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 he was treated to a televised tour of the space station's new Japanese compartment, courtesy of  Takao Doi.

The astronauts spent the remainder of their day configuring tools for the fourth STS-123 spacewalk and reviewing spacewalk procedures.

he fourth spacewalk will be used to replace a remote power control module and test a shuttle tile repair material. The repair material test was originally scheduled for Discovery’s mission last October, but was rescheduled so that problems with the station’s solar arrays could be addressed. Foreman and Mission Specialist Robert Behnken are slated to begin the mission’s fourth spacewalk at 6:28 p.m. Thursday

The primary purpose of the detailed test objective is to evaluate the Shuttle Tile Ablator-54 (STA-54) material and a tile repair ablator dispenser in a microgravity and vacuum environment for their use as a space shuttle thermal protection system repair technique. Spacewalkers Robert Behnken and Mike Foreman will set up for the test on the outside of the Destiny lab.

The Tile Repair Ablator Dispenser (T-RAD) is similar to a caulk-gun.  Both spacewalkers will use the T-RAD to mix and extrude the STA-54 material into holes in several demonstration tiles.  The spacewalkers will watch for swelling of the material and work it in until it is smooth by tamping the material with foam-tipped tools. The repaired samples and tools will be stowed in Endeavour’s cargo bay for return to Earth.  The samples will undergo extensive testing on the ground.

The goal is to complete this test before space shuttle Atlantis flies to the Hubble Space Telescope in August. Unlike missions to the space station, Atlantis’ crew members wouldn’t be able to wait on the station for another shuttle to bring them home if Atlantis was damaged.

In addition during the fourth spacewalk the astronauts will replace a failed Remote Power Controller Module on the station’s truss.

Before going to sleep, Mission Specialists Robert L. Behnken and Mike Foreman entered the station’s Quest airlock for the standard “camp out,” during which the nitrogen is purged from their bodies. They are slated to begin the mission’s fourth spacewalk at 6:28 p.m. EDT.