NASA announced that the STS-123’s astronauts have successfully completed the fifth and final spacewalk and Endeavour’s crew is now preparing for the end of their visit to the International Space Station.

Mission Specialists Robert L. Behnken and Mike Foreman began the fifth spacewalk of STS-123 at 4:34 p.m. EDT on Saturday. Rick Linnehan, also a mission specialist, coordinated their activities from inside the orbiting complex. They completed the fifth spacewalk of STS-123 at 10:36 p.m. EDT Saturday.

During the spacewalk, robot arm operators grappled the Orbiter Boom Sensor System (OBSS) and the two spacewalkers assembled an umbilical designed to keep the boom safe during its time in the harsh space environment. Then the robot arm handed the OBSS off to Behnken and Foreman, who stowed it on the station’s S1 Truss.

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.

Behnken installed the Materials International Space Station Experiment 6 on the outside of the European Space Agency’s Columbus laboratory, and Foreman inspected the starboard Solar Alpha Rotary Joint.

According to NASA mission managers, Foreman found no evidence that orbital debris had struck the joint, which eliminated one possible cause. The space station flight director Dana Weigel said that NASA hopes to have a plan for dealing with the jammed joint by the end of the month, the Associated Press reported.

As the final spacewalk ended, much of flight day 14’s morning will be off-duty time for shuttle crew members. Later on the day they will also hold the joint crew news conference, wrap up equipment and logistics transfers between the station and shuttle and check out rendezvous tools. Highlighting flight day 15 are crew farewells, hatch closings, undocking, Endeavour’s fly-around of the station with pilot Johnson at the controls, and departure.

Landing preparations, including checkout of the flight control system and the reaction control system, are the focus of flight day 16. The crew members will stow items in the cabin and hold a deorbit briefing just before bedtime. Deorbit preparations, and landing at the Kennedy Space Center (KSC) on flight day 17 (Wednesday) wind up Endeavour’s lengthy and demanding STS-123 mission to the ISS.

During their 17-days mission, the Endeavour’s astronauts delivered to the ISS the first pressurized section, Japanese Experiment Logistics Module (ELM-PS), of the future Kibo (Hope) Japanese module and the Canadian Space Agency’s newest contribution to the station, the Special Purpose Dexterous Manipulator or Dextre.

After the STS-123 mission, NASA plans another ten, including four more in 2008, to complete construction of the ISS by September 30, 2010, when NASA's three-shuttle fleet is to be retired.

Image Credit: NASA TV