but mixing your comment with a few others, maybe a nuke plant on the ground that cracks the co2 in the atmosphere to make carbon neutral hydrocarbon fuel.
Probably? It would be a disaster every time one crashes, would carry a huge proliferation and terrorism risk. Oof.
In the 50's some countries were that crazy and they even put reactors in space. Two of which crashed and one contaminated a huge area in Canada. Luckily common sense prevailed and these things don't happen anymore. Though nuclear ships still exist, there's only a few icebreakers in the civilian fleet AFAIK.
But yeah RTGs are very nasty stuff too. They are much easier to secure against breaking apart on re-entry though (although dropping a concentrated plutonium source into a random place is not a great idea either obviously).
I don't think any are used on current earth-orbiting sats though: https://en.wikipedia.org/wiki/Radioisotope_thermoelectric_ge...