Tim Cahill

I have no problem with the adventure travel movement. It makes better, more sensitive people. If you get people diving on a coral reef, they're going to become more respectful of the outdoors and more concerned with the threats that places like that face and they're going to care more about protecting them than they would have before.

The importance of heart health became very real for me when my father died of heart disease seven years ago. Having experienced the loss first hand, I am inspired to do everything I can to break the cycle and prevent families from losing loved ones to this preventable disease.

Supplying fuel for a Mars expedition from the lunar surface is often suggested, but it's hard to make it pay off - Moon bases are expensive, and just buying more rockets to launch fuel from Earth is relatively cheap.