The US missile defence shield aims to prevent devastating loss of life following a missile attack from a rogue nation.
Yet in a new study, physicists from the American Physical Society revealed that if Son of Star Wars is built, Canada, Russia and swathes of Europe would be placed at serious risk of catastrophe by chemical, biological or nuclear weapons from partially destroyed intercontinental ballistic missiles (ICBMs).
The concept of shortfall damage has been the subject of previous speculation, but the APS report has confirmed the threat is real.The US missile defence strategy involves hitting a bullet with a bullet. Interceptor missiles will attack incoming missiles at three stages of flight: soon after launch, when they are in orbit, or as they approach their target. Missiles are most vulnerable to intercept in their boost phase, defined as the first three minutes of flight, as at this point they are less able to deploy countermeasures to confuse those targeting them.
The Bush administration is very enthusiastic about the programme. In a National Security Policy Directive in late 2002, the president instructed the Missile Defence Agency (MDA) to begin deployment of missile defence capabilities this year. He plans to spend $10bn on the programme in 2005, though the scheme has met with scepticism from Democrats and Republicans alike. Bush’s presidential rival John Kerry indicated he would spend less.
The technology used for the boost phase will be the $22bn Northrop Grumman-led kinetic energy interceptor (KEI), capable of flying at over 5km per second. The system is based on existing technologies, using rocket motors borrowed from the SM-3 missile’s design coupled with other established rocket motor designs. The MDA expects delivery of this in 2013-2015.
But the APS report concludes that it would be difficult to destroy a missile’s warhead or submunitions as well as its booster. As the two are loosely coupled, it would be more likely that the warhead would detach and survive. This warhead – which is hardened to survive re-entry – would then continue on a trajectory that would most likely reach heavily populated areas.
All trajectories to the US from North Korea pass over Canada and Russia, while those from Iran pass over Europe. Only two to three minutes would be available to achieve a boost phase intercept, even assuming the development of substantial improvements in systems for detecting and tracking missiles. In order to avoid munitions shortfall on other countries, the US would either have to ensure that it destroyed both the warhead and missile or intercept it within a specific window of 10-20sec to ensure any shortfall fell in the sea. This would be extremely difficult.
‘Technically you can hit an ICBM with a missile. The challenge is getting close enough and being able to make the decision in time,’ said APS study staff director David Mosher of the RAND Corporation.
‘ICBMs have a burn time of three to four minutes during which you have to detect and track, launch the interceptor, have this fly 500-1,000km, then destroy the missile before its warhead is deployed.
‘Space-based sensors identify bright things, so you must discount false alarms by taking time to see if it remains bright and if it moves. You can’t have interceptors flying about everywhere, and it might tick off our neighbours a bit when they land there.’
Destroying the rocket and its payload would be complicated by the fact that the speed and trajectory of a missile in its boost phase is not uniform.
‘The missile is unpredictable in its movements, so you must be able to divert the interceptor,’ said missile defence critic and professor of science, technology and national security policy at MIT, Theodore Postol. ‘The weight of the kill vehicle goes up if it needs to carry more propellant and have thrusters. You therefore need systems that are much bigger than the type of rocket they have been speaking about.’
Naturally, the MDA defended the scheme. ‘The kinetic interceptor is in the very early R&D stage,’ a spokesman said. ‘If we don’t get the missile at this stage then we have the mid-course defence and also the terminal defence stage of the Patriot missile. The multiple operations will be integrated. In our view it’s a very promising technology.’
MDA director Lieutenant General Henry Obering has said that he would like US allies to participate in the missile defence program as it would allow them to benefit from the coverage provided. But in reality, it seems that Europe would have to host a mid-phase interceptor for its own safety.
While interceptor sites have been prepared at Fort Greely in Alaska and the Vandenburg airbase in California, a third base is planned for Europe, possibly within Britain or eastern Europe.
But the mid-phase system has also been criticised. To be effective, it must take guidance from satellites and radar and use sensors to pick out the warhead from possible decoys. However, the kill vehicle and its booster have never been test launched together.
Target identification and command and control software has apparently not been flight tested either, meaning its reliability is questionable.
Even if the shield is completed, it could be destined to stand idle. There are doubts that nations such as North Korea or Iran could ever be capable of building a complex ICBM. The CIA also insists that terrorist, not missile attacks are the biggest threat to the US.
If a rogue nation were to try to launch a remote attack, it could easily go round the shield by using a cruise missile. ‘These can be made from a modified aircraft with a remote pilot system.’ said Postol.
For years the threat of a nuclear counter-attack prevented ICBM strikes from the Soviet bloc. Following the examples set by the crushing of the Taliban and Saddam Hussein, some argue that deterrence will prove more reliable and less expensive than destroying ICBMs. For those of us living under the flight path, let’s hope so.
<b>The report is available <link>here=http://www.aps.org/media/pressreleases/101504.cfm</link></b>.