The correct answer would be the safety of the astronauts.
Considering that the NASA program was out to accomplish tasks that no person has done before, there was significant risk when trying to met these goals. For example, no man had ever been to the moon before 1969. Since no man had been there before, it was an enormous risk trying to send someone to the moon. There is no experience or training a person could go through in order to be prepared. One mistake could result in the death of these astronauts.
