xxvii a headset that is plugged into an audio display panel. There are approximately 20 audio conference channels or “loops” on a given display, and 10 displays to choose from. Using the display, the controller can select which loops to listen to and which one loop on which to talk. Four loops are reserved as the primary channels for the astronauts and ground to communicate. These are designated as Space-to-Ground 1, 2, 3, and 4. Additional channels are described in Chapter 13. One of the first skills a controller needs to master is the ability to listen to multiple conversations simultaneously, picking out the things that affect him or her directly, hold conversations above the cacophony, and stop everything instantly when there is a call on the space-to-ground loops from the crew. To facilitate this process, the FCT uses codes and special phrases to keep discussions concise and crisp, as described in Chapter 10. Staffed by NASA and contractor engineers (primarily from the Boeing Company), the Mission Evaluation Room (MER) also supports operations. As the primary contractor of the ISS since the early days of the program, the Boeing Company and its subcontractors designed and built the majority of the US ISS hardware. These MER personnel retain and manage valuable design specifications, manufacturing documentation, and general system knowledge that is highly beneficial for the operation of the space station. The MER supports the operations team with a structure similar to that of the FCT (i.e., a Command and Data Handling subject matter expert that supports the Communications Rf Onboard Network Utilization Specialist flight controller). Each MER discipline has its own call sign and set of loops to communicate among themselves or the FCT. As with the controllers, the MER team has a leader called the MER manager, which is similar to the flight director. The MER manager is consulted if a question comes up during operations, such as how something worked in testing or how the software might respond in a particular configuration. If the MER does not have the information on hand, he or she will consult with the vast Boeing organization to collect and provide the data. Generally, the MER is staffed only between the hours of 9:00 a.m. - 5:00 p.m., Monday- Friday, but is supported around the clock during major activities or if an anomaly occurs. In the event of an anomaly, it is the MER’s function to gather data, ascertain the problem, and devise a fix. These activities are coordinated with the FCT throughout such investigations. As owners of the ISS, the Program Office also has a team that supports operations on a regular basis. This team, the ISS Management Console, provides coordination with the program management, including keeping them apprised of all activities, successful or not, as well as coordinating with the management teams of the other partners. Finally, representatives from the international partners maintain some presence in the Mission Control Center-Houston, mainly to help with the integration of the operations from day to day. Most notable among the partners presence is that of the Russians, who maintain a small team of flight controllers, trainers, and a flight director as part of what is called the Moscow Support Group. Besides performing coordination tasks, the group can operate the Russian Segment in the event of a significant problem with the control center near Moscow. Likewise, NASA maintains a small team in Russia known as the Houston Support Group. NASA and the international partners also exchange support group personnel, though sometimes only during critical mission phases. Flight control is different for the ISS than it was for the shuttle and earlier spacecraft. In the case of the Space Shuttle, the astronauts were responsible for most operations, and the ground followed along. Almost all commands to the vehicle were “switch throws” or other similar operations by the crew. In contrast, the vast majority of the ISS commands are sent from the ground. This allows the crew to focus more on the science payloads and less on vehicle operations. A typical day during a shuttle mission saw the FCT uplink less than 500 commands. The collective station FCTs, located all around the world, routinely send 50,000 commands per day to the ISS. It takes several years to become a certified flight controller (see also Chapter 10). Although, generally, the team is made up of engineers—and positions and degrees are highly correlated (e.g., an electrical engineer