307 DAY IN THE LIFE: RISKY AND REWARDING SPACEWALKS—SPACE SHUTTLE MISSION STS-120/ISS-10A CHAPTER 18 The Original Mission One of the top objectives for STS-120 was to deliver the pressurized module called Node 2 by robotically removing it from the Space Shuttle cargo bay and installing it on a temporary location on Node 1. The Node 2 module was a critical element in that the European Space Agency (ESA) and Japan Aerospace Exploration Agency modules would attach to it, making way for new countries to have permanent presence on the ISS after the many years they spent building their respective part of the station on the ground. The 10A mission and subsequent stage operations to move Node 2 to the forward position had to be completed prior to the much-anticipated shuttle mission carrying the ESA Columbus module, which was due to launch in December 2007. Another key assembly objective was the transfer (relocation) of truss segment P6 from the central zenith (i.e., upper) part of the ISS, where it had temporarily been placed for 7 years, to its final assembly-complete location at the far-port end of the truss (Figure 1). Prior to this mission, the large P6 solar array blankets had to be retracted (i.e., folded, accordion- style) so they would not sway or flap and possibly break when P6 was moved to the port side. During the STS-120 mission, the team would perform the robotic transfer and EVA bolting of P6 (Figure 2) onto the end, followed by commanding re-deploy of the arrays (Figure 3). Figure 1. The ISS as seen from the Space Shuttle as it departed during STS-118, the mission immediately prior to STS-120. P6 is located in the center of the truss, with its solar arrays folded up in the long blanket boxes (as shown in the inset photo).