How do these circuits deal with random bit flipping from cosmic rays?
Continuous voting on hard real-time systems
The CPUs of Spacecraft Computers in Space
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Re: The CPUs of Spacecraft Computers in Space
#12How do these circuits deal with random bit flipping from cosmic rays?
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Re: The CPUs of Spacecraft Computers in Space
#13Space flight computers in the public sector are generally 15-20 years behind the types of hardware we commonly work with on the ground, as I think this page shows. We now have pretty capable low-power SoCs and FPGAs that we've yet to see broadly leveraged for govt. space applications. SpaceX flies Starlink with Xilinx FPGAs, while NASA and DoD are still baselining new platforms on incredibly expensive (albeit rad-har…
My understanding is that certification is the bottle neck, in both time and cost. No one wants to spend the money or time to flight certify something new when something already battle tested will suffice. But your comment makes me wonder if the private sector doesn't have those certification requirements? The other differentiating factor is that the private sector is not sending multi-year (indeed multi-decade) deep…
Flagship multi-year science missions are generally conservative with technology choices, but some NASA projects are intended as technology demonstrations and can on take more risks.
So like the Perseverance rover on its way to Mars is powered by redundant RAD 750s (same as Curiosity), but the Ingenuity helicopter along for the ride is powered by a Snapdragon 801.
It will be interesting to see how it holds up.
Re: The CPUs of Spacecraft Computers in Space
#14Stick an Apple M1 chip in it and be done with it :)
Re: The CPUs of Spacecraft Computers in Space
#15Space flight computers in the public sector are generally 15-20 years behind the types of hardware we commonly work with on the ground, as I think this page shows. We now have pretty capable low-power SoCs and FPGAs that we've yet to see broadly leveraged for govt. space applications. SpaceX flies Starlink with Xilinx FPGAs, while NASA and DoD are still baselining new platforms on incredibly expensive (albeit rad-har…
The RAD750 (edit - the whole RAD family, there are newer models available) remains the standard because it's the highest performance rad-hard design available, period. If you're putting an expensive satellite in orbit for 5,10 years, the cost of the processors is insignificant compared to everything else.
The real problem is that we don't have good solutions for improving the performance of rad-hard designs, so we're stuck with older, larger process sizes that limit what can be implemented. Look at the lengths involved in getting A* to run on Curiosity, and you see just how limiting the hardware is. Everyone, Nasa especially, wants more compute available.
In low earth orbits and shorter mission durations, you can get away with redundant hardware instead of rad-hard. Most of the damage done by radiation is upsets, so you can reboot the affected hardware and keep going. But on an unprotected design some of the damage can be permanent, and thus redundancy alone isn't enough for longer/farther missions.
Re: The CPUs of Spacecraft Computers in Space
#16Space flight computers in the public sector are generally 15-20 years behind the types of hardware we commonly work with on the ground, as I think this page shows. We now have pretty capable low-power SoCs and FPGAs that we've yet to see broadly leveraged for govt. space applications. SpaceX flies Starlink with Xilinx FPGAs, while NASA and DoD are still baselining new platforms on incredibly expensive (albeit rad-har…
The RAD750 (edit - the whole RAD family, there are newer models available) remains the standard because it's the highest performance rad-hard design available, period. If you're putting an expensive satellite in orbit for 5,10 years, the cost of the processors is insignificant compared to everything else. The real problem is that we don't have good solutions for improving the performance of rad-hard designs, so we're…
> The RAD750 remains the standard because it's the highest performance rad-hard design available, period.
RAD5500?
Re: The CPUs of Spacecraft Computers in Space
#17[deleted]
Re: The CPUs of Spacecraft Computers in Space
#18Earlier quoted context omitted.
The RAD750 (edit - the whole RAD family, there are newer models available) remains the standard because it's the highest performance rad-hard design available, period. If you're putting an expensive satellite in orbit for 5,10 years, the cost of the processors is insignificant compared to everything else. The real problem is that we don't have good solutions for improving the performance of rad-hard designs, so we're…
> The RAD750 remains the standard because it's the highest performance rad-hard design available, period. RAD5500?
You're right, the RAD5500 and family are available. I should have said the whole BAE RAD family.
The reality hasn't changed much, though, there's really only one game in town for high rad-hard performance, and it's still well behind conventional processors.
Re: The CPUs of Spacecraft Computers in Space
#19[deleted]
> Saying there are physical backup controls is a bit like saying there are backup controls at the bottom on your new TV.
Can you expand on this? Are you against physical backup controls?
Re: The CPUs of Spacecraft Computers in Space
#20Reminds me of this post comparing the CPU and RAM of the Apollo 11 flight computer with modern USB chargers. (spoiler alert: the USB charger wins)
https://forrestheller.com/Apollo-11-Computer-vs-USB-C-charge...
Hacker News comment link: https://news.ycombinator.com/item?id=22254719