On a long flight, you settle into a routine of work, observing the Earth, taking photographs and keeping in touch with your loved ones via email and short phone calls, when the antenna is pointed at the Tracking, Data, Relay Satellite System.

Sometime around the three-to-four-month point, you start thinking that you wouldn't mind going home. But, psychologically, you have prepared yourself for the long flight.

Even after a ten-to-fourteen-day mission to space, the return is dramatic. Your balance system is turned upside down, and you feel very dizzy. When you stand up for the first time, you feel about five timеs heavier than you expеct.

What do you think about during a long flight? Spaceflight is a life-changing event. I thought a lot about my life on Earth. I gained a new perspective.

Looking down at our beautiful world , I couldn't help but be struck by the fact that while everything looks vibrant and peaceful — intellectually — I knew that great suffering was happening in many of the lands over which we flew. It was difficult for me to resolve this conflict. As a result, I appreciated life much more than I had before, and it made me reflect on what really is important.

The anticipation of return builds as you get close to your return date. The arrival of your replacement crew is a joyous occasion. Not only are you glad to see your friends, you are also glad because it means that you can go home soon. You look forward to the reunion with your loved ones, to looking back with satisfaction on a job well done.

Do I miss space? Sometimes, a little bit. After each short space shuttle flight, I couldn't wait to go back up. But, after my long flight, it was like eating a big, satisfying meal. Ten years later, I am still satisfied. But, I suspect that after not too much longer, I will again start to get hungry.