You flew on five Space Shuttle missions. What were they like?
Each mission is dramatically different. My first mission was focused primarily on Earth’s atmosphere and looking at ozone distribution, so the ozone hole over Antarctica, for example, and the chemical species that contribute to the destruction of the ozone layer. We had a number of very different sensitive instruments and a satellite on board to study ozone balance.
Then on my second flight we went up to the Mir space station, where I conducted and led the first joint US-Russian spacewalk, which was an incredible experience, and on that flight I was the flight engineer for the mission. Following that I flew with my boyhood hero, Senator John Glenn, who was the first American to orbit Earth. He returned to space at age 77, and so I was aboard not just as the flight engineer and to fly the robotic
