# H-II Transfer Vehicle

> retired Japanese automated cargo spacecraft

**Wikidata**: [Q266487](https://www.wikidata.org/wiki/Q266487)  
**Wikipedia**: [English](https://en.wikipedia.org/wiki/H-II_Transfer_Vehicle)  
**Source**: https://4ort.xyz/entity/h-ii-transfer-vehicle

## Summary
The H-II Transfer Vehicle (HTV), also known as Kounotori, was a retired Japanese automated cargo spacecraft designed to resupply the International Space Station (ISS). Operated by the Japan Aerospace Exploration Agency (JAXA), it played a key role in delivering pressurized and unpressurized cargo to the ISS from 2009 to 2020.

## Key Facts
- **Type**: Retired automated cargo spacecraft, part of the cargo spacecraft class.
- **Operator**: Japan Aerospace Exploration Agency (JAXA).
- **Service Period**: 2009 (maiden flight) to 2020 (retirement).
- **Launch Vehicle**: H-IIB rocket, a Japanese expendable launch system.
- **Dimensions**: Approximately 9.8 meters in length and 4.4 meters in diameter.
- **Mass**: Launch weight of 16,500 kg; wet weight of 10,500 kg.
- **Payload Capacity**: Maximum of 6,000 kg, with 5,200 kg for pressurized cargo and 1,500 kg for unpressurized cargo.
- **Manufacturer**: Prime contractor Mitsubishi Heavy Industries, with contributions from Mitsubishi Electric (avionics) and IHI Corporation (propulsion system).
- **Power Source**: Solar cell panels.
- **Notable Missions**: Included HTV-1 (maiden flight) and multiple Kounotori missions (e.g., Kounotori 2, Kounotori 9).

## FAQs
### Q: What was the H-II Transfer Vehicle used for?
A: The H-II Transfer Vehicle was used to resupply the International Space Station (ISS) with both pressurized and unpressurized cargo, including food, equipment, and experiments.

### Q: When did the H-II Transfer Vehicle operate?
A: It operated from 2009, with its maiden flight on September 10, 2009, until its retirement in 2020.

### Q: What replaced the H-II Transfer Vehicle?
A: The HTV was replaced by the HTV-X, the next-generation cargo spacecraft developed by JAXA.

### Q: How much cargo could the H-II Transfer Vehicle carry?
A: It had a maximum payload capacity of 6,000 kg, with 5,200 kg for pressurized cargo and 1,500 kg for unpressurized cargo.

### Q: Who manufactured the H-II Transfer Vehicle?
A: The prime contractor was Mitsubishi Heavy Industries, with Mitsubishi Electric handling avionics and IHI Corporation responsible for the propulsion system.

## Why It Matters
The H-II Transfer Vehicle was a critical component of international space station logistics, ensuring the continuous resupply of the ISS with essential cargo. As Japan's first automated cargo spacecraft, it demonstrated the country's advancing capabilities in space technology and its commitment to international space cooperation. The HTV's ability to carry both pressurized and unpressurized cargo made it a versatile tool for supporting long-duration human spaceflight. Its retirement in 2020 marked the end of an era but paved the way for the more advanced HTV-X, continuing Japan's contributions to space exploration.

## Notable For
- **First Japanese Automated Cargo Spacecraft**: The HTV was Japan's first spacecraft designed to autonomously resupply the ISS.
- **High Payload Capacity**: It could carry up to 6,000 kg of cargo, making it one of the most capable resupply vehicles of its time.
- **Versatile Cargo Delivery**: Unique ability to transport both pressurized and unpressurized cargo, including large external payloads.
- **International Collaboration**: Played a key role in supporting the ISS, a multinational effort involving space agencies from around the world.
- **Named After the Oriental White Stork**: The nickname "Kounotori" (meaning "white stork" in Japanese) symbolized the spacecraft's role in delivering vital supplies to the ISS.

## Body
### Overview
The H-II Transfer Vehicle (HTV), also known as Kounotori, was a robotic spacecraft developed by the Japan Aerospace Exploration Agency (JAXA) to resupply the International Space Station (ISS). It was part of the cargo spacecraft class, designed to transport essential supplies, equipment, and experiments to the ISS.

### Development and Manufacture
The HTV was manufactured by Mitsubishi Heavy Industries as the prime contractor, with Mitsubishi Electric responsible for the avionics and IHI Corporation handling the propulsion system. The spacecraft was named "Kounotori" after the Oriental White Stork, symbolizing its role in delivering cargo to the ISS.

### Technical Specifications
- **Dimensions**: The HTV was approximately 9.8 meters in length and 4.4 meters in diameter.
- **Mass**: It had a launch weight of 16,500 kg and a wet weight of 10,500 kg.
- **Payload Capacity**: The spacecraft could carry a maximum of 6,000 kg of cargo, with 5,200 kg allocated for pressurized cargo and 1,500 kg for unpressurized cargo.
- **Power Source**: The HTV was powered by solar cell panels.
- **Volume**: The pressurized cabin had a volume of 14 cubic meters.

### Operational History
The HTV's maiden flight, HTV-1, took place on September 10, 2009. Over its operational lifetime, the spacecraft completed multiple missions, including Kounotori 2 through Kounotori 9, all of which successfully resupplied the ISS. The HTV was launched using the H-IIB rocket, a Japanese expendable launch system specifically designed for this purpose.

### Retirement and Legacy
The HTV was retired in 2020, marking the end of its service. It was replaced by the HTV-X, the next-generation cargo spacecraft developed by JAXA. The HTV's legacy includes its significant contributions to the ISS and its role in advancing Japan's space technology capabilities.

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## References

1. [Source](http://www.jaxa.jp/press/2010/11/20101111_kounotori_e.html)
2. [Source](https://www.mhi.com/technology/review/sites/g/files/jwhtju2326/files/tr/pdf/e501/e501068.pdf)
3. [Source](https://humans-in-space.jaxa.jp/en/htv-x/specifications/)
4. Freebase Data Dumps. 2013
5. [Source](https://global.jaxa.jp/projects/rockets/htv/)
6. [Source](https://global.jaxa.jp/activity/pr/brochure/files/rocket03.pdf)
7. [Source](http://www.jaxa.jp/countdown/h2bf2/overview/htv_e.html)
8. [Source](https://iss.jaxa.jp/en/htv/overview/)
9. [Source](http://www.jaxa.jp/projects/rockets/htv/design_e.html)
10. [Source](https://www.orbital-velocity.com/htv)
11. BabelNet