H-II

launch vehicle

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June 17, 2026

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The H-II was an all-Japanese launch vehicle developed by the National Space Development Agency. It was designed to use cryogenic propellants in both stages and featured an advanced first-stage rocket engine. First launched in 1994, the H-II proved to be very expensive due to its reliance on Japanese-manufactured components. This led to the development of the H-IIA, which incorporated foreign components and simplified manufacturing to reduce costs. The H-IIB is a variant of the H-IIA specifically designed to launch the H-II Transfer Vehicle (HTV), an uncrewed Japanese spacecraft that carries supplies to the International Space Station.12

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launch vehicle
Japan
…an all-Japanese launch vehicle, the H-II, using cryogenic propellants in both stages and a very advanced first-stage rocket engine. The H-II was first launched in 1994; it proved a very expensive vehicle because of its total dependence on Japanese-manufactured components. Thus, Japan decided in 1996 to develop an H-IIA vehicle…
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…an all-Japanese launch vehicle, the H-II, using cryogenic propellants in both stages and a very advanced first-stage rocket engine. The H-II was first launched in 1994; it proved a very expensive vehicle because of its total dependence on Japanese-manufactured components. Thus, Japan decided in 1996 to develop an H-IIA vehicle…
Read More