H3 Launch Vehicle
H3 rocket model in Kakamigahara Aerospace Science Museum November 8, 2019 02.jpg
A model of the H3 Launch Vehicle
FunctionMedium-lift launch vehicle
ManufacturerMitsubishi Heavy Industries
Country of originJapan
Cost per launchUS$50 million (H3-303S) [1]
Height63 m (207 ft) [2]
Diameter5.27 m (17.3 ft) [2]
Mass574,000 kg (1,265,000 lb)
(Gross for H3-24L Variant) [3]
Payload to SSO
Mass4,000 kg (8,800 lb)
(H3-30S/L) [2]
Payload to GTO
(∆V=1500 m/s)
Mass4,000–7,900 kg (8,800–17,400 lb)
(H3-24S/L) [2][4]
Launch history
StatusCurrently being manufactured
Launch sitesTanegashima, LA-Y
First flightNET 2022 (planned) [5]
No. boosters0, 2 or 4
Powered bySRB-3
Maximum thrust2,158 kN (485,000 lbf) [3]
Specific impulse283.6 s (2.781 km/s)
Burn time105 seconds
First stage
Powered by2 or 3 LE-9
Maximum thrust2,942 or 4,413 kN (661,000 or 992,000 lbf) [3]
Specific impulse425 s (4.17 km/s)
PropellantLH2 / LOX
Second stage
Powered by1 LE-5B-3[3]
Maximum thrust137 kN (31,000 lbf)
Specific impulse448 s (4.39 km/s)
PropellantLH2 / LOX

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.[6]

As of July 2015, the minimum configuration is to carry a payload of up to 4,000 kg (8,800 lb) into Sun-synchronous orbit (SSO) for about 5 billion yen, and the maximum configuration is to carry more than 6,500 kg (14,300 lb) into geostationary transfer orbit (GTO).[2] The H3-24 variant will deliver more than 6,000 kg (13,000 lb) of payload to lunar transfer orbit (TLI) and 8,800 kg (19,400 lb) of payload to geostationary transfer orbit (GTO)(∆V=1830 m/s). As of January 2022, the first H3 is planned to be launched in 2022 or later.[5]


The development of the H3 was authorized by the Japanese government on 17 May 2013.[7] 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.[8][better source needed]

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.[2]

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 1,471 kN (331,000 lbf) is the most challenging and important development element.[9]

Firing tests of the LE-9 first-stage engine began in April 2017.[10]

In August 2018, the first tests of the solid rocket boosters were carried out.[11]

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.[5]

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.[12] 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.[3][13]


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.[14] W-type fairing is similar to L-type except wider 5.4 m diameter.[15]

As of November 2018, three configurations are planned: H3-30, H3-22, and H3-24.[14]

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 1,500 m/s (4,900 ft/s) 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.[14]

As of October 2019, 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.[16] It would have a payload capacity of 28,300 kg (62,400 lb) to low Earth orbit.[17]

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.[18]

As of 2018, MHI is aiming to price the H3 launch service on par with SpaceX's Falcon 9.[18]

Planned launches

See also: List of H-II series and H3 launches § Planned launches

Sources: Japanese Cabinet[19]

Date and time (UTC) Flight Type Launch site Payload(s) Outcome
TBD[5] TF1 H3-22S[20] LP2, Tanegashima Japan ALOS-3 Planned
2022 (TBD)[21] TF2 H3 LP2, Tanegashima Japan ALOS-4 Planned
2022 (TBD) F4 H3 Japan DSN-3 Planned
2022 (TBD) H3 United Kingdom Inmarsat[clarification needed] Planned[citation needed]
2023 (TBD) H3 Japan ETS-IX Planned
2023 (TBD) H3 Japan QZS-5 Planned
2023 (TBD) H3 Japan QZS-6 Planned
January 2024[22][better source needed] F3 H3-24W Japan HTV-X1 Planned
2024 (TBD) H3-24W Japan HTV-X2 Planned
2024 (TBD) H3 Japan QZS-7 Planned
2024 (TBD) H3-24L Japan MMX Planned
2025 (TBD) H3 JapanIndia Lunar Polar Exploration Mission Planned
2025 (TBD) H3 Japan IGS Planned
2025 (TBD) H3 Japan IGS-Optical 9 Planned
2026 (TBD) H3 Japan IGS Planned
2027 (TBD) H3 Japan JDRS-2 Planned
2027 (TBD) H3 Japan IGS Planned
2027 (TBD) H3 Japan ALOS-3 Successor Planned
2028 (TBD) H3 Japan IGS-Radar 9 Planned
2028 (TBD) H3 Japan IGS Planned
2028 (TBD) H3 Japan ALOS-4 Successor Planned
2028 (TBD) H3 Japan LiteBIRD Planned
2029 (TBD) H3 Japan Himawari Successor Planned
2029 (TBD) H3 Japan IGS-Optical 10 Planned
2029 (TBD) H3 Japan IGS-Radar 10 Planned



  1. ^ Clark, Stephen (19 September 2017). "Japan's MHI wins deal to launch satellite for Inmarsat". Spaceflight Now. Retrieved 20 September 2017.
  2. ^ a b c d e f 新型基幹ロケットの開発状況について (PDF) (in Japanese). 2 July 2015. Retrieved 8 July 2015.
  3. ^ a b c d e "H3 Launch Vehicle Brochure" (PDF).
  4. ^ Space News
  5. ^ a b c d "H3ロケットの試験機1号機の打上げについて" (in Japanese). JAXA. 21 January 2022. Retrieved 21 January 2022.
  6. ^ Shinya Matsuura (2 February 2021). H3ロケットの主エンジン「LE-9」熱効率向上で世界初に挑戦 (in Japanese). Nikkei Business. Archived from the original on 24 January 2022. Retrieved 23 January 2022.
  7. ^ "JAXA H3 booster". China Post. 19 May 2013. Archived from the original on 9 September 2013.
  8. ^ "H3 Development Update thread".
  9. ^ Shinya Torishima (24 September 2020). "H3ロケット開発を襲った"魔物"とは?、エンジンに見つかった技術的課題" (in Japanese). Mynavi news. Archived from the original on 1 October 2020.
  10. ^ LE-9 燃焼試験 (in Japanese). JAXA. Archived from the original on 1 March 2020. Retrieved 21 January 2020.
  11. ^ "Test-firing of booster for H3 rocket". NHK World. 27 August 2018. Retrieved 27 August 2018.
  12. ^ "Development of the LE-X Engine" (PDF). Mitsubishi Heavy Industries Technical Review. 48 (4). December 2011.
  13. ^ 2020年:H3ロケットの目指す姿 (PDF) (in Japanese). JAXA. 8 July 2015. Retrieved 8 July 2015.
  14. ^ a b c H3ロケットの開発状況について (PDF) (in Japanese). JAXA. 29 November 2018. Retrieved 29 November 2018.
  15. ^ 衛星フェアリングとは (in Japanese). JAXA. Retrieved 25 September 2022.
  16. ^ Space News
  17. ^ Henry, Caleb (25 October 2019). "Mitsubishi Heavy Industries mulls upgraded H3 rocket variants for lunar missions". SpaceNews. Retrieved 13 January 2020.
  18. ^ a b Henry, Caleb (12 July 2018). "Blue Origin to offer dual launch with New Glenn after fifth mission". SpaceNews. Retrieved 5 August 2018. H3 is on track for a 2020 debut with a price meant to be on par with SpaceX's Falcon 9.
  19. ^ "宇宙基本計画工程表 (令和2年度改訂)" (PDF) (in Japanese). Cabinet Office (Japan). 15 December 2020. Retrieved 29 April 2021.
  20. ^ H3ロケットの開発状況について (PDF). 宇宙開発利用部会 (in Japanese). 10 December 2019. Retrieved 10 December 2019.
  21. ^ "Change of Schedule for the H3 Launch Vehicle Project". JAXA. 11 September 2020. Retrieved 11 September 2020.
  22. ^ Eric Berger [@SciGuySpace] (26 October 2022). "The debut of Japan's new ISS cargo supply ship, HTV-X, has been delayed from January 2023 to January 2024. It will launch on Japan's H3 rocket, which also has yet to make its debut" (Tweet) – via Twitter.