> You are confidently incorrect.

No, he's not. Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space.

> AWST: So, NASA does not require SpaceX to use radiation-hardened computer systems on the Dragon?

John Muratore: No, as a matter of fact NASA doesn't require it on their own systems, either. I spent 30 years at NASA and in the Air Force doing this kind of work. My last job was chief engineer of the shuttle program at NASA, and before that as shuttle flight director. I managed flight programs and built the mission control center that we use there today.

On the space station, some areas are using rad-hardened parts and other parts use COTS parts. Most of the control of the space station occurs through laptop computers which are not radiation hardened.

> Q: So, these flight computers on Dragon – there are three on board, and that's for redundancy?

A: There are actually six computers. They operate in pairs, so there are three computer units, each of which have two computers checking on each other. The reason we have three is when operating in proximity of ISS, we have to always have two computer strings voting on something on critical actions. We have three so we can tolerate a failure and still have two voting on each other. And that has nothing to do with radiation, that has to do with ensuring that we're safe when we're flying our vehicle in the proximity of the space station.

I went into the lab earlier today, and we have 18 different processing units with computers in them. We have three main computers, but 18 units that have a computer of some kind, and all of them are triple computers – everything is three processors. So we have like 54 processors on the spacecraft. It's a highly distributed design and very fault-tolerant and very robust.

[1] - https://aviationweek.com/dragons-radiation-tolerant-design

> Dragon is using CotS, non rad-hardened CPUs. And it's rated to carry humans to space.

Those are not independent facts. They put the hardware inside, behind the radiation shielding they use to keep the astronauts safe. It's why regular old IBM laptops work on the Space Station too. That kind of shielding is going to blow your mass budget if you use it on these satellites.

SpaceX, which prefers COTS components when it can use them, still went with AMD Versal chips for Starlink. Because that kind of high performance, small process node hardware doesn't last long in space otherwise (phone SoC-based cubesats in LEO never lasted more than a year, and often only a month or so).

Carrying humans to space is not the same use case as spending long periods of time in orbit.