Imagine a crew crammed into an Orion capsule for the 445 day and 700 plus day mission planned to sample asteroids, especially since Obama foolishly cancelled the Altair lander.
On top of that, no one is going to Mars, or even to an asteroid, without NASA relaxing its standard on the individually calculated lifetime probability of "Radiation Exposure Induced Death," or "REID." An astronaut today is grounded if that calculation exceeds (or is expected to exceed 3 percent), and the sad fact is that a round trip ticket to Mars exceeds that standard going out the gate.
And nuclear rockets won't best the Holmann transfer orbit travel time by more than a third.
Handing the Moon over the Chinese is one of the dumbest ideas to come down the pike since the missile scandals of the Clinton administration.
Yeah, radiation is the big, big problem.
Apparently you would really need walls made of about 6 feet thicknesses of lead or concrete.
Very difficult problem.
Apparently we have proof-of-concept for a magnetic radiation shield, though.