I wasn't the first teacher in space. Christa McAuliffe, who was killed in the 1986 Challenger disaster, was first. I was second.
Space always fascinated me. When I was a kid, I'd enjoyed camping with the Girl Scouts, gazing at the stars and wondering. But space was something I just saw men doing. I didn't think I could be part of it.
Years later, President Reagan said he wanted to send a teacher into space. I saw this as a terrific opportunity for learning, a way to bring that world into the classroom.
It was a long application: you had to write five or six essays and design a teaching project to carry out up there. Ten of us came back for a week of poking and prodding at the Johnson Space Centre in Houston.
Christa was chosen to go into space and I was back-up. I felt that she was the right person. I joked about feeding her poison cookies, but she was my friend.
The Challenger disaster was a terrible time. So much went through my mind - `Is everyone OK?' and `Gosh, the families' - but it never occurred to me that it could have been me.
A couple of weeks later, Nasa asked if I wanted to carry on. It was an easy decision. You had kids across the country watching adults in a difficult spot. We had to do the right thing: find out what went wrong, fix it, and go on.
It was a long wait. I didn't go into space until August 2007, more than 20 years later. I was thinking: `Finally, we're launching. We'll be at the International Space Station in a couple of days.' I had this huge grin on my face - though I'm sure it was plastered back with the thrust.
When the shuttle takes off, you go from zero to 17,500mph in eight minutes. It felt like the whole orbiter was pressing up through my back and chest.
Then you are in free-fall around Earth. There is a lot of work to do right after the launch, and everything that isn't strapped down is floating around you.
It took me two or three days to adjust to the weightlessness. Your body fluid shifts upwards, faces look rounder. Your brain is being told that your body has too much liquid in it, so you urinate a lot. Your inner ear and your eye tell you two different things: it feels like you're upside down, but there is no upside down in space. At first, you try to keep the ceiling above you, but after a few days, up is wherever your head is. That's when it starts being fun.
Everything is a highlight. Looking out of the window at Earth is so satisfying. We orbited it every 90 minutes, so every 45 minutes you'd get a sunrise or sunset: layers of blue and orange.
When our solar panels caught the sun, they glowed gold. You're awash with white light and the ocean is brilliant blue - it felt like we were sailing over it. Space travel is very challenging, but at that moment it felt a natural thing to do.
You want to spend time looking out of the window. But we were helping to build the space station. I loved using the robotic arm. There's a lot of geometry, algebra and trigonometry involved: it's maths in action.
I'm still bringing space to kids. We learn about the science, maths and engineering of space exploration. Some want to be astronauts, and I'm sure they can get there.
When my grandfather was born, we had no cars. By the time he died, he could watch the first space shuttle launch on TV. As long as you have the imagination and will to keep exploring, you can do anything.
Barbara Morgan works as distinguished educator in residence at Boise State University, Idaho. She was talking to Adi Bloom.