CHAPTER 20 DAY IN THE LIFE: WHEN MAJOR ANOMALIES OCCUR 364 introducing the potential for lethal ammonia to leak into the crew cabin (see Sidebar: A failure that could become deadly!). A multitude of other decisions were going to be necessary. For example, several things went wrong on the last series of 2010 EVAs that were discussed in the standard post-event Lessons Learned meetings that now needed to be addressed, including one of the QDs that was stubborn on the last set of spacewalks. The crew had to literally bang on it with a heavy tool. What would happen if that technique did not work? New Extravehicular Mobility Unit Information The spacesuit teams received new data during the Team 4 effort, and they had to use this fresh information to sort out which spacesuit parts were the least likely to have clogged- up water separators if there was a problem with the water system of the entire fleet. The data were from some water filters that had been used on orbit, and they indicated that some filters were contaminated. These filters could have put particles in the system that made their way to the EMU water separator, creating the clog that backed up the water that spilled into the helmet. The EMU team started digging through the historical usage of those filters to determine which spacesuits had been exposed to those filters. Ironically, a spare water separator was being flown to the ISS. However, it was loaded into the Cygnus vehicle and would not be available to install into an EMU as a clean spare until after the vehicle arrived. This presented yet another item to consider when looking at the order of events. The Next 3 Days, Dec 14-16, 2013 Troubleshooting Team Progress The team at this point had turned its focus to trying to control the temperature of Loop A by partially closing off flow to the radiator using the Radiator Return valve. This valve is not intended to be stopped at incremental positions however, the team members realized that they could start to move the valve and then remove power before it reached its final position with a goal to find a good partially open state for various temperatures. However, “fine” control this way would require new software to help with managing the temperatures through orbital day and night cycles and constantly changing internal heat loads. The initial short- term goal was to be able to bring the temperatures up high enough in Loop A to temporarily allow for the heat exchangers to be used for a couple of weeks. The team was on its way to doing so, but a large-enough temperature swing occurred and Loop A shut down again. The team was learning a lot about how to control the system, but it was becoming more and more clear that controlling the system with these techniques was just “buying time.” Eventually, the Pump Module would need to be replaced to keep the complexity down for operating the Thermal Control System. Unfortunately, as predicted, the thermal control experts were getting stretched very thin, working too many things at once. Cygnus Team Progress The Cygnus launch needed to slip for other reasons by 1 day, so it was announced that the mission would launch on December 20. This provided some relief for the team. The increment, Cygnus, and engineering teams were working on how to fly the mission by having the crew install power jumpers to the communication system and berthing system to provide redundancy during rendezvous and installation, respectively. Once the Cygnus was berthed, the crew would have some new cooling fluid jumpers that could be hooked up to provide internal cooling for the power distribution boxes. Parallel planning for the Cygnus mission and the EVAs were going to come to a decision point around Tuesday evening. The crew and ground would begin operations that would be needed for either EVA or Cygnus and would preclude the other (e.g., moving the SSRMS to support the EVAs was required on Wednesday jumper install for Cygnus occurred on Wednesday). These operations could possibly be pushed back a day or two, resulting in a delay in one of the operations however, the loss of days in the increasingly tight window of opportunity this month was a concern. Extravehicular Activity and Analysis Team Progress The team uplinked preliminary procedures for the crew members to study, and they started getting the suits ready. The crew members got way ahead in their work, which kept the work that the ground teams had to complete as the long pole in the tent in terms of schedule. To answer the question about whether a low ammonia line pressure is required for EVA crew manipulation of the lines, a team of EVA specialists, ammonia line experts, and astronauts