The two spacewalkers, Mark Fossum and Ronald Garran, have completed their second mission outside the International Space Station. . The 7-hour, 11-minute excursion ended at 6:15 p.m. EDT Thursday.

The spacewalkers installed two cameras on the Japan Aerospace Exploration Agency’s Kibo laboratory. These cameras will be used to judge clearances for the module’s robotic arm.

Kibo, which means hope in Japanese, will be the largest module of the ISS, and represents Japan’s contribution to space exploration. The lab is formed by three parts: a storage room, the lab itself and an extension resembling a porch where outside space experiments will be carried out.

Discovery has delivered the second part of the lab last week, and its crew is currently working on installing it. The storage room was brought to the ISS last March and has been stored on the station.

Garan and Fossum also prepared the laboratory’s top active common berthing mechanism for the attachment of the smaller section of the module, the Japanese Experiment Logistics Module - Pressurized Section, which was delivered during STS-123.

In addition, the two spacewalkers made preparations for a nitrogen tank assembly swap they will make on their third spacewalk. They also removed an external television camera that had a failing power supply.

Fossum also inspected the space station's port solar alpha rotary joint, or SARJ. Unlike the starboard SARJ, the port SARJ has performed flawlessly. The inspection was done to ensure the port SARJ remains in good condition.

The crew that remained inside took advantage of the space inside the so far empty module and had some space fun, making flip flaps and bouncing on the labs’ bare walls. After joking around a little bit, they went back to work and started to install some of Kibo’s racks.