If you think about the energy that a rocket engine has to put out and all the fuel and you're sitting on top of like a bomb. And on the Space Shuttle, that big orange tank is filled with liquid hydrogen and liquid oxygen, the white cell rocket boosters on the sides are filled with solid propellant. There's a lot of energy in all those chemicals there and you've got to control it in a way so it doesn't explode. So, there's a lot of plumbing, a lot of valving, a lot of control systems, and it's a very complicated thing. So, how do you bring the price of that down?

In 2006, I became the fist American to be allowed to go visit their astronaut center in China in Beijing. I think that it makes sense for the U.S. to work with China in the future and I hope to see, if the political atmosphere between the United States and China allow for us to do more cooperation together, especially in the area of human space flight. I think in the same way that it's help improve the relations between the U.S. and Russia; it would help to improve the relations between the U.S. and China.

I hope that China will continue with space exploration. It would be logical to have international co-operation. I hope that it will come about and that I can be involved in it.

Coming down under a parachute is quite different as well. You hit the ground pretty hard, but all the systems work very well to keep it from hurting, so it doesn't even hurt when you hit. It was a great experience to be able to do both.

One of my challenges was to try to photograph the Great Wall of China. And I did actually take some photos, but it was hard to discern the wall with the naked eye.

The space station mission was kind of the culmination of all of my experience of being a NASA Astronaut, so it had brought all of my previous experience into play. I had to learn the Russian language to a fluent level so that I could function as the co-pilot of the Soyuz Spacecraft that we flew up and back from the space station. And then the challenge of being the Commander of the whole expedition, a six and a-half month flight aboard the international space station. I felt the burden of the whole mission on my shoulders, which was fine, and fortunately everything did go well.

The ultrasound that has application not only in space for a long mission or for a mission to the Moon or Mars, but also in remote areas on the Earth. Not even just - I'm not even talking about expeditions like to the Antarctic, but just a remote area, a small town somewhere. The local doctor is not going to know everything, and so if that person can link in with a diagnostic ultrasound to the hospital in New York City through the internet, then they can do a very quick diagnosis of something that's wrong with someone that's in this remote area.