309 DAY IN THE LIFE: RISKY AND REWARDING SPACEWALKS—SPACE SHUTTLE MISSION STS-120/ISS-10A CHAPTER 18 Original Pre-Mission Spacewalk Planning Most of the United States On-orbit Segment EVAs that occurred during ISS assembly were planned to occur during shuttle missions using shuttle crews, despite the fact that qualified spacewalking ISS crew members were constantly manning the ISS. This occurred for several reasons. First, the shuttle launched new ISS elements and pieces of hardware that usually needed specialized training for assembly or deploy choreography, and crews had to dedicate a lot of time to study for some assembly EVAs. Training time was not as available for ISS crew members since they had an extensive multiyear training plan just to learn how to run the day-to-day operations on the ISS. This training included Russian language study and extensive international travel. Furthermore, ISS crew members were often committed to launching in a Russian Soyuz vehicle, and the Soyuz launch schedules were not typically tied directly to the shuttle launch schedule. In some cases, ISS crew members had used precious time to train for shuttle-present EVAs, only to see shuttle missions moved out of their Expedition due to launch slips. As a result, assembly EVAs were assigned to shuttle crew members that would launch with the new elements. Shuttle crews performing these EVAs could dedicate a large amount of time training for EVAs, which meant greater efficiency during the tasks—e.g., less time was spent in space discussing the preferred location for a tether since crew members had already tried out a few locations while in training and decided upon the best approach. Figure 4. The crew on orbit in the ISS during STS-120/ISS-10A: Top row: (left to right) Dan Tani, (extravehicular [EV] number 3, EV-3), Scott Parazynski (EV-1), Doug Wheelock (EV-2). Middle row: (left to right) Stephanie Wilson (robotic arm operator), Pam Melroy (shuttle commander and robotic arm operator), Paolo Nespoli (primary intravehicular (IV) crew member that aids the EVA crew during suit-up and the EVA). Bottom row: (left to right) Clay Anderson (ISS crew member), Peggy Whitson, (ISS commander, EV-4), Yuri Malenchenko (cosmonaut, EV-5), George Zamka, (robotic arm operator).