HTV

Japanese space tug designed for launch by the H-2A for International Space Station resupply. The HTV would carry International Standard Payload Racks but it had no docking capability. Instead, the HTV would rendezvous with the Canadian robotic arm which then would grapple it and move it to one of the Space Station's docking hatches.

NASDA HTV 1999 Credit- NASDA via Marcus Lindroos

The September 1988 Space Station Intergovernmental Agreement allowed ESA and NASDA to use the Ariane-5, H-2A or other indigenous launchers for resupplying their Station modules. NASA promised to provide all the necessary rendezvous and docking information to designers in Europe and Japan. Each partner would pay the full cost of maintaining its own hardware elements on the Station and they would also have to reimburse NASA for using Space Shuttle and Tracking and Data Relay Satellite services. The Japanese HTV could transport about 7t of pressurized, unmanned cargo to the Space Station.

The $203 million Progress/ATV type 'H-2 Transfer Vehicle' was originally scheduled for a 2001 test launch. The Japanese were to have launch two 15-metric ton HTV vehicles per year as their contribution to ISS operations. Pre-Phase B studies were started in 1995. The HTV would require the development of a new twin-core version of the H-2A launcher. Each HTV could carry 7,000kg of pressurized supplies (8 International Standard Payload Racks) but no propellant. Japanese government officials were now increasingly worried about the Japanese Experiment Module's future operating cost. Japan would be expected to contribute $410-450 million per year -- half of it for ISS operations (NASDA's share was 12.8%) and the rest for ancillary infrastructure costs. The total budget could amount to almost a third of NASDA's total budget by 2005.

Article by Marcus Lindroos

Update as of January 2005: The selected contractor, MHI Mitsubishi Japan reported that the net payload was down to 6 metric tons and that

The HTV was the transfer vehicle to deliver daily goods such as water, food and clothing and experimental equipment to JEM (Japanese Experiment Module) and other countries' stations after the completion of the assembly of the International Space Station.

This vehicle was unmanned, launched by H-IIA, and approaches the station automatically, and was maintained and moored by the station facility. After the completion of its work, it would self-destruct itself and disappear when it re-enters the atmosphere.