Assembling Special Purpose Dexterous Manipulator (SPDM), named Dextre by removing covers and installing arm components on its main body.

Evaluating the Shuttle Tile Ablator-54, or STA-54, material and a tile repair ablator dispenser for use as a shuttle thermal protection system repair technique. The Tile Repair Ablator Dispenser, or T-RAD, is similar to a caulk gun. They used TRAD to mix and squirt out the STA-54 material into holes in several demonstration tiles. The repaired samples will be returned to Earth for extensive testing.

Moving the Orbiter Boom Sensor System, the 50 ft. extension of the shuttle's robotic arm, to a temporary location on the station's main truss or backbone. The OBSS was left on the station because shuttle Discovery doesn't have enough room in its cargo bay to carry both the boom and the large Japanese pressurized module on the STS-124 mission. The spacewalkers also installed a new trundle bearing assembly in the starboard Solar Alpha Rotary Joint to allow the joint to rotate a little bit more if necessary. That SARJ has had limited ability for several months, and metallic debris has been found inside it. Additional spacewalk tasks included inspecting the SARJ and collecting debris samples.

Installing a spare antenna on the station's truss, or backbone, and a bracket for ammonia lines on the Unity module. They lubricated the grapple mechanism on the Payload Orbital Replacement Unit Attachment Device on the Mobile Base System and lubricated the snares of the hand of the station's Japanese robotic arm.

Installing the GATOR (Grappling Adaptor to On-Orbit Railing) bracket to the Columbus laboratory and an additional ham radio antenna. They installed on the truss an antenna for wireless helmet camera video. They also relocated the Floating Potential Measurement Unit that records electrical potential around the station as it orbits the Earth and deployed a bracket to attach cargo on the truss.