1) No nearbye gamma ray bursts in the last few hundred million years.

2) No global scale impact events since the advent of civilization.

3) A large nearbye moon to serve as a stepping stone and a lure to space (a point we've passed).

4) A planet capable of sustaining human civilization besides the one of our origin in the same solar system (Mars).

5) An orderly system of planetary orbits in our solar system.

6) 3 beutiful gem planets in one solar system (ours, Jupiter, Saturn). 2 to draw our interest in space and one to reflect on in awe once we reached it.

7) 2 or more worlds in our own solar system with a significant possibility of supporting alien life (Mars, Europa + long shots Ganymede, Enceladus, Callisto, and Titan).

8) A planetary sized moon in the outer solar systems frozen reqion to serve as a possible time capsule for our own lost history (Titan).

9) A sun of optimal size and composition to promote multicellular life.

10) A country with wealth vast enough to blaze the trail into space.

11) The triumph of capitalism providing more and more people with the individual wealth capable of following that trail.

Regards,
Mark