275 DAY IN THE LIFE: IN-FLIGHT MAINTENANCE CHAPTER 16 When The Nearest Handyman is You Colonel Timothy Kopra, Expeditions 20 and 46/47 The ISS is a world-class orbiting laboratory. Every day, the crew members on board conduct a variety of experiments that will help us prepare for going out beyond Earth’s orbit, discovering fundamental aspects of science, and improving life on Earth. The space station is an amazing place to work and live, but the environment we have is only what we have created and maintained. Outside of the station’s thin aluminum hull is a vacuum that is completely inhospitable to life. It is so vital, then, that we maintain and sometimes repair the systems on board that provide our clean atmosphere, water, electricity, thermal control, and communications, just to name a few. One of the key components of our life support system on the space station is the Carbon Dioxide Removal Assembly (CDRA). After we extract the oxygen that our body needs when we inhale, we exhale a significant amount of carbon dioxide (CO 2 ). Each person exhales around 20 liters (5 gallons) per hour, for a total of 120 liters (32 gallons) per hour introduced into our atmosphere when there is a crew of six on board. Humans are very sensitive to even low amounts of CO 2 when we breathe it in. Just a fraction of 1% of CO 2 in the air can give you a headache, cause fatigue, and affect how clearly you think. The primary CDRA installed in Node 3 failed in February 2016, when the fan motor controller malfunctioned. This device controls the operation of the blower that provides airflow through the CDRA. The task of replacing the motor controller was a bit like removing the engine from a small car and then replacing some of the components attached to it. The CDRA was located in a rack about the size of a large refrigerator behind some panels. It is tightly installed within the rack and connected to other parts of the system. After removing the panels to get access to the CDRA, Scott Kelly and I followed the well-crafted procedures developed by the ground maintenance team to slide the CDRA out, disconnect it, and remove it from the rack. After this, we were able to get to work on the repair. We floated the large CDRA through the station to a maintenance work area (our workbench), located in Node 2. While zero gravity makes it easy to move around a large piece of hardware such as the CDRA, it can be a bit tricky to secure it and set it up for maintenance. We used a set of bungee cords on the maintenance work area to keep the CDRA in place while still providing access for the maintenance tasks. Since considerable time is dedicated to removing a CDRA, the ground team decided that we should also replace some other parts that were not in top working order. We were tasked with replacing a heater controller and one of CDRA’s valves as well as the motor controller. Earlier in the morning, we had collected the spare components and all of the tools that we needed for removing and replacing each part. The rest of the job was pretty straightforward: Scott and I worked together to replace the failed components using the procedures that described in detail which tools to use and the steps to remove the components and install the new ones. After the removal and replacements were complete, we worked in reverse, floating the CDRA back to Node 3, installing it back into the rack, and reattaching the panels. We then waited with anticipation as the ground team performed the activation steps to make sure it all worked. We were glad to hear the call from Mission Control that the Node 3 CDRA was again up and running. One lesson that this relatively routine maintenance task highlights for me is how important it has been for us to have a highly functioning team to keep the ISS operational every day. Teams of experts on the ground have the in-depth knowledge of all of the systems and hardware on board, and they are the ones who identify the failures that occur, develop the thorough and clear procedures, train us to make the repairs, and manifest the replacement parts and tools for maintenance. We have a team of teams that keep our space station flying, and they frankly do such an outstanding job that they make it look easy. And it certainly is not.