I do celebrity ski races all over the world.

By refocusing our space program on Mars for America's future, we can restore the sense of wonder and adventure in space exploration that we knew in the summer of 1969. We won the moon race; now it's time for us to live and work on Mars, first on its moons and then on its surface.

When I am getting ready to cross a street, I look both ways before crossing. My bones, my muscles, are not what they used to be, so I am careful when I go up and down stairs, because I've heard stories of older people falling and having very disabling injuries. I have enough things that begin to go a little bit wrong as I get a little bit older.

I want to reach a new generation. That's why I am Twittering now. I have a BlackBerry, an iPhone and a Mac.

Going to Mars would evolve humankind into a two-planet species.

At the core of the risk-free society is a self-indulgent failure of nerve.

My own American Dream was to serve my country as best I could and make a difference in America - and in the world.