H-II Transfer Vehicle

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The H-II Transfer Vehicle (HTV) is an unmanned spacecraft on which the Japan Aerospace Exploration Agency, JAXA has been working since 1997 to resupply the Kibo Japanese Experiment Module (JEM) on the International Space Station, and the rest of the station, if need be.

It is a larger and slightly simpler vehicle than the Russian Progress spacecraft currently used to bring up supplies to the station, since it does not have a complex docking and approach system. Instead it is planned that it will be flown just close enough to the station to be grabbed by Canadarm2, which will bring it to a berthing port on Node 2 of the ISS.

The HTV will be launched from the Tanegashima Space Center in Japan by a Japanese H-IIB rocket. About the size of a bus (approx. 10 meters long and 4.4 meters in diameter), the HTV will carry supplies in two different holds: One will be pressurized, with a capacity for 6,000 kg and the other will be open to space, with a 1,600 kg capacity. It will also have a tank to deliver up to 300 kg of water to the station. The pressurized section will contain a maximum of 8 International Standard Payload Racks (ISPR) and will be unloaded by station crew, working in a shirtsleeve environment. ISPR's can be transferred to ISS only by Space Shuttle, HTV, or planned NASA Ares V. The open section will be unloaded by the Japanese remote manipulator system. The first test launch will be in 2008.