That seems to say it’s for a radiation-hardened design:
“In 2021, NASA solicited proposals for a trade study for an advanced radiation-hardened computing chip with the intention of selecting one vendor for development. This contract is part of NASA’s High-Performance Space Computing project”
They also say:
“The processor will enable spacecraft computers to perform calculations up to 100 times faster than today’s state-of-the-art space computers”
and
“Our current spaceflight computers were developed almost 30 years ago,”
That, for me, also points towards a radiation-hardened design. If it isn’t, 100 times faster than 30 years ago is an incredibly low hurdle to clear.
Also, it’s a $50 million firm-fixed-price contract. I have no idea whether that’s a sharp price for this, so can’t judge how much risk SiFive takes on with this.
Seems it's not quite as dire as one might imagine, for example the DAHLIA project is using ST's 28nm FDSOI process[1].
In any case, I found this[2] article interesting and illuminating, which goes into different aspects of radiation hardening, including how the "old = safe" isn't strictly true.
You are correct, since chips designed at around 5-7 nm are much more likely to be hit with radiation. However, by scaling up the chip, you can be a lot more tolerant to it. Because of this, most chips are fabbed at around 28 nm. Generally, you want a mix of both things. You can harden a chip by shielding it, but that doesn't stop everything, so you add some fault tolerance.
this was developed for the HPSC program whose goal was to develop a replacement for the RAD750, and the "100 times performance" requirement is wrt that.
That seems to say it’s for a radiation-hardened design:
“In 2021, NASA solicited proposals for a trade study for an advanced radiation-hardened computing chip with the intention of selecting one vendor for development. This contract is part of NASA’s High-Performance Space Computing project”
They also say:
“The processor will enable spacecraft computers to perform calculations up to 100 times faster than today’s state-of-the-art space computers”
and
“Our current spaceflight computers were developed almost 30 years ago,”
That, for me, also points towards a radiation-hardened design. If it isn’t, 100 times faster than 30 years ago is an incredibly low hurdle to clear.
Also, it’s a $50 million firm-fixed-price contract. I have no idea whether that’s a sharp price for this, so can’t judge how much risk SiFive takes on with this.