> Interesting! ESA has been using a custom SPARC V8 rad hard architecture: https://en.wikipedia.org/wiki/LEON

While LEON isn't going away any time soon (especially given the recent release of the new LEON-5), I very much get the impression that the long-term plan is to replace it with RISC-V based solutions such as NOEL-V. Nobody can throw out working systems, but if you are starting something brand new, does it really make sense to base it on an ISA which the rest of the industry has essentially abandoned? Even its originator (or successor thereto) has basically walked away from it. Aerospace stuff is as expensive enough as it is already, getting stuck on a niche legacy ISA seems like a recipe to only make it even more expensive.

If you look at the page for the gr765 the parent poster linked to, you can see that the customer can choose the gr765 with either SPARC or RISC-V cores. I think you're right that the plan is to transition to RISC-V, given that the SPARC ecosystem otherwise is pretty moribund.

Interestingly enough, the LEONv3 architecture also underlies the SkyTraq Venus8 GPS/GNSS chips, which are in the Navspark arduino-compatible modules, which means there's a really, really accessible toolchain for 'em. Just add the board support URL to the IDE, and voila, you're building for LEON.

The NavSpark Mini is still $36 for a 6-pack, making it one of the cheapest uCs with a floating-point unit. (The ESP32 technically has one, but its performance is inexplicably poor.)

I'm not clear on whether SkyTraq's chips have all the error-correcting goodies that're in other LEON implementations; would those be baked in by default?

NASA has mostly been using a PowerPC.

https://en.wikipedia.org/wiki/RAD750

Are any of these boards available for regular people at a regular person kind of price? Or is it 1000s of USD for an evaluation board?

It’s super hard to get pricing info for radiation hardened chips that are currently being sold, let alone just buying one from Digi-Key. It’s pretty damn annoying if you just want the one super robust chip for a system supervisor or something else like that, to have no idea how to plan the design for a cost budget before you begin doing a lot of contact work talking to people for price quotes. It’s a weird ecosystem that feels surprising antiquated compared to the more modern parts of the embedded ecosystem that I’m familiar with.

Worst price I can remember off hand was $15 grand USD for a radiation hardened microcontroller, pretty sure it was an Arduino mega family chip I could have gotten the industrial quality version of for $25 bucks from Digi-Key… if I didn’t want it radiation hardened.

$40k for a QML-V RTG4. Something like $100-150k for the newest Virtex 6 Ultrascale. You can get an engineering model for like a quarter of the price.

Can you even buy one without running afoul of ITAR?

I'm slightly surprised you could even buy a rad-hardened microcontroller, but maybe microcontrollers are considered simple enough that they are exempt?

I’m pretty sure the reason a lot of it is behind such gatekeeping and onerous sales process crap is because of ITAR. Dealing with American companies is the god damn worst for anything like this. So much so I’ll actively avoid anyone US based. I am building a satellite, and America has lots of cool space tech… but it’s globally second class compared with any other country since some of them give so little of a shit about arms control (they import their real weapons from countries like the USA, UK, etc and so any space tech is just so tiny a niche businesses they don’t care) that it’s more paperwork to get through customs upon arrival than it is to buy stuff like solar panels and other basic stuff from the USA due to ITAR.

Get that from the USA and your basically in for a polite colonoscopy before they even tell you their prices (only slightly exaggerating)

Most of the time, it's easy to just put a microcontroller core into an FPGA but sometimes you just need some basic operations and don't have a lot of power to spare for an FPGA you won't fully utilize. The Atmel chip is perfect for this situation, TI makes one too. It's not going to be good for a 15 year GEO mission but there's still a niche to fill with these parts.

I recently saw an article where a guy got Ada/SPARK up and running on one of those Gaisler chips. Was super neat to see, kind of made me want to play with Ada.

I love Ada, but the tooling is hell. Alire is a great start for a package manager, but it's still clunky and parallel projects like the ada language server still don't build with it for some reason.