I don't believe that human beings will ever be able to exist independently of earth without radically more advanced technology, in every field.
If you consider the amount of support the early American colonists required from Europe, despite how primitive their society was in comparison to ours, colonization of space would require an immense amount of infrastructure that simply doesn't exist beyond the earth's surface. Materials that we take for granted, like hydrocarbons and plastics, are unobtainable off-earth. More seriously, the moon and Mars have almost no native sources of energy. Everything would need to be shipped from earth at tremendous expense.
Obviously, it would be possible to put men on the moon or Mars and support them with an endless train of supplies from earth, but in the event of some catastrophe on earth that interrupted the flow of materiel, those colonies would become deathtraps rather than refuges.
>Materials that we take for granted, like hydrocarbons and plastics, are unobtainable off-earth.
Yes, plastics are useful, but they're not a necessity for very many things. They were invented in the past century. In the short term, many things are unobtainable, but longer term, space contains a hell of a lot of material in a large variety. If there's a reason to figure out ways of doing things in space, we will figure them out.
>More seriously, the moon and Mars have almost no native sources of energy.
Solar cells work well in space for small needs, and fission provides great fuel energy density for larger needs. Both of these work fine in an environment bereft of oxygen.
There's no reason they couldn't be self-sustaining long-term.
If you consider the amount of support the early American colonists required from Europe, despite how primitive their society was in comparison to ours, colonization of space would require an immense amount of infrastructure that simply doesn't exist beyond the earth's surface. Materials that we take for granted, like hydrocarbons and plastics, are unobtainable off-earth. More seriously, the moon and Mars have almost no native sources of energy. Everything would need to be shipped from earth at tremendous expense.
Obviously, it would be possible to put men on the moon or Mars and support them with an endless train of supplies from earth, but in the event of some catastrophe on earth that interrupted the flow of materiel, those colonies would become deathtraps rather than refuges.