Many propulsion systems designed for interstellar travel are last-ditch, desperation schemes with very small chances of a payoff. The decidedly iffy status of some of the propulsion concepts so far discussed – the Alcubierre Drive, Sonny White’s warp drive – have led some star travel proponents to conceive of other exotic, “alternative,” or overly imaginative propulsion methodologies: flying through wormholes, for example, or crackpot faster-than-light schemes such as tachyon drives. But those concepts are so far-out and unlikely as to be well beyond even Hail Mary desperation status. There are some further theoretically possible systems, however, that just might work. The least implausible of them all is the controlled nuclear fusion drive. It was this type of engine that would supposedly propel the otherwise unworkable Bussard Interstellar Ramjet as well as the second stage of the Project Daedalus starship. In its favor is the fact that nuclear fusion is the single Hail Mary propulsion technology that is currently under active development.