up-close examinations of the shuttle's thermal protection system, including the reinforced carbon-carbon panels on the leading edges of the shuttle's wings as well as the nose cap of the orbiter.
Ground teams will closely examine the imagery and data collected by the OBSS scan to ensure one last time that Endeavour's heat-resistant tiles are safe for re-entry.
This inspection is typically completed after the shuttle has undocked from the space station, but because the crew will stow the OBSS on board the station during the fifth and final spacewalk of the mission tomorrow, the inspection was completed earlier. The OBSS will be stowed on the station in preparation for Discovery's flight in May due to the size of the Japanese pressurized Kibo module it will be carrying. Once Discovery's crew installs that module on the station, it will pick up the OBSS left behind by Endeavour and will bring it back to Earth after performing inspections.
The crew also continued transfers of cargo and equipment between the shuttle and the station. Tonight, astronauts Bob Behnken and Mike Foreman began the campout period inside the station's Quest airlock to purge the nitrogen out of their bodies. This will be completed in advance of tomorrow's spacewalk, which is scheduled to last 6.5 hours.