Be Unreasonable

The reasonable man adapts himself to his environment.
The unreasonable man adapts his environment to himself.
Therefore, all progress is due to unreasonable men.

In this case, NASA is taking the reasonable approach. If the astronauts experience bone loss, radiation damage, etc., then change their diet, give them drugs, or whatever to get them through it.

The unreasonable approach is to notice that astronauts do not have millions of years of evolution in near zero G conditions. So, provide them with artificial gravity. This can be achieved by spinning. Radiation shielding is expensive, but possible. 10 meters of water all around should do it. Since this weighs as much as a battleship, one should consider electrostatic and magnetic deflection as lighter and therefore cheaper alternatives. And one should test these technologies. Half a trillion dollars has been spent on the International Space Station.

Going to the Moon was unreasonable. Audacious aeronautical research, like the X15, was unreasonable. That's what NASA was created for. NASA is being reasonable when being unreasonable is called for.