Originally posted by KazetNagorra
I don't think it would be economically efficient at that scale. And of course, a nuclear powered car would be far too dangerous.
That depends on the kind of power. If it was from fusion, say by some kind of miracle we found out we could make a 100 horsepower sized tokamak the size of a clothes washer or something, then the power would be derived from helium or deuterium or some such. Or our miracle fusion unit could be a small laser fusion device like the upcoming laser ignition experiment. If it was either of those devices there would be no danger of nasty contaminants, at least not even in the same ballpark as that represented by some kind of small fission reactor. Also, there is already a nuclear battery, albeit on a tiny scale right now. It works by taking a known alpha ray emitting isotope and using it to charge up a nanosized capacitor which bends and then shorts out when the charges build up enough to physically bend the nanobeam, it shorts out and transfers its tiny charge of electrons to an external circuit. Of course at this stage of the game it is spitting out nanowatts but if billions of the things can be designed, there would be no moving parts (except for the nanocantalevers) and would also not be much danger in a collision. Of course right now I don't thing the existing unit could power a digital watch much less a car, obviously billions of them running in parallel would be required.
Besides, a fission reactor in space for unmanned craft doesn't need much in the way of shielding, no wet ware to worry about and the electronics and/or photonics inside can be built to withstand thousands of rads of radiation so those puppies can be practically a floating radiation machine. BTW, antimatter reactors are a lot further along, engineering wise than fission or fusion reactors for spacecraft. Of course antimatter reactors would be the cats meow for anything but it's not going to happen on earth in THIS millenium anyway.