STS-123 Coming To A Close  

Endeavour’s crew completed additional inspections of the space shuttle’s heat shield using the Orbital Boom Sensor System (OBSS) Friday. The detailed inspection performed by Commander Dom Gorie, Pilot Greg Johnson and Mission Specialist Takao Doi included 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. Friday night, 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 was completed in advance of Saturday’s spacewalk, which was scheduled to last 6.5 hours.

Mission Specialists Robert L. Behnken and Mike Foreman began the fifth spacewalk of STS-123 at 4:34 p.m. EDT. Rick Linnehan, also a mission specialist, is coordinating their activities from inside the orbiting complex made up of space shuttle Endeavour and the International Space Station.

Behnken and Foreman have successfully attached the Orbiter Boom Sensor System (OBSS) to the station’s S1 Truss. With the OBSS in the grip of the station’s robot arm earlier, the two spacewalkers assembled an umbilical designed to keep the boom safe while it is stored in the harsh space environment. Then, the robot arm handed the OBSS off to Behnken and Foreman to be placed on S1.

The next component of the Japan Aerospace Exploration Agency’s Kibo laboratory, which will be delivered on space shuttle Discovery during the STS-124 mission, is too large to accommodate the OBSS in the shuttle’s payload bay. Once the next element of Kibo is installed on the station, Discovery’s astronauts will detach the OBSS left behind by space shuttle Endeavour, use it to perform tile inspections and bring it home.

In addition, the spacewalkers have successfully installed the Materials International Space Station Experiment 6 on the outside of the European Space Agency’s Columbus laboratory, an activity the astronauts were unable to complete during the mission’s third spacewalk. They also will perform other tasks including an inspection of the starboard Solar Alpha Rotary Joint.

With the final STS-123 spacewalk complete, flight day 14 will see the crew of Endeavour prepare for the end of their visit to the station. The orbiter will undock Monday and return to Earth Wednesday.

FMI: www.nasa.gov