CHAPTER 18 DAY IN THE LIFE: RISKY AND REWARDING SPACEWALKS—SPACE SHUTTLE MISSION STS-120/ISS-10A 322 high-tech imaging sensors at the tip to be unpowered for several hours. The worry was that the sensors would get too cold and become damaged, resulting in the inability to inspect the thermal protection system of the shuttle prior to reentry. The ability to perform inspections became important after the Space Shuttle Columbia accident. The shuttle mission management team had to carefully consider the possibility that this operation might break these sensors. Chance Favors the Prepared Mind Colonel Doug Wheelock STS-120/ISS-10A and Expedition 24/25 The inside of a spaceship offers a level of normalcy. The temperature and atmospheric pressure are fairly constant. It is easy to get lulled into a false sense of safety. But the moment you open the hatch, the rules change. Oblivion resides on the other side of your thin helmet visor. You are now engulfed in a dangerous environment of chance. And, as we know, chance favors the prepared mind. During our 18 months of intensive training, Scott Parazynski and I worked diligently in NASA’s Neutral Buoyancy Laboratory and Virtual Reality Laboratory. We did whatever we could, as many times as we could, to replicate the spacewalking environment, talking through every conceivable contingency. I grew up hearing the mantra “Practice makes Perfect.” However, when preparing for spaceflight, that mantra is more accurately “Perfect Practice makes Perfect.” No room for error, and complacency is met swiftly with dreadful consequence. The moment arrived for my first spacewalk. With the reduced pressure inside the suit, I could hear a difference in my voice, which gets deeper at the lower pressure. Scott opened the hatch and said, “Oh wow! Wait until you see this, Wheels! We’re over the Himalayas!” Nothing quite compares to that first step out into the vast universe. Your home planet is far beneath your feet. Everything and everyone you have ever known…all on that blue planet. And you’re not there. The feeling is quite profound, and difficult to put into words. Space is visually spectacular and completely breathtaking because of our blue planet. It is an explosion of color in the sunlight, an oasis of motion and light, suspended in an empty sea of darkness. You feel vulnerable. Fragile. Fear is your constant companion. The Earth is distracting from this vantage point. It is difficult to stay focused, but you have to get back to work. My second EVA was amazing, bolting down the nearly 19-ton P-6 truss and solar arrays to the far port end of the ISS truss. We finished the task and returned to the airlock. Our team worked through the deployment commands for the solar arrays. Scott and I were cleaning up when the “abort” command was broadcast. I knew that couldn’t be good, but I had no idea how that moment would shape my life and work, as well as teach me lessons about leadership, teamwork, and perseverance that have changed who I am as an astronaut and leader. The solar array got snagged by a frayed guidewire, and the situation was dire. The next few days were full of confusion, doubt, and despair. How could we ever repair a torn array? Hours and hours passed. We talked about what was likely going on down in Mission Control in Houston. We were sure NASA had pulled out all the stops to help us fix the station and get us home safely. I remember talking with Scott in the intervening days about how it felt like Apollo 13. I had worked at NASA for 11 years at this point. A calm assurance washed over me in that moment. I realized that the reason it was so quiet on the voice loops was because they were testing a potential solution. I knew in my heart that some sharp engineer turned to our team and said, “Hey…what if…”? I knew that one day we would look back and remember this as one of NASA’s finest hours. Initially, the team estimated the boom sensors would be unpowered for 12 hours, with the sensors getting too cold after being unplugged between 5 and 8 hours. The robotics plan was changed so that the shuttle robotic arm would hold the boom for some of the preparations, thereby reducing the exposure to around a predicted 8 hours. After looking at the environment, the analysts concluded it might remain warm enough to prevent the sensors from becoming damaged. Because of the criticality of the boom usage for this repair and some conservatism in the thermal analysis, the mission management team agreed to use the boom. They accepted the risk that these sensors