It was in the back of my mind, even while I was going to school, but it wasn't until I was at university studying engineering that I thought, well what do I really want to do? And I kind of came back to that and I said, well the degrees I'm trying to get are going to qualify me to apply. And so, that's what I did after I finished my, or after I was getting my doctorates. That's when I first applied to NASA.

I actually had four space flights altogether, three times on shuttles. My second flight was really unique for me because I was going back into space, first of all. The first one was like an appetizer at a nice dinner. You know, you want to go up and you want more. So, the second time I got into space, it was neat because I got to actually do two space walks.

My advice for an aspiring astronaut is to really follow your passion. I mean, study something that interests you, but also qualifies you to apply. NASA recruits from a wide variety of backgrounds. I know people who have applied to be an astronaut who ask me, well should I do this or should I do that. And I said, you know, it doesn't matter. The basic requirements are you have to be in good health, and you have to have a good heart, I mean in a technical way, not to be a kind person, well that helps. Study something that you like and do well in it.

Tinkering is something we need to know how to do in order to keep something like the space station running. I am a tinkerer by nature.

I grew up bilingual, I grew up speaking Chinese in the home, Mandarin Chinese with my parents, and I learned English because I was born and raised in the U.S. That really gave me an edge. I understand that, from the experts, if you grew up bilingual, your brain kind of gets wired to accept a new language. It was a very serious deal because not only did I have to learn Russian to a high degree in order to function as a necessary member of the crew, but also I knew that the Russians that came over that made an effort and had some success in learning English, those were the folks we trusted.

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.

There is no one area of chemical engineering that specifically helped me in my career as an astronaut, it was more the general education in engineering. Also, it was a very difficult and rigorous course. So, it made me strong and resourceful.