpaceX stock going up, this makes perfect sense as a thing to say and even make minor motions towards in order to make him richer. People will support it too since it pattern matches with the thing prior TSLA holders got rich off of, and so people will want to keep the musk vibes high so that their own $tsla holdings go to the moon. Make sense now?

adastra22 8mo ago
The story here is even simpler. SpaceX is going public this year. Elon made a monumentally shitty investment in Twitter and then poured a stupid amount of money into xAI at the peak of the cycle. By having SpaceX buy xAI, he gets to swap worthless shares in that company for more SpaceX liquidity. Simple as that.
- rockemsockem 8mo ago
  Really seems silly to think that the guy with $800 billion is spending most of his time maximizing his money.
  - z3t4 8mo ago
    He probably have 700 billion in loans and need to pay rent
  - kadoban 8mo ago

greengrassi 8mo ago

When they talk about "space" they are, right now, talking about the moon. Which has some gravity. They are putting the data centers on the moon. And the satellites are lunar satellites not earth-orbit satellites. Lonestar physical data center payload landed on the moon in Feb 2025 and Sidus space developing the lunar satellites.

adastra22 8mo ago
They are not. xAI/SpaceX is talking about millions of satellites in sun-synchronous orbit.
- nosianu 8mo ago
  Yeah, the cost of doing it on the moon would be even more astronomical. Then there also is the three second of round-trip latency to consider (ca. 2.6 s just the signal, but processing adds a bit more).

mike_hearn 8mo ago

It sounds hard but it shouldn't not make sense. 1. Solving cost of launching mass has been the entire premise of SpaceX since day one and they have the track record. 2. Ingress/egress aren't at all bottlenecks for inferencing. The bytes you get before you max out a context window are trivial, especially after compression. If you're thinking about latency, chat latencies are already quite high and there's going to be plenty of non-latency sensitive workloads in future (think coding agents left running for hours on their own inside sandboxes). 3. This could be an issue, but inferencing can be tolerant to errors as it's already non-deterministic and models can 'recover' from bad tokens if there aren't too many of them. If you do immersion cooling then the coolant will protect the chips from radiation as well. 4. There is probably plenty of scope to optimize space radiators. It was never a priority until now and is "just" an engineering problem. 5. What mass manufacture? Energy production for AI datacenters is currently bottlenecked on Siemens and others refusing to ramp up production of combined cycle gas turbines. They're converting old jet engines into power plants to work around this bottleneck. Ground solar is simply not being considered by anyone in the industry because even at AI spending levels they can't store enough power in batteries to ride out the night or low power cloudy days. That's not an issue in space where the huge amount of Chinese PV overproduction can be used 24/7.

FranklinJabar 8mo ago
> There is probably plenty of scope to optimize space radiators. It was never a priority until now and is "just" an engineering problem. Well, it's a physics problem. The engineering solution is possibly not cost efficient. I'd put a lot of money that it isn't.
- bborud 8mo ago
  That bit reminded me of someone who wanted us to design a patch the size of a small postage stamp, at most 0.2mm thick, so you could stick on products. It was to deliver power for two years of operation, run an LTE modem, a GNSS receiver, an MCU, temperature and humidity sensor and would cost $0.10. And it would send back telemetry twice per day.

energy123 8mo ago

> 5. Energy production will be cheaper from earth Sun-synchronous orbit means solar panels collect the same amount 24/7. I guess that's the #1 benefit. Cheap energy.

donkey_brains 8mo ago
Read the whole sentence. He’s talking about the cost to make solar panels that can be deployed in space, not the efficacy of said panels.

Symmetry 8mo ago

Regarding 3, they're almost certainly thinking of putting these in SSO where the radiation environment isn't too much worse than you see on the ISS. If they were going to go outside the Van Allen belts it would be a different story.

matthewdgreen 8mo ago

The whole AI bubble makes way more sense if you model it not as rational economic activity, but rather as the actions of a rogue AI slowly taking over our institutions and redirecting them towards its goals. Data centers in space make no sense economically, but think of how survivable the rogue AI will be once we build those orbiting data centers! (I am joking about this, but it's weird that my logic makes sense.)

tgtweak 8mo ago

Added some math on my comment that outlines the boundaries of economics of this considering most of what you mentioned.

mghackerlady 8mo ago

for the chips to both be radiation hardened and as powerful as our current chips they'd need to be massive. There's a reason the mars rover uses a PowerPC G3

UltraSane 8mo ago

It doesn't make sense. It is just Musk trying to pump up SpaceX valuation before the IPO.

RGamma 8mo ago

Think Elon: A swarm of advanced AIs working from space, untouchable for most, steering execution of his power fantasy on earth. And if not he has military goons to sell it to. The technical discussions here are distractions to the avoid dealing with the glaring dissonance that for the vast majority none of this will improve life on earth.

MarceliusK 8mo ago

On the engineering side, your list pretty much nails why this reads as sci-fi dressed up as a roadmap