WORRIED by a possible military threat from North Korea, Japan鈥檚 Defence
Agency plans to step up research on a system to shoot down ballistic
missiles.
It will borrow heavily from research conducted for the US Department of
Defense, which is developing a similar programme called the Theater High
Altitude Area Defense System (THAAD). Japanese government officials hope to sign
a formal collaboration agreement with the Pentagon before the end of the
year.
Missile launches will be tracked by satellite, then intercepted by missiles
fired from warships stationed in the Sea of Japan. This will mean hitting a
small target, travelling at around 3 kilometres per second, within 10
minutes鈥攖he time it would take a Rodong 1 missile to fly from North Korea
to Japan. The Rodong 1 is an updated, long-range version of the Russian Scud,
used by Iraq during the Gulf War.
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Many analysts doubt that the plan is feasible鈥攅specially given that the
five tests of THAAD conducted so far have all been unsuccessful. They also point
to the low success of the US Patriot missile system against Iraq鈥檚 Scuds: a 1992
report from the US General Accounting Office said the confirmed hit rate was
only 9 per cent.
鈥淚t鈥檚 not easy,鈥� says Susumu Takai, an expert on space-based weapons systems
at the National Institute of Defence Studies in Tokyo. 鈥淭he Rodong 1 will be
flying at 3 kilometres a second. Under a US-Russian treaty, antiballistic
missiles aren鈥檛 allowed to go much faster than that.鈥�
The agency will not disclose details of the proposed technology, although it
claims computer simulations have shown it could work in principle. 鈥淭o make it
more accurate we need to improve the technology,鈥� says agency spokesman Takuhiko
Fukui. 鈥淚 don鈥檛 say yes, we can do this and I don鈥檛 say no, we can鈥檛.鈥�
The agency is asking for just 拢5 million in the coming financial year
to strengthen its research effort. But to develop and deploy the system would
cost billions. Elements of the system may be under development already, however.
Last week, Japan announced plans to launch four reconnaissance satellites: two
with optical cameras, and two fitted with radar, that could serve as the
system鈥檚 鈥渆yes鈥�.
Because these satellites will be below geostationary orbit, they will not be
able to monitor North Korea鈥檚 missile launch sites continuously. To do that,
Japan would need data from American geostationary satellites fitted with
infrared sensors, which can analyse the shape of the hot exhaust plume from a
ballistic missile launch.
鈥淎n infrared-sensor satellite would immediately alert ground and sea-based
radar,鈥� Takai suggests. The same satellite could track a missile as long as its
engine was burning. When it went into free fall, however, it would have to be
tracked by radar and satellites in lower orbits. Computers would have just one
or two minutes to work out the trajectory of the incoming missiles.