Priorities :

8. Because it is there , for the thrill of doing it.

7. Science exploration

1. Alien life in fact 1 is really a subset of 7 as said JC

10. Improving our technology. learning living in space by doing it.

I don't believe mars can be a lifeboat for Earth. The Earth future is on Earth.

I hope competition between the nations and war will not be brought to the heaven.