Overview of the H-IIB Launch Vehicle

Opening the Door to Future Space Mission

Japan has been developing its own launch vehicles, based upon various researches and experiments. Among launch vehicles, the H-IIA launch vehicle has been supporting satellite launch missions as a major large-scale launch vehicle with high reliability.
It is the H-IIB launch vehicle that is an upgraded version of the current H-IIA launch capacity and will be expected to open the door to a new possibility for future missions, including cargo transport to the International Space Station (ISS) and to the Moon.
The H-IIB launch vehicle has two major purposes. One is to launch the H-II Transfer Vehicle (HTV) to the ISS. HTV will carry not only necessary daily commodities for the crew astronauts, but also experimental devices, samples, spare parts and other necessary research items for the ISS. The other is to respond to broader launch needs by making combined use of both H-IIA and H-IIB launch vehicles. In addition, H-IIB's larger launch capacity will make it possible to perform a simultaneous launch of more than one satellite, and will reduce the cost. This will contribute to ensuring vitalization of the Japanese space industry.

Special feature 1: Japan's First Cluster Engine

Clustering multiple engines allows us to increase the thrust. The H-IIB has two liquid rocket engines (LE-7A) in the first-stage, instead of one for the H-IIA. It has four SRB-As attached to the body, while the standard version of H-IIA had two SRB-As. In addition, the H-IIB's first-stage body has expanded to 5.2m in diameter from 4m of H-IIA's one. It has also extended the total length of the first stage by 1m from that of H-IIA. At the result of such enhancement, the H-IIB needs propellant 1.7 times more than the former.
Clustering several engines, whose performance is already fixed, has the advantage in shortening the period and reducing the cost for its development.

Special feature 2: Mounting Four Solid Rocket Boosters

The H-IIB Launch Vehicle is equipped with four Solid Rocket Boosters (SRB-As) whereas only two SRB-As are attached to the standard H-IIA. The H-IIA Launch Vehicle No 11 with four SRB-As (H2A204 type) was successfully launched in 2006, thus we utilized already verified technology in the H-IIB to improve its launch capability.

Special feature 3: Low Cost, Low Risk, Accelerated Development

At the time of launching HTV, the H-IIB will use a special fairing for HTV. However, in other parts, it will take over most of the specifications and structures of on-board equipments and ground systems already used for the H-IIA. These efforts are designed to reduce development risk and cost. Moreover, it will share the launch facility with the H-IIA and be launched from Yoshinobu Launch Pad of the Tanegashima Space Center.

H-IIB Launch Vehicle Specifications

Length 56.6m
Mass 531ton (without payload mass)
Guidance Method Inertial Guidance Method

H-IIB Launch Vehicle Launch Capacity

Geosynchronous Transfer Orbit (GTO) 36,000km 8ton
Orbit for HTV (Inclination:51.6 degrees) 350km-460km 16.5ton

Kew word: H-IIA Launch Vehicle

H-IIA, Japan's primary large-scale launch vehicle, is designed to meet diverse launch demands, at lower cost and with a high degree of reliability, by making the best use of the H-II launch-vehicle technology.
We can flexibly respond to diverse launch needs for various payload weights by attaching a different combination of Solid Strap-on Boosters (SSB) and Solid Rocket Boosters (SRB-A) to the standard type H-IIA Launch Vehicle (H2A202 type.)

Item H2A202 H2A2022 H2A2024 H2A204
Launch Capacity
about 3.8t About 4.2t About 4.7t About 5.8t