H-II

H-II rocket at Tsukuba science museum & planetarium
Function	Medium-lift launch vehicle
Manufacturer	Mitsubishi Heavy Industries Nissan Motors (sub) Alliant Techsystems (sub, for the SRBs)
Country of origin	Japan
Size
Height	49 m (161 ft)
Diameter	4 m (13 ft)
Mass	260,000 kg (570,000 lb)
Stages	2
Capacity
Payload toLEO
Mass	10,060 kg (22,180 lb)
Payload toGTO
Mass	3,930 kg (8,660 lb)
Associated rockets
Family	H-II family
Based on	H-I
Derivative work	H-IIA
Comparable	Ariane 4,LVM3
Launch history
Status	Retired
Launch sites	Tanegashima,LA-Y1
Total launches	7
Success(es)	5
Failure	1
Partial failure	1
First flight	3 February 1994
Last flight	15 November 1999
Boosters
No. boosters	2
Maximum thrust	1,540 kN (350,000 lbf)
Specific impulse	273 s (2.68 km/s)
Burn time	94 seconds
First stage
Powered by	1 ×LE-7
Maximum thrust	1,078 kN (242,000 lbf)
Specific impulse	446 s (4.37 km/s)
Burn time	346 seconds
Propellant	LH2 /LOX
Second stage
Powered by	1 ×LE-5A
Maximum thrust	121.5 kN (27,300 lbf)
Specific impulse	452 s (4.43 km/s)
Burn time	600 seconds
Propellant	LH2 /LOX
[edit on Wikidata]

TheH-II (H2) rocket was a Japanesesatellite launch system, which flew seven times between 1994 and 1999, with five successes. It was developed byNASDA in order to give Japan a capability to launch largersatellites in the 1990s.^[1] It was the first two-stageliquid-fuelled rocket Japan made using only technologies developed domestically.^[2] It was superseded by theH-IIA rocket following reliability and cost issues.

Prior to H-II, NASDA had to use components licensed by the United States in its rockets. In particular, crucial technologies ofH-I and its predecessors were from theDelta rockets (the manufacturer of the Delta rockets,McDonnell Douglas, laterBoeing and theUnited Launch Alliance, would later use the H-IIA's technologies (the rocket itself is the successor to the H-II) to create theDelta III, albeit short lived). Although the H-I did have some domestically produced components, such asLE-5 engine on the second stage andinertial guidance system, the most crucial part, the first stage engine, was a licence-built version of the Thor-ELT of the US. By developing theLE-7liquid-fuel engine and thesolid booster rockets for the first stage, all stages of H-II had become "domestically developed".

The H-II was developed under the following policies, according to a NASDA press release:^[1]

1. Develop the launch vehicle with Japanese space technology.
2. Reduce both development period and costs by utilizing developed technologies as much as possible.
3. Develop a vehicle which can be launched from the existingTanegashima Space Center.
4. Use design criteria which allows sufficient performance for both the main systems and subsystems. Ensure that development will be carried out properly, and safety is taken into account.

The H-II was new, incorporating larger LH₂/LOX tanks, and a new upper stage, consisting of a cylindrical LH₂ tank with a capsule-shaped LOX tank. The LH₂ tank cylinder carried payload launch loads, while the LOX tank and engine were suspended below within the rocket's inter-stage. The second stage was powered by a singleLE-5A engine.^[3]

Development of the LE-7 engine which started in 1984 was not without hardships, and a worker died in an accidental explosion. The first engine was completed in 1994, two years behind the original schedule. TheRocket Systems Corporation (RSC), a consortium of 74 companies includingMitsubishi Heavy Industries,Nissan Motors, andNEC, was established in 1990 to manage launch operations after the rockets' completion. In 1992, it had 33 employees.^[4]

In 1994, NASDA succeeded in launching the first H-II rocket, and succeeded in five launches by 1997. However, each launch cost 19 billion yen (US$190 million), too expensive compared to international competitors likeAriane. (This is in part due to thePlaza Accord's changes to the exchange rate, which was 240 yen to a dollar when the project planning started in 1982, but had changed to 100 yen a dollar by 1994.) Development of the next-generationH-IIA rockets started in order to minimize launch costs.

In 1996, RSC signed a contract with theHughes Space and Communications Group to launch 10 satellites. The successive failure of flight 5 in 1998 and flight 8 in the following year brought an end to the H-II series and the contract with Hughes.^[5] To investigate the cause of the failure and to direct resources into the H-IIA, NASDA cancelled flight 7 (which was to be launched after F8 due to changes in schedule), and terminated the H-II series.^[2]

• 
  The Ground Test Vehicle of H-II, now installed atTsukuba Space Center.
• 
  The first and second stages of the canceled Flight 7, at a hangar inTanegashima Space Center.

• H-II Orbiting Plane (HOPE)
• H-II Transfer Vehicle (HTV)
• H-II (rocket family)
  • H-IIA
  • H-IIB
• Comparison of orbital launchers families
• Comparison of orbital launch systems

Wikimedia Commons has media related toH-II launch vehicles.

• H-II Launch VehicleArchived 2013-10-30 at theWayback Machine, JAXA.

• Mitsubishi Heavy Industries space launch vehicles
• Vehicles introduced in 1994
• Expendable space launch systems

• Articles with short description
• Short description is different from Wikidata
• Commons category link is on Wikidata
• Webarchive template wayback links