H3 (rocket)

The H3 Launch Vehicle is an expendable launch system in development in Japan. H3 launch vehicles are liquid-propellant rockets with strap-on solid rocket boosters and are planned to be launched from Tanegashima Space Center in Japan. Mitsubishi Heavy Industries (MHI) and JAXA are responsible for the design, manufacture, and operation of the H3. The H3 is the world's first rocket to use an expander bleed cycle for the first stage engine.

, the minimum configuration is to carry a payload of up to into Sun-synchronous orbit (SSO) for about 5 billion yen, and the maximum configuration is to carry more than into geostationary transfer orbit (GTO). The H3-24 variant will deliver more than of payload to lunar transfer orbit (TLI) and of payload to
geostationary transfer orbit (GTO)(∆Ｖ=1830 m/s).
, the first H3 is planned to be launched in 2023 or later.

Development

The development of the H3 was authorized by the Japanese government on 17 May 2013. The H3 Launch Vehicle is being jointly developed by JAXA and Mitsubishi Heavy Industries (MHI) to launch a wide variety of commercial satellites. The H3 was designed with cheaper engines compared to the H-IIA, so that manufacturing the new launch vehicle would be faster, less risky, and more cost-effective. JAXA and Mitsubishi Heavy Industries were in charge of preliminary design, the readiness of ground facilities, development of new technologies for the H3, and manufacturing. The main emphasis in design is cost reduction, with planned launch costs for customers in the range of US$50–65 million.

In 2015, the first H3 was planned to be launched in fiscal year 2020 in the H3-30 configuration (which lacks solid-rocket boosters), and in a later configuration with boosters in FY2021.

The newly developed LE-9 engine is the most important factor in achieving cost reduction, improved safety and increased thrust. The expander bleed cycle used in the LE-9 engine is a highly reliable combustion method that Japan has put into practical use for the LE-5A/ B engine. However, it is physically difficult for an expander bleed cycle engine to generate large thrust, so the development of the LE-9 engine with a thrust of is the most challenging and important development element.

Firing tests of the LE-9 first-stage engine began in April 2017.

In August 2018, the first tests of the solid rocket boosters were carried out.

On 21 January 2022, the launch of the first H3 was rescheduled to FY 2022 or later, citing technical problems regarding the first stage LE-9 engine.

Vehicle description

The H3 Launch Vehicle is a two-stage launch vehicle. The first stage uses liquid oxygen and liquid hydrogen as propellants and carries zero, two or four strap-on solid rocket boosters (SRBs) (derived from SRB-A) using polybutadiene fuel. The first stage is powered by two or three LE-9 engines which uses an expander bleed cycle design similar to the LE-5B engine. The fuel and oxidizer mass of the first stage is 225 metric tons. The second stage is powered by a single engine which is an improved LE-5B. The propellant mass of the second stage is 23 metric tons.

Variants

Each H3 booster configuration has a two-digit plus letter designation that indicates the features of that configuration. The first digit represents the number of LE-9 engines on the main stage, either "2" or "3". The second digit indicates the number of SRB-3 solid rocket boosters attached to the base of the rocket, and can be "0", "2" or "4". All layouts of the solid boosters are symmetrical. The letter at the end shows the length of the payload fairing, either short, or "S", or long, or "L". For example, an H3-24L has two engines, four solid rocket boosters, and a long fairing, whereas an H3-30S has three engines, no solid rocket boosters, and a short fairing. W-type fairing is similar to L-type except wider 5.4 m diameter.

, three configurations are planned: H3-30, H3-22, and H3-24.

A previously mentioned variant, the H3-32, was cancelled in late 2018 when the performance of the H3-22 variant, sporting one less engine on the core booster, was found to be greater than anticipated, putting it close to the H3-32's performance. While the H3-32 would have provided greater performance, JAXA cited SpaceX's experience with their Falcon 9 rocket, which routinely lifted commercial communications satellite payloads to less than the gold standard geostationary transfer orbit (GTO) of of delta-V remaining to get to geostationary orbit, leaving the satellites themselves to make up the difference. As commercial clients were apparently willing to be flexible, JAXA proposed redefining their reference transfer orbit to something lower, believing commercial clients would prefer the less expensive (if slightly less capable) H3-22 rocket, even if the client had to then load additional propellant onto their satellite for it to reach GEO, than a more expensive H3-32.

, MHI is considering contributing two variants for the Gateway project: an extended second stage variant, and the H3 Heavy variant which would comprise three first-stage liquid-fuel boosters strapped together, similar to Delta IV Heavy and Falcon Heavy. It would have a payload capacity of to low Earth orbit.

Launch services

H3 will have a "dual-launch capability, but MHI is focused more on dedicated launches" in order to prioritize schedule assurance for customers.

As of 2018, MHI is aiming to price the H3 launch service on par with SpaceX's Falcon 9.

Planned launches

Sources: Japanese Cabinet

Notes

* A Japanese Fiscal Year starts in April of the year and ends in March of the next year. For this case, it denotes launch will occur no earlier than 1 April 2022, and no later than 31 March 2023.

References

External links

JAXA H3 English page

JAXA H3 pamphlet

JAXA TODAY No.10

{{Expendable launch systems

H-III
Expendable space launch systems