Well, in my considered opinion you are apparently opposed to the concept of space travel. In that case may I simply suggest you stay home?
You don't really think we will just shoot people to Mars without any knowledge of what they might be subjected to do you?
When they first built railroads people were of the opinion that the human body would cease to function if it exceeded 60 miles per hour. The brain could not handle the speed and would no longer allow the body to stay alive. I think that has been put to rest.
The point is we don't know but we will learn.