re: #1 Anymouse

I disagree that current technology cannot shield the crew, given my reading of this report by NASA. science.nasa.gov

The problem is not the tech, but the spacecraft design we’ve used so far. The material of choice has been aluminum, since it is lightweight and strong. All of our manned spacecraft have been necessarily launched from the ground, so saving weight has been a major design consideration.

I would assume that a manned mission to Mars would require the spacecraft to be assembled in orbit, simply because of its likely size. So, conceivably other, more absorptive materials than Al could be used. The NASA article mentions plastics and even liquid H2, at least for the crew quarters. Engineers could probably develop some other materials besides those.

But, anyone signing up for such a mission would have to know in advance that their chances of radiation damage would be substantially higher than just hanging around Earth. I’m pretty sure most would still take the risks. While not addressed in the linked NASA report, another issue would be the radiation exposure on the Martian surface. Mars has a very thin atmosphere and a very weak magnetic field, so anyone walking around on the surface would still be exposed to potentially harmful radiation. Again, I assume space engineers could design suitably shielded EVA suits to help minimize the damage.