When we are trying to model things like some colonies far away from civilization we must realize that those colonies are extreme projects. Extreme projects require extreme people, who want to put everything into those projects. Only extreme people can handle things in extreme conditions. The colonies far away from the civilizations like cities are, of course, extreme projects. But those colonies are located on Earth. And those people can sail away from those colonies if something goes wrong. If something goes on the moon the rescue craft will come to the base after a couple of days. And that thing is that those couple of days might feel very long. There are planned hypothetical moon cities. Even if the gravitation on the moon is very weak those colonists can use so-called sumo suits for keeping their muscles in condition. So those heavy clothes can compensate for the weak gravitation. But when we are thinking about things like Mars stations the conditions are even more...