The third EVA will be conducted. (See the section on spacewalks for details.)

After setup, Herrington will enter a bay in the SO Truss and operate two CIDs allowing ground controllers to begin work on the MBSU reconfiguration. From there, Herrington will move to the top center of the P1 Truss and attach a foot restraint at the end of the Canadarm2. Herrington will then ingress the foot restraint and Pettit, at the arms controls, will maneuver him to the starboard end of the P1. There Herrington will begin the installation of a dozen 1-inch SPDs on lines linking the Radiator Beam Valve Modules (RBVMs) and the radiator junction box.

He then gets off the arm and continues with the 1-inch SPD installations, moving out toward the outboard end of the P1. During this three-hour-plus phase of the spacewalk, Herrington will install a total of 18 SPDs.

Meanwhile Lopez-Alegria installs two 1-inch SPDs at the Z1 to P6 interface, and then moves to the bottom of the Z1 Truss at its junction with the U.S. laboratory Destiny. There he will install two 1-inch SPDs. Next he moves to the Moderate Temperature Loop Heat Exchanger on the labs exterior, removes a Micro Meteoroid Orbital Debris shield and installs two 1-inch SPDs, and finally reinstalls the shield.

His next task is at the pump module on P1. There he will install three 1-inch SPDs and a half-inch SPD.

Lopez-Alegria will take a break from SPD installation with his next activity, reconfiguration of electrical harnesses that route through Main Bus Switching Units. That 40-minute task, involving relocating two dustcaps and changing four cable connections from two foot restraint positions in the interior of the S0 Truss in bay 4, is completed by Lopez-Alegria about four hours into the spacewalk. Following the RBVM SPD installation, Herrington will focus his attention on the Ammonia Tank Assembly (ATA) umbilicals. The P1 ATA is on the starboard-most bay of P1 on the aft face. That 40-minute job, linking the ATA to ammonia lines in the stations cooling system and the Nitrogen Tank Assembly lines to the ATA, involves relocation of four quick disconnect caps and hookup of four connections. Herrington also will install one -inch SPD during that process.

Herringtons final task of spacewalk No. 3 is installation of three 1-inch and one -inch SPDs on S1 Pump Module connector lines. Lopez-Alegria also will move to S1, to install four 1-inch SPDs on Flex Hose Rotary Coupler (FHRC) QDs. Those tasks accomplished, both spacewalkers will begin an EVA cleanup period and then move into the airlock.

Lopez-Alegria and Herrington install more than 40 SPDs during STS-113 spacewalks.

NASA TV Schedule for Flight Day 8

Orbit  Item                              EST (GMT Minus 5)103    ENDEAVOUR CREW WAKE UP              08:20 AM       (begins FD 8)103    ISS CREW WAKE UP                    08:50 AM103    EVA #3 PREP BEGINS                  09:35 AM104    MOBILE TRANSPORTER MOVEMENT FROM    11:05 AM       WORKSITE 4 TO WORKSITE 7106    SSRMS WALKOFF FROM DESTINY TO MBS   01:00 PM106    EVA #3 BEGINS                       02:20 PM109    SSRMS WALKOFF FROM MBS TO DESTINY   05:30 PM109    MOBILE TRANSPORTER MOVEMENT FROM    07:00 PM       WORKSITE 7 TO WORKSITE 4111    EVA #3 ENDS                         08:50 PM111    MISSION STATUS BRIEFING             09:30 PM       (time subject to change)113    ISS/ENDEAVOUR CREW SLEEP BEGINS     12:20 AM

Endeavour mission specialist Michael Lopez-Alegria describes the third spacewalk:

"That spacewalk is almost totally dedicated to installation of the spool positioning devices, the SPD. I'm going to be putting some on part of the station that isn't the P1 so I'll get to go back to my old stomping grounds, the Z1 Truss, put some there, put some on the jumpers between the Z1 Truss and the Lab, and then a couple of more on a Lab heat exchanger, which is going to require me removing a panel to get access to a couple of QDs that are in there."

"In the meantime John is going to be doing the same thing on some quick disconnects that are on the truss itself. He's going to be doing part of that task based on the SSRMS, the arm with his feet restrained there, and part of them, part of it what we call free floating, basically just holding on. The other thing we're going to do on that EVA is go up inside the S0 truss and do a little bit more electrical work disconnecting some electrical connectors and basically doing a reconfiguration, which will allow power then to flow all the way down to the outboard truss segments once they're installed."

Endeavour mission specialist John Herrington talks about the third spacewalk:

"The third spacewalk is the one that's changed a lot in our planning process. Now we have to go pretty much around a large portion of the station and install what are called spool positioning devices. They're small little devices we will put on some of the ammonia lines that run throughout the station. And, what this positioning device does, it allows us to put it on to a fluid connector and manipulate the fluid connector such that there's a possibility that pressure could build up in these fluid lines and we don't want them to, so we have to install these devices to make sure the fluid connector stays in a position where we could take it off at one time if we have to. If the pressure builds up on these connectors, there's a possibility that sometime later on, you know, say, two, three years from now, if we have to take it off, we might not be able to. So, the engineers have decided that we needed to put these devices on these connectors to prevent that from occurring so we can continue the assembly sequence. So we, Mike and I, pretty much run around on the third EVA and install a lot of these devices on fluid jumpers. So that takes up a good portion of that EVA."

"There's some place down on Z1 that that'll be done on the Z1; to the Laboratory, that has to be done. We will do it on EVA 2; we actually install a couple on those, on some ammonia lines that we also install big one-and-a-half-inch ammonia lines, so we will have already have installed some of those on EVA 2 I have some on, Mike will install some on EVA 2 as well, in a different portion, but I have to go down the top portion, the zenith portion of P1, and install about eighteen of these. So it's going to require some robotic operations, I'll be in the arm for probably a good portion of the EVA. And then I'll get off and I'll free float and I'll install more of these devices on some more connectors."