I saw a show on PBS about this, and I think it would be very cool to have a huge ship take off from the blast of a nuclear explosion. Of course the environmentalists would go nuts, but it would make space travel cheap and usefull What you are describing sounds like Orion. Small nuclear bombs with a little fuel dropped from the spacecraft, explode, and the plasma that was the fuel, expand against a pusher plate, and shock absorbers take most of the G's for a safe ride for the inhabitants. When the project was first concieved, the scientists thought that "clean" fission bombs were "just around the corner" so they didn't think pollution would be a big problem. They also designed a smaller version, to be sent up in 2 sections on Saturn V rockets. While this is a very fast mode of transportation, I don't think it will ever become reality. The public will never be comfortable with a spaceship powered by several thousand low yield nuclear bombs. However, it would be a feasible way to rid ourselves of the stockpiles of nuclear weapons that many people seem think we can just "get rid of". VadersLaMent, I've heard of the M2P2, and I agree, it doesn't sound practical for anything other than space probes. If I read correctly, it would be usefull in blocking radiation once you get past the earth's magnetosphere, so it would still be a good thing to have. The americium 242 nuclear fuel sounds almost too good to be true. Lets hope NASA and other space agencies help with the research of this. As for manned interstellar travel, I think the best we can hope for is a breakthrough in the way we produce anti-matter. As long as we can produce a lot of the stuff and cheaply, it will be our window to the stars.