Two U.S. astronauts on space shuttle Endeavour finished the mission's fourth and final spacewalk on Monday, doing some chores outside the International Space Station, according to NASA TV.

Most important of all, Mission specialists Steve Bowen and Shane Kimbrough finally completed the cleaning and lube job on the station's right-side solar array joint. They replaced the final one of the 12 bearings for the massive gear.

This jammed joint has had limited use since September 2007. The repair work took all of the mission's four spacewalks to complete. "Finally!" Bowen said about 2.5 hours into today's spacewalk when they really wrapped up the tough task. "Thanks for your work," NASA's mission control radioed up, echoing with applause.

During the spacewalk, the duo also teamed up to remove a multi-layer insulation blanket from Japan's Kibo laboratory. Bowen installed a GPS antennas atop Kibo.

Kimbrough then moved to the opposite end of the station's truss to lubricate the left-side solar array joint as a preventative maintenance step. The left gear has been working fine, but the spacewalkers reported some slight wear on its surface as they perform the grease job.

After finishing all of the assigned tasks, they returned safely to the Quest airlock of the station at 7:31 p.m. EST (0031 GMT on Tuesday).

Earlier on Monday, NASA's mission control decided that Endeavour will spend one extra day docked at the station to allow more time to troubleshoot problems with the station's new water recycle system.

The recycler was delivered to the station aboard Endeavour. It is designed to process urine and sweat back into drinkable water. Astronauts reported they recorded repeated early shutdowns during the system's test runs, and they are trying to remedy the glitch.

Now, Endeavour's mission is officially a 16-day mission that will feature a Thanksgiving Day at the space outpost. It will undock with the station and leave for home on Nov. 28.