The STS-131 crew arrived at the Kennedy Space Center on Monday ( March 1 ) for a week of standard prelaunch training and a full-dress launch rehearsal known as the Terminal Countdown Demonstration Test. Space Shuttle Discovery will carry the Crew and a multi-purpose logistics module filled with science racks to the International Space Station. The racks will be installed in the laboratories aboard the station. The mission has three planned spacewalks, with work to include replacing an ammonia tank assembly, retrieving a Japanese experiment from the station's exterior, and switching out a rate gyro assembly on the S0 segment of the station's truss structure.