Yeah, we should probably not do this in LEO, where orbits decay and half of the potential acceleration vectors lead back down to Earth. Fortunately, it takes a lot of energy and precision to de-orbit anything heavy that is in geosynchronous orbit or beyond.
If the fissile material could be acquired by asteroid mining, then it would never need to pass through the Earth's atmosphere. I know that still sounds way out there, but I think that uranium or thorium would actually be a great material for kicking off asteroid mining. A small amount will pay off in a big way, it is a very dangerous thing for humans to mine on Earth, and, like the parent mentioned, we really don't want to fly it around where it can fall on us.
If the fissile material could be acquired by asteroid mining, then it would never need to pass through the Earth's atmosphere. I know that still sounds way out there, but I think that uranium or thorium would actually be a great material for kicking off asteroid mining. A small amount will pay off in a big way, it is a very dangerous thing for humans to mine on Earth, and, like the parent mentioned, we really don't want to fly it around where it can fall on us.