Elon Musk on making life multi-planetary

The journal Nature spoke to SpaceX founder Elon Musk about the privatization of space flight. On April 30, SpaceX plans to launch a Falcon 9 rocket from Kennedy Space Center to the International Space Station, making it the first commercial company to send a craft to the ISS. From Nature:

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Do you see a space-faring civilization as a way of defending humanity against a catastrophe on Earth? Absolutely. We would be backing up the biosphere. We wouldn't just be preserving humanity, we would be preserving much of life. It is certainly possible for some calamity to come along — as we see in the several major extinction events in the fossil record. Humanity has obviously developed the means of destroying itself, so I think we need planetary redundancy to protect against the unlikely possibility of natural or man-made Armageddon.

It is important that we take action now to make life multi-planetary, because this is really the first point in the 4-billion-year history of Earth that it has been possible. That window of possibility will hopefully be open for a long time, but it may only be open for a short time. That's why I think urgent action is required on making life multi-planetary.

"Backing up the biosphere"