VASIMR: Space propulsion advances

Several years ago, at JSC on a consulting assignment to help NASA prioritize funding for future systems, I watched a test-firing of the plasma ignition system for an interesting, if far from mature, superhigh-efficiency propulsion technology called the Variable Specific Impulse Magnetoplasma Rocket (VASIMR). Now being tested in Houston by the Ad Astra Rocket Company, founded by former astronaut and VASIMR inventor Franklin Chang-Diaz, the system has advanced to the point of test-firing an engine "to spaceflight levels." This version used 30kw of power: a flight test engine to be tried at the ISS in 2012 or later will use 200kw. Power levels in the hundreds of megawatts, for which the only practical near-term option is a nuclear fission reactor, would be needed for the ultimate goal: an engine that could send a spaceship to Mars in 39 days.