9. Underground Cities
Another big problem with Martian colonization is cosmic radiation. Our buff atmosphere protects us from the toxic rays the sun barfs out, but Mars has a very thin atmosphere in comparison. To solve this problem, many scientists think Martian bases should be subterranean, and that settlers should only venture to the surface with adequate protection. We have a hunch that astronaut on the right is just pretending to work but is actually watching Doctor Who on an iPad.