Colonel Terry Virts always knew he wanted to be a pilot or an astronaut.

He had pictures of galaxies and planes on his walls as a child.

He never thought he could actually become an astronaut, but he did the things he had to do to qualify.

He got a mathematics degree, went into the Air Force, and eventually became a test pilot.

In 2000, he was accepted to the astronaut candidate program.

"I was excited beyond belief.

This is my boyhood dream, and I finally made it happen.

But the initial training was fun.

It was something different every day.

As a pilot I had to learn how to fly the space shuttle, for launch and landing, and all the piloting tasks."

Virts received training in medicine, science and the Russian language.

And he learned how to repair and maintain the International Space Station.

Eventually he was taught how to walk in space.

His first trip to space was in 2010, when he piloted the shuttle Endeavor.

"The first space flight is amazing.

First of all, walking out of the space shuttle is an amazing experience.

I've never been so proud of being an American because I know Americans have built that.

It was the most amazing flying machine ever built, and I got to fly it as pilot.

It was awesome."

Four years later, Virts returned to space as flight engineer of the International Space Station, later assuming command.

That mission lasted 200 days, during which he conducted three spacewalks, totaling almost 20 hours.

"There's nothing like spacewalking.

It's a very unique experience.

You're in this very heavy, very stiff spacesuit that's basically a spaceship.

It has its own oxygen and carbon dioxide systems, a cooling system, communication, and a jet pack.

It's a small spaceship.

Except for there's a one-milimeter-thin plastic glass, and on the other side of that is space.

You almost felt like you can see or hear God out there.

It's really an awesome experience."

Virts said one of his favorite things to do in space is to take photographs.

He has shared hundreds of pictures of our planet on Twitter.

"It's just beautiful.

You feel like you're seeing the heavens and earth.

Your home planet is over there, and you're over here.

It's a surreal, emotional experience, and so the little silly things you watch on the news every night just don't matter.

They are just not a big deal.

So, from that point of view, your perspective changes."

Virts said every astronaut's favorite mission is the next one.

He is waiting for his turn to go back to space.

Questions 19 to 22 are based on the recording you have just heard.

19. What is Colonel Terry Virts' boyhood dream?

20. What did Virts learn in the astronaut candidate program?

21. What does Virts find from his experience of spacewalking?

22. What is Virts' favorite thing to do in space?