Discovery Mission Specialists Mike Fossum and Piers Sellers will work on the International Space Station's mobile transporter and install a pump module today on the second of three spacewalks of the STS-121 mission.
The shuttle crew was awakened at 1:08 a.m. CDT by "Clocks," performed by Coldplay. It was requested by Sellers' family for the day of the second spacewalk.
The spacewalk is scheduled to begin at 7:13 a.m. and expected to last nearly seven hours. First, Fossum and Sellers will make their way to the shuttle's payload bay to a spare pump module for the station's thermal control system. Once there, they will attach it to the fixed grapple bar which will allow Mission Specialists Lisa Nowak and Stephanie Wilson, inside at the controls of the robotic arm, to maneuver the pump to the external stowage platform.
While the module is being moved, Fossum and Sellers will stay in the payload bay and get ready for their next task, replacement of a trailing umbilical system (TUS) reel assembly, this one on the nadir side of the mobile transporter.
After they reconfigure the payload bay for the activity, they'll then translate to the starboard zero truss segment, to get it ready for retrieval. Fossum will disconnect electrical cables while Sellers changes out the assembly. Once it is ready, they will leave that site to go to the stowage platform and assist with the detaching and installation of the pump into its permanent storage location. That pump is onboard as a spare should it be needed in the future.
The two spacewalkers will then return to the truss and remove the TUS reel assembly. Fossum, on the end of the robotic arm, will take the reel assembly to the payload bay. Sellers will move there on his own, and set up for the swap of that assembly with a new one. After the swap is complete, the two will go back to the worksite to install the new reel assembly, reroute the power and data cable and thus restoring the desired redundancy to the mobile transporter and enabling it again to be used for continued station assembly tasks.
Shuttle Commander Steve Lindsey and Pilot Mark Kelly will support the spacewalk with Lindsey monitoring the vehicle systems and video/television set ups and Kelly overseeing activities and coaching the spacewalkers.
The Expedition 13 crew, Commander Pavel Vinogradov and flight engineers Jeff Williams and Thomas Reiter, will be working steadily throughout the day transferring trash and unneeded equipment and supplies for return to Earth in the multipurpose logistics module Leonardo. More than 4,300 pounds of cargo will be packed for the return to Earth.
The next STS-121 mission status report will be issued Monday evening, or earlier if events warrant.
