Well, nuclear power isn't harder because you put it in a car, but it's a great way to add to the complexity of the system as a whole. Putting a nuclear reactor

Well, nuclear power isn't harder because you put it in a car, but it's a great way to add to the complexity of the system as a whole. Putting a nuclear reactor in space (as we still do, I think the most recent Mars rover had one) greatly reduces the risk of it directly causing deaths, since it's really far away from humans for most of its service life.