The largest payload ever delivered to the International Space Station, the Japan Aerospace Exploration Agency's Kibo laboratory's pressurised module, is now operational following its installation at the ISS by the Space Shuttle Discovery crew during the 15-day STS-124 mission set to end on 14 June.

The laboratory, whose name in Japanese is "hope", consists of six components. Its main section, the 15,900kg (34,980lb) pressurised module, is 4.39m (14.4ft) in diameter and 11.1m long.

The other five sections are the robotic manipulator system (RMS), the experimental logistic module (ELM-PS), the exposed facility (EF), the experimental logistic module exposed section (ELM-ES) - which acts as an EF storage space and can be returned to Earth using the Shuttle - and the inter-orbit communications system.

Discovery's mission, the 123rd Shuttle launch, was the second flight to install the components of the Kibo laboratory. Mission STS-123 delivered the RMS and ELM-PS, a storage section.

Mission STS-127, also known as ISS assembly mission 2J/A, will put in place the EF and ELM-ES.

The delivery of Kibo follows the installation of the European Space Agency's Columbus laboratory in February. The pressurised module is also the penultimate ISS module to be delivered. Only Node 3 remains to be taken to the station by Shuttle, by 2010.

During mission STS-124, the installation of Kibo's pressurised module was spread over three extravehicular activities on the fourth, sixth and ninth flight days, and each spacewalk was about 6h 30min long.

All three of the spacewalks were conducted by NASA mission specialists Michael Fossum and Ron Garan. JAXA's astronaut Akihiko Hoshide was involved in the use of the ISS robotic arm for the pressurised module's installation and was the first to use Kibo's RMS.

The first spacewalk saw the pressurised module attached to the port side of Node 2. The orbiter boom sensor system (OBSS) was also retrieved from the space station's S1 truss.

It had been left there by the orbiter Endeavour's crew during mission STS-123 in March. The OBSS had to be left behind because Discovery could not launch with it and Kibo because of the size of the JAXA laboratory.

Normally an orbiter uses the OBSS to inspect its thermal protection system before and after ISS docking, but Endeavour was unable to carry this out after it left the station in March and neither was Discovery once it was in orbit on 31 May.

Flight day five of STS-124 saw the pressurised module opened by the crew. The second spacewalk the following day saw preparations for moving the ELM-PS, temporarily attached to the Harmony module's zenith port, to the pressurised module's common berthing mechanism on its zenith port using the ISS robotic arm, Canadarm2.

The ELM-PS was attached to the pressurised module on flight day seven. This was followed by the RMS initial deployment by Hoshide on day eight.

Other non-Kibo related tasks carried out during the mission included a nitrogen tank assembly replacement on the S1 truss, the swopping out of external television camera equipment and the fitting of a new trundle bearing assembly for the station's starboard rotary joint.

The joint's outer race ring was also cleaned of metal debris. The rotary joint has experienced vibration and higher than expected power usage and it was inspected on STS-123. The S1 truss nitrogen tank is used as part of the station's environmental control system.

Discovery has also delivered ISS Expedition 17 flight engineer Gregory Errol Chamitoff, who replaces Garrett Reiseman. Reiseman had been Expedition 17 and Expedition 16 flight engineer, but will return to Earth with the orbiter.

Orbiters routinely deliver and return experiments to and from the station. For STS-124 NASA has delivered three experiments for life sciences research and JAXA's commercial payload programme has provided another set of experiments.

Following STS-124 the next major milestones for ISS operations, before the arrival of Node 3, will be the increase of the crew from three to six by next May and sometime after that the arrival of Japan's first automatic cargo spacecraft, the H-IIB transfer vehicle, which will be launched by the Mitsubishi Heavy Industries H-IIB rocket on the booster's maiden flight.

The next Shuttle mission is STS-125, planned for October. This is the last servicing mission for the Hubble Space Telescope.

Source: Flight International