H-IIB
| H-IIB No. F8 at the launch pad in September 2019 | |
| Function | Medium-lift launch vehicle | 
|---|---|
| Manufacturer | Mitsubishi Heavy Industries | 
| Country of origin | Japan | 
| Cost per launch | US$112.5 million | 
| Size | |
| Height | 56.6 m (186 ft) | 
| Diameter | 5.2 m (17 ft) | 
| Mass | 531,000 kg (1,171,000 lb) | 
| Stages | 2 | 
| Capacity | |
| Payload to LEO | |
| Mass | 19,000 kg (42,000 lb) | 
| Payload to ISS (carrying the HTV) | |
| Mass | 16,500 kg (36,400 lb) | 
| Payload to GTO | |
| Mass | 8,000 kg (18,000 lb) | 
| Associated rockets | |
| Family | H-II family | 
| Based on | H-II, H-IIA | 
| Derivative work | H3 | 
| Comparable | |
| Launch history | |
| Status | Retired | 
| Launch sites | Tanegashima, LA-Y2 | 
| Total launches | 9 | 
| Success(es) | 9 | 
| First flight | 10 September 2009 | 
| Last flight | 20 May 2020 | 
| Carries passengers or cargo | H-II Transfer Vehicle | 
| Boosters – SRB-A3 | |
| No. boosters | 4 | 
| Height | 15 m (49 ft) | 
| Diameter | 2.5 m (8 ft 2 in) | 
| Gross mass | 76,500 kg (168,700 lb) each | 
| Propellant mass | 66,000 kg (146,000 lb) each | 
| Maximum thrust | 2,305 kN (518,000 lbf) | 
| Total thrust | 9,220 kN (2,070,000 lbf) | 
| Specific impulse | 283.6 s (2.781 km/s) | 
| Burn time | 114 seconds | 
| Propellant | HTPB | 
| First stage | |
| Height | 38 m (125 ft) | 
| Diameter | 5.2 m (17 ft) | 
| Gross mass | 202,000 kg (445,000 lb) | 
| Propellant mass | 177,800 kg (392,000 lb) | 
| Powered by | 2 × LE-7A | 
| Maximum thrust | 2,196 kN (494,000 lbf) | 
| Specific impulse | 440 seconds (4.3 km/s) | 
| Burn time | 352 seconds | 
| Propellant | LH2 / LOX | 
| Second stage | |
| Height | 11 m (36 ft) | 
| Diameter | 4.0 m (13.1 ft) | 
| Gross mass | 20,000 kg (44,000 lb) | 
| Propellant mass | 16,600 kg (36,600 lb) | 
| Powered by | 1 × LE-5B | 
| Maximum thrust | 137 kN (31,000 lbf) | 
| Specific impulse | 448 s (4.39 km/s) | 
| Burn time | 499 seconds | 
| Propellant | LH2 / LOX | 
H-IIB (H2B) was an expendable space launch system jointly developed by the Japanese government's space agency JAXA and Mitsubishi Heavy Industries. It was used to launch the H-II Transfer Vehicle (HTV, or Kōnotori) cargo spacecraft for the International Space Station. The H-IIB was a liquid-fueled rocket, with solid-fuel strap-on boosters and was launched from the Tanegashima Space Center in southern Japan. H-IIB made its first flight in 2009, and had made a total of nine flights through 2020 with no failures.
H-IIB was able to carry a payload of up to 8,000 kg (18,000 lb) to Geostationary transfer orbit (GTO), compared with the payload of 4000–6000 kg for the H-IIA, a predecessor design. Its performance to low Earth orbit (LEO) was sufficient for the 16,500 kg (36,400 lb) H-II Transfer Vehicle (HTV). The first H-IIB was launched in September 2009 and the last H-IIB was launched in May 2020.