On Apollo 11 in route to the Moon, I observed a light out the window that appeared to be moving alongside us. It was either the rocket we had separated from, or the 4 panels that moved away when we extracted the lander from the rocket and we were nose to nose with the two spacecraft. So in the close vicinity, moving away, were 4 panels. And i feel absolutely convinced that we were looking at the sun reflected off of one of these panels.

History will remember the inhabitants of this century as the people who went from Kitty Hawk to the moon in 66 years, only to languish for the next 30 in low Earth orbit. At the core of the risk-free society is a self-indulgent failure of nerve.

We have the ability, at such high fidelity, to simulate the physical world through computers. But when the spiritual world or human behavior comes into play, we don't have a very good model for that at all.

I came to dedicate my life to opening space to the average person and crafting designs for new spaceships that could take us far from home. But since Apollo ended, such travels were only in our collective memory.

To send humans back to the moon would not be advancing. It would be more than 50 years after the first moon landing when we got there, and we'd probably be welcomed by the Chinese. But we should return to the moon without astronauts and build, with robots, an international lunar base, so that we know how to build a base on Mars robotically.

I have no doubt that humans will go to Mars. And I feel that America has led so many things in space - we have invested so much, and we have a lot to gain - that America could and should be the nation that should lead the settlement of Mars.

Just as Mars - a desert planet - gives us insights into global climate change on Earth, the promise awaits for bringing back to life portions of the Red Planet through the application of Earth Science to its similar chemistry, possibly reawakening its life-bearing potential.