Why do we have programs to build habitation on Mars, and we have programs to look at colonizing the moon, but we do not have a program looking at how we colonize our own planet?
为什么有在火星建立居住地的计划， 而且我们有研究开拓月球殖民地的计划， 但我们没有一个研究如何开拓我们自己的行星的计划？