The station and shuttle crews also prepared hardware to be used in a shuttle tile repair test on the next spacewalk, and got some much needed off duty time. March 20 (Flight day 10) The crews of Space Shuttle Endeavour and the International Space Station got some off-duty time at the beginning of their 10th day in orbit. They also spoke to Japanese Prime Minister Yasuo Fukuda and participated in interviews with U.S. media. The astronauts spent the remainder of their day configuring tools for the fourth STS-123 spacewalk and reviewing spacewalk procedures. Before going to sleep, Mission Specialists Robert L. Behnken and Mike Foreman entered the station's Quest airlock for the standard "camp out". March 21 (Flight day 11) Mission Specialists Robert L. Behnken and Mike Foreman completed the fourth STS-123 spacewalk at 04:28 UTC, spending six hours and 24 minutes on the excursion. The two shuttle crew members replaced a failed Remote Power Control Module — essentially a circuit breaker — on the station's truss. However, there were difficulties removing a power connector from the Z1 truss. With Mission Specialist Rick Linnehan coordinating their activities from inside the orbiting complex, the spacewalkers also tested a repair method for damaged heat resistant tiles on the Space Shuttle. This technique used a caulk-gun-like tool named the Tile Repair Ablator Dispenser to dispense a material called Shuttle Tile Ablator-54 into purposely damaged heat shield tiles. The sample tiles will be returned to Earth to undergo extensive testing on the ground. March 22 (Flight day 12) The STS-123 crew performed the final inspection of Space Shuttle Endeavours heat shield using the shuttle's robot arm and the Orbiter Boom Sensor System (OBSS). Gorie, Johnson, and Doi surveyed the orbiter's wings and nose cap to ensure that no damage had occurred to the tiles that protect Endeavour from the heat of reentry. The crews spent the remainder of their day configuring tools and reviewing procedures for the flight's final spacewalk. This included the standard "camp out" in the station's Quest airlock for Behnken and Foreman. March 23 (Flight day 13) Michael Foreman and Robert Behnken completed their six-hour EVA at 02:36 (UTC), attaching a 50 ft (15 m) inspection pole to the International Space Station and completing other chores. Foreman and Behnken hooked an extra-long power cord to the inspection pole, to keep its lasers and cameras warm for the next two months, then