On Mon, 10 Dec 2018 09:22:20 +0000, Dim Streater, an especially retarded,
troll-feeding, troll-feeding senile idiot, blathered:

Why are these not used on earth?

Probably not that cheap, once you've made the Pu-238.

You've certainly turned out to be one the most devoted suckers of the
unwashed Scottish ******'s cock, senile Dim! LOL