> A colony on mars, even of significant size and population, is 100% condemned to certain death if separated from Earth It would be in the near future, true. I

> A colony on mars, even of significant size and population, is 100% condemned to certain death if separated from Earth It would be in the near future, true. In fact, the key milestone for humanity being truly multi-planetary is that each planet must be independently self-sufficient. There's no laws of physics that would prevent human life on Mars or Venus from eventually becoming self-sufficient. The time-frames to get to that point are large (mid-hundreds to low-thousands of years by my random guess). A thousand years isn't that long in terms of the evolution of the species, though, and are the time scales we should be thinking of multiplanetary life on.