NASA is working hard on this issue and I'm confident that over the next decade research will yield solutions for at least normal space radiation levels. Localized magnetic field generators or new materials development or whatever. The ideal would be materials that could be used not only in base and spacecraft construction, but in space suits as well!

Obvioulsy Chris, if humans are to explore other planets there has to be a solution to radiation exposure. A Mars mission is even more dependent on that than a Lunar mission. If it doesn't happen then we are going nowhere. If it does, then the 3-4 month rule will go too.

As for a visiting a vault, what would you call the Space Station? What would you call a Mars base? Anywhere we go in the known universe will require living in a "vault" for the forseeable future. The key is making it big and safe enough.

And to repeat my original view, I think it would be foolhardy to send astronauts on a 2-3 year mission to Mars if they have never had long duration off world practice.