Astronauts prepare for fourth spacewalk

HOUSTON, March 20 (UPI) -- Space shuttle Endeavour and International Space Station crews enjoyed some off-duty time Thursday before the fourth spacewalk of the STS-123 mission.

National Aeronautics and Space Administration controllers in Houston said the spacewalk, to begin at 6:28 p.m. EDT Thursday, will focus on testing a new shuttle heat shield repair method. The technique uses a tool similar to a caulk-gun to dispense a material called Shuttle Tile Ablator-54 onto purposely damaged heat shield tiles.

The treated sample tiles will then be returned to Earth aboard Endeavor to undergo testing.

At the beginning of their 10th day in orbit Thursday, the crews spoke with Japanese Prime Minister Yasuo Fukuda and participated in interviews with various U.S. media representatives. NASA said the astronauts spent the remainder of their day configuring tools for the spacewalk and reviewing spacewalk procedures.

Astronauts Robert Behnken and Mike Foreman spent their sleep time in the space station's Quest airlock for the standard "camp out," during which the nitrogen is purged from their bodies to prepare them for their spacewalk.