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…
Could they not offload a lot of compute to ground based computers and submit results back via radio? Or are these real-time applications?
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…
Could they not offload a lot of compute to ground based computers and submit results back via radio? Or are these real-time applications?
I was thinking, instead of that, what if you had a separate isolated tiny computer on spacecraft, that was powered by its solar panels (so there's no electrical wiring, or other connection to it), and have its own radio. And this separate computer could use the latest bleeding-edge CPU, and be encased in a radiation-hardened shell. It would use its radio to talk to the slower main computer, and do math really fast locally, and if need be, beam the results to Earth, or to a nearby orbiting satellite.
Space 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…
I had to select a processor that controls the camera in the GOES-R ABI. The image processing is all done by custom hardware so all that was needed was microcontroller level performance. It turns out there are very limited options in this space and all of them are quirky outdated architectures with limited available tooling.
The RAD750 in particular is a bit of a nightmare because of the high pin count, need for a support chip, and the 32-bit bus forces the use of more RAM and ROM than a smaller micro would need. I took a pass on that. I also never have liked IBM's reverse bit numbering and the implications it has on SRAM power consumption.
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…
How do you battle test a RAD prototype? Stick it in microwave like device with ionizing radiation and see how many bit-flips occur?
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…
Could they not offload a lot of compute to ground based computers and submit results back via radio? Or are these real-time applications?
The whole point of implementing A* on Curiosity was to give it some navigation autonomy. The time delay in getting sensor data back to earth, coming up with a motion plan, then sending the plan back to be executed imposes tight limits on how fast the rover can drive, what kinds of terrain it can cover, and ultimately how much science can be done. Local autonomy for basic "go over to than weird-looking rock" tasks is a major improvement.
Space 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…
> Starlink with Xilinx FPGAs, while NASA and DoD are still baselining new platforms on incredibly expensive (albeit rad-hard) PowerPC RAD750 and similar.
Ignoring that Starlink isn't very far away, I would assume NASA stuff would also have FPGAs and ASICs on them - they aren't CPUs and aren't used like them.
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…
How do you battle test a RAD prototype? Stick it in microwave like device with ionizing radiation and see how many bit-flips occur?
It depends on where the spacecraft is going as radiation environments differ. I've taken parts to be exposed by a proton line at a particle accelerator. For some environments they just use Cobalt-60 as a radiation source.
There's three basic ways this is done: 1: By process, where chips are created with special or larger features to better resist cosmic rays. This is Expensive since they're made in very low volumes and the cost of the new fab line can't be spread among many millions of units. Instead, a few thousand chips might be made. 2: By design, where redundant systems such as triple redundant memory or voting computers are used.…
As sending mass to space becomes cheaper I wonder if shielding will become more popular... Maybe there is some oil-like material that could serve bath as a cooling bath and as a radiation shield?
Polyethylene is usually used to shield against cosmic rays. Nearly identical shielding performance as water. Slightly less weight per volume. Can be formed easily and retains its shape.
Space 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…
> Starlink with Xilinx FPGAs, while NASA and DoD are still baselining new platforms on incredibly expensive (albeit rad-hard) PowerPC RAD750 and similar. Ignoring that Starlink isn't very far away, I would assume NASA stuff would also have FPGAs and ASICs on them - they aren't CPUs and aren't used like them.
Some NASA orgs have tried using FPGAs as a way to get around software requirements, to varying levels of success