Or, really astronaut hero Franklin Chang-Diaz has one. Seed magazine has an interview with Dr. Chang-Diaz in which he describes how he’s using magnets and radiation to get to Mars in about a month:
In fact, with the power close to what a nuclear submarine generates, you could use VASIMR to fly humans to Mars in 39 days. A chemical rocket makes the trip in eight months. That’s eight months of exposing your astronauts to debilitating cosmic radiation and weightlessness. By the time they get to where they’re supposed to work, they’re gonna be in bad shape—almost invalids! They’ll have to spend a big chunk of their time just recovering from the trip.
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But once we have this capability, Mars isn’t really the only place that we can go. With a megawatt-class VASIMR, basically we will have access to the entire solar system. Mars is an interesting place, but so are Europa and Ganymede and Enceladus and Titan. These are places where we might find extraterrestrial life. Even with the 200-kilowatt solar-powered VASIMR we could do amazing things. We’re developing a concept to drive it close to the Sun, between Venus and Mercury, where it can get a momentum boost and catapult a probe into the outer solar system at high speed. This would let us deliver a package to Jupiter in one-and-a-half years; otherwise that trip takes about six.