Mission Control Center, Houston, Texas

HOUSTON - The crew will take another look at space shuttle Endeavour's heat shield today using the Orbiter Boom Sensor System, which will be stowed on the exterior of the International Space Station during tomorrow's fifth and final planned spacewalk of the mission.

The crew started its day at 12:28 p.m., with the song "Enter Sandman" performed by Metallica. The song was played for Mission Specialist Robert L. Behnken.

Shuttle Commander Dominic Gorie, Pilot Gregory H. Johnson and Mission Specialist Takao Doi will start the inspection of the shuttle's heat shield at 3:03 p.m., beginning with the leading edge of the shuttle's right wing. After taking time out for lunch, they'll continue just after 6:30 p.m. with the shuttle's nose cap and left wing leading edge.

The survey's place in the mission's timeline is different than in past flights. Normally the inspection is done after the shuttle has undocked from the space station. But Endeavour's crew is planning to leave the Orbiter Boom Sensor System - or OBSS, an extension attached to the shuttle's robotic arm that includes cameras and a laser system used to look for damage to the shuttle's heat shield - behind for the next shuttle visit, and so is doing the survey earlier than usual.

The OBSS is being left on the station to leave extra room in the cargo bay of space shuttle Discovery, the next shuttle to visit the space station. Discovery will be bringing the Japanese Experiment Module to the station, and there is not enough room in the cargo bay for both it and the OBSS. Discovery will bring the OBSS back to Earth at the end of its mission.

The next STS-123 status report will be issued near the end of the crew's day, about 3 a.m. Saturday, or earlier if events warrant.

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