You had it with the fusion reactor. Manned exploration of the solar system is pretty much contingent on having fusion power. Once we do that, we can create co

You had it with the fusion reactor. Manned exploration of the solar system is pretty much contingent on having fusion power. Once we do that, we can create constant thrust engines as well as light up greenhouses where ever. At least, those of us with some significant cash could. I suppose cheap fusion could be dangerous, as well. Imagine every Joe Sixpack with a railgun powered by Mr Fusion. (sort of a Snowcrash meets Back to the Future dystopia)