I was stumbling on the internet when I came across this awesome infographic. Many people believe that Mars is the optimum place for human habitation. However as the picture shows, the radically different atmospheric composition and less than half the earth’s gravity make permanent settlements on Mars very unlikely.
First the thin atmosphere allows harmful radiation through. It also somewhat negates carbon dioxide’s greenhouse effect, leading to low temperatures and hazardous exposure to sunlight. This will make agriculture or any other extensive surface based activity very costly (because of the additional preventive infrastructure).
Second, low gravity means the human muscles will start to atrophy if they stay for long on Mars. This will be specifically true for children or older people. So unless some sort of artificial gravity technology is made, Mars will remain strictly a research or a tourist spot.