As soon as we saw outer space as a frontier to be visited, all of the things our bodies took for granted had to be considered problems
Perhaps nothing has reminded humans more of our fundamental organismness than traveling to outer space. All of the things our bodies take for granted on Earth -- gravity, atmosphere, oxygen, a relatively narrow range of temperatures -- suddenly had to be considered as problems to be solved. NASA scientists and their corporate counterparts at places like Douglas Aircraft attacked the problem like engineers, not biologists.
To them, the body was, or at least could be viewed as, a machine. And that meant its materials and processes could be subjected to QA. What kind of exposure could humans take to heat and radiation? What level of vibration caused debilitating testicular pain? What kind of acceleration knocked them out? How long could they operate under stress? What did weightlessness do to them? They drew curves, extrapolating out to death and incapacitation, and then began to work on the solutions that would keep people out of the danger zone.
In later years, everything seems very official and thought-out, but in the couple of years after Yuri Gagarin's milestone flight into outer space, very little was actually known about how humans would respond to the extraterrestrial environment or what kinds of spaceships they might need to stay alive.