CHAPTER 20 DAY IN THE LIFE: WHEN MAJOR ANOMALIES OCCUR 356 of the Cygnus cargo vehicle, which was scheduled to launch a week later (December 18). The Mission Control team was also preparing for an ISS reboost to a slightly higher altitude (see Chapters 7 and 8), so the team in Houston positioned a torn part of the Starboard Thermal Radiator Rotary Joint (TRRJ) to point away from the thrusters due to the forces generated when the thrusters fire during a reboost (Figure 1). Figure 1. Torn sheet on the Starboard TRRJ. This TRRJ is usually pointed away from planned thruster firings unless the radiator needs to point in their direction for other reasons. The tear was first noticed in 2008. Since there is ample cooling, the sheet has not been repaired. As comes around every so often, a relatively routine action kicked off an unforgettable moment for those in Mission Control. After moving the radiator, the team noticed warning indications. Station Power, Articulation, Thermal, and Analysis (SPARTAN): “Flight, SPARTAN, I see the warning...” The flight controller in charge of the power and external cooling system, SPARTAN, announced the detection of an alarm to the team. SPARTAN and the team quickly determined the external cooling system Loop A had shut down and was no longer circulating fluid to cool about half of the equipment on the ISS (see Chapter 11, Figure 6). Loop A is one of two external cooling lines circulating ammonia via an external pump. Loop A circulates ammonia through the starboard radiator (the other string, Loop B, pumps fluid through the port radiator). An alarm sounded on board due to the significance of losing half of the external station cooling. Everyone in all Mission Control Centers quickly scanned their data and looked for the right procedures to address these questions: What caused the problem? Are temperatures starting to increase? What is the correct response to immediately “safe” (i.e., protect) systems? The ground team had to quickly diagnose the warning messages and determine what had caused the shut down since about half of the US On-orbit Segment ISS equipment was cooled by that loop and could start to overheat. As