Chang Díaz believes that VASIMR could usefully glean its electric power from solar panels if it was operating close to the sun (Mars would be the extreme outer limit) or from onboard nuclear reactors further away. He calculates that a nuclear VASIMR craft could get to Mars in just 39 days, as opposed to the many months a chemical-rocket ship would take.

If I recall correctly, the fictional “Lyle Drive” mentioned in Stranger In A Strange Land required only twelve days for an Earth-to-Mars trip, but this is still one heck of a lot better than current technology. 🙂

A test version is going to be installed on the International Space Station, “where it would use solar power to maintain the ISS’ orbit without the need for frequent, expensive resupplies of chemical rocket fuel.”