It’s safe to say that Franklin Chang-Diaz knows what he’s talking about when he discusses the space experience. An astronaut who has logged seven flights and over 1600 hours in space (a period that includes three spacewalks), Chang-Diaz has been making even more impressive news in recent times with his Ad Astra Rocket Company, where the VASIMR (Variable Specific Impulse Magnetoplasma Rocket) is under development. It’s heartening to think of VASIMR undergoing space-based tests, a future that is now in the cards with the news that NASA has plans to test the VASIMR engine aboard the International Space Station.
We naturally think long-term here, but VASIMR’s uses in potential missions to Mars (Chang-Diaz talks about a 39-day trip to the planet!) and beyond will first have to be shaken out in near-Earth orbit. But ponder a VASIMR gradually becoming operational, mounting missions to communications satellites that are now economically all but unreachable. Indeed, VASIMR sets up the potential for servicing a wide range of space technologies, keeping them viable even as we move back to the Moon and find the need to service and re-supply a colony there, a tricky and expensive process with chemical rockets.
This is heady stuff that’s coming in the short term. Here’s what Chang-Diaz told an interviewer late last year, when asked about timelines for the technology:
We are on a fast track to complete the first flight-like VASIMR prototype, the VX-200 by early 2008. This device will be in all ways identical to the flight engine but will not fly. We plan to complete the characterization of this prototype by mid 2008 and begin the design of the VF-200-1 and the VF-200-2, the first flight engines, which will be ready for flight in late 2010 and 2011 respectively. By 2012 we expect to have both engines operating in space in two different venues. By the middle of the next decade we plan to fly more powerful engines in a lunar cargo vehicle, which is presently in our drawing boards. This vehicle could enable economically sustainable re-supply services to the Moon colonies and also be used to access space resources such as water and metals on comets and near Earth asteroids. By the end of the next decade, Ad Astra plans to begin construction of a lunar rocket test facility that will enable us to fully test the very powerful VASIMR rockets needed for missions to Mars and beyond. These rockets require a vacuum and a suitable facility large enough is not practical to build on Earth.
Using plasma heated by radio waves and channeled magnetically, VASIMR offers major benefits in fuel efficiency and thrust in a system that can be adapted for robotic cargo missions as well as faster manned operations. The ISS would not only provide the venue for early testing in space but also point to a major future use, the maintenance of large structures in orbit without burning far more inefficient rocket fuel to do the job. At the ISS, the plasma drive would draw its power from solar panels, but the kind of output needed for a mission to Mars would inevitably demand an onboard nuclear powerplant.
Thus we circle back to the nuclear issue, an obvious political problem that has plagued the development of space systems designed for operations far from the Sun. Remember the fear inspired by Cassini’s 1999 Earth flyby on its way to Saturn? Cassini’s radioisotope thermoelectric generators (RTGs) have to be used in venues where the Sun’s rays are weak, but anti-nuclear activists spoke of an environmental catastrophe if the craft hit the Earth. The obvious success of the mission has only put the nuclear question on hold rather than answering it. Mars in 39 days is a grand concept, but it means a nuclear option is in play that will generate more than its share of renewed protests. Brace yourself.