The Race to The Red planet - Episode 2
The human factor in the Mars project is the most difficult aspect of the plan. There are three main problems with sending humans to Mars. One is the psychological impact of detention for 18 months. The second is physiological - to feed the human body for a year and a half only with dried food. The third is contamination: humans carry billions of germs that could contaminate returned samples and / or contaminate the Martian biosphere.