H3 (rocket)

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H3 Launch Vehicle
FunctionMedium-lift launch vehicle
ManufacturerMitsubishi Heavy Industries
Country of originJapan
Cost per launchUS$ 50 million (H3-303S)[1] (2017)
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 GTO
(∆V=1500 m/s)
4,000–6,500 kg (8,800–14,300 lb)[2]
Launch history
StatusIn development
Launch sitesLA-Y, Tanegashima
First flightFY2020 (planned)[2]
No. boosters0, 2 or 4
Thrust2,158 kN (485,000 lbf)[3]
Specific impulse283.6 seconds (2.781 km/s)
Burn time105 s
First stage
Engines2 or 3 LE-9
Thrust1,472 kN (331,000 lbf)[3]
Specific impulse425 seconds (4.17 km/s)
FuelLOX / LH2
Second stage
Engines1 LE-5B-3[3]
Thrust137 kN (31,000 lbf)[3]
Specific impulse448 seconds (4.39 km/s)
FuelLOX / LH2

The H3 Launch Vehicle is an expendable launch system in development in Japan. H3 rockets are liquid-propellant rockets with strap-on solid rocket boosters and are planned to be launched from the Tanegashima Space Center in Japan. Mitsubishi and the JAXA have been responsible for the design, manufacture, and operation of the H3.

As of July 2015, it was planned that the minimum configuration is to carry a payload of up to 4 tonnes into sun-synchronous orbit for about 5 billion yen, and the maximum configuration is to carry more than 6.5 tonnes into geostationary transfer orbit.[2][need quotation to verify]H3-24 can carry more than 6 tonnes payload into lunar transfer orbit.

The first H3 without solid-rocket boosters is planned to launch in fiscal year 2020,[Note 1] and with boosters in FY2021.[2][4]


The development of H3 was authorized by Japanese government 17 May 2013.[5][full citation needed] The H3 Launch Vehicle is being developed jointly by JAXA and Mitsubishi Heavy Industries (MHI) to launch a wide variety of commercial satellites. H3 was designed with cheaper engines compared to H-IIA, so that manufacturing the new launch vehicle would be more cost-effective, with less risk, in a shorter period of time. JAXA was in charge of preliminary design, readiness of the ground facility, and development of new technologies for the H3, while Mitsubishi Heavy Industries is responsible for manufacturing.[clarification needed] The main emphasis in design is cost reduction, with planned launch costs for customers are in range of US$50–65 million.[6][better source needed]

In August 2018, the first tests of the solid rocket boosters were made.[7]

Vehicle description[edit]

The H3 Launch Vehicle is a two-stage rocket. The first stage uses liquid oxygen and liquid hydrogen as propellants and carries zero, two or four strap-on solid rocket boosters (derived from SRB-A3) powered by polybutadiene. The first stage is powered by two or three LE-9 engines which uses expander bleed cycle similar to LE-5B.[8] The fuel & oxidizer mass of first stage is 225 ton. The second stage is powered by a single engine which is an improved LE-5B. The propellant mass of second stage is 23 ton.[3][9]


Each H3 booster configuration has a two-digit and a 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 solid boosters are symmetrical. The letter in the end shows the length of the payload fairing, either short "S" or long "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.[10]

As of November 2018, three configurations are planned: H3-30, H3-22, and H3-24.[10]

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 geosynchronous transfer orbit of 1500 m/s of Delta-V remaining to get to GEO, 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.[10]

Launch services[edit]

H3 will have a "dual-launch capability, but MHI is focused more on dedicated launches" in order to prioritize schedule assurance for customers.[11]

As of 2018, MHI is aiming to price the H3 launch service on par with SpaceX's Falcon 9.[11]

Planned launches[edit]

Sources: Japanese Cabinet[12]

Date and time (UTC) Flight Type Launch site Payload(s) Outcome
2020 (TBD) TF1 H3-30S LP2, Tanegashima Japan ALOS-4 Planned
2021 (TBD) TF2 H3-2? LP2, Tanegashima Japan ETS-IX Planned
2021 (TBD) H3-24L Japan HTV-X1 Planned
2022 (TBD) H3 Japan GOSAT-3 Planned
2022 (TBD) H3 Japan DSN-3 Planned
2022 (TBD) H3 United Kingdom Inmarsat Planned
2023 (TBD) H3 Japan QZS-5 Planned
2023 (TBD) H3 Japan QZS-6 Planned
2023 (TBD) H3 Japan QZS-7 Planned
2024 (TBD) H3-24L Japan MMX Planned
2024 (TBD) H3 Japan IGS Planned
2025 (TBD) H3 Japan LiteBIRD Planned
(TBD) H3 Japan IGS-Optical 9 Planned


  1. ^ 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 2020, and no later than 31 March 2021


  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 f "H3 Launch Vehicle Brochure" (PDF).
  4. ^ http://www.japantimes.co.jp/news/2013/12/25/national/science-health/jaxa-plans-to-test-new-large-rocket-from-2020/#.U3KqNIGSzcw
  5. ^ https://www.chinapost.com.tw/asia/japan/2013/05/19/378945/Japan-may.htm
  6. ^ http://forum.nasaspaceflight.com/index.php?topic=21491.15
  7. ^ "Test-firing of booster for H3 rocket". NHK World. 27 August 2018. Retrieved 27 August 2018.
  8. ^ "Development of the LE-X Engine" (PDF). Mitsubishi Heavy Industries Technical Review. December 2011.
  9. ^ 2020年:H3ロケットの目指す姿 (PDF) (in Japanese). JAXA. 8 July 2015. Retrieved 8 July 2015.
  10. ^ 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.
  11. ^ 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.
  12. ^ "宇宙基本計画工程表 (平成29年度改訂)" (PDF) (in Japanese). Cabinet Office. 12 December 2017. Retrieved 29 December 2017.

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