Eileen Collins became a NASA astronaut in 1991. She flew four space shuttle missions, two as pilot and two as commander. In fact, she was the first woman pilot and first woman commander of a shuttle. She spent a total of more than 537 hours in space. Collins was inducted into the International Space Hall of Fame in 2001.
The first thing you feel in space is clumsiness. You are going to bump into things. You are going to feel a little bit disoriented. You are going to see your crew members floating by you upside down. It takes a little while to get used to this. I found, on my first flight, it took me three days to get to the point to where I was able to zip around and work as efficiently as I can on Earth. It is almost like getting on roller skates and trying to do work around the house on roller skates. You are just having some problems until you get good at it.
The ceiling is still the ceiling, and where the floor was is still the floor. Although as you get more experienced up there in space, you can start using the volume in different ways. For example, I discovered that the best place for me to sleep was on the ceiling. I tried sleeping on the ceiling with my face facing the ceiling and with my face facing the floor, or laying on my side, so to speak. So I always tied my sleeping bag to the ceiling in the middeck and slept there. The shuttle cockpit, flight deck, and middeck look very small when you walk in the trainer on Earth, but really when you get up in space you have more volume than you think you would, because you can walk on the ceiling, for example.