Spacewalking is almost a magical experience. You're holding on to a human creation with one hand. And that is your only link with the other six billion of us. And you are in between the bottomless blackness of the rest of the universe and the incredible rich colors of the world. Horing by endlessly at eight kilometers a second next to you. It is just a phenomenal, stupifying experience. While I was doing spacewalks, building canon arm, at one point I got vertigo. I thought that's weird, why did I get vertigo? And I realized like when you sit beside a truck at a stoplight and it starts to move and you feel like you're moving backwards and you're dizzy for a second, I looked over and it was because Africa was going by. I thought that's new for me. It's extremely distracting to work during a spacewalk and you have to wrench yourself away from the wonder of it and the beauty of it, the magnetic beauty of looking at the world to focus on the task at hand. I wish everyone on earth could see the world the way that I've had a chance to do the way that the other space travelers have had a chance to see how thin the atmosphere is. It's an onion skin protecting us from the blast of all the other stars in creation. The fragility of the water on the surface, it's so shallow, you cannot avoid becoming a better steward of the earth when you better chance to see it the way we see it. The shuttle has been the great lifter of humanity to space. Almost three quarters of everybody who flew in space flew on the shuttle. It's been a tremendous human invention that has opened the door of space to us. But like all human inventions, we think of better ideas and we, things age, the robot and the sailboat and the catamaran and the power chip and the steam engine and the locomotive and the magnetic levitation train. That's all the same sort of process. The shuttle is the same way it has served us tremendously well. We've learned so much about how to fly safely in space and it makes me sad to see the end of a great vehicle and at the same time it makes me very optimistic. We built something great, we've learned a tremendous amount from it and we're moving forwards.