| H-II Transfer Vehicle |
H-II Transfer Vehicle |
| Description |
| Role: |
Unmanned spacecraft intended to resupply the Kibō Japanese Experiment Module on the International Space Station, and the rest of the station, if necessary. |
| Crew: |
unmanned |
| Dimensions |
| Height: |
10 m (including thruster) |
| Diameter: |
4.4 m |
| Payload: |
6 tons |
| Performance |
| Endurance: |
Solo flight about 100 hours, stand-by more than a week, docked with the ISS about 30 days |
|
| Apogee: |
460 km |
|
| Perigee: |
350 km |
|
| Inclination: |
51.6 degrees |
|
The H-II Transfer Vehicle, or HTV, is a robotic spacecraft intended to resupply the Kibō Japanese Experiment Module (JEM) on the International Space Station, and the rest of the station, if need be. The Japan Aerospace Exploration Agency, JAXA, has been working on the design, on and off, since the early 1990s. Originally intended to be launched in 2001, it is currently planned to enter operation in 2009. HTV is about 9.2 m long (including maneuvering thrusters at one end) and 4.4 m in diameter. Empty, it weighs 10.5 tons. HTV is a larger and 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 pull it to a berthing port on Harmony Module (Node 2) of the ISS. HTV can carry supplies in a combination of two different "segments" that can be attached together. One is a pressurized hold with a capacity of 6,000 kg, which includes an optional docking adapter at one end to allow it to be unloaded in a shirt-sleeves environment. It is designed specifically to carry eight International Standard Payload Racks (ISPR) in total. It will also have a tank to deliver up to 300 kg of water to the station. The other is a lighter and slightly longer unpressurized segment, which includes a hatch on the side to allow it to be unloaded remotely. The baseline configuration, known as the "Mixed Logistics Carrier", uses one pressurized and one unpressurized segment and can carry 7,600 kg of cargo in total and is 9.2 m long. When two pressurized units are used together the cargo decreases slightly to about 7,000 kg, and the overall length is reduced to 7.4 m[1]. These numbers are somewhat vague in the various sources, some suggesting that the pressurized/unpressurized combination carries only 6,000 kg in total, less than the pressurized/pressurized combination, which should be heavier. No sources suggest an unpressurized/unpressurized combination is planned, perhaps due to the overall length. The HTV will be launched from the Tanegashima Space Center in Japan by a Japanese H-IIB rocket, an uprated version of the existing H-IIA Rocket launcher. The first test launch is expected in 2009.
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