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Radiation hardened CPUs like RAD750 are radiation hardened for up to 1000 gray. Cool. But, as CPUs have advanced way ahead their mechanical counterparts in miniaturization and fragility, energy dissipation and costs per kg to orbit have lowered, wouldn't just a simple lead shield start being more economic?.

Obviously, Rad-Hard CPUs need to stand a very harsh environment besides radiation, from extreme temperatures to vibration. In summary, shouldn't we be talking now about Space-Hard computing rather than Rad-Hard computing?

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  • $\begingroup$ Great question about an important distinction! Different question but related: What makes Insight's RAD750 processor so radiation resistant? (compared to 1998 iMac's PowerPC 750) $\endgroup$
    – uhoh
    Mar 5 at 2:52
  • $\begingroup$ I don't have details to give you a full answer, but I'm aware of testing that's been done in radiation cells on the ground to prove exactly this sort of "modern processor with shielding" scheme works. Per those tests, it does. $\endgroup$
    – Erin Anne
    Mar 5 at 2:58
  • $\begingroup$ I know from at least one S/C (Cassini/Huygens) (a former colleague of me was electrical engineer for an instrument): they used a shielded processor. Instead of lead, they used gold and aluminum. (The same mass of aluminum shields the primary radiation as good as the same mass of lead but because of the additional volume less deceleration radiation is emitted). Not posting this as an answer, because i just have the oral information and no source to link. $\endgroup$
    – CallMeTom
    Mar 5 at 6:57
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Every computational device used in space has to be tolerant to vibrations. Launch is a very shaky process. Every computational system used in space has to be tolerant of various forms of radiation. The Earth's atmosphere and magnetosphere provide very nice shielding against solar and cosmic radiation. That shielding is gone above the Van Allen Belts.

Note that I wrote "system" rather than "device". Making every device in a computational system be tolerant to radiation is one way, but not the only way to make a computational system be tolerant to damage by radiation. SpaceX, for example, uses massive redundancy with somewhat radiation-tolerant computers to overcome the radiation challenges of being in space.

There's a huge downside to using radiation hardened devices: They are computational devices from the previous millennium that are slow (all-caps SLOW), have limited memory, and have even more limited storage capacity. We saw that recently with the landing of the Perseverance. The very cool videos of that landing came about because of the use of computational systems that were not radiation hardened. That landing video would not have been possible using radiation hardened devices. The use of non-hardened devices was allowed because the data captured, recorded, and later transmitted back to Earth was not mission critical.

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