After they successfully competed the three spacewalks, the crew of space shuttle Discovery is preparing the end of joint operations today and the return home. 

During their mission, the astronauts have delivered and installed the Kibo pressurized science laboratory, also known as the JPM.

The JPM is the largest pressurized module on the station. The module is cylindrical in shape and is 11.2 meters (36.7 feet) long and 4.4 meters (14.4 feet) in diameter, about the size of a large tour bus. The JPM has a total mass (when fully assembled) of 15.9 tons. Up to 23 racks (10 of which are international standard payload racks) can be accommodated inside it.

The JPM is primarily equipped with station common hardware. Two grapple fixtures are mounted on the external surface to allow the space station’s robotic arm to grapple and move the JPM. An Active CBM is provided on the zenith side of the module for attaching the JLM. The JPM has a small scientific airlock through which exposed experiments, or orbital replacement units (ORUs), can be transferred between the Kibo pressurized and unpressurized facilities.

Kibo’s robotic arm is fixed at the upper side of the JPM endcone. The JPM has an 8-rack equivalent length, but the presence of the JEM airlock and the CBM hatch for access to the JLM limits rack installation. For each of the four walls inside the JPM, with the exception of the zenith wall, six racks can be installed in a continuous row. The zenith wall will hold five racks in a row.

The JPM is equipped with two windows, located just above the JEM airlock. The crew can clearly see the Kibo unpressurized facilities through these windows. The crew also will be able to observe and monitor the unpressurized facilities with external television cameras mounted on the JPM.

Assembly of the Kibo pressurized facilities was completed during the STS-124 mission. In turn, the Kibo Exposed Facility (EF) and the Experiment Logistics Module-Exposed Section (ELM-ES) are scheduled to be launched on the STS-127 (2J/A) mission. By the summer of 2009, Japan’s unmanned cargo transfer spacecraft, the HTV, will initiate its operations. The HTV will be launched aboard the H-IIB launch vehicle from the Tanegashima Space Center in Japan, and begin transferring supplies, payloads and cargo, both pressurized and unpressurized, to the station.

During the preparations for return, the Discovery’s astronauts will transfer spacewalk equipment and at least one spacesuit back to Discovery. They will enjoy some off-duty time and also will check out the tools and equipment needed for undocking activities.

At 3:57 p.m. EDT, the two crews will bid farewell to one another.

Also, the STS-124 astronauts delivered Expedition 17 Flight Engineer Greg Chamitoff, who replaced Garrett Reisman, now a mission specialist returning to Earth aboard Discovery.

Chamitoff will join expedition commander and Russian Air Force Lt. Col. Sergei Volkov, 35, and Flight Engineer Oleg Kononenko, 43, who were launched to the complex in the Soyuz TMA-12 spacecraft on April 8 from the Baikonur Cosmodrome in Kazakhstan. Chamitoff will return to Earth in the fall on shuttle mission STS-126, while Volkov and Kononenko will return in the Soyuz in October.

Update: Discovery undocked from the International Space Station today at 7:42 a.m. EDT, ending its almost nine-day stay at the orbital outpost. On Tuesday, The STS-124 and Expedition 17 crews bid one another farewell, and closed the hatches between the two spacecraft at 4:42 p.m.