4 ms·

Maybe a stupid question, but couldn’t they put there something “cutting-edge” next to the existing system? Then if that fails then whatever, the rest of the sys

Maybe a stupid question, but couldn’t they put there something “cutting-edge” next to the existing system? Then if that fails then whatever, the rest of the system is still functional as expected, but at least they know that in the future what they would need to change to be able to use the new technologies in that environment. Although I can imagine that even the smallest weight increase could cause issues, so probably that’s the reason.

wongarsu 6y ago
Ingenuity (the Mars helicopter) has a much more modern processor that isn't particularly radiation hardened, and instead just restarts within milliseconds on any fault (fast enough to recover if it happens in flight). If Ingenuity does well I wouldn't be surprised to see a similar design in a future rover.
grishka 6y ago
They did this exact thing with the helicopter — it's using a Snapdragon SoC that runs Linux.
josho 6y ago
But now you’ve added weight and need to remove something else. As a tangent, I remember a talk from Grady Booch where he put software cost in terms of mass that needed to be added to your rocket. So every new feature cost weight by requiring more chips and more fuel.
m4rtink 6y ago
Scott Manley mentioned in one of his recent videos about Perserverance that they have an FPGA on board the rad hardened PPC main cpu can offload tasks to, such computer vision based navigation during landing. Not sure what the long term plan is for that hardware - I guess they can just do stuff more slowly on the main CPU if it gets fried by radiation. Or maybe being an FPGA the can just isolate the radiation affected regions over time and use the rest ?
- reilly3000 6y ago
  You got me curious and I found a product listing with a rather amazing explanation of what they're doing for radiation-proofing. Radiation Performance > RTG4 FPGAs are immune to radiation-induced changes in configuration, due to the robustness of the flash cells used to connect and configure logic resources and routing tracks. No background scrubbing or reconfiguration of the FPGA is needed in order to mitigate changes in configuration due to radiation effects. Data errors, due to radiation, are mitigated by hardwired SEU resistant flip-flops in the logic cells and in the mathblocks. Single Error Correct Double Error Detect (SECDED) protection is optional for the embedded SRAM (LSRAM and uSRAM) and the DDR memory controllers. This means that if a one-bit error is detected, it will be corrected. Errors of more than one bit are detected only and not corrected. SECDED error signals are brought to the FPGA fabric to allow the user to monitor the status of these protected internal memories. https://www.microsemi.com/product-directory/rad-tolerant-fpgas/3576-rtg4 https://www.microsemi.com/product-directory/rad-tolerant-fpg...
  - m4rtink 6y ago
    Wow, a rad hard FPGA! Now that's something I didn't expect - thanks for digging this up! :)
pkaye 6y ago
I know the camera image compression happens on a x86 processor. Not sure if it is rad hardened. It would be okay if the processor is not doing critical work and can be power cycled due to a rare SEU failure. Also the same with the helicopter uses a mobile phone processor. Also some of the components are not rated for long term use. The microphones they installed will probably fail due to extreme temperature cycling. The helicopter is expected to last only 4 uses and anything beyond that is a bonus.

wongarsu 6y ago

Ingenuity (the Mars helicopter) has a much more modern processor that isn't particularly radiation hardened, and instead just restarts within milliseconds on any fault (fast enough to recover if it happens in flight). If Ingenuity does well I wouldn't be surprised to see a similar design in a future rover.

grishka 6y ago

They did this exact thing with the helicopter — it's using a Snapdragon SoC that runs Linux.

josho 6y ago

But now you’ve added weight and need to remove something else. As a tangent, I remember a talk from Grady Booch where he put software cost in terms of mass that needed to be added to your rocket. So every new feature cost weight by requiring more chips and more fuel.

m4rtink 6y ago

Scott Manley mentioned in one of his recent videos about Perserverance that they have an FPGA on board the rad hardened PPC main cpu can offload tasks to, such computer vision based navigation during landing. Not sure what the long term plan is for that hardware - I guess they can just do stuff more slowly on the main CPU if it gets fried by radiation. Or maybe being an FPGA the can just isolate the radiation affected regions over time and use the rest ?

reilly3000 6y ago
You got me curious and I found a product listing with a rather amazing explanation of what they're doing for radiation-proofing. Radiation Performance > RTG4 FPGAs are immune to radiation-induced changes in configuration, due to the robustness of the flash cells used to connect and configure logic resources and routing tracks. No background scrubbing or reconfiguration of the FPGA is needed in order to mitigate changes in configuration due to radiation effects. Data errors, due to radiation, are mitigated by hardwired SEU resistant flip-flops in the logic cells and in the mathblocks. Single Error Correct Double Error Detect (SECDED) protection is optional for the embedded SRAM (LSRAM and uSRAM) and the DDR memory controllers. This means that if a one-bit error is detected, it will be corrected. Errors of more than one bit are detected only and not corrected. SECDED error signals are brought to the FPGA fabric to allow the user to monitor the status of these protected internal memories. https://www.microsemi.com/product-directory/rad-tolerant-fpgas/3576-rtg4 https://www.microsemi.com/product-directory/rad-tolerant-fpg...
- m4rtink 6y ago
  Wow, a rad hard FPGA! Now that's something I didn't expect - thanks for digging this up! :)

pkaye 6y ago

I know the camera image compression happens on a x86 processor. Not sure if it is rad hardened. It would be okay if the processor is not doing critical work and can be power cycled due to a rare SEU failure. Also the same with the helicopter uses a mobile phone processor. Also some of the components are not rated for long term use. The microphones they installed will probably fail due to extreme temperature cycling. The helicopter is expected to last only 4 uses and anything beyond that is a bonus.