183 DAY IN THE LIFE: PREPARING FOR THE UNEXPECTED CHAPTER 10 Figure 4. A team of operators performs a simulation (different than the one discussed in the text) under the direction of Flight Director Courtenay McMillan (Tranquility Flight, bottom left). The simulation control room, formerly used for conducting Space Shuttle missions, is set up exactly like the main ISS flight control room (see Introduction). into the cabin, so this is an ammonia leak, it is leaking into the US Segment. GC: Two minutes to a TDRS handover. [This means that link with the Tracking and Data Relay Satellite (TDRS) is swapping from one satellite to another as the ISS orbits the Earth, and there will be a brief loss of communications until the radio link is established on the other satellite. During an emergency, it is critical for the team to understand when the ground does or does not have a communication link with the ISS.] ADCO: FLIGHT, ADCO per rule B2-359 we need to enable auto-handover to the Russians. [The Attitude Determination and Control Officer (ADCO) is quoting a flight rule that indicates that if there is a chance the gryoscopes will not be able to maintain the control of the ISS, “auto handover” should be enabled. Auto handover is the process by which the US and Russian attitude control systems can take and give control to each segment. In the case of an ammonia leak into the cabin, an action that the team can take to mitigate danger to the crew is to vent the ammonia in the external loops overboard, which is a sufficiently large enough propulsive force on the ISS that the US control moment gyroscopes cannot maintain attitude control and, therefore, Russian thruster control