Analysis The US intends a further test of its ballistic-missile defence system, as haggling over budgets and where ground stations will be based continues.
According to reports, the Pentagon's Missile Defence Agency (MDA) planned its latest test for Thursday, but bad weather near the Alaskan launch site of the target rocket has caused delays. The trial is expected to proceed today or over the weekend.
When it does, a Ground-based Mid-course Interceptor fired from Vandenberg airforce base in California will attempt to knock out a target in outer space, 100 to 200 miles above the Pacific. The target will take off from the Kodiak Island launch complex, and will duplicate the flight profile of an intercontinental ballistic missile (ICBM) warhead.
The Ground-based Interceptor is a triple-stage rocket tipped with a 150-lb "Exo-Atmospheric Kill Vehicle" which uses information from surface radars and its own sensors to intercept and destroy ballistic warheads during the "mid-course" phase of their flight, as they travel toward their target outside the Earth's atmosphere.
Using an interceptor kill vehicle travelling at 7,000mph to hit a reentry vehicle going more than twice as fast, in vacuum, is an extremely difficult feat. However, it seems that it may be within the grasp of Pentagon technology. A Ground-based Interceptor from Vandenberg successfully hit a target fired from Alaska in such a test last September, according to the MDA, indicating that the concept is potentially workable.
The MDA says the objective of the test is not just to repeat September's successful result, but also to upgrade the system.
"The overall objective of the test, like all of them, is to measure system performance so that we can make it better," according to the MDA's Rick Lehner.
Some commentators have speculated, however, that the test may be timed to coincide with ongoing funding wrangles in Washington. The Bush administration is tangling with Democrats who have provisionally lopped $160m off a $301m Pentagon request to begin preparations for deployment of Ground-based Interceptors in Poland and an accompanying radar in the Czech Republic.
The Democrats contend that the Ground-based Interceptor isn't proven kit, and the test last September wasn't conducted under realistic conditions. They say the funds could be restored, however, once ongoing negotiations over the interceptors' European deployment are successfully completed. The President's opponents also want to divert funding away from the technologically ambitious Mid-Course space interceptors to other missile-defence kit which they believe offers better value for money. A successful test now would weaken this position.
There are certainly plenty of other missile-defence programmes running, hungry for federal cash. This is intentional; the Pentagon argues that only a layered defence can hope to succeed.
The first gauntlet which enemy ICBMs will have to run in the all-singing MDA future would be "Boost Phase Defense," in which hostile rockets would be destroyed as they accelerated up through the atmosphere. Two systems are under development here; the Airborne Laser and the Kinetic Energy Interceptor, still firming up.
Of the two, the Airborne Laser is the more advanced. In it, a megawatt-class Chemical Oxygen Iodine Laser (COIL) is being mounted in a jumbo jet equipped with infrared sensors which can spot the fiery exhaust plume of a missile as it launches. The idea is that the high-energy COIL beam will be held on a vulnerable, pressurised liquid-fuel stage of the boosting missile, which should cause it to come apart in short order.
Ground tests of the COIL energy cannon have been successful, according to the MDA. The weapon is now being mounted in a Boeing 747, and a flight test against a missile is planned for 2008.
The Airborne Laser is the only part of the modern Ballistic Missile Defence effort which seems really gee-whiz. Even this is quite restrained compared to the technologies which were expected back in the 1980s when President Reagan launched his Strategic Defence Initiative (SDI), promptly dubbed "Star Wars."
Under Star Wars, it was thought, the US might develop all kinds of astounding tech to get round the huge difficulties of kinetic interceptions at orbital speeds. Electromagnetic railguns, particle beams, and X-ray lasers were anticipated, perhaps powered by nuclear explosions. America was expected to take the battle against the Soviets into space, basing many of its weapons in orbit. In the event, SDI became horrendously expensive without producing much result and was deep-sixed after the Red Army's retreat from Europe.