Today's wake-up call at 12:28 p.m. CDT, 'Blue Sky' by Big Head Todd and the Monsters, was played for Mission Specialist Rick Linnehan, who will serve as the spacewalk coordinator for today's 6.5-hour-long excursion by Mission Specialists Robert L. Behnken and Mike Foreman.
When the hatch on the Quest airlock opens at 5:28 p.m., Behnken and Foreman will translate onto the International Space Station's truss. Behnken will replace a failed circuit breaker called a Remote Power Controller Module, while Foreman reconfigures cables on a nearby switching box to provide a redundant power source for the Control Moment Gyroscopes which control the station's attitude in orbit without the use of propellant.
The major job for Behnken and Foreman on this spacewalk is a demonstration of the Tile Repair Ablator Dispenser -a caulk-gun-like device -to apply a substance called Shuttle Tile Ablator-54 (STA-54) into purposely damaged heat shield tiles. The test samples will be returned to Earth to undergo extensive testing on how STA-54 performs in the environment of space. The work will be done at a worksite the spacewalkers will set up on the nadir side of the Destiny laboratory.
During the spacewalk other members of the crews will continue the transfer of supplies from Endeavour to the space station. Flight Engineer Garrett Reisman has his afternoon blocked out for more handover discussions with his predecessor, European Space Agency astronaut Leopold Eyharts, who is coming home with shuttle Commander Dominic Gorie and his crew.