Like most things where one cannot do repeated, controlled experiments, no one really knows where the truth lies apart from some vague notions. What is used as t

Like most things where one cannot do repeated, controlled experiments, no one really knows where the truth lies apart from some vague notions. What is used as the "truth" will be a political decision. I think in the case of going to Mars, building a ship that can get there, land, and come back is the hard part. Finding out how bad or not the radiation will be on people will be found out by the people who end up going. Inform them the best we can, so they can make their own decision, monitor their radiation doses, so we can learn more about long-length, high-level radiation exposure in humans, and let people decide if they want to risk it. As long as the radiation dose is not so high to make them sick in the first few years and ruin the mission, let people take the risk if they want to. I don't see why going to another planet should have to be less risky than taking a wagon on the Oregon Trail, to allow people to try it. A safety first philosophy will not get humans living off of Earth.