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H-I rocket
Function Carrier rocket
Manufacturer McDonnell Douglas (design)
Mitsubishi Heavy Industries (production)
Country of origin  Japan (production)
 United States (design)
Height 42 metres (138 ft)
Diameter 2.44 metres (8.0 ft)
Mass 142,260 kilograms (313,630 lb)
Stages 2 or 3
Payload to LEO 3,200 kilograms (7,100 lb)
Payload to GTO 1,100 kilograms (2,400 lb)
Associated rockets
Family Thor
Comparable Delta 3000, PSLV
Launch history
Status Retired
Launch sites LA-N, Tanegashima
Total launches 9
Successes 9
First flight 12 August 1986
Last flight 11 February 1992
Boosters - Castor 2
No. boosters 6 or 9
Engines 1 TX-354-3
Thrust 258.9 kilonewtons (58,200 lbf)
Specific impulse 262 sec
Burn time 37 seconds
Fuel Solid
First stage - Thor-ELT
Engines 1 MB-3-3
Thrust 866.7 kilonewtons (194,800 lbf)
Specific impulse 290 sec
Burn time 270 seconds
Fuel RP-1/LOX
Second stage
Engines 1 LE-5
Thrust 102.9 kilonewtons (23,100 lbf)
Specific impulse 450 sec
Burn time 370 seconds
Fuel LH2/LOX
Third stage (optional)
Engines 1 UM-129A
Thrust 77.4 kilonewtons (17,400 lbf)
Specific impulse 291 sec
Burn time 68 seconds
Fuel Solid

The H–I or H–1 was a Japanese liquid-fuelled carrier rocket, consisting of a licence-produced American first stage and set of booster rockets, and all-Japanese upper stages. It was launched nine times between 1986 and 1992. It replaced the N-II, and was subsequently replaced by the H–2, which used the same upper stages with a Japanese first stage.

The first stage of the H–I was a licence-built version of the Thor-ELT, which was originally constructed for the US Delta 1000 rocket. The stage had already been produced under licence in Japan for the N-I and N-II rockets. The second stage was entirely Japanese, using an LE-5 engine. On launches to Geosynchronous transfer orbits, a Nissan–built UM-129A solid motor was used as a third stage. Depending on the mass of the payload, either six or nine US Castor 2 SRMs were used as booster rockets.

Launch history

Date/Time (GMT) S/N Payload Orbit Remarks
12 August 1986, 20:45 15(F) EGP (Ajisai) LEO 9 SRMs, 2 stages
27 August 1987, 09:20 17(F) ETS-5 (Kiku-5) GTO 9 SRMs, 3 stages
19 February 1988, 10:05 18(F) CS-3A (Sakura-3A) GTO 9 SRMs, 3 stages
16 September 1988, 09:59 19(F) CS-3B (Sakura-3B) GTO 9 SRMs, 3 stages
5 September 1989, 18:11 20(F) GMS-4 (Himawari-4) GTO 6 SRMs, 3 stages
7 February 1990, 01:33 21(F) MOS-1B (Momo-1B) LEO 9 SRMs, 2 stages
28 August 1990, 09:05 22(F) BS-3A (Yuri-3A) GTO 9 SRMs, 3 stages
25 August 1991, 08:40 23(F) BS-3B (Yuri-3B) GTO 9 SRMs, 3 stages
11 February 1992, 01:50 24(F) JERS-1 (FUYO-1) LEO 9 SRMs, 2 stages

When the H–1 was announced in 1986, company representative Tsuguo Tatakawe clarified that it would only be used to launch indigenous (i.e. Japanese) payloads, that only two launches per year could be mounted, and that the launch window consisted of a four-month period in which Japanese fishing fleets were not active (the falling launch boosters may damage fishing nets in the ocean waters).[1]

See also


  1. Japan's H–1 and H–2 rockets, Air & Space/Smithsonian, February/March 1987, p. 19
  • Wade, Mark. "Delta". Encyclopedia Astronautica. Retrieved 31 August 2008.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • McDowell, Jonathan. "Thor". Orbital and Suborbital Launch Database. Jonathan's Space Report. Retrieved 31 August 2008.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>
  • Krebs, Gunter. "H-1". Gunter's Space Page. Retrieved 31 August 2008.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>