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Missile Program

Japan has an active commercial space launch program using several types of solid- fuel rockets, which could provide the basis for a long-range ballistic missile program. Under the conditions set by the Allied Powers following World War II, Japan was forbidden to develop rockets until 1955.(1) The solid-propellant M-4S, capable of placing a 180 kg payload in a 250 km orbit, was started in 1963 and four vehicles were launched in the period between 1970 and 1972. The M-4S is no longer in production or in service. The M-3C (195 kg in 250 km orbit) and the M-3H (290 kg in 250 km orbit) were the next generation of rockets first launched in 1974. They also are no longer in production or service, having been superseded by the M-3S-II (780 kg in 250 km orbit), first launched in 1985. The initial M-3S-II launches injected Japan's first interplanetary probes, Sakigake and Suisei, toward Halley's Comet.(2) The M-3S-II is also considered to be capable of a surface-to-surface range of 4,000 km with a 500 kg payload(3)

Development of the new M-V rocket was begun in 1989 and first launched in 1995. The M-V is more than twice the weight of the M-3S-II (130,000 kg vs. 61,700 kg). It will is able to place a 1,800 kg into low earth orbit or inject a 300-400-kg payload into space for planetary surveys.(4) Apparently, the M-V would be capable of intercontinental range as a ballistic missile.

1 - A comparison of Japanese solid rocket motor launch vehicles and American intercontinental ballistic missiles (ICBMs) is interesting. Although precise calculations would be even more interesting, these rough numbers indicate rather clearly Japanese competence in this field.

State	System		Length Diameter Mass  Payload

Japan	J-1		33 m	1.8 m	 89 t	0.8 t
	M-V		31 m	2.5 m	130 t	2.0 t

USA	Minuteman III  	18 m	1.8 m	 35 t	1.2 t
	MX Peacekeeper 	22 m	2.3 m	 85 t	4.2 t


If converted to ballistic missile applications, the M-V would seem likely to give Japan an ICBM roughly equivalent to the MX Peacekeeper, and the J-1 would probably give Japan an ICBM surpassing the performance of a Minuteman III.

2 - The H-2 launch vehicle core stage propellants are cryogenic liquid hydrogen and oxygen. As such, it is ENTIRELY unsuited for conversion to ballistic missile applications. Although it is comparable in performance to the American Titan 34D launch vehicle, the Titan 3 family has never been used as an ICBM, and was only very briefly considered for such an application in the early 1960s, when though was given to using it to carry very high yield (~100 MT) nuclear warheads.

The Japanese launch vehicles have a lower payload fraction than the American ICBMs for at least three reasons:

Firing these vehicles on long-range (~12,500 km) ICBM trajectories would increase their throw-weight by roughly a fifth right off the bat. Assuming that a Japanese ICBM would have a "Moscow Criteria" range, the distance from Hokkaido to Moscow is only 7,000. Even adding a "Washington Criteria" only gets the requirement up to about 10,000 km. The nominal range of the Minuteman III is 13,000 km and that of the Peacekeeper some 12,000 km. Firing the Japanese vehicles to a 7,000 km range would roughly double the throw-weight relative to their space launch payload (these estimates are just gut hunches, since each rocket performs differently on depending on how the propellant is allocated between stages).

The J-1's first stage is overly large relative to the rest of the stack, which results in poor performance relative to gross liftoff mass. An operational Japanese ICBM, as opposed to an emergency lash up, would use a more optimal configuration, yielding better performance.

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