Hi I've not seen "The Martian" yet, but I have followed some of the online comments about the supposed radiation levels the film's protagonist would experience whilst stranded on Mars. By "radiation", I assume this to comprise of the solar wind and cosmic rays, both of which, I gather - aside from the occasional GRB event - bombard the surface of Mars at a rate averaging around 30 mSv per hour during a typical solar minimum. To date, however, I can find nothing that describes what the radiation levels would be were a truly powerful – i.e. X-class – solar flare, to strike the Martian surface. I ask this question because as a result of all the talk about lengthy manned explorations of Mars planned for the 2030s, I do wonder what sort of additional protection (if any?) would be needed to shield astronauts from such solar outbursts.